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Articles from 2006 In April


Russia's Chicken Suspension Could Hurt

To paraphrase Oliver Hardy: "Well, this is certainly a fine mess you've gotten us into, Alexei!" Alexei here is Alexei Gordyev, Russia's Minister of Agriculture, who announced on Thursday that Russia would suspend all chicken imports while it installs a new permitting system to cure a laundry list of import ills. That list includes shipments that were offloaded without permission, incomplete or false documents, fake products (what would someone use to make "fake" chicken?), and failure to observe storage regulations.

Most news reports state Gordeyev's position that the changes will only take a couple of weeks and imply that everything will be just fine then. A more interesting commentary is offered by Kommersant, a Russian daily online news service (http://www.kommersant.com/page.asp?id=670447), which claims that this move is driven far more by protests from Russia's poultry producers and poultry importers. Two of Kommersant's sources do not believe the disruption will be that short-lived. In addition, it appears that an inspection fee of $110 to $115/ton will be included in the new import permit system, thus driving up the price of imported chicken.

It does seem pretty fishy that this move comes just a few weeks after Russian producers and importers demanded that the government cut imports by 30% to bolster prices, which had dipped because of consumer concerns over bird flu. I know I am a biased economist, but the term "follow the money," certainly seems to fit here.

Regardless of the reason, we must now consider the consequences.

First, if this only lasts a couple of weeks, it may not be too bad. The "if" and "may" hedges in that statement are absolutely intentional and, I think, necessary. We simply do not know how this will unfold.

Second, the chicken situation going into this event is worse than it was in 2002, when Russia imposed a ban on chicken imports for alleged sanitary concerns, but probably more as retaliation to U.S. tariffs on steel. We currently have just over 867 million pounds of chicken in freezers whereas in March 2002 we had 808 million. That's not a huge difference, but it is in the bad direction, for sure. Chicken prices, though, are significantly lower now. NE boneless/skinless chicken breasts are in the area of 98 cents/lb. (vs. $1.31 in early-March 2002) while leg quarters are 18 cents (less if you want to buy a large quantity) versus 22 cents in March 2002.

Third, we have plenty of other meat. Beef production is over 5% larger than last year, while U.S. pork production is up nearly 1.3% and chicken is still 4.7% larger than in 2005. Interestingly, those numbers in 2002 were +4.5%, +2.8% and +4.5%, respectively, in early-March 2002. So we had plenty of meat available then, too.

The concern of course is that any slowdown in chicken exports will cause pork and hog prices to fall as they did in 2002. Figure 1 shows that the magnitude of the reduction on hog prices was considerably greater than the magnitude of the reduction in 12-city broiler prices. The second stoppage of shipments to Russia in August 2002 drove hog prices to cycle lows and caused some huge troubles with basis levels in September 2002.

Chicago Mercantile Exchange (CME) Lean Hogs futures did not react very negatively to the news on Thursday, with contracts losing 20 to 35 cents. Any indication of a lengthy delay in resuming chicken exports will be very negative for futures prices.

Canada's Sow Herd Slippage Continues
Statistics Canada released its April Hog Statistics report on Wednesday, and the numbers show a continuing slow decline in Canada's breeding herd from both last year and last quarter. The Canadian herd now numbers 1.641 million breeding animals, 0.4% fewer than on April 1, 2005. Ontario and Quebec accounted for the entire reduction in Canadian numbers.

The shocking numbers in this report, though, are the market hog numbers and especially those for pigs weighing less than 20 kg. (45 lb.) Those numbers are 5.7% smaller than last year, with inventories in Ontario coming in nearly 9% smaller. We expected lower numbers in the east due to well-publicized problems with PMWS (since renamed porcine circovirus-associated disease or PCVAD). What we didn't expect were 8.8% fewer lightweight pigs in Manitoba!

A good portion of this decrease, though, is attributable to elevated pig exports to the United States -- most likely due to duties on imported corn. Canadian exports of lightweight pigs to the United States during February and March (roughly the time period in which pigs weighing 20 kg on April 1 would have been born) exceeded last year by 174,623 head. Had those pigs stayed home, Canadian light pig inventories would have been down only 1.9%. These trade spats matter.

I look for these pig exports to slow now that the duties have been ended, but I also expect the Canadian sow herd to continue to shrink slowly. Canada will remain a major supplier of weaned and feeder pigs to the United States, but that just isn't as attractive with an US$0.87 Canadian dollar as it was with a US$0.63 Canadian dollar back in early 2002.




Click to view graphs.

Steve R. Meyer, Ph.D.
Paragon Economics, Inc.
e-mail: steve@paragoneconomics.com

Canadian Corn Duty Waived

I'm a big fan of the TV show, Law & Order. In fact, I have watched so many episodes so many times (thanks to the miracle of satellite TV) that I can spot the soon-to-be-tainted evidence very quickly. You know the evidence I mean -- the DNA-carrying cigarette butt that is resting at a spot beneath the dead center of a king-sized bed or the bloody glove retrieved from a hermetically sealed bathroom medicine chest that could be found only with an x-ray machine.

The second that the TV cop shows it to his partner with an "I gotcha" grin, I know that those poor, put-upon district attorneys are going to have to make a case without that piece of evidence. Do these TV cops never watch TV? If they did, they would know better and we would not know nearly as much about legal technicalities and not have nearly as many anger fits at the judges who gleefully use them so much.

The point (and I bet you were wondering if I would ever get to it) is that technicalities come into play in legal proceedings. While perhaps not exactly using a technicality, Canada's International Trade Tribunal found this week that imports of U.S. corn had not injured the Canadian corn industry and thus ordered a halt to the $1.65/bu. (CAN$) duty. All duties collected since December will be refunded.

Interestingly, this is the same reason that the U.S. International Trade Commission last year struck down antidumping duties that the United States had imposed on imported Canadian feeder pigs and market hogs. Neither agency decided that subsidies had not been paid nor that product was not being dumped. They both simply concluded that regardless of what was going on, the action had not injured the respective domestic industries.

It appears that the Tribunal may have done us all a favor.

This is a huge win for the Canadian livestock sector. At a recent meeting in the United States, ag economist Ron Plain at the University of Missouri pointed out that Canada has five times as many cows and twice as many sows as it needs to feed itself. A supply of low-cost grain is rather important to a country in that position. Had the duty been allowed to continue, I feel confident that both sectors would have been much smaller five years from now, with cattle and hog feeding taking the biggest hit and the two packing industries being decimated.

In addition, this is a big win for U.S. livestock producers. The higher cost of feed in Canada was already having an effect on animal flows and that effect was going to grow. Imports of feeder pigs from Canada are up 16% this year. Those shipments were 6% smaller last year when there was no duty in spite of the fact that the Canadian-U.S. exchange rate was more supportive to exports.

Comparisons for feeder cattle imports to a year ago cannot be made due to the import embargo that was in place in 2004 and 2005. Year-to-date feeder cattle imports are over 60% larger than those of 2003, the last year in which imports were made during the January-April time frame. That may not be a good comparison, but it is the best we can do.

Imports of Canadian market hogs are less that 2% larger than last year, but have moved from as much as 6% below year-ago levels in February to above year-ago levels in recent weeks. I expected this number to jump in May when hogs could be shipped to the United States to garner a refund of the duty on any imported corn fed to them. Now, that will not happen, thereby reducing potential hog supplies in the United States

Again, it would be best for the United States and Canada to harmonize their farm policies. I'm not sure it can be done, given the vastly different situations from which the two countries would begin those negotiations, but any move toward a more common policy would help prevent these costly trade spats. Besides, the technicalities may not continue to save us!

Hog Market Encouraging
Things sure look better in the hog markets than just one week ago. USDA's average net prices from Friday morning's Prior Day Slaughtered Swine report (HG201) show significant improvement over last week. The average net negotiated price is $5.18/cwt. carcass higher than just one week ago, while the average net total price (includes contract purchases) is $4.44/cwt. carcass higher. Thursday's USDA cutout value was $3.50/cwt. carcass higher than one week earlier.

The cash rally has, as predicted, carried all Chicago Mercantile Exchange (CME) Lean Hogs futures contracts higher as well. The increases range from $3-$5/cwt., depending on the contract of interest, and show no technical signs of a slowdown. This rally should provide some pricing opportunities that you should consider carefully on at least a part of your third and fourth quarter production. August Lean Hogs are now within $1 of their contract life high and other contracts beyond June are all within reasonable reach of contract life highs.

You may be afforded a rare opportunity -- the chance to have passed on one good opportunity, and the chance to actually get another one.




Click to view graphs.

Steve R. Meyer, Ph.D.
Paragon Economics, Inc.
e-mail: steve@paragoneconomics.com

Gestation Management-An Overview

Sow Condition Scoring Guidelines

Sow herd culling and mortality rates have reached unacceptable levels in some herds.

Reproductive failure is the most common reason sows are culled from the breeding herd.

Many of these cull sows are excessively thin after nursing a large litter, are experiencing nutritional deficiency due to poor feed intake or have other health problems. Higher replacement rates naturally increase associated costs.

Benefits Are Multifold

Economic viability of the sow herd hinges on longevity, among other factors. At $200 gilt replacement cost and $44 market price, it takes at least three parities for a sow to reach a positive net present value — that is, the point where a sow essentially pays for herself.

For a sow to remain in the herd, she must farrow, nurse and wean a large litter, then breed back within an acceptable period of time. If she falls short, then she is culled.

One important approach to reducing culling and mortality rates is to improve sow body condition during gestation. The attached poster was developed to help pork producers more effectively evaluate sow body condition, and to ensure appropriate nutrition is provided to every sow in the breeding-gestation facility.

Sow body condition is critical to the overall health, welfare and productivity of breeding herd females. Without proper nutrient management, sows can quickly fall into a state of poor reproductive performance and increased susceptibility to disease.

If a sow begins to utilize body reserves (fat used as an energy source, muscle used as a protein source), she will soon metabolize these tissues and lose body weight.

Conversely, when a sow consumes more energy than she needs for normal body maintenance and fetal development, excessive weight gain will occur. This results in wasted feed and decreased reproductive performance.

Maintaining proper body condition helps sows accomplish their reproductive tasks; therefore, it is essential that the caretakers of the sow herd have the ability to evaluate body condition.

Indicators of Body Condition

The ability to assess body condition requires both subjective (visual) and objective (measurable) evaluation of body condition indicators.

Breeding herd managers must be properly trained. Failure to do so will result in incorrect feeding levels and sows that are either too thin or too fat. Either extreme will be detrimental to sow productivity and economic efficiency.

It is important to note that assessing body condition is not limited to estimating the sow's level of backfat. Correct evaluation of body condition relies on accurately assessing a combination of weight, backfat and the lean muscle mass of each sow.

While backfat is a good indicator of the metabolic status of a sow, subjective body condition scoring alone will not determine backfat thickness and energy reserves.

An objective approach to determining body condition score was developed by Kansas State University, and is based on an estimate of weight and the measurement of backfat thickness.

Backfat estimates can be gathered using ultrasound equipment, which operates on the principle of sound waves bouncing off tissues of varying densities (skin, fat, muscle, bone).

“A-mode” ultrasound is the most common ultrasound equipment used, and the Renco Lean-Meater (Renco Corp., Minneapolis, MN) is a good example of a user-friendly tool for estimating backfat thickness. The very portable units can be operated with minimal training and a read-out is provided in millimeters of backfat thickness.

Several other A-mode machines, also used for pregnancy diagnosis, have the capability of measuring backfat depth. These dual-purpose machines are more costly, however. A-mode ultrasound does not have the capability of measuring loin muscle area.

More sophisticated, and costly, “B-mode” ultrasound equipment is also available. Often referred to as “real-time” ultrasound, these machines reflect a video-displayed, two-dimensional image to visualize fat and muscle. Many B-mode ultrasound machines utilized for pregnancy detection also have backfat thickness and loin muscle depth and area-measuring capabilities. These machines require more training to be used effectively.

Measuring Backfat

To estimate backfat thickness accurately using ultrasound, it is critical to place the transducer in the correct location consistently. The easiest location to identify is the last rib. See Figure 1 as a reference for finding the last rib.

The ultrasound operator should palpate the area near the rear flank until the last rib is found. Moving upward, the transducer should be placed 2.5 in. off the midline of the sow's spine. If A-mode ultrasound is used, it is best to take two readings, then record the highest of the two values.

Scoring Body Condition

If subjective body condition scoring is the preferred method on a farm, ultrasound should be used as a guide for training. Even an experienced stock-person can benefit from periodic training to ensure visual evaluation is accurate.

Body condition scores tend to drift slowly away from the “ideal” over a period of time. Sometimes it is valuable to have an experienced, outside observer come in to periodically evaluate sow condition. This practice is especially beneficial when new genetic lines are introduced into the sow herd.

In order to properly establish body condition scores, it is critical to understand the points of evaluation and be able to distinguish between fat and muscle.

Sows should be scored early in gestation to ensure proper feeding levels. Begin by locating the ribs, backbone and hips (or hook bones) of the sow (Figure 1). These points of the sow's body are used because the tissue between the skin and bones is fat tissue. Focus on the shoulder blades, ribs, backbone and hip bones. It is important to evaluate more than one of these areas when assessing body condition, because animals deposit fat at different degrees at different locations.

The line drawings in Figure 2 help illustrate the physical appearance of sows at different body condition scores, including the difficulty of detecting the bones at key points of the sow's body.

The photos in the attached poster provide real examples of these body condition scores. The “high” and “low” view from the rear of the sow provides visual references at each body condition score. The approximate range in backfat associated with each score serves as an additional reference.

A sow with a body condition score of “3” is considered optimum. These sows will enter the farrowing crate with adequate fat reserves to sustain them through lactation. These sows should eat and milk well, and exit the farrowing crate with a body condition score of about 2.5 at weaning.

Sows with a condition score of 1 (excessively thin) or 2 (thin), should receive additional feed in order to attain a score of 3 before they farrow.

For sows exiting farrowing in poor condition (<14 mm [0.55 in.] backfat), it may be advantageous to skip a heat cycle so they can accumulate more body reserves (backfat) before breeding.

Extremes Cause Problems

It should be every farm's goal to have no sows with a condition score of “1,” because these sows are in a compromised state of welfare and very likely will not exhibit signs of estrus. If bred, often they will not successfully maintain pregnancy.

Sows that are too thin as they enter the farrowing crate are unable to consume enough feed to both lactate and accumulate the weight gain needed for body maintenance. These sows are often in a state of energy depletion at weaning and often do not successfully return to estrus.

Sows may lose 2 to 4 mm (0.08-0.16 in.) of backfat during a lactation period, but they should not fall below 14 mm, the minimum level of reserves required for a sow to successfully rebreed.

Most reproductive hormones are made from a base of fat molecules and, therefore, body condition influences reproductive events.

A good target for sows is between 18 to 20 mm (0.70-0.78 in.) of backfat prior to farrowing. Adequate fat reserves provide the energy needed to lactate successfully.

We do not want excessively fat sows, however. Research has shown that fat sows may have difficulty farrowing, consume less feed in lactation and potentially wean lighter litters. In addition, their subsequent litter is often smaller.

Body condition should be evaluated periodically during gestation. This will prevent sows that were evaluated as too thin from becoming too fat as they receive extra feed.

Conversely, sows can become thin during gestation and require adjustments to their feed allotment.

One telltale sign that sow body condition is not being evaluated, or the scores are not being accurately utilized, is to examine the automatic feed drops in gestation. If all or a vast majority of the feeders are on the same setting, an assessment of gestation feeding management is likely warranted.

Note that backfat reserve levels will vary from farm-to-farm and among different genetic lines. Producers should consult with their genetic supplier for the recommended body reserves for sows.

Producers may find it beneficial to crate or pen sows according to body condition score to make management of sows easier.

If a significant percentage of sows fall within either of the extreme body condition scores (1 or 5), then a complete evaluation of gestation and lactation management, nutritional programs and health status should be conducted to determine the reason for the disproportionate number of low or high scores.

Finally, increasing feed and weight gain of the sow two weeks prior to farrowing goes primarily towards fetal growth and not towards body condition.

To Order More Posters

Additional copies of the “Sow Body Condition Scoring Guidelines” poster are available by contacting Newsham Genetics at 515-557-9352 or via their web site, www.Newsham.com (Click the “contact” bar to view order form). Posters are also available by calling Pork Checkoff at (800) 456-PORK.

Figure 2. Body Condition Scores of Sows
Score Condition Ease of detection: ribs, backbone, hip bones
1 Emaciated Obvious
2 Thin Easily detected with pressure
3 Ideal Barely felt with firm pressure
4 Fat None
5 Overly fat None

Optimizing Cull Sow Value

When is the best time to market cull sows?

Before pork producers can answer this seemingly easy question, some additional questions must be thought through:

  • Is space available in the gestation barn or an alternative facility to feed cull sows?

  • Are the cull sows healthy, but just thin?

  • Should I sell cull sows immediately after weaning — as “wet” sows?

  • Should I allow sows to dry up and attempt to add weight in order to add value?

  • How much do cull sows weigh at present?

  • Should I attempt to add weight to sows that have failed to conceive after ample attempts to rebreed?

  • What is the expected market price if sows are sold immediately after weaning vs. feeding them for a specific period of time?

  • What are the feed costs for feeding cull sows, and is storage space available for a cheaper, alternative diet designed for them?

If the answer to the first question is “no,” then the decision is easy.

However, most producers choose to give cull sows some time for their udders to dry up. Fewer than 5% of cull sows are marketed as “wet” sows, according to the U.S. Department of Agriculture (USDA) Market News Service.

Sow herd replacement rates are averaging 50% or higher in many U.S. commercial pork operations. Typically, open sows are given ample opportunity to rebreed. Consequently, a large proportion of sows are being marketed after being found as open, and long after nursing their last litter.

Additionally, wet sows are steeply discounted, typically $5/cwt. or more, based on USDA Market News Service reports. Hence, under most U.S. production systems, economic or production factors make it ill-advised to market the majority of cull sows immediately after weaning.

Understanding The Cull Sow Market

It is important to have a good understanding of the current market prices, by different weight classes, when making decisions about when to sell cull sows.

Prices for cull sows follow monthly and yearly trends and cycles similar to market hog prices. Cull sow prices are typically reported for four separate weight classes (see Figure 1). This graph also shows the yearly cull sow market price average from 1996 through 2005.

Most pork producers don't need to be reminded of the years when the price for market hogs reached unprecedented lows. The lowest prices for cull sows occurred in 1998-1999 and 2001-2002. Additionally, the price pattern between the four different cull sow weight classes was nearly identical across the 10-year period.

In addition to fluctuations in price that occur across years, a substantial difference in price between the different sow weight classes occurs within years (Figure 2).

From 1996 to 2005, the price difference between selling lightweight sows (300-450 lb.) and the next weight class (450-500 lb.) averaged $3.13/cwt. However, there can be substantial fluctuations in this price differential. Typically, when cull sow prices and market hog prices were low, as seen in 1998-1999 and again in 2001-2002, there was little, if any, price differential and, at times, there was even a disadvantage in feeding cull sows to a heavier weight category.

If a producer wanted to add weight to cull sows, the price received for the 300- to 450-lb. weight class needed to cover both the fixed and variable costs, or it would have been a losing proposition.

But, when market hog and cull sow prices are relatively high, there can be a substantial premium for feeding sows that fall in the 300- to 450-lb. weight range up to the next weight class (450-500 lb.). Generally, there is only about a $1.50/cwt. price advantage for increasing the weight of cull sows two weight classes.

Producers should also be aware of the historical, monthly price fluctuations to identify the most opportune time to add weight and value to cull sows.

Figure 3 shows the monthly cull sow price averages from 1996 to 2005. It appears that the summer months (May through August) typically offered slightly better prices for cull sows across the four different weight classes.

After examining the monthly price differential between the four cull sow weight classes, it is apparent that the greatest monthly price differential was between the 300 to 450 and the 450 to 500-lb. weight classes (Figure 4). And, within the 12-month span, the greatest differential between these two weight classes occurred in November through February, and averaged over $4.75/cwt. across the 10-year time period evaluated.

Again, it is important to keep in mind that substantial year-to-year and month-to-month variation can exist in cull sow prices. Likewise, producers should be aware of the current prices across all weight classes when considering whether to feed cull sows to attain greater returns.

Choose Cull Sows Wisely

Identifying sows that are healthy and low mortality risks is crucial when deciding whether to feed cull sows to heavier weights.

Obviously, some healthy sows with superior performance in lactation will leave the farrowing crate quite thin. These sows may be good candidates to feed.

However, sows that are thin because they are not healthy (possible ulcer or respiratory conditions) or are lame usually are not good candidates to feed for additional weight gain. Similarly, sows with shoulder sores may not be good candidates for further feeding, depending on how severe the sore is or if it appears to be causing lameness.

The relatively unthrifty and lame sows should be sold as quickly as possible or be euthanized in a timely, humane manner. Remember, if these animals have been treated, it is critical to follow all withdrawal times, according to label and veterinary instructions.

In addition to sow health, it is important to consider the likelihood that sows are capable of adding weight efficiently.

Little information exists regarding the average daily gain and feed efficiency of the modern lean genetic sows. As a result, the National Pork Board funded a project to estimate the cull sow performance from modern genetic lines and provide producers with a tool to better evaluate sow body condition.

Twenty-nine modern, lean-type sows were purchased from a large production system and housed on a separate site. Seventeen of the smaller sows were housed in crates, while 12 larger sows were housed in pens.

During an initial adjustment period (24-36 hours), the health status of each sow was evaluated by an Iowa State University swine veterinarian, and treated as needed. Of note, the greatest problem the sows exhibited upon arrival was lameness, followed by respiratory disease, digestive disorders and shoulder sores.

All sows were fed a commercial, 14% gestation ration. Sows received fresh feed approximately every 12 hours. Any feed that was not consumed was removed and weighed to calculate feed disappearance. This figure was used to estimate the amount of feed offered for the next 12-hour period.

Fresh, clean water was available by standard, automatic water bowls in crates and pens.

Initial body condition scores (BCS) were assigned to each sow using last-rib backfat measurements as outlined by Tri-State Nutrition Guide. Backfat measurements were obtained using real-time (B-mode) ultrasound equipment, operated by a National Swine Improvement Federation-certified ultrasound technician. Backfat, loin muscle area and depth were evaluated at the 10th rib using the same machine.

In addition to the real-time ultrasound measurements for fat and muscle, a commonly used A-mode ultrasound machine, the Lean-Meater from Renco, Inc., was also used to estimate fat depth.

The BCS distribution appears in Table 1. Seventeen of 29 sows had an initial BCS of 1, while eight and four sows had an initial BCS of 2 or 3, respectively. Sows were photographed at the beginning of the study and when they attained the next BCS. Body condition scoring was undertaken at approximately two-week intervals.

Using the real-time ultrasound as the standard, the A-mode ultrasound machine tended to overestimate sows having a BCS of 1 and 2 (by 1.7 mm) and underestimate BCS of 4 and 5 (by 2.4 mm and 3.4 mm of backfat), respectively.

Sows with a BCS of 3 had similar values, regardless of whether A-mode or B-mode ultrasound machines were utilized to estimate fat depth. For heavier-conditioned sows or sows with more fat cover, A-mode machines frequently have difficulty detecting the third fat layer.

It is important to become familiar with the equipment used to estimate BCS and apply it consistently. In this manner, any under- or over-prediction bias that occurs when assigning BCS will be minimized.

At each BCS increase, average daily gain (ADG), feed efficiency (FE), average daily feed intake, days for BCS increase (DAYS) and weight gain (WT) were calculated.

Sows were removed from the trial after meeting one of two criteria — successfully reaching a BCS of 5 or failure to gain weight over two, 14-day intervals. Sows removed from the trial were transported to the Iowa State University Veterinary Diagnostic Lab for necropsy evaluation to determine any similarities between sows that completed the trial compared to those that did not.

Sow performance by initial BCS is listed in Table 2. The results showed that sow performance declined with each additional BCS increase, regardless of the beginning BCS. In other words, the most rapid and efficient weight gain is attained when adding one additional BCS.

For example, sows that began the trial at a BCS 1 had an ADG of 4.3 lb./day and FE (Feed:Gain) of 2.3 when taking them to BCS 2. The performance of these same sows dropped to 2.5 lb./day ADG and 4.1 FE when adding the second BCS.

This trend held for sows that had a BCS of 2 at the beginning of the trial. The performance of these sows was 3.4 lb./day ADG and 3.9 FE. When adding the second BCS, the same sows' performance dropped to 2.9 lb./day ADG and 4.7 FE.

It is likely that the sows have some compensatory gain that is more efficiently added in the first BCS step.

If producers decide to feed cull sows, it is imperative that they carefully monitor performance relative to market price. In most cases, producers can only justify adding additional weight to sows that are thin (BCS 1 and 2 or in the 300 to 450-lb. weight category). This is when the fastest and most efficient weight gain occurs, and where the greatest increase in market price occurs — taking sows from the 300-450-lb. to the 450-500-lb. weight class.

Payback Potential

Table 3 illustrates breakeven sow market price under three different operational costs/day and three different feed costs (both expressed on a per-sow basis). These values are calculated for sows with different BCS starting points, and are based upon the corresponding ADG and FE shown in Table 2.

Producers should carefully compare the breakeven prices in Table 2 with the historical prices discussed earlier in the article. These values, along with the current cull sow market prices, will be useful for producers determining whether or not to feed cull sows.

Operational costs/day, excluding feed costs, greatly influences the profitability of feeding cull sows. Market prices needed for profitability rapidly increase as fixed costs rise beyond $0.50/head/day.

The situation is similar with feed costs. If the price of feed increases to more than $0.07/lb. ($140/ton), it will be extremely difficult to make feeding cull sows to heavier weights profitable. The only likely exception to this case involves cull sows that lost excessive body condition due to outstanding performance throughout lactation, have no health problems and are in the lowest weight class (300-450 lb.).

A cautionary note: once the first condition score has been added to cull sows, market prices need to increase a minimum of $13.26/cwt. (using $0.05 feed cost and $0.25 operational costs) before profit thresholds can be reached again, and that price situation is not likely to occur.

Closing Thoughts

It is very important to determine if health is the likely reason a sow is thin. Sows that have obvious health issues are not good candidates to feed to heavier weights. Frequently, it is difficult to add weight to unhealthy sows, and they are at a greater risk of dying.

After carefully evaluating sow health, you will need a great deal of information to determine whether or not to feed cull sows to heavier weights. Current market price and the relationship between different cull sow weight class prices will help estimate the potential for additional revenue if cull sows are fed to heavier weights.

Additionally, you should evaluate historical monthly and yearly price fluctuations relative to current prices to aid in your decision. You will have to determine whether existing, relatively low-cost facilities are available for feeding cull sows. High operational costs (due to labor allocation and/or facilities) will likely make feeding cull sows unprofitable.

It is also important to control feed costs when adding weight to cull sows. It may even be necessary to develop a specialized, low-cost, cull-sow diet in order to add weight economically and efficiently.

Realistically, profit can be captured only when feeding healthy sows, with the lowest price feed available, and with cheap, underutilized or depreciated facilities.

Table 1. Distribution of Sows by Beginning and Ending Body Condition Score (BCS)
Number of Animals within each ending BCS
Original BCS 1 2 3 4 5 Total
1 1 1 3 3 8
2 1 2 1 3 10 17
3 4 4
Total 2 3 1 6 17 29
Table 2. Cumulative Performance of Cull Sows by Beginning Body Condition Score (BCS)
Cumulative Additional BCS
Trait Beginning BCS Adding the first BCS Adding the second BCS Adding the third BCS Adding the fourth BCS
Feed efficiency, lb. 1 2.28 4.11 4.15 5.63
2 3.93 4.70 5.16
3 3.53 5.41
Average daily gain, lb./day 1 4.30 2.52 2.72 2.04
2 3.38 2.90 2.72
3 2.74 2.05
Feed intake, lb. /day 1 9.60 10.12 11.12 11.51
2 11.83 12.58 13.80
3 10.73 11.02
Weight gain/BCS increase, lb. 1 81.00 120.41 187.72 195.00
2 70.90 115.43 155.12
3 65.26 98.30
Feed/BCS increase, lb. 1 21.73 50.77 72.49 95.50
2 23.52 43.61 55.50
3 36.85 66.88
Table 3. Breakeven Cull Sow Price/cwt. by Beginning Body Condition Score (BCS), Assuming Three Different Operational Costs/Day and Three Different Feed Prices
Feed Price, $/lb. ($/ton)
Operational Costs, $/day1 $ 0.05/lb. ($100/ton) Addition of the first, second and third BCS $ 0.07/lb. ($140/ton) Addition of the first, second and third BCS $ 0.09/lb. ($180/ton) Addition of the first, second and third BCS
Beginning BCS 1 2 3 1 2 3 1 2 3
$ 0.25 1 17.21 30.47 29.94 21.77 38.69 38.24 26.33 46.91 46.54
2 27.05 32.12 34.99 34.91 41.52 45.31 42.77 50.92 55.63
3 26.77 39.25 33.83 50.07 40.89 60.89
$ 0.50 1 23.03 40.39 39.13 27.59 48.61 47.43 32.15 56.83 55.73
2 34.44 40.74 44.18 42.30 50.14 54.50 50.16 59.54 64.82
3 35.90 51.44 42.96 62.26 50.02 73.08
$ 0.75 1 28.84 50.31 48.32 33.40 58.53 56.62 37.96 66.75 64.92
2 41.84 49.36 53.37 49.70 58.76 63.69 57.56 68.16 74.01
3 45.02 63.64 52.08 74.46 59.14 85.28
1Operational costs include all expenses, excluding feed costs.

Neutralizing Chronic, Acute Disease Challenges

Sow and gilt health maintenance in gestation is impacted by a host of factors. The traditional approach to sow and gilt health uses “health” and “disease” synonymously. It is more correct to consider disease status as one element of overall health.

Each new veterinary discovery reveals that diligent attention to nutrition, management and environment can enhance the ability of the immune system to neutralize disease challenges to the sow or gilt. Disease challenges are increasingly complex; disease organisms are increasingly evasive of the immune system, and some, like porcine reproductive and respiratory syndrome (PPRS) virus, attack the immune system directly and use immune cells to replicate.

Managing sows and gilts to insure the immune system has maximum ability to neutralize challenges is critical.

Observation is Critical

It is also clear that when treatments exist for a particular disease, the effectiveness of treatment improves when it is applied early in the infection process. Early detection requires that caretakers have keen observation skills, so the disease is detected before clinical signs become severe.

Subtle changes are the first signs of disease onset. Detecting these changes in sow and gilt health requires consistent, daily observation and detailed communication of changes in animal status among multiple caretakers.

A consistent process for observing animals is the most important. Subtle changes in animal attitude or behavior, respiratory rate, activity level and general appearance can indicate the start of a disease problem. If a different person observes a sow from a different position at a different pace, at a different time of day, subtle changes in behavior and appearance can exist that have little to do with changes to the sow's disease or health status. This is especially the case in chronic conditions that develop slowly over time but have significant impact on lifetime performance.

Typically, observation of gestating sows occurs only at feeding. This allows detection of very sick animals that are off feed or fail to rise and eat, but it does not allow for detection of subtle changes in respiratory rate.

Gestating sows are best observed at rest, when they are calm. Finding a time when the barn is at rest will facilitate observation of subtle and earlier signs of infection. All animals should be observed every day.

Traditional approaches to sow and gilt gestational health have focused on acute disease conditions. This is because acute illness in the gestating sow or gilt frequently has repercussions for the current litter. When the disease or health condition results in abortion, the economic loss is obvious and the urgency to address the disease problem is highest.

Other authors of this Blueprint have made strong cases for the significant economic impact of chronic, non-disease impacts on health. The discussion that follows begins with general recommendations targeted to management of health in sows and gilts, followed by some specific consideration of hoof lesions and cystic ovaries.

Acute Health Management

Work with your veterinarian to identify the specific diseases in your system. Acute disease management is a very farm-specific activity.

Successful farms utilize veterinary diagnostic assistance to characterize the specific diseases present and the best interventions for each situation. Additionally, successful managers recognize that all medications and vaccines have some degree of negative impact on the performance of the sow and gilt.

In situations where a disease is present (in the case of antibiotic use) or exposure occurs (in the case of vaccine), there is a clear overall benefit to the correct use of these interventions. However, when the treatment or vaccine is misapplied or unnecessary, the benefit will not be realized and harm may even result.

In addition to increasing cost and adding labor, using vaccines that are not necessary can stress sows because they are designed to elicit an immune response. This immune response can limit feed intake and redirect energy resources away from pig development or replacement of sow or gilt body condition.

Needles have been shown to transfer viral diseases. And, the risk of abscesses and broken needles is a reality.

Antibiotics that are not needed, even when applied via feed or water, can have negative impacts on the normal, protective bacteria of the intestinal tract. Additionally, research shows that bacteria have the ability to trade genetic material, which contributes to the spread of antibiotic resistance. Developing resistance in non-pathogenic bacteria may have repercussions when pathogenic bacteria arrive at the farm.

The least effective, and even detrimental to health on sow farms, is the use of so-called “preventive shots.” Eliminate these preventive injections, which commonly consist of antibiotics plus other pharmaceuticals designed to provide blanket protection against several conditions that may be problems in the herd.

Considering a few characteristics of antibiotics in general helps illustrate the limited value of this practice. Few antibiotic formulations remain in the sow or gilt's system at effective levels for extended periods of time. The only bacteria that are affected are those present at the time of injection. Additionally, to effectively treat most bacteria requires multiple treatments.

Antibiotics do not sterilize the animal of pathogens, and recovery from disease still relies on the animal's immune system. Additionally, the mixing of several pharmaceuticals for injection constitutes a practice called “compounding” which, except for specific circumstances, is an illegal practice.

The true cost of so-called preventive shots is a sense of false security and a relaxed diligence in finding and correcting the sources of the problems these injections are thought to address. Again, in addition to all of the health-related issues, the practice of preventive shots contributes to higher economic costs on the sow farm.

Feed, Water Medications

Remember that most clinical diseases can be accompanied by decreased feed and water intake. Consequently, administering antibiotics via feed and water can miss the most affected animals.

Often, water and feed medications are consumed at the highest rate by the healthiest animals, since they are unaffected by disease. The animals most in need of treatment frequently consume the least feed or water medication due to the adverse impacts of the disease condition they are experiencing. Rely on individual animal treatment using injectable antibiotics as much as possible for clinical cases.

Recognize that disease profiles on farms change over time. Make sure that you are not treating for, or attempting to prevent, a disease problem that does not currently represent a risk to your operation. Eliminate treatments and vaccinations that do not address a problem diagnosed in your herd. Use only vaccines and antigens against diseases diagnosed in your herd or for which exposure is likely.

Substantial savings can occur when producers eliminate combination vaccines that include antigens for diseases sows are not exposed to. Be sure to consult your veterinarian before making changes to a successful program.

If you're concerned about removing the potential protection of certain antigens, the use of sentinel animals to assess risk might be useful. This generally involves removing the vaccine from a small subset of the herd, and monitoring them for the disease of concern before committing to a whole herd change.

Focus on Prevention

Realize that prevention is always the cheapest and, in the case of some diseases, the only intervention available. It is time for pork producers to begin applying rational, science-based biosecurity interventions in earnest.

Often, the simplest interventions are most effective. For example, changing boots and coveralls and washing hands have been shown to interrupt the transmission of many swine pathogens. This must be done diligently. Each lapse undermines the efforts of the whole operation.

When implementing a biosecurity program, it is important to keep a few concepts in mind:

  • Simple tasks are more likely to be done regularly and correctly.

  • Avoid the “all or none” mentality. Biosecurity is about reducing risk. Every little improvement reduces the risk over time.

  • Divide and conquer. Separate ages and different health status animals as much as possible with different apparel and equipment.

  • If it stinks, wash it. Manure and pig secretions are often as effective at transferring pathogens among animals as animals themselves.

  • Focus on what you can control. Keep employees focused on this. Do not allow risks that you cannot control to become an excuse to relax effort against risks you can control.

  • Help employees understand what is at risk. Most employees are motivated by contributing to a successful team.

  • Keep pets out, control rodents and birds and know where visitors have been before they arrive.

Chronic Conditions

The most recent slaughter evaluation of cull sows at Iowa State University (ISU) evaluated 3,158 animals and found more than 67.5% (2,131 animals) had foot lesions. Additionally, there were 6.3% (199 animals) with cystic ovaries.

Preliminary evaluation suggests hoof lesions were widespread. Sows with higher body condition scores were more likely to have cystic ovaries. This may indicate that sows with cystic ovaries remain undetected in inventory and gain weight while not contributing to the productivity of the herd.

Cystic Ovaries

A relatively low prevalence of cystic ovaries can impact farm productivity significantly and yet remain difficult to diagnose and treat.

The first step is to monitor and record sow reproductive performance so that animals that repetitively fail to conceive can be identified and targeted for further examination. Cystic ovaries remain challenging to identify in the live animal, but progress has been made.

Research has demonstrated that cystic ovaries can be diagnosed by transrectal as well as transabdominal real-time ultrasound similar to that used for pregnancy detection.

Additionally, serum progesterone levels are reportedly elevated in sows with cystic ovaries. These levels can be detected by recently developed commercial enzyme-linked immunosorbent assay kits, which are also used for identifying elevated progesterone levels in pregnant sows.

These tools can be more effectively applied to identify cystic ovaries in a targeted, at-risk population than as a screening tool for the whole farm. It also reinforces the necessity for good records to help accurately identify the high-risk sows in your herd.

The lesions most commonly seen in the ISU survey were large, bilateral, multicystic ovaries without gross structures such as corpus lutea that indicated recent pregnancy or ovulatory activity. Most of these ovaries had a gross appearance of cysts with thickened walls that suggested luteinized tissue was present.

The presence of luteinized tissue would be expected to produce progesterone, inhibiting estrus activity and behavioral signs of estrus. The fact that they were usually bilateral suggests a systemic problem, such as a disruption of routine hormone fluctuations in the sow, rather than structural problems with the ovaries themselves.

The causes of cystic ovaries are many, but the most commonly recognized include causes of impaired luteinizing hormone (LH) surge that lead to ovulation failure, which subsequently leads to the development of cystic ovaries. Increased incidence of cystic ovaries has been associated with shortened lactation lengths, zearalenone toxicity and other stressors. In the current study, an increased incidence of cystic ovaries was associated with heavier body condition.

Hoof Lesions

The hoof lesions observed in this ISU study were significantly more prevalent than expected by the research team. A range of factors and combinations of factors, including injury and nutritional deficiencies, undoubtedly causes hoof lesions.

A key concern with a survey analysis of the problem, especially postmortem, is that the foot is a complex structure designed to endure cuts, abrasions and limited, small cracks.

The hoof is primarily composed of dense, hard tissue that is no longer supplied with blood and nutrients. As a result, cuts, cracks and abrasions are not repaired, but rather replaced by new growth from the top of the hoof. The difference between normal wear and a problem is difficult to discern. Another result of the normal hoof growth process is that treatment interventions may not have immediate results. Disciplined patience is critical in order to correct the problem long-term.

In live animals, evaluating soundness can guide decisions regarding hoof lesions. Given the limited capacity for hoof repair, maintaining an environment that preserves hoof integrity and foot health is key. The first and most obvious steps are to eliminate injury hazards.

Keep in mind that some injuries can be traumatic, such as cuts or splits due to uneven or sharp surfaces or the protrusion of bolts from penning. Injuries can also be the result of chronic impact on the foot. Slick surfaces can change the animal's gait and weight distribution, resulting in abnormal wear or cracks over time. Several studies have agreed with the ISU study, which found that lesions are more common in rear feet. No cause for this has been confirmed.

Flooring, crates, crowding and handling as gilts have all been indicated as key contributors to lameness in sows. Creating the desired flooring conditions is a delicate balance between too rough and too slick for heavy sows.

Concrete floors certainly can be used with success, but are particularly difficult to design with the correct balance. Concrete floors that are too rough result from the use of particulates that have incorrect grain size and consistency, or floors that have broken down due to organic acids and wear.

New concrete can be slippery and have sharp edges, and chemicals that result from the curing process can be irritating to sensitive structures of the foot. Poor flooring can be improved by altering texture, taking steps to reduce moisture, providing padding or removing sharp points.

Biotin, also known as vitamin H, supplementation has received attention as a potential treatment for hoof problems, but its impact depends on several factors, and results are limited to a narrow range of circumstances. Biotin supplementation has been useful in diets that are deficient, but additional supplementation in diets that have adequate biotin has not been shown to improve hoof lesions.

Corn is a good source of biotin, but other substrates such as milo and barley may be deficient. Biotin can only be expected to improve hoof integrity. Lameness issues that result from pad or sole injuries should not be expected to respond to biotin supplementation. Close inspection of both the diet and the feet of lame sows can provide direction on the use of biotin supplementation.

Both acute and chronic disease problems in gestation rely on accurate diagnosis and individual animal approaches to treatment. Research continues to show significant associations between body condition and acute disease problems such as pneumonia, as well as chronic problems such as lameness.

Survey Shows Lower Incidence of PSE

A national survey of the pork packing industry in 2005 suggests that the incidence of pale, soft and exudative (PSE) pork was significantly less than in a similar study conducted three years earlier.

Packers harvesting 82% of the hogs marketed in the United States last year reported a 3.34% incidence of PSE. That compares to 15.5% in a National Quality Audit in 2002. Some plants reported 40% of pork was PSE.

PSE pork is low quality, becomes dry and tough with little flavor, and is unsuitable for many pork products.

The Pork Checkoff and the University of Missouri coordinated the latest survey, conducted by the Pork Quality Solutions Advisory Group, a subcommittee of the Pork Checkoff's Animal Science Committee.

The Pork Quality Solutions Advisory Group suggested that the 2002 audit might have overestimated the amount of classical PSE pork by associating individual quality traits, such as pale color and softness, with PSE. In the 2005 survey, the goal was to find “classic PSE” meat — pork that was pale, soft and watery.

A member of the Animal Science Committee, pork producer Brian Zimmerman of Beatrice, NE, says the pork industry still needs to improve pork quality.

“Three percent PSE is still too high, and it is costing our industry millions of dollars/year,” says Zimmerman, who co-owns and manages the family's farrow-to-finish operation.

Fatty Acids Create Healthier Pork

One day, pork products could join mackerel, tuna and salmon as heart-healthy sources of omega-3 fatty acids, says a University of Missouri animal scientist.

For the first time, researchers have developed pigs producing omega-3, the beneficial compound known for improving cardiovascular fitness and reducing the risks of heart disease.

“All mammals, humans included, do not naturally produce omega-3s, so the only way to get these essential fatty acids is through your diet,” says Randall Prather, University of Missouri animal scientist, whose laboratory produced the pigs. “Omega-3 pork would give consumers a new choice, and avoid concerns about heavy metal contamination in some fish species.”

Five Large White boars born at the university in Columbia, MO, last November are producing levels of fatty acids equal to or greater than pigs fed an omega-3-rich diet.

Besides consumers, pork producers also could benefit from pigs that produce omega-3 fatty acids. “The pigs themselves would be healthier, so sows could remain in a breeding herd longer and reduce replacement costs,” remarks Prather. “Consumers also would likely be willing to pay a premium for omega-3 pork, so there could be a value-added economic benefit.”

Researchers produced the omega-3 fatty acids in the pigs by inserting a gene called “fat-1,” which was isolated from the roundworm, Caenorhabditis elegans. The fat-1 gene provides the genetic instructions for producing an enzyme that converts less-desirable omega-6 fatty acids found in cereals, whole-grain bread and baked goods to omega-3.

Prather collaborated with laboratories led by Yifan Dai and Rhobert Evans at the University of Pittsburgh and Jing Kang at Massachusetts General Hospital in making the discovery. Prather explains that though cloning was used to insert the fat-1 gene, conventional breeding will be used to increase the herd.

When the National Swine Research and Resource Center opens later this year on the university campus, the omega-3 pigs will be integrated into the center's collection of swine models used for biomedical research, says Prather, co-director of the center.

PRRS Research Grants

Three researchers received the 2006 Advancement in PRRS Research Awards from Boehringer Ingelheim Vetmedica, Inc. (BIVI).

This is the fourth year that BIVI has provided $75,000 in research grants to independent swine researchers to investigate ways to control porcine reproductive and respiratory syndrome (PRRS).

This year's recipients and projects are:

  • Jeff Zimmerman, DVM, Iowa State University — evaluate the performance of different diagnostic tests in detecting the PRRS virus;

  • Claudia Munoz-Zanzi, DVM, University of Minnesota — study the sensitivity of PRRS virus polymerase chain reaction for pooled serum and blood swab samples of boars during acute infection; and

  • Scott Dee, DVM, University of Minnesota — evaluate the impact of blood testing procedures on the early detection of infection in gilts.

Feed Sows For Condition, Productivity

When designing a feeding program for gestating sows, it is important to remember the overall goals for the nutrition program:

  • Prepare sows to be in proper body condition at farrowing;

  • Maximize reproductive performance (farrowing rate, litter size); and

  • Meet the daily nutrient requirements at the lowest cost possible (measured as cost/sow/day).

Overfeeding gestating sows creates unnecessary expenses and potential problems with impaired mammary development, and reduces feed intake in lactation.

Over-conditioned sows used to be the main problem on swine farms. In recent years, thin sows have become a more prevalent problem. Too little backfat reserves can reduce reproductive performance and increase sow mortality. Low backfat reserves also can be an animal welfare concern as thin sows have a greater chance of developing shoulder sores.

Accurate Feeding Levels

There is little disagreement on the importance of having sows in the correct body condition at farrowing. Although there is some disagreement on whether the ideal backfat level at farrowing should range between 16-18 mm (0.62-70 in.) and 18-21 mm (0.70-0.82 in), most people agree that the most important point is to have as few sows as possible under 15 mm (0.59 in.) or over 24 mm (0.94) at farrowing.

The big disagreement among nutritionists, veterinarians and barn managers is over the best way to set feeding levels to make sure sows are not under-or over-fed in gestation.

Backfat scanning on commercial farms has convinced us that a visual body condition score is a poor predictor of actual backfat levels. The best correlation we have found between backfat and condition score on any farm we have measured is an r2 of 0.23, suggesting that body condition score only explains about 23% of the variation in backfat levels.

If body condition score is used to set feeding levels, feed usage should be tracked and backfat at farrowing should be monitored periodically using ultrasound measurement to try to reduce swings in backfat levels for the entire farm (see sidebar). If over 75% of the sows are between 15 and 24 mm at farrowing, you are doing a pretty good job of setting feeding levels during gestation.

Because of our frustration with condition scoring, we have tested and implemented a method to feed sows based on backfat and body weight estimates using the concepts proposed by the late swine nutritionist Frank Aherne, which are presented below.

Whether you feed sows based on body weight and backfat or on body condition score, it is useful to understand the energy requirements of the sows, and the energy level of your gestation diet to determine feeding range for your situation.

Gestating Sows Requirements

The maintenance requirement of the sow accounts for the majority of the feed requirement. Thus, an estimate of body weight is extremely important to accurately feed the sow.

Because weighing individual sows is not feasible on many farms, we have established weight categories that can be estimated by using a girth or flank measurement.

Girth is measured with a cloth tape directly behind the front legs and in front of the first mammary glands. The flank measurement is measured immediately in front of the back legs from the point of one flank over the back of the sow to the point of the other flank. The flank-to-flank measurement is much easier to obtain, especially when sows are housed in gestation stalls.

Because body weight is important in determining the daily feed allotment, it is essential that a high percentage of sows are measured for their body weight estimate.

The daily feed requirement for the sows to maintain body weight increases approximately 0.3 lb. for every 50 lb. increase in sow weight for sows fed a corn-soy diet (Table 1). The sows' maintenance requirements will increase as sows gain weight during gestation.

The next biggest component of the gestation feed requirement is the amount of weight or backfat that you want the sow to gain. If you only feed the sows the maintenance feeding level, they will maintain body weight, but will lose backfat. Sows require approximately ¼ lb. of feed daily for a low level of weight gain to maintain backfat. The daily feed requirement increases approximately 0.4 to 0.5 lb./day for every 3 mm (0.12 in.) increase in desired backfat gain during gestation (Table 2).

Backfat can be measured with one of several different ultrasound machines. The Renco machine is used on some farms because of the relatively low cost. Real-time ultrasound machines used for pregnancy diagnosis can also be used for backfat measurement.

It is critical to properly train the individuals gathering ultrasound measurements, particularly the point where backfat is measured. Sows are scanned at the last rib, approximately 2.5-3 in. off the midline. We recommend scanning the sow on both sides, then averaging the values to determine backfat.

The last component of the gestation feed requirement is fetal and uterine gain. Fetal gain in late gestation increases exponentially, thus, feeding levels should be increased by 1 to 2 lb./day during the last two weeks of gestation to meet this need.

The daily energy requirement for fetal and uterine gain (330 kcal) during the rest of gestation can be met by a relatively low feed level of 0.25 lb.

The requirements for maintenance, weight or backfat gain and fetal growth are added to determine the total daily feed requirement (Table 3).

Set Feeding Levels

Once each week, the person responsible for setting feeding levels scans sows for backfat and determines the weight category for all sows bred during the previous week. The backfat is written on the sow card, and the feeding level is adjusted using a table customized for the farm, based on the energy density of their diet and volume of their feed boxes.

At approximately seven weeks after mating, sows that are visibly very thin are marked and scanned to determine if backfat gains are on target. Approximately 10 to 15% of the sows will have to be scanned at this time.

If the sows are not reaching targets, feed intake is increased by 1 lb./day. Sows remain on their feeding level until Day 100 of gestation, when the feeding level is increased by 2 lb./day for the last two weeks before farrowing.

The procedure is relatively simple and easy to implement. The three critical issues for success are:

  1. A person must be trained to scan and estimate weight;

  2. Know the energy level of the gestation diet; and

  3. Know the volume being dropped at each feed box setting.

Full details on procedures and the spreadsheet can be found at: www.asi.ksu.edu/swine under the swine Extension sow feeding tools link.

Gestation Feeding Patterns

Feeding levels in particular stages of gestation have been shown to influence sow productivity and performance of their offspring. The periods when excessive feed intake are most detrimental are immediately after breeding (Day 0 to Day 2) and from Day 75 to Day 90 of gestation for gilts.

High levels of feed intake after breeding can reduce embryo survival in gilts. Providing gilts high levels of feed from Day 75 to Day 90 of gestation can increase fat deposition in the mammary gland and reduce milk production.

From a practical perspective, feeding pattern is less important than providing a total energy level over the entire gestation period that prevents excessive fat gain or inadequate body reserves at farrowing.

Feeding Once vs. Twice Daily

Although research on this subject is limited, feeding sows once vs. twice a day doesn't appear to change production parameters. Therefore, the choice of feeding frequency is a personal choice.

Some producers cite improved sow satiety and decreased ulcer potential as the reason for choosing twice-per-day feeding. Others will argue that feeding twice a day increases sow agitation and noise levels in the barn. A real advantage with twice-per-day feeding is that synthetic amino acids can be used without worrying about the reduced utilization that occurs when sows are fed once daily.

A practical concern with twice-per-day feeding is that most gestation boxes are relatively large and difficult to set accurately at the low feeding levels required.

Genetic, Parity Differences

Genotype of the sow doesn't have a major impact on the feed requirements for maintenance or fetal gain. However, genetics can vary in sows' milk production and lactation feed intake.

Sows with high levels of milk production and low lactation feed intake will require higher levels of feed during the subsequent gestation period to recover the weight and backfat lost during lactation. If the sows are fed with the weight and backfat procedure, feeding levels will automatically be adjusted to meet the requirement of different genetics.

Similarly, older sows require higher levels of feed intake to meet their maintenance requirement because they are heavier than younger sows. If feed levels are adjusted as sows become heavier, the higher feed requirements for older parities will automatically be met.

Amino Acid Levels

A corn-soybean meal diet containing 0.60 to 0.65% lysine will meet the requirements of most sows. Because threonine requirements are higher for maintenance than many other amino acids, L-threonine must be added with L-lysine HCl if synthetic lysine is used in the diet. Remember, synthetic amino acids are only used at about 50% efficiency when sows are fed once a day.

If parity segregation is being practiced, different gestation diets can be used. The gestation diet for first-parity sows can be formulated to a higher lysine level (0.65%), and the diet for older sows can be formulated to a lower lysine level (0.50 to 0.55%), depending on energy level of the diet.

Water is Critical

Like all areas of production, clean, fresh water should be made available at all times. While this suggestion seems simple, it can be a source of concern if water is not an area of focus.

Plugged nipple waterers, poorly designed water troughs, or incomplete filling of troughs because of feed blockage can all lead to inadequate water intake in gestation. A part of the daily schedule on sow farms should be to ensure that all sows have access to feed and water.

Other Nutrients

Sow gestation diets need to contain the normal minerals and vitamins added to growing pig diets. Besides higher levels of calcium and phosphorus, sow gestation diets also should contain higher levels of specialty vitamins required for fetal development, such as folic acid, choline and biotin. In recent years, research has demonstrated that sow productivity can be further improved with additions of other nutrients, such as chromium and carnitine.

Table 1. Energy and Feed (lb./day) Required to Maintain Body Weight

Dietary energy, kcal/lb.
Sow weight, lb. ME, kcal 1,400 1,500
350 4,741 3.4 3.2
400 5,240 3.7 3.5
450 5,724 4.1 3.8
500 6,195 4.4 4.1
550 6,654 4.8 4.4
600 7,103 5.1 4.7

Tracking Gestation Feed Usage

Regardless of whether backfat and weight or body condition scoring is used to set the daily feed allowance for each sow, it is useful to get a global picture of gestation feed usage for a swine farm to determine whether any long-term trends towards over- or under-feeding is occurring. This can be done simply by dividing the total feed delivery for the period by the number of gestation places in the farm and the number of days in the period.

Certainly, if the sow space is not fully utilized on the farm, this measure will need to be adjusted for actual inventory. However, for most farms, simply knowing the number of gestation spaces is adequate. This calculation is especially useful in production systems with multiple sow farms to determine if one sow farm routinely feeds 5.5 lb./day, while another farm routinely feeds 4.6 lb./day when provided the same gestation diet.

In reality, most farms should have gestation feed usage of 7.2 to 7.8 Mcal metabolizable energy (ME)/sow/day. This equates to 5.1 to 5.5 lb./day of a gestation diet containing 1.4 Mcal ME/lb. or 4.8 to 5.1 lb. of a diet containing 1.5 Mcal ME/lb. If feed usage for the farm is outside of these bounds, reasons for the discrepancy should be explored.

For this example, a 3,000-sow farm containing 2,800 gestation crates used 1,210 tons of feed in a six-month period. The calculations are as follows:

Total Feed/Crates × Days = 1,210 tons × 2,000 lb./2,800 crates × 182 days = 4.75 lb./day

A period of six months or longer should be used with this method to account for fluctuations in feed deliveries. A six-month rolling average is a good method for tracking gestation feed usage.

Table 2. Energy and Feed (lb./day) Required for Backfat Gain

Dietary energy, kcal
Backfat gain, mm ME, kcal 1,400 1,500
0 342 0.24 0.23
3 991 0.71 0.66
6 1,649 1.18 1.10
9 2,307 1.65 1.54

Table 3. Feeding Levels (lb./day) for Gestating Sows Based on Backfat and Weight Category at Breedinga

Backfat at breeding, mmb
Flank-to-flank, in. Estimated weight, lb. 9 to 11 12 to 14 15 to 17 >18
< 35.5 250 to 325 5.0 4.4 3.9 3.4
35.6 to 38.0 325 to 400 5.5 5.0 4.4 3.9
38.1 to 41.0 400 to 475 5.9 5.4 4.9 4.3
41.1 to 44.0 475 to 550 6.4 5.9 5.4 4.8
> 44.0 550 to 650 6.9 6.4 5.8 5.3
aBased on a diet containing 1,500 kcal ME/lb.
Feeding level should be increased by 2 lb./d on Day 101 of gestation.
bMost ultrasound machines measure backfat in millimeters (mm); to convert mm to inches, multiply mm by .039.

Future Research in Gestation Feeding

While optimizing gestation sow feeding to maximize performance and longevity will continue, more specialized research associated with fetal development will grow in popularity.

Specifically, research includes utilizing omega-3 fatty acids of eicosapentaenoic (EPA, C20:5) and docosahexaenoic (DHA, C22:6). These fatty acids are believed to assist in the development of brain function, which may lead to a more viable pig at birth.

Organic selenium sources are now available for use in sow diets. It has been shown that sows fed organic vs. inorganic selenium resulted in higher levels of selenium in sow colostrum and milk, and in piglet tissue. However, impacts on fetal development are currently less known.

Feeding gestation sows L-carnitine has been shown to enhance muscle fiber development in fetuses, which has ultimately led to a greater loin muscle depth and percentage of lean. The exact mode of action for L-carnitine's ability to improve fetal growth and development is unknown. However, it is most likely related to its ability to influence energy metabolism, increase maternal IGF-1 concentrations and influence maternal leptin concentrations.

These are examples of future research areas influencing fetal development, which will continue to improve gestating sow performance.

Gestation Sow Housing Options Abound

The method of housing sows during the breeding-gestation phases of pork production has undergone considerable transition during the last 40 years.

The move to housing sows indoors had several major drivers:

  • A worker could more easily manage a larger number of sows (feeding, vaccinating, mating and moving individual animals);

  • A worker could more easily manage the environmental aspects needed by the sows;

  • More sows could be housed in a smaller area; and

  • Reproductive performance of the herd would be enhanced.

The move to individual gestation stalls made feeding easier, prevented sows from fighting during mixing and feeding, allowed for individual health care and vaccination, provided better control of the dunging area, prevented sows in estrus from excessively riding each other, and allowed more sows to be housed in a specific amount of space.

Although gestation stalls offer the benefits of controlled management, many perceive them to be a welfare problem. As a result, many pork producers are seriously considering their options for housing gestating sows.

Whether constructing a new gestation facility or remodeling an existing one, sow welfare is just one aspect of a total decision-making process that involves many other factors, including capital costs, anticipated performance, ease of management and operating cost.

Health and welfare of sows

People who want individual stalls banned believe that the requirements of the sow are freedom from malnutrition, thermal discomfort, physical discomfort, lack of exercise, injury, disease, suppression of all normal behaviors, fear and stress. Although there is disagreement as to how welfare should be assessed, scientists have assessed the well-being of gestating sows and gilts according to the animal's social behavior, health status, skin lesions, feet and leg soundness, locomotion, muscle weight and bone strength, concentration of cortisol, immune system function, heart rate and reproductive performance.

Some people perceive that the housing of sows as a group is more welfare-friendly. However, the housing of sows in groups can have welfare problems, such as: (1) aggression during mixing of animals; (2) aggression at time of feeding; (3) bullying by dominant animals; (4) injuries of feet, leg and back due to excessive riding of each other during estrus; (5) excessively high feed intake by dominant animals that results in fat sows; (6) excessively low feed intake by subordinate animals that results in thin sows; (7) vulva biting; and (8) wounds and scars from fighting.

The rate of injuries, body lesions, claw lesions and body condition scores can be influenced by feeding method, parity distribution within the pen, floor space per animal, use of bedding and physical properties of the floor.

Sows with low social status within a group have injuries on a greater number of body areas than sows with high social status one week after mixing into either static or dynamic groups. Also, sows with a low social status have a greater number of bodily injuries four weeks after mixing into static groups. Although injury scores have a wide fluctuation for sows housed in an individual stall or pen containing an electronic sow feeder, total injury scores have been reported to be higher for sows housed in pens than for sows housed in stalls.

Group housing of sows

It is important that producers realize there is more than just one group housing system. Some of the many factors involved with group housing are number of animals per pen; size of animals per pen; amount of space per animal; type of flooring (total slats, partial slats, solid concrete floor); use of mold-free bedding, method of feeding (mechanical or non-mechanical, floor feeding, individual feed drops, interval feeding, trickle feeding); use of feeding stalls (locked, unlocked, self-locking, computerized); geographic location; genetic composition of sows; temperament of animals; safety aspects for workers; and complexity of accomplishing work tasks (estrous detection, mating animals, moving animals, feeding animals).

Each group housing system has benefits and drawbacks. Therefore, producers must decide what they want to achieve, and then implement the design components that will most likely reach those goals.

Following is a discussion of numerous aspects of sow gestation management that must be considered:

Reproductive performance

The method of housing sows plays an important, but not exclusive, role in determining reproductive performance of sows. Genetics, health, environment, geographic location, worker skill, management procedures and other factors also impact reproductive performance.

Although a large number of studies have been published comparing sow performance in different housing systems, care must be taken when interpreting data generated from records gathered from several different farms. It is difficult to make absolute conclusions that one type of housing is better than another, because most farms have only one system and, therefore, do not test housing options under the same management and environment.

Table 1 on page 11 shows the influence type of gestation housing has on number of piglets born alive/litter for 19 sets of data. There is no clear and consistent pattern to identify which housing system is the best.

In studies comparing stalls vs. group housing, the percentage indicating a numeric increase in number of piglets born alive/litter was evenly split between sows housed in stalls and sows grouped in pens.

An analysis of records from 71 farms in northern Italy found that housing sows in individual stalls during the entire reproductive cycle (mating and gestation), compared to other housing systems, gave better performance in number of piglets born/litter, farrowing rate and number of piglets weaned/sow/year (Table 2).

The records also showed that grouping sows at 28 to 50 days after insemination produced more weaned pigs/sow/year compared to grouping sows at 14 to 28 days after insemination.

A Swedish study found the number of piglets born alive/litter was greater when sows were housed in stalls compared with sows housed in a group immediately after service and fed with an electronic sow feeder (Table 3). However, in the same study, Herd 2 found a numeric increase of 0.2 piglets born alive/litter for sows housed in groups compared with sows housed in stalls.

Feeding systems

Feed intake during gestation is restricted to prevent excessive body weight gain and fat deposition.

It is known that excessive feed intake during early gestation increases embryonic death in gilts, but not in multiparous sows.

Excessive feed intake during gestation decreases feed intake during lactation. Excessive underfeeding of gestating sows can reduce piglet birth weight, piglet viability and lower body fat reserves at farrowing and weaning.

Research has shown that food deprivation for 48 hours after ovulation is associated with changes in reproductive hormones, changes in metabolic hormones, a decrease in number of sperm cells transported to the sperm reservoir of the oviduct, a lower cleavage rate of embryos and a delayed transport of ova. Fasting of sows on Days 10 and 11 of gestation can also have detrimental effects on reproduction. Thus, the control of feed is a major consideration when designing and managing a gestation facility.

  • Electronic sow feeding (ESF) system

    The computerized feeding system allows sows to be loosely housed and fed individually. The computer can be used to change the total volume of feed each sow receives, and it can be adjusted to give each sow her entire meal in a single visit or during several smaller meals throughout the day.

    Aggressive physical acts, particularly vulva biting, do occur while sows are waiting for their turn to enter the feeder.

    The suggested number of animals per electronic feeder is 40 to 65 sows. The minimum space/sow ranges from 18 to 32 sq. ft. In general, bedding is not used with an electronic sow feeding system in the United States.

    There are essentially two management schemes for ESF:

    Option A uses a static group of 40-65 sows/pen with only one electronic feeding station. All animals in the group are in the same phase of production.

    Option B uses a dynamic group from about 80 up to 200 sows with two to five electronic feeding stations. Every week sows enter and leave the group; thus, the animals are in different productive phases. The introduction of bred sows to an existing group at one to eight days after mating has increased the incidence of bred sows returning to estrus by 10% and reduced litter size by 0.2 piglets/litter compared with introducing bred sows at 22 to 29 days after mating.

    Although the data in a Swedish study is confounded between type of group (dynamic or static) and feeding method (ESF or floor-fed), farrowing rate and litter size born alive was not different when sows were grouped four weeks after mating (Table 3, Herd 3). However, the percentage of sows removed from the group was two times greater in the dynamic housing method.

    Research in Canada found a larger number of piglets born/100 sows bred when sows were mixed more than 35 days after breeding, compared with mixing less than seven days after breeding (Table 4). Although the use of an ESF system helps ensure that sows receive the correct feed allowance, sows with low social ranking have lower bodyweights, higher injury levels, lower position in the feeding order and are displaced more often from the drinkers than high-ranking sows.

  • Feeding-resting stalls

    This feeding system allows the sows to freely roam in a large pen with other sows except when they are fed. The surface of the lying area can be total slats, partial slats, solid concrete with bedding or solid concrete without bedding. The sows enter body-length, individual feeding stations (one feeding stall/sow), where they are fed on the floor or in a trough that continues in front of all the stalls. The purpose of this system is to reduce aggression during feeding. Because each sow can randomly enter any feeding stall, individualized rationing is not possible.

    Body-length stalls are used to improve the welfare of the sows. The body-length feeding stalls are also used as a resting area.

    When bedding is used, the feeding stalls are placed on an 8- to 16-in.-high platform, depending on depth of bedding. The minimum amount of space provided/sow is 14.8 sq. ft.

  • Self-locking or manual-locking individual feeding stall

    Self-locking feeding stalls are designed so the rear opening is closed when a sow enters the stall (Figure 1). Manual-locking stalls allow for easier vaccination, estrous detection and artificial insemination, for example.

    Because each sow can randomly enter any of the feeding stalls, individualized rationing is not possible with this feeding system unless each sow is fed by hand.

  • Non-locking individual feeding stall

    Researchers have investigated the influence of the length of feeding stall partition (19.5 in. wide × 6.5 ft. long body-length stall, 19.5 in. wide × 15.6 in. long shoulder-length stall, or no partition) and type of food (wet or dry) on the amount of aggression, frequency of changing position at the trough and duration of time at feeding trough in groups of pregnant sows.

    When sows were provided dry feed, it was reported that increasing the length of partitions resulted in a significant reduction in the number of bites, total aggressive behaviors and displacement at the trough. Time spent at the trough increased.

    When sows were provided wet feed, the number of bites or duration of time feeding at the trough was not different between body-length and shoulder-length partitions.

    Top-ranking sows received less bites toward their head, shoulder and body, and were less frequently displaced at the trough than sows with a lower ranking when eating from a trough with no partition or shoulder partition. Vulva bites were greater when sows consumed either wet or dry feed from a feeding stall with a body partition, compared to a shoulder-feeding stall or a stall with no partitions. Individualized rationing is not possible with this feeding system.

  • Trickle feeding system

    Another method to possibly limit aggression and feed intake by dominant sows is the trickle feeding system. Sows are usually kept in stable groups (4 to 60 sows) and shoulder-length barriers (19 to 24 in. long) separate the feeding trough. An auger apparatus slowly delivers 0.2 to 0.4 lb. of food/minute over a period of approximately 15 to 30 minutes.

    In the ideal system, there is no incentive for sows to move away from the feeder to bully other sows. The slow rhythm of feed distribution encourages the sows to remain at the feed space for the duration of the feeding period. Because each sow can randomly enter any feeding space, individualized rationing is not possible with the trickle feeding system.

  • Floor feeding

    When feeding on the floor, the highest incidence of aggression occurs during the first 30 minutes after feed is delivered. As expected, dominant sows defend the center of the pile of feed. Subordinate sows quickly grab food at the edges and move only when forced to do so. Unequal feed intake between sows within the group has detrimental effects on body reserves, especially for the low-ranking sows.

Body weight gain is reportedly 40 to 50 lb. lower for low-ranking sows compared to high-ranking sows when floor-fed. Aggression over food during a single feeding is not totally eliminated by providing piles of feed at several locations within the feeding area (Figure 2).

Space requirement

Although the amount of space needed/sow or gilt is a critical factor, the optimal amount of space needed/sow or gilt when group-housed during gestation has not been adequately investigated. The suggested space requirement when sows or gilts are housed in groups in the United States appears in Table 5.

Group size

The optimal number of sows/pen and management procedures have not been adequately investigated. A wide range in number of sows/pen and management procedures are utilized.

With respect to reproductive performance in two research projects, farrowing rate and litter size were not different over the range of five to 40 sows or 12 to 28 sows/pen.

In reality, group size is often confounded with group stability because larger groups can usually only be operated on a dynamic basis. Because the number of pens and size of pens often cannot be easily changed, pork producers quite frequently add recently bred sows to a pen during the breeding phase and during the first 30 days of gestation. The variation in number of sows bred/week or group is a contributing factor to this problem.

Ease of management

Each type of breeding-gestation facility design has advantages and disadvantages, as previously noted. An important consideration when designing a breeding-gestation facility is the ease in performing estrous detection; artificial insemination, pregnancy detection; health procedures; moving of animals (width of alley, open gates cutting off alley, ease of working gate latch); and feeding and watering.

The ease to successfully artificially inseminate estrous females is particularly noteworthy. If weaned sows are housed in groups, a procedure must be implemented whereby estrous sows can be inseminated without being ridden by other sows during the insemination process.

Table 1. Influence of Gestation Housing System on Number of Piglets Born Alive/Litter
Group-housed indoors
Feeding stall
Location of study Stalls indoors Floor fed Locked Open Electronic feeder Trickle feeder
Nebraska 9.80 9.60
Netherlands 10.31 10.11
Sweden 11.03 10.88 11.13
Sweden 11.80 11.50
United Kingdom 10.77 10.70
Netherlands 10.70 10.90 11.00 10.70
Sweden 10.20 10.10 11.30
Sweden 10.40 10.20
Sweden 11.42 11.21 11.34
Texas 8.90 9.90
United Kingdom 10.20 10.50
Sweden 10.02 10.32
Minnesota (Parity 1) 9.80 10.50
Minnesota (Parity 2) 10.11 10.12
Denmark (Herd 1) 11.20 10.70
Denmark (Herd 2) 11.40 11.60
Denmark (Herd 3) 11.90 11.40
Kansas 9.77 9.77
Sweden
(gilts) 9.10 9.70
(sows) 11.8 10.8
Table 2. Influence of Housing Method on Reproductive Performance (71 farms in Northern Italy)
Method houseda
Item G S SG1 SG2 GS
Weaning to mating Group Stall Stall Stall Group
Stage of gestation
0 to 14 days Group Stall Stall Stall Group
14 to 28 days Group Stall Group Stall Stall
28 to 50 days Group Stall Group Group Stall
50 to 110 days Group Stall Group Group Stall
Farrowing rate, %
1997 76.28 77.71 69.60 72.68 70.03
1998 75.85 76.61 70.56 70.59 69.77
Average number of piglets born alive/litter
1997 9.89 10.24 9.49 9.78 10.14
1998 9.87 10.18 9.50 9.63 10.24
Number of piglets weaned/sow/year
1997 19.78 20.82 18.61 19.27 19.28
1998 19.47 20.66 18.06 18.38 18.92
aG is group housing for the entire time of mating and gestation.
S is stall housing for the entire time of mating and gestation.
SG1 is stall housing during mating and grouping during 14 to 28 days of gestation; group housing remaining period of gestation.
SG2 is stall housing during mating and grouping during 28 to 50 days of gestation; group housing remaining period of gestation.
GS is group housing during mating and housing in stalls 14 to 28 days of gestation; stall housing remaining period of gestation.
Table 3. Influence of Gestation Housing System on Sow Performance
Item Herd 1 Herd 2 Herd 3
Type of housing Dynamic group Dynamic group Stall Dynamic group Stall Dynamic group Static group
Feeding ESF1 ESF Individual ESF Individual ESF Floor
Type of flooring Partly slotted Deep litter Partly slotted Partly slotted Partly slotted Partly slotted Partly slotted
Time of mixing After service After service After service 4 wks after service 4 wks after service
No. litters 313 348 354 455 265 364 365
Sows removed, % 17 13 29 24 12
Farrowing rate, % 83 84 87 86 94 94 95
Liveborn per litter 10.7a 10.7a 11.3b 11.9 11.7 11.8 12.0
(Nielsen, 2003)
1ESF = electronic sow feeder; a,bMeans differ (p < .05)
Table 4. Influence of Gestation System on Live Piglets per 100 Sows Bred
Mixed pre-implantation
(< 7 days after mating)
Mixed pre-implantation
(> 35 days after mating)
Item Stalls Static Dynamic Static Dynamic
Gilts 763 666 678 734 763
1st parity 894 891 855 965 914
2nd parity 973 906 958 929 1,020
Mature sows 951 910 884 995 995
(Gonyou, 2004)
Table 5. Recommended Space Requirements for Sows and Gilts Housed in Groups (MWPS-43)
Animal Body weight, lb. Solid floor (sq. ft./head) Fully and partially slotted (sq. ft./head)
Breeding gilt 250 to 300 40 24
Breeding sow 300 to 500 48 30
Gestating gilt 250 to 300 20 14
Gestating sow 300 to 500 24 16

Fixed and Variable Cost

The National Pork Board recently released a CD, “Sow Housing Alternatives Calculator,” which contains spreadsheets to estimate the cost of building or remodeling a gestation facility.

The spreadsheets evaluate the production and financial implications of remodeling an existing individual-stall gestation facility to house sows in groups, building a new gestation facility to house sows as groups, and constructing a new hoop structure that houses sows and feeds them either indoors or outdoors.

The main input categories of the model include cost of building structure, cost of equipment, annual ownership cost and annual variable cost of gestation facility. The following annual ownership costs can be easily changed: labor, feed, utilities, veterinary and health supplies, semen, loan payment and depreciation on breeding stock. The user can enter known values or have the computer calculate values.

After the total annual ownership and variable costs are calculated, the user can change the reproductive performance values (farrowing rate, litter size, litters/sow/year) to estimate their effect on cost of the gestation phase/pig weaned.

Managing Sows In Gestation

Sow herd management is generally broken into the three phases of a sow's life — gestating a litter, nursing a litter and not pregnant but getting ready for the next litter.

The longest of the three phases — gestation — could arguably be the most critical phase. In the very early stages of pregnancy, between Days 11 and 12 after ovulation, the fertilized eggs produce estradiol, a hormone that is critical to the recognition of pregnancy. Within the next two to six days, the new fetuses will attach to the uterine wall of the sow, and the placenta is formed to provide a metabolic exchange between the fetuses and the sow.

The placenta is a transitional endocrine organ that produces hormones and is responsible for maintaining the pregnancy, stimulates the maternal mammary glands and promotes the growth and development of the new litter. From start to finish, this process known as gestation takes roughly three months, three weeks and three days. Toward the end of gestation, 2-3 weeks before the litter is born, fetal growth is accelerated, putting greater physiological and nutrient demands on their mother.

It is this phase of pork production — managing sows in gestation to maximize reproductive prolificacy — that this 42nd edition in the Blueprint series is devoted to.

Gestation Management

Central to managing gestation effectively is the proper care and feeding of sows and gilts. Done well, females will remain productive through numerous parities. Poor management in this critical stage will result in high sow culling rates and excessive mortalities.

One of the tools pork producers and veterinary consultants use to guide sow management is evaluating body condition when sows are weaned, and at regular intervals throughout the gestation period. Between pages 6 and 7, you will find a special “Sow Body Condition Scoring Guidelines” poster to help managers and employees in evaluating sow condition.

Supplementing the poster, an adjoining article elaborates on the indicators of sow body condition, outlines methods for measuring weight and backfat, and presents guidelines for utilizing body condition scores in the feeding and management of gestating sows.

Additional articles follow with more detailed discussions on sow housing alternatives, nutrient management for improved condition and productivity, and the health care and maintenance of gestating sows.

A percentage of sows in any breeding herd will fail. Some will be culled voluntarily for poor prolificacy or poor disposition. Others will be culled involuntarily — most commonly for reproductive failure. A few sows will die.

In an effort to get a better handle on why sows are culled, Iowa State University researchers, funded by Pork Checkoff, investigated the physical and reproductive condition of over 3,000 culled sows delivered to two midwestern packers. Their report begins on page 28.

All sows are eventually culled, of course. Closing this Blueprint edition, the final article discusses the cull sow market and reviews management and economic parameters producers should consider in an effort to optimize the value of those cull sows.

Sow Culling Benchmarks

Several metrics serve as indicators of a sow herd's success or failure — farrowing rate, pigs born alive/litter, mummified and/or stillborn pig rates, average sow parity, pigs weaned/mated female/year, sow culling rate and sow mortality rate. All can be used to measure success or failure, but the latter three are most often quoted.

The 2004 year-end PigChamp report shows farrowing rate averaging 77.7% on the 225 farms in the benchmarking database (Table 1). A closer look at the upper and lower 10 percentile reinforces the significant differences in death rate and culling rate. On average, the database reports death rates at nearly 8% and culling rates pushing 44%. In pigs, the difference between the upper and lower 10% averages 5.5 pigs/mated female/year.

Turning to another dataset from Swine Management Services, Fremont, NE, Table 2 shows data from 150 farms out of their benchmarking database of 225 farms. Farms that were expanding, depopulating, repopulating or starting up were dropped from the dataset. Farm size ranged from 300 sows to 11,000 sows. The most recent 52 weeks of data from each farm was used, which represents 289,217 sows.

The pigs weaned/mated female/year (PW/MF/Y) figure is used as a standard metric because farms differ in the way they enter gilts into their production records.

Figure 1 shows the distribution of farms falling between 17.5 and 27.0 PW/MF/Y. The productivity of the 150 farms displays a typical bell-shaped curve. However, when culling and death loss levels are expressed as a percentage and related to PW/MF/Y (Figure 2), sow culling trends do not differ, notes SMS's Ron Ketchem. “This leads us to think there are several variables that affect sow culling decisions that may not be under the control of management, such as cull sow price, flow of replacement gilts, age and repair of facilities, etc. (However), the trend for mated female death loss shows a slight drop as farms increase PW/MF/Y. This suggests that the top-producing farms are doing a better job of finding and treating the health-challenged animals.”

Looking at culling rate only (not shown), the range from 15% up to 80% is noteworthy. Likewise, sow death loss ranges from 3% up to 19%, reinforces that stockmanship and finding and treating health-challenged females has a big impact on productivity.

Benchmarking data offers industry guidelines, but genetics, management and herd health play a large role in lifetime productivity.

Table 1. PigChamp 2004 Year-End Summary (N= 225 Farms)
Measurement Average Upper 10 percentile Lower 10 percentile
Total number of services 3,768.60 7,573.00 896.00
Number of sows farrowed 3,042.52 6,388.00 721.00
Farrowing rate, % 77.72 85.40 67.80
Pigs weaned/mated female/year 21.25 23.70 18.20
Culling rate, % 43.82 29.10 58.90
Death rate 7.87 3.70 12.00
Table 2. Swine Management Services Sow Herd Benchmarking Data*
Farm Rank Pigs Weaned/Mated Female/Year Culling Rate,% Death Rate,% Total Farms Total Mated Females
Top 10 % 24.70 53.81 7.82 15 31,121
Top 25% 23.87 50.18 8.81 38 85,112
Top 50% 23.12 50.73 9.53 75 170,170
Total Farms 21.99 49.85 9.82 150 289,217
Bottom 50% 20.30 49.13 10.16 75 122,030
Bottom 25% 19.48 50.62 10.66 37 59,249
*NPPC Production and Financial Standards calculations