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Articles from 2005 In April

Producing Repeatable, Efficient Growth

Pork producers in our client base are searching for predictable, efficient growth with every insemination in the breeding barn and with every load of weaned pigs. These clients have challenged each other to improve production and identify those drivers of efficiency that have allowed them to produce more pork with less work and cost and to generate more profit.

This article will discuss recent advances and some of the simple math behind our decisions.

From Sows to Weaners

One simple strategy many of our smaller clients have adopted is to stop breeding sows and join a weaned-pig sow center. The sow centers have afforded them the opportunity to focus on on-farm milling and efficient growth of all-in, all-out (AIAO) pig flow and update facilities while still reducing total labor needs.

Apart from labor and economics of trips for the sow center, pig growth and single-filling barns greatly enhance facility throughput.

Larger producers are looking at the same flow dynamics. A producer with a 1,200-head barn or a 2,400-head site wanting to single-fill is considering ownership in a larger 5,000- or 6,000-sow farm. A 6,000-sow farm producing 22 pigs/sow/year can easily fill a 2,400-head site/week with all barrows in one barn and all gilts in the other.

Greater sow herd efficiencies have allowed our 6,400-head site at 24.5 pigs/sow/year to produce over 3,000 pigs each week.

Producing 3,000 pigs/week would allow that producer with a 2,400-head barn site to fill half of the site with barrows and half with gilts, all within seven days of age. Plus, he could meet the needs of another producer-member in the group requiring a 600-head barn site filled in that same week.

Logistics requires a balance of all the producers in the group so that an even, predictable schedule will meet the pig flow requirements of the entire group.

Balancing these sow herd efficiencies with barn site fill time and barn flow requires a great deal of communication and cooperation.

Later Weaning Challenges

Our challenge as a management service and production system is to weigh the benefits of increased lactation length on the overall production of the entire system.

Producers throughout the industry have moved quickly toward increasing lactation length. In 2003, Kansas State University (KSU) aggressively promoted its benefits: nearly $0.90/pig/day of age as average lactation length increased from 15.5 to 20.5 days. This was highly predictable, highly repeatable research that we have begun to implement within our production system.

In general, the research says that nearly $1 a day for each day of weaning over 15 days is predictable as you get closer to 21 days of age. This is value provided throughout the growing period.

The KSU research also evaluated mortality, with a predictable difference of up to 4% in group mortality.

Going All-In, All-Out

AIAO is seen as an absolute requirement for growing pig facilities. Hotel-style nurseries with several rooms lining a hallway have even come into question in efforts to reduce the spread of respiratory disease. The chief concern is limiting the spread of porcine reproductive and respiratory syndrome (PRRS) virus, and most critically, managing the disease in PRRS-positive sites.

For that reason, AIAO has been a generally accepted practice for years. We have now begun to add further “gold standards” in our production system, with such critical control points as minimum age and weight.

In our system, 16-day minimum age and 7-lb. minimum weight are weaning targets. This will soon be changed to 18-day minimum age and 8-lb. minimum weight.

Increasing Weaning Age

Cate Dewey, DVM, University of Guelph, Ontario, and others have given talks on increasing weaning age without adding farrowing crates. She addressed several limits to farrowing utilization in 2001 at the American Association of Swine Veterinarians annual meeting:

  • Increasing number of times weaned per week

    Minimum age drives the total improvement in lactation length. You will not be able to improve more than 0.5 days in average lactation length by weaning more than twice per week.

  • Reducing the number of days loading time prior to farrowing

    Decreasing load time prior to farrowing is somewhat risky in a fully productive breeding barn because the system, in essence, is already full. Moving time is often two to three days prior to farrowing, depending on the number of weanings per week. Inventory of prefarrow sows at any given day will allow you to monitor this practice and manage the farrowing barn appropriately. Reduction to three days prior to farrowing would be ideal if you are weaning three times per week. If weaning twice per week, it may be necessary to load up to five days prior to farrowing with a range of three to five days.

  • Restricting split weaning and bump weaning

    Split weaning is a common practice to improve wean-to-estrus interval and pig weaning weights by essentially reducing the number of piglets on the last three to five days of lactation. However, this practice does pull younger pigs ahead and reduces the lactation length of those piglets. Bump weaning is also common and requires high-quality, mid-lactation nurse sows. Bump weaning should be restricted when lactation length is already tight and weaning age has been reduced to the minimum age.

  • Adding farrowing crates

    This is certainly the only predictable way to achieve increases in the production of high-quality pigs.

Denmark's swine industry has maximized later weaning strategies by driving all lactation to above 21 days. Gilts are commonly lactated over 30 days.

Additional farrowing crates are necessary in most modern U.S. systems to exceed 16 days lactation.

Farrowing Economics

Table 1 on page 23 describes two options for determining farrowing crate utilization.

The most common way to determine the necessary number of farrowing crates in a production system would be to calculate the desired farrowings per week and simply provide enough farrowing crates for three groups in the farrowing house.

For example, if total crates available were to be three times the farrowing target, your common farrowing target would be the desired number of farrowings per week based off of the sow herd inventory.

As shown in Option #1 in Table 1, many producers in our system were looking at 2.45 litters/sow/year as an optimum and predictable number for their system. For example, in a 2,400-sow farm, 2.45 litters/sow/year would require 113 litters farrowed/week. The 113 farrowings/week and 360 farrowing crates were thought to be the proper parameters to provide three full weeks of farrowing crate capacity.

But several concerns surfaced. Most notable was that while the 14-day minimum lactation length was a predictable number that we could manage, the number of total sows farrowed/week varies both with season and farrowing productivity. When 120 sows were farrowed/week, we were still able to maintain that 14-day minimum. However, the average lactation length and number of litters weaned/week were increased in an effort to keep this minimum in place. We also found this approach produces too little predictability and too much variability.

Option #2 in Table 1 is the use of desired lactation length as opposed to desired farrowings/week to drive farrowing capacity. Desired lactation length of 14 days, plus the spread in ages of litters weaned/week and the average prefarrow load days, led to a different calculation method. This calculation adds the minimum lactation length, spread of weaning ages/week and average number of load days prior to farrowing, then divides the sum by seven (days in a week).

For example, a minimum lactation length of 14 days, plus a spread of 3.5 for two weanings/week and the additional three days for an average prefarrow loading, equals 14 plus 3.5 plus 3 divided by 7. This calculation provides the 2.92 (or roughly 3) factor, which made us feel three was the appropriate number for providing three full weeks of sows, or three full farrowing groups in the farrowing house at any one time.

We now know that we would want a minimum lactation length of 18 days and a spread of 2.33. Using this calculation, 18 days of minimum lactation plus 2.33 (7 days divided by 3 weanings per week) plus 3 days of prefarrow loading time, on average, requires at least 3.3 available groups in farrowing.

From this math, we conclude that if our 2,400-sow farm needs to reach 113 farrowings/week to meet our desired litters/sow/year, then we need to provide at least 373 farrowing crates on this farm (113 farrowing crates times 3.3 groups).

Our calculation would also tell us that if we add one more 24-crate farrowing room, we are then simply providing 397 total farrowing crates, using our 3.3 factor for groups. We can farrow 116 sows on a weekly basis and still not have to lactate any sows for less than 18 days.

If this farm runs at two weanings/ week instead of three, we will need to use 3.5 as the farrowing group's total, which would push our total crate needs over 397.

Farrowing Crate Economics

As with all decisions in swine production, economics must be balanced along with production. The economics of adding 24 farrowing crates was $2,300/farrowing crate, or $230/pig space, based on 10 pigs produced/litter.

In that system, those additional pig spaces made perfect sense if we were able to achieve that $1/day payback for every day we exceeded that 15.5 average lactation length. We simply went from a 15.5 to an 18.75 average lactation length, or $3.20/pig value on every pig that would be added back for the investment of $55,200 (24 more crates at $2,300/crate). At 22 pigs/sow/year on a 2,400-sow farm, the investment of $55,200 brings greater value of $3.20/pig on 52,800 pigs in the first year. The payback time is less than six months.

Note that nothing was factored in for improved sow productivity. Sow herd fertility improves wean-to-service interval, litter size and overall herd productivity.

Performance Targets

To judge performance of those growing pigs, review performance targets within the system and where the system is going (Table 2). A 12-lb. weaning weight would provide many producers with a high-quality pig easy to start, and present little challenge within that first five to seven days coming on feed.

Just two years ago, producers were looking at 10- and 11-lb. average starting weights. Our top 10% goal would be to bring these producers a 14-lb. pig as quickly as we can move it into the system. This 14-lb. pig would include a 20-day average lactation length in our system, based on a change of 0.5 lb. of weaning weight for each additional day beyond 15- to 16-day lactation lengths.

Average Daily Gain's Impact

The greatest number driving productivity and throughput is average daily gain. Monitoring daily gain is a tool we are only now beginning to understand with automatic sorting technology or even simple portable scales.

This technology established that a single-fill population close in age at start time, as well as optimum in weaning weight, would lead to less variability throughout the group. Combining that with appropriate feeder and water space and square footage for growth should result in a uniform population on the right path to ideal growth.

Research trials from both Mike Brumm at the University of Nebraska and Noel Williams with PIC have provided guidance in determining both the ideal welfare and environment for optimum, profitable performance throughput for the system.

Brumm has shown that pigs will require a minimum 1.5 in. of stainless steel dry-feeder space/pig in our system. What this means is that each 14-in. dry-feeder hole can support nine pigs. Pens with 25 pigs/pen have a three-hole feeder available. Pens with 50 pigs/pen are allowed both sides of a three-hole, dry feeder.

This 1.5 in. of stainless steel feeder space/pig is the same whether you are talking nursery pigs or finisher pigs.

As with the feeders, no more than 25 pigs are started on a drink cup or nipple waterer. Many producers using swinging waterers have two nipples available, but we still have to recognize that this may, in many cases, provide only one available drinking space.

Managing to Reduce Variation

In many of the automatic sorting systems, we have gone to 2 in. of stainless steel dry-feeder space/pig.

PIC's Williams has provided us with both the tube and dry-feeder recommendations. PIC requirements with our pigs have led us to a minimum of 2 in. of trough space/pig with tube feeders and a maximum of 11 pigs/tube feeder. Tube feeders serve as a competitive feeding environment as opposed to dry feeders, and therefore, additional space is necessary in this system.

As we evaluate growth and variation within the system, we still have to get back to start weight and fill time and their effect on variation for the population. Refer to Figures 1 & 2.

In evaluating start weight variation, recognize that the standard deviation of early-weaned pigs has commonly been placed at 2 lb. In a bell-shaped curve of a normal population, with a 12-lb. average weaned pig, 2.5% of that group will still fall in the 6- to 8-lb. range.

What this means is that for an average load of 1,000 pigs delivered, with an average weight of 12 lb., there will still be 25 pigs that fall between the weight range of 6 to 8 lb. If we don't want any pigs less than 7 lb., then it is critical to find a method to reduce variation, either by removing the pigs or providing them a way to gain additional weight prior to starting in the nursery.

Weaning Variation

Nurse sow and bump wean activities are most common if farrowing crates are available. However, we still need to recognize that it is a normal population, and variation is going to begin at weaning time.

University of Minnesota's John Deen, DVM (See “Solutions to Control Variation,” p. 30), has shown that a 7-lb. pig at weaning time is three times more likely to die in the nursery. A 2-lb. entry variation becomes a 10-lb. variation at slaughter.

Accepting these simple rules of thumb, it is then necessary to do our very best at reducing variation at the earliest stage possible, providing the best environment and facilities throughout the pig's life.

Earlier Move to Finishing Profitable

The growth rate of an early-weaned pig is by no means a bell-shaped curve. We recognize that the aggressive growth phase may certainly be compromised by square footage reductions in the nursery phase.

A few producers in our system are now looking at moving pigs out of the nursery earlier and providing additional finishers or finisher spaces in an effort to maximize the growth phase of today's high-lean pigs. What this means is that pigs are achieving 2-lb./day average daily gain in the 50- to 250-lb. growth period. Therefore, it becomes detrimental to have a 70-lb. pig at 3 sq. ft., sacrificing this aggressive growth potential. Some of our clients have moved these pigs at 6 to 6.5 weeks of age into 7.5 sq. ft./pig space to maximize their growth potential.

In a 25.5-week system, or at 8.5 weeks in the nursery phase, this change would mean that a system of one nursery and two finishers now becomes a system of one nursery and three finishers. The nursery is simply run at 6.375 weeks, and three separate finishers house pigs for 19 weeks. This approach is paying dividends to our clients.

Other clients have looked at reducing pig space from 7.5 sq. ft. to 7 sq. ft. The change has brought behavioral and daily gain differences in our production system. Anything under 7.5 sq. ft./pig has become detrimental to the productivity of pigs in our system.

Table 1. Farrowing Crate Calculations

Option #1: Farrowing Crates Available — The decision is driven by the desired number of farrowings/week.

Total number of farrowing crates divided by the desired number of farrowings/week

Calculation: (Herd size X 2.45 litters/sow/year ÷ 52 weeks in a year)

Example: 2,400 sows X 2.45 ÷ 52 = 113 farrowings/week

Results: 360 farrowing crates (per room) ÷ 113 = 3.18 ratio (number of weekly groups in farrowing at any one time)

Option #2: Lactation Length — The decision is driven by the desired minimum lactation length.

Calculation: Minimum lactation length + age spread + load days ÷ 7

Age spread = 7 (days in a week) ÷ the number of times pigs are weaned/week.

Load days = the number of days prefarrowing for sows in a farrowing barn (three days is a common number of load days if pigs are weaned three times/week)

Target: 3.3 ratio allows a 17-day minimum lactation length/pig

3.5 ratio allows an 18-day minimum lactation length/pig

Farrowing target X formula = the number of farrowing crates necessary per room to achieve a minimum lactation length/pig

Example: 113-day farrowings/week target

X 3.3 ratio = 373 crates (17-day minimum lactation length)

X 3.5 ratio = 396 crates (18-day minimum lactation length)

Table 2. Performance Targets
Current Production Top 10 Target
Average weaning weight 12 lb. 14 lb.
Average weaning age 16 days 20 days
Average daily gain (wean-to-finish) 1.65 (1n + 2f)a 1.70 (1n + 2.1f)b
Average daily feed intake 3.97 lb./day 3.97 lb./day
Feed:gain 2.4 lb. (1.4 n + 2.7f)c 2.34 lb. (1.4n + 2.48f)d
Slaughter weight 270 lb. (156 days on feed) 280 lb. (156 days on feed)
a1n=1-lb. average daily gain in nursery rooms and 2f= 2-lb. average daily gain in finishing facilities.
b1n= 1-lb. average daily gain in nursery rooms and 2.1f= 2.1-lb. average daily gain in finishing facilities.
c1.4n=1.4 lb. feed:gain in nursery rooms and 2.7 lb. feed:gain in finishing facilities.
d1.4n=1.4 lb. feed:gain in nursery rooms and 2.48 lb. feed:gain in finishing facilities.

New Advertising Campaign Launched

The National Pork Board has taken its “Pork. The Other White Meat” advertising program, launched in 1987, to the next level. After an 18-month research effort, the “Don't Be Blah” campaign was launched.

Research found that many women ages 25 to 49 have children under the age of 17, and characterize their lifestyles as modern, hectic and family-centered. These women described pork as an old-fashioned, special-occasion meal.

“We wanted to create clever, contemporary, risk-taking messages that would capture consumers' attention,” says Craig Christensen, immediate past president of the Pork Board and a pork producer from Ogden, IA.

The campaign, announced recently at Pork Industry Forum in Orlando, FL, will be carried through television and radio commercials, magazines, Internet Web sites and in-store promotions.

The new television ads are being aired in Chicago, Philadelphia, Atlanta, Dallas-Fort Worth, Denver and Sacramento. Magazine advertising includes O magazine, Cooking Light, People, Parade and Reader's Digest.

The new campaign is leading consumers in record numbers to the pork checkoff's redesigned Web site.

“It's just phenomenal,” says Pamela Johnson, director of Consumer Communications for the Pork Board. “By March 21, shortly after the launch of the new ‘Don't Be Blah’ campaign, the site had more than 150,000 visitors. Prior to the new campaign, the average was 60,000 visitors per month in 2004.”

Hall of Fame Award

R.H. (Moe) Mohesky, president and chief executive officer of Clover M. Farm Inc., Sharpsburg, NC, received the Pork Industry Hall of Fame Award from the National Pork Producers Council (NPPC) at Pork Forum.

During his 30 years with Cargill's Feed Division, Mohesky served in a variety of local, state and national leadership positions, including NPPC president. He is also a past president of the Carolina/Virginia Feed Industry Council and was chairman of the U.S. Meat Export Federation.

NPPC Picks New Leaders

A new slate of officers and board members were selected at the recent annual meeting of the National Pork Producers Council (NPPC) at Pork Industry Forum.

Elected president is Don Buhl, the Tyler, MN, owner of Buhl's Ridge View Farm Inc., a wean-to-finish operation that markets 20,000 hogs. Buhl was president of the Minnesota Pork Producers Association in 1996.

Joy Philippi, a pork producer from Bruning, NE, is president-elect. She owns Pine Alley LLC, which includes a 2,000-head nursery that handles 14,000 pigs annually, from weaning to feeder pig size, for a local producer network.

New NPPC vice president is Lois Britt of Mount Olive, NC. She serves as special assistant to the president of Murphy-Brown LLC and owns a crop and livestock farm.

Elected recently to the NPPC board of directors were:

  • Sam Carney of Adair, IA, owner of Carney Farms, a wean-to-finish production system that markets 6,000 hogs annually.

  • Mark Street of Ephrata, WA, owner of Sun Basin Pork Farms, which includes a wean-to-finish operation marketing over 2,000 hogs/year.

  • Dan Sutherland of Watertown, WI, who works at Johnsonville Sausage LLC and will serve as the Packer Processor Industry Council representative on the NPPC board.

Solutions To Control Variation

Managing variation in pig production involves examining what can be accomplished within the current production system model.

For example, if we realistically look at the potential output of a typical grow-finish barn, we can see huge differences in performance and financial rewards.

My definition of variation is not meeting the potential of a high-quality output. A high-quality output is where the number of pigs sold is equal to the capacity of the barn, and each pig is sold or transferred at its economically optimum weight.

In many ways, we fail miserably at this aim of creating a high-quality output.

Documenting Failures

So where do we fail?

There are five broad areas in nursery and grow-finish barns, listed as follows:

  1. Barns are not filled to capacity. In other words, there are empty spaces in the barn that are not earning an income. This is recognized as a real revenue loss and is to be avoided on most farms. The challenge, in many cases, is for the sow farm to be more vigilant in managing variation of reproductive output.

  2. The capacity of a barn is filled, but some pigs are not marketed due to death. Late-stage mortality is particularly expensive to a hog operation.

  3. A portion of the pigs grows slowly and is sold to a secondary market as cull pigs.

  4. A portion of the pigs grows slowly and is sold to the regular slaughter plant, but at a discount. This discount can either be on the base price, or simply based on a lower amount of margin due to less pounds sold.

  5. A portion of the pigs grows quickly and is sold above optimum weight, which also results in discounts. This is managed on most farms by early marketing.

For analytical purposes, under-filling barns are analyzed separately in many cases, as it is a result of variation in reproductive output. Likewise, overweight pigs are analyzed separately, as the challenge is in sorting and marketing.

Dead Pigs, Culls, Lights

The main quality concerns are actually in the area of what we call DCLs, known as “dead pigs, culled pigs and light pigs.” The major quality constraints are when the pig stops breathing or stops growing.

In most hog barns in North America, the causes of mortality and slow growth are often interrelated.

For most infectious disease challenges, we see a wide range of disease expression — from sudden death to subclinical signs of disease with slower growth. It is often useful to group all poor-quality pigs into one category. In doing so, DCL rates are often over 10% in grow-finish barns.

Financial Analysis

The first challenge in any analysis is to attribute some sort of financial cost to the problem. Figure 1 shows a simple graph where we examined the margin over variable costs for 110 closeouts of grow-finish barns within one system. We kept all prices equal, and simply compared the financial performance of the groups by defining the variability of the margin attributable to three variables.

The first category consists of the DCL pigs.

The next category represents average daily gain for those pigs outside of the DCLs. We have emphasized average daily gain, as fixed costs of the building and contract costs are often the second-largest cost category in rearing grow-finish pigs.

The third variable is feed conversion for the pigs that survive to market weight. Historically, we have emphasized feed conversion as the major opportunity for profit improvement because it is the largest cost of rearing grow-finish pigs.

Time and time again, we have seen that the feed conversion of the DCLs provides the most contribution to variation in profitability, and thus comprises the area of greatest opportunity for improvement.

I think the reason this area has often been underemphasized is because, as an industry, we have emphasized cost of production instead. Cost of production analyses rarely categorize pigs in terms of deads, culls or lights.

In doing so, cost of production analyses do not recognize unrealized income. The real losses due to poor-performing pigs are in the area of reduced value, often called an “opportunity cost” or money left on the table.

To understand the opportunity cost problem, I often ask producers to estimate the losses associated with a good, 250-lb. pig dying in the grow-finish barn. The common answer is the pig could have been marketed at 280 lb. at a value of about $125. The only production cost “savings” is the feed the pig would have eaten from 250 to 280 lb. — about $5. The difference, $120, is the opportunity cost of that pig dying. This is captured in Figure 1, but is not captured in normal profit-and-loss statements.

Another example: Lightweight pigs sold at a discount may bring in $90 instead of $125, with feed savings of $10. Sale price and feed savings equals $100, leaving a loss of $25 in opportunity costs that are never captured in our current record-keeping systems.

Financial analysis, for the purposes of analyzing variation, thus involves some level of pro forma analysis. In other words, we need to estimate what income the farm could earn if a pig did not die or grow slowly.

These are calculations beyond the profit-and-loss statement, but can be done easily by producers. This process involves simple “what if” questions such as, “If the pigs did not die, how much extra profit would there be?”

Combining the elements of the DCL category often result in an opportunity cost of greater than $10/pig placed. A characteristic of this opportunity cost is the huge variation from group to group and from farm to farm. In quality control terms, it can be viewed as an uncontrolled cost.

The wide variation brings into question whether farm management is conducting adequate analysis and control efforts.

I would argue that variation has been under-analyzed and thus is a much greater cost than it should be.

Identifying Causes of Variation

Variation can have two broad sources. The first is the quality of the inputs. In this case, we are particularly looking at the quality of the pigs that entered the barn. The old saying, “Well begun is half done,” still resonates in the pig world. However, we rarely analyze quality of pigs at entry.

The second source of variation is within the barn. Problems crop up that cause some pigs to fail. This is an easy divider, though the more we look at this area, the less obvious the split between quality of pigs at entry and the variation processes that occur afterwards.

The big problem in growing pig records is that the focus has been on managing averages. This is useful when looking at interventions that may have a similar effect across all pigs.

Usually, nutritional interventions are expected to have the same impact on each pig. However, the opposite is quite often true when it comes to disease control.

Managing averages is different than managing individual pigs. A strong argument can be made that the essence of good pig care is in differentiating the needs of pigs. Yet records and management emphasize that the averages tell the story.

Influence of Disease

Disease produces differential effects on pigs, particularly in the case of bacterial disease. We see some pigs that are not affected, while others are devastated.

Thus, an intervention with any disease control method will benefit some pigs more than others. The DCL pig category often captures the great majority of pigs affected by a disease mechanism. With the challenges and variation we see in most herds, the DCL pig category is often the best description of problems in variation.

Specifically, the problem of tail-enders is an example of not meeting a minimum specification for growth. This constitutes a better measure of variation than classical measures such as standard deviation or coefficient of variation.

Questions About DCL Pigs

Our best successes and understanding of variation have been in identifying causes of these DCL pigs. We have three major questions for analysis at this point:

  1. What are the characteristics of pigs at entry that make them more likely to be poor-quality pigs at exit?

  2. Do the problems of poor-quality pigs at entry precipitate disease outbreaks?

  3. What can we do?

Poor Pig Characteristics

The first question is where we have spent most of our time. We have found that the quality of a pig at entry, particularly in the nursery, has a huge effect on the likelihood it will survive and thrive. To assess that risk, we use odds ratios, which are the ratio of the success rate between good pigs and pigs at risk.

For instance, we have found that the failure rate (of DCLs) in one herd was 5.1% for pigs entering the nursery at greater than 8 lb. For pigs entering at less than 8 lb., the failure rate was 16.8%. Therefore, the odds ratio of failure, due to pigs entering the nursery at less than 8 lb., is 3.3 times greater than pigs entering at greater than 8 lb. (16.8% divided by 5.1%).

Other factors found to increase the odds of failure in the nursery include the parity of the dam, gender, crossfostering, source herd and age.

In our experience, weight is the biggest consideration for entry into the nursery. Pig weight has a direct effect on its ability to grow, and often, mount an immune response. Lightweight pigs are much more likely to be chilled and mount a poor defense against infectious disease challenges. They also may have more competition for resources, such as heat and feeder space.

In our analyses of pigs within groups, older pigs with the same weight as younger pigs actually had a higher odds ratio of failure. A pig that grows slowly before weaning is often a problem after weaning.

Gilt progeny also present a challenge. They are more likely to die, and tend to grow slower in the nursery. Pigs from gilt litters may also have a reduced ability to mount a good defense against infectious disease challenges. Gilt progeny are also more likely to be lightweights, a factor contributing to their poor performance.

High Prevalence of Poor Pigs

The second problem with poor-quality pigs at entry is that disease problems are more prevalent. This is a difficult area to study, but it appears that some of the outbreaks of disease we see precipitated in nursery and grow-finish barns are actually due to a high prevalence of susceptible pigs.

We see this especially with either lightweight pigs or progeny of gilts. Once we reach a certain threshold, say 40% of the nursery pigs from gilts, we see a higher likelihood of infectious disease outbreaks, such as Haemophilus parasuis. This may be because these pigs are more likely to carry agents into the barn or because they are more likely to be susceptible to infections.

What Should We Do?

With quality management, we must recognize that we have pigs with different requirements coming into our barns.

The challenge is twofold. First, we must create a population that is more homogeneous. This puts pressure back on the supplier of pigs. Sow units must spend more time creating a homogeneous population from week to week, in terms of age, weight of weaned pigs and parity profile, for example. This puts real pressure on the sow unit to look at factors other than simple output of weaned pigs. Factors such as stabilizing the number of sows bred and number of gilts introduced, which may have considerable value in downstream pig quality, are also important.

Focusing on DCLs also allows for better differential care, with stockmanship helping to lower the odds of the pig failing. In many ways, the best test of stockmanship is the ability to manage poor pigs. Many of our reward systems fail to recognize this because our recordkeeping systems are inadequate.

We must also recognize that extraordinary efforts are valid for a subpopulation of pigs within our barn. High-quality feed, extra heat and intensive disease control are all quite rewarding for at-risk pigs.

There are also processes that create DCLs not associated with quality at entry. In some cases, this may be due to inadequate data, or there is nothing available to control. Here disease control methods are definitely still needed. For instance, vaccinating for Mycoplasmal pneumonia is a solid method of disease control.

Management must be able to evaluate the financial impact of variation. This will involve more pro forma budgets of the potential incomes created when we get this problem under control. Opportunity costs of poor pigs must have a central part of the discussion in management circles. As long as we focus on cost of production, variation will be underplayed.

The Final Challenge

The real challenge with managing variation is in managing the decision-making process. The swine industry has gone through a time of emphasizing improvement in productivity and then minimizing costs.

We are in the next level of challenge now — managing quality and improving the value of our product. Where there is a large amount of variation in performance, there is the greatest opportunity to improve the quality of the product. Mortality and slow growth are the first two qualities that we must look at more closely.

Switching from a cost-minimization management model has its challenges. We have to move away from a simple management strategy that focuses on average performance and average costs. We must collect more data at the correct level. Our pigs are evaluated at the individual pig level, and therefore our data must reflect that.

Our losses are also seen when individual pigs do not meet minimum requirements. Again, our records must reflect that. Finally, once we have collected that data, we are in good shape to do the correct analyses and improve the value of our pig crops.


Reducing variation not only has financial rewards, it makes management simpler. One of the biggest problems in our management of pig performance is “noise.” In other words, the range of performance is so wide that we cannot accurately detect changes.

We need more stable and predictable performance before we can truly refine pig production and actually lower costs. That is a vision that few pork producers currently carry, but it is an exciting one.

Luce Receives Service Award

The National Pork Board honored William Luce with its distinguished service award at Pork Industry Forum.

“Luce's dedication and commitment to pork producers is very apparent. The programs he developed and the research he has conducted have had national impact,” says Dave Culbertson, National Pork Board president.

Luce served as Extension swine specialist for over 30 years at Oklahoma State University, retiring with the rank of Regents Professor. After retirement, he worked as coordinator of Educational Programs for the Oklahoma Pork Council.

Luce developed and managed the state's boar test stations and coordinated the auction of performance-tested gilts and boars.

Optimizing Reproductive Efficiency

Maximizing throughput or production of a pork enterprise begins with the breeding herd. In order to achieve a consistent flow of pigs, and the minimum variation biologically possible, sows must first be bred, piglets born, and viable pigs weaned in sufficient numbers to meet production targets.

For most producers, between 18 and 26 pigs are produced annually, for every breeding female. The sow herd eats and takes up space and labor regardless of productivity, so it costs almost as much to produce 18 pigs as 26.

Obviously, there is a great deal of variation in pigs/sow/year (P/S/Y) between farms. The P/S/Y that can be achieved by an operation is dependent on facility type, management practices, health, nutrition and genetics.

Also, fluctuations in pig flow occur from changes in management practices, health and personnel throughout the year. Many farms also experience seasonal effects on reproduction.

With all of these factors and the inherent biological variation, pork producers face a stiff challenge to optimize reproductive efficiency and maximize throughput.

Establish Your Goals

What is optimal reproductive efficiency for the breeding herd? As previously discussed, P/S/Y is a good measure, and the most commonly tracked statistic for monitoring performance of the breeding herd.

However, to truly measure the impact of reproductive efficiency on throughput for the entire operation, a more complete statistic would be the pounds of weaned pigs/mated female/ year (Figure 1, page 14).

With this measure, not only are the numbers of pigs produced by each female tracked, but also the size and viability of the weaned pigs, which will impact their future performance and variability in growth.

A reasonable goal would be 275 lb. of weaned pigs/mated female/year. This can be achieved with 2.3 litters/mated female/year, 11 pigs born alive/litter, 9% preweaning mortality and weaning 12-lb. pigs at an average age of 18.5 days. These components then become our areas of opportunity for improvement.

Achieving Your Goals

To maintain optimal reproduction and throughput, a complete understanding of an operation and its productivity are required. Table 1 provides some key productivity indicators to maximize throughput, along with suggested target values. Which indicators to focus on will depend on individual operations.

Most farms should verify that they have targeted an optimal weaning age, work toward increasing the average parity of the sow herd and achieve two matings per service period. Herds with a low P/S/Y should focus on improving breeding techniques that enhance farrowing rate and reduce non-productive sow days. Farms that are average in P/S/Y should look at methods of improving litter size in addition to breeding techniques. Farms that are already doing an excellent job with P/S/Y can look more closely at reducing preweaning mortality and improving litter weights to further maximize throughput.

The need for farms to focus on differing areas based on productivity is illustrated in Table 2. Good breeding techniques and low non-productive sow days make it possible to achieve 2.5 litters/sow/year. When comparing the three sections of Table 2 (blue, black, red) on page 16, it becomes apparent that litters/sow/year and the traits and management techniques that impact it are the most important factors in maximizing P/S/Y.

Obviously, improvements in the number of live born pigs will also increase P/S/Y — but even with 12 live piglets, if litters/sow/year is 2.1 or less, 25 P/S/Y cannot be achieved. Table 2 also demonstrates how reducing preweaning mortality can improve throughput, but large reductions in mortality often come at a fairly high cost.

The remainder of this article will describe in greater detail these indicators and their impacts on optimal reproduction and maximum throughput.

Litters/Mated Female/Year

To maximize the annual pounds of weaned pigs/mated female, an optimal number of litters/female must be achieved. The PigChamp datashare program reports that the top 10% of participating farms achieve 2.5 litters/mated female/year, while the lower 10% reach only 2.08. This results in a 20% reduction in throughput, assuming equivalent performance in other parameters.

Non-productive days: The most significant factor that affects litters/mated female/year is non-productive sow days. The best opportunity for improving throughput and minimizing non-productive days is by reducing the interval from weaning to insemination. Even with older weaning ages, greater throughput can be achieved if the breeding female is pregnant within five days after weaning.

Areas to focus on when reducing non-productive days include sow feeding programs, body condition, insemination techniques, estrous detection, pregnancy detection, gilt pool management, weaning age, parity distribution and sow mortality and culling.

Breeding technique and conception rate: Assuming the sow herd is reproductively healthy and fertile semen is provided, conception rates are most greatly influenced by the breeding technician and his/her heat detection methods and insemination technique. It is not surprising that there are dramatic differences in breeding technicians (Table 3 on page 17).

Technicians need an adequate knowledge of physiology and anatomy in order to make prudent decisions while inseminating females. Careful training of personnel charged with breeding the females, coupled with tracking their performance and a program for continual process improvement, can increase throughput. Reproductive performance also tends to be greater for farms that achieve a higher percentage of multiple matings.

Another concern is what is referred to as insemination fatigue. Farrowing rates may decline when individuals are presented a large number of females in estrus at a given time (Table 4 on page 17). Strategies should be in place to detect and correct this potential problem. Develop a standard routine with rest breaks after 10 to 15 sows.

Research has also shown that reproductive performance of females and boars is higher on farms where animals don't fear humans.

Heat detection: Careful heat detection is essential to minimize the number of non-productive sow days and weaning-to-insemination interval. The failure to detect estrus or breed a sow when in heat will automatically add another 21 days to the number of non-productive sow days.

Heat detection is very labor-intensive and time-consuming, so consequently, most operations do not check heat more than once per day. What becomes more important is the thoroughness and quality of heat detection.

It is important to remember that each female is an individual and will show slightly different signs of estrus. Systematic and consistent heat checks enable one to become familiar with the normal situation of all females and when they are in estrus. The standing reflex is enhanced by intense periods of boar exposure.

However, prolonged boar exposure may result in habituation and fatigue. Use boars to check for estrus in small groups. If the boar is placed in the alley in front of the sow, then estrous detection is a two-person job: one handles the boar and the other checks the sow.

Weaning age: Weaning age is obviously another important influence on litters/mated female/year. But to optimize overall reproductive efficiency, weaning age must be set at an optimal level. Reducing the lactation length will decrease the subsequent fertility of the female by extending the weaning-to- insemination interval, reducing conception rate and decreasing subsequent litter size.

Therefore, to maximize throughput in an operation, the weaning age must be set where it does not significantly reduce sow reproductive performance. In most herds, the greatest impacts on reproduction are observed for lactations of less than 17 days. If a sow is to be rebred, she needs a minimum of three days of nursing to suppress the secretion of lutenizing hormone, avoiding the formation of follicular cysts, or the sow may exhibit erratic estrous patterns or remain anestrus. Carefully monitoring and maximizing lactation feed intake to achieve more than 12 lb./day can minimize the impact of shorter lactations.

Sow feeding and condition: Nutrition and feeding management play a vital role in reproductive performance during each phase of the cycle.

After selection, the gilt pool should be limit-fed to prevent over-fattening prior to breeding, which will impact reproductive performance.

For sows, the feeding period from weaning through rebreeding is critical to reverse the severe drain on nutrient reserves during lactation and to promote conception. However, some level of feed restriction is required to reduce milk flow. Generally, 6 to 8 lb. of feed is appropriate.

Nutritional management during gestation should provide planned increases of 80-100 lb. for Parity 1, 80-90 lb. for Parity 2-5, and 55 lb. for sows greater than five parities. These targets should vary according to sow maturity, body weight at breeding and body condition. Overfeeding during gestation has a well-documented detrimental impact on feed intake during lactation that results in tissue loss for the sow, decreasing her ability to return to estrus.

Maximum feed intake needs to be achieved during lactation to maintain body condition. Extremely thin sows resulting from inadequate energy intake during lactation often experience reproductive failure. A dip in litter size occurs on some farms for Parity 2 sows. The body condition of the sows at Parity 1 during farrowing, and their management during lactation, likely play major roles in whether litter size dips in Parity 2.

Feed intake during lactation is maximized by increasing feeding frequency, ensuring that feed is fresh, increasing the energy density of the diet, and providing for a constant water supply that can deliver 0.25 gal./minute.

Parity distribution: Herds with a high throughput also tend to have a higher average parity. Higher average parity will result in decreased wean-to-estrus interval, increased farrowing rate and increased litter size. Parity 1 sows often exhibit a 0.5- to 2-day longer wean-to-estrus interval than multiparous sows.

Gilts typically exhibit a 10 to 15% lower farrowing rate than multiparous sows. Farrowing rate will remain relatively constant from Parities 2 to 5, but will decrease with high-parity sows.

Generally, litter size is also lowest at Parity 1, increases up to Parity 4 or 5, then tends to level off until it begins to decrease around Parity 7 or 8. In addition, younger sows are more susceptible to increased non-productive sow days associated with reduced lactation length than higher-parity sows.

All of these factors, plus the investment in breeding animals, demonstrates the need for producers to maintain a higher average herd parity to retain more females at, or near, their peak reproductive performance.

Sow mortality and culling: The loss or removal of sows from the herd for non-reproductive reasons will also reduce the overall reproductive rate by increasing non-productive sow days and lowering the average parity. Careful selection of replacement females plus proper management can reduce both sow mortality and sow culling rates.

Gilt pool management: Management of the gilt pool will also significantly contribute to non-productive sow days. If the average gilt is bred on her second or later estrus, another 21 to 42 days will be added to non-productive days. Focus on proper feeding, health acclimation, boar stimulation, heat detection and breeding.

Live Born Pigs/Litter

The contribution of litter size to throughput is important, but not as great as minimizing non-productive sow days. While the genetic program plays an important role in litter size, remember heritability is only 10%. This means 90% of observed variation in litter size is due to other factors.

To maximize the genetic contribution of litter size, a sound genetic improvement program should be followed, along with production and selection of parent females that have maximum maternal heterosis.

To achieve large litter size, sows should be fed to appetite (6 to 8 lb.) postweaning and for the first three weeks of pregnancy. Both high- and low-feeding levels for the first three weeks may compromise the number of fetuses.

Stress prior to, during and following breeding can produce high levels of embryo mortality. Stress on the female can be in the form of physical stress from handling, interacting with other animals or heat stress.

Animals should always be properly handled and not fear their caretakers. It is also important to avoid or reduce sow movement or mixing, especially during critical periods of gestation.

One of the most common mistakes in management is a failure to recognize that females during breeding and gestation are also susceptible to heat stress when temperatures reach and exceed 80-85°F for any period. Heat stress has its most detrimental effect on reproductive performance during two critical stages of the gestation period — the first 30 days and the last 30 days.

In the normal breeding female, 30% of the potential litter number (number of eggs ovulated) are lost within the first 30 days of pregnancy, making management of the female in the first 30 days critical to the production of large litters of viable pigs.

Preweaning Mortality Rate

Mortality of newborn pigs at or soon after birth also represents a major loss of throughput. Preweaning mortality is reduced by attended farrowing, a warm and hygienic environment, adequate care and nutrition of the mother and heavier birth weights.

The easiest way to decrease preweaning mortality is to have a stockperson present during farrowing. Balance the additional labor costs against potential gains. Through attended farrowing, struggling piglets find the udder and are able to nurse and consume adequate colostrum. Also, piglets that would be crushed can be placed in a safe spot under a heat lamp until they can compete for a teat.

Providing the proper thermal environment is the second most critical aspect to reducing preweaning mortality. Ensuring that the sow is not too hot, and the piglets are warm, can be difficult. However, success in both areas will allow the sow to have maximum feed intake, providing the pigs with greater nutrition and greater ability to combat the challenges of malnutrition and disease.

A clean environment also goes a long way in providing a disease-free environment for both the sow and the piglets. Sow health cannot be overlooked. Unhealthy sows, lame sows, and sows with pressure sores are less likely to be adept at lying and responding to their piglets and thus have a higher incidence of crushing.

Target Weaning Weights

The weaning weight of the pig will play a role in the throughput experienced in the nursery and finishing phases. In general, minimize the number of pigs that are less than 9 lb. at weaning. Tracking litter weaning weights and the number of lightweight pigs in a litter can be useful in recognizing problems.

Common reasons why pigs may be below target weaning weights include weaning age, light birth weight, increased number born alive and lack of adequate nutrition from the sow, or diseases like scours, porcine reproductive and respiratory syndrome, joint infections or Streptococcus meningitis.

Table 1. Productivity Measures to Maximize Throughput
Datashare Summarya
Productivity Measure Suggested Value Mean Upper 10% Lower 10%
Pigs weaned/mated female/year > 19 19.1 23.3 17
Non-productive sow days < 60 74 47 103.5
Weaning age, days < 24 18.2 21.1 15.2
Farrowing rate, % > 80 75.6 84.8 64.1
Number born alive > 10.0 10.3 11.1 9.5
Average sow parity > 3.5 3.5 4.3 2.7
Preweaning mortality, % < 14.0 13.4 8.7 17.7
Multiple matings, % > 95 83.4 99.5 66.7
Sow mortality, % < 8.0 7.8 3.2 13.1
21-day litter weight, lb.b > 120
aData for 2003 reported from 199 U.S. farms
bNot reported in PigChamp Annual Datashare Summary
Table 2. Achieving Pigs/Sow/Year Targets with Differing Live Born Pigs, Preweaning Mortality and Litters/Sow/Year
Preweaning Mortality, %
Born Alive 4 6 8 10 12 14 16 18 20
12 28.8 28.2 27.6 27.0 26.4 25.8 25.2 24.6 24.0
11.5 27.6 27.0 26.5 25.9 25.3 24.7 24.2 23.6 23.0
11 26.4 25.9 25.3 24.8 24.2 23.7 23.1 22.6 22.0
10.5 25.2 24.7 24.2 23.6 23.1 22.6 22.1 21.5 21.0
10 24.0 23.5 23.0 22.5 22.0 21.5 21.0 20.5 20.0
9.5 22.8 22.3 21.9 21.4 20.9 20.4 20.0 19.5 19.0
9 21.6 21.2 20.7 20.3 19.8 19.4 18.9 18.5 18.0
8.5 20.4 20.0 19.6 19.1 18.7 18.3 17.9 17.4 17.0
8 19.2 18.8 18.4 18.0 17.6 17.2 16.8 16.4 16.0
Litters/sow/year = 2.5
Preweaning Mortality, %
Born Alive 4 6 8 10 12 14 16 18 20
12 26.5 25.9 25.4 24.8 24.3 23.7 23.2 22.6 22.1
11.5 25.4 24.9 24.3 23.8 23.3 22.7 22.2 21.7 21.2
11 24.3 23.8 23.3 22.8 22.3 21.8 21.3 20.7 20.2
10.5 23.2 22.7 22.2 21.7 21.3 20.8 20.3 19.8 19.3
10 22.1 21.6 21.2 20.7 20.2 19.8 19.3 18.9 18.4
9.5 21.0 20.5 20.1 19.7 19.2 18.8 18.4 17.9 17.5
9 19.9 19.5 19.0 18.6 18.2 17.8 17.4 17.0 16.6
8.5 18.8 18.4 18.0 17.6 17.2 16.8 16.4 16.0 15.6
8 17.7 17.3 16.9 16.6 16.2 15.8 15.5 15.1 14.7
Litters/sow/year = 2.3
Preweaning Mortality, %
Born Alive 4 6 8 10 12 14 16 18 20
12 24.2 23.7 23.2 22.7 22.2 21.7 21.2 20.7 20.2
11.5 23.2 22.7 22.2 21.7 21.3 20.8 20.3 19.8 19.3
11 22.2 21.7 21.3 20.8 20.3 19.9 19.4 18.9 18.5
10.5 21.2 20.7 20.3 19.8 19.4 19.0 18.5 18.1 17.6
10 20.2 19.7 19.3 18.9 18.5 18.1 17.6 17.2 16.8
9.5 19.2 18.8 18.4 18.0 17.6 17.2 16.8 16.4 16.0
9 18.1 17.8 17.4 17.0 16.6 16.3 15.9 15.5 15.1
8.5 17.1 16.8 16.4 16.1 15.7 15.4 15.0 14.6 14.3
8 16.1 15.8 15.5 15.1 14.8 14.4 14.1 13.8 13.4
Litters/sow/year = 2.1
Table 3. Effect of AI Technician (256 sows/technician) on Reproductive Throughput
Technician Farrowing Rate (%) # Born Alive/Litter Total # Born/Litter # Pigs Produced
1 90.6 10.3 11.0 2,348
2 85.9 10.5 11.2 2,310
3 81.6 10.3 11.0 2,153
4 89.1 10.2 10.8 2,346
5 89.8 10.4 11.1 2,413
6 67.8 8.5 9.3 1,377
Flowers, 1993
Table 4. Effect of AI Technician Fatigue on Reproductive Throughput
Matings/Day Technician (n) Farrowing Rate (%) Born Alive
1-5 24 86.7x 10.7
6-10 54 85.2x 10.5
11-15 59 78.3x,y 10.3
>15 39 71.4y 10.3
SEM 5.2 0.3
x,yValues in the same column with differing superscripts are significantly different at P < 0.05.
Flowers, 1996

How to Reduce Seasonal Infertility

The seasonal decrease in sow fertility during the summer and early fall is a common and costly phenomenon on many farms, and can contribute greatly to variability in numbers of pigs produced. From July to September, sows take longer to return to estrus after weaning, have reduced ovulation rates and a higher incidence of anestrus than at other times of the year. Sows mated during this period often exhibit a 10% decrease in farrowing rate and sometimes a 0.5- to 1.0-pig decrease in litter size.

The following steps can reduce the impact of seasonal infertility.

  • Incorporate the most advanced methods of ventilation and cooling into all phases of gilt development and sow productivity, and make sure they work. Don't wait until sows and gilts are already heat stressed. Activate systems earlier to periods of prolonged, high-ambient temperatures.

  • Schedule animal activities in the early morning and evening, when temperatures are not as extreme. This practice benefits both employees and breeding females.

  • Set up a cool zone (reduced heat index) for the gilt acclimation phase.

  • Implement strategies to reduce or avoid sow movements and mixing. Reevaluate estrous detection strategies to ensure optimal reproductive stimulation, and that insemination protocols are used to avoid late estrual inseminations.

  • Evaluate specific problems (i.e., anestrus or prolonged wean-to-estrus interval) and apply hormonal treatments when needed.

  • Feed nursing sows smaller quantities of more nutrient-dense diets more often.

  • Overcompensate for an increase in seasonal anestrus by having 10 to 15% more gilts available for breeding. However, avoid overcrowding of additional gilts.

  • Consider implementing an early-wean/split-weaning program during the summer that will reduce the metabolic demand on lactating females.

  • Utilize genetics that have documented records for superior appetite and feed intakes.

Ruling Expected In Dumping Case

The U.S. International Trade Commission is expected to vote in April on whether dumping Canadian hog imports have caused or threatened to cause injury to the U.S. hog industry.

“U.S. producers already know the answer to this question,” says Jon Caspers, past president of the National Pork Producers Council and a pork producer from Swaledale, IA.

“Canadian subsidies have distorted hog and pork markets. The Canadians have not reduced hog production since April 1996. Hog producers in the United States have unfairly shouldered all the pain of market adjustment. We will not sit by as part of our industry is unfairly exported to Canada,” he adds.

On March 7, the U.S. Department of Commerce reaffirmed its October 2004 ruling that Canadian producers are dumping live hogs in the United States. The Commerce Department announced that provisional antidumping duties averaging 10.63% will be placed on imports of live hogs from Canada.

Throughput The Ultimate Test for Production

It sounds simple enough. Flow as many pigs as you can through a given set of facilities to maximize profits (income over expense), while at the same time providing proper animal care.

But as all pork producers know, the facts paint a vastly different picture. Pork production is a biological process, and with this process comes variation.

The challenge is to match pig flow or throughput to a finite set of facilities with a given set of constraints. Here, throughput is defined as the level of pork production in its many stages of lifetime growth.

The Role of Variation in Production

The impact of variation in pig numbers is evident every year in the marketplace. Summer's hog prices are generally higher because fewer pigs are available for slaughter. In contrast, low hog prices in the fall are mostly due to a large increase in available numbers.

These variations in the number of pigs available for slaughter generally happen in the face of a relatively stable number of females in the breeding herd and a relatively fixed amount of facilities.

However, as a larger percentage of swine production in the United States converts to confinement facilities, there is less flexibility to deal with the variation in throughput.

Managing Variation

While it is easy for nursery and grow-finish owners and managers to blame the farrowing site for variation in pig numbers, the reality is that management of variation is still as much an art as it is a science. Managers of farrowing facilities have a fixed number of farrowing crates, often associated with a fixed number of gestation spaces.

When all of the sources of variation in reproductive performance are factored in, it's no small wonder there is any consistency in output at all. Not only do litter sizes vary, but so do factors such as the age at first estrus, number of days for return to estrus, conception and farrowing rates and the number of females that must be replaced. All of these factors add to the complexities of having a fixed number of pigs weaned per week, per farrowing group.

Production Challenges

The challenge of variation in the farrowing facility plays out in nursery and grow-finish facilities. With finishing facilities now costing upwards of $200/pig space, the decision to add extra space to accommodate the variation in pig flows becomes a serious consideration of capital investment.

In both nurseries and finishers, the decision ultimately comes down to one of capital investment (and ultimately cost of production) vs. possible compromises in pig performance. Deciding how much space to build for production, and what happens to pig performance if space is reduced, is the ultimate balancing act all producers struggle with as they invest in production facilities.

Fill, Marketing Concerns

Compounding the pig flow-throughput issue is the changing nature of nursery and grow-finish production facilities. With all-in, all-out (AIAO) pig flows, empty spaces cannot be utilized in the manner common to continuous-flow facilities.

With continuous-flow facilities, an empty pen can be filled at any time by an incoming group of pigs. With AIAO, to preserve the integrity of the system, a pen (or room or building) remains empty until the last pig is removed from the facility.

Maintaining AIAO pig flow presents a major challenge for finishing facilities because pigs are commonly removed for slaughter over a period of weeks in order to match up with packer payment matrixes. Currently, the best estimate is that 90% of all pigs sold to slaughter from finishing facilities in the United States come from production units where pigs are removed over a period of time.

Generally, if pig age at placement in the finishing facility is within 7-10 days, pigs are sold to slaughter over a three- to four-week window. During this sale period, pig spaces in the facility naturally remain empty with AIAO management.

From the production side of the financial equation, it makes much more sense to sell or empty entire barns at one time vs. over a period of weeks. This assures that every pig space has a pig-earning income (i.e., gaining weight) every day.

The challenge of this selling strategy, however, is that slaughter payment matrixes are designed by individual packers to reward producers for pigs that most closely fit their weight and quality needs. U.S. slaughter plants have different needs, as evidenced by the wide range in payment grids currently available.

The Impact of Selling Strategies

Table 1 provides an example of the impact that selling all pigs from a facility vs. removing pigs over a three-week period has on sale weight and income.

Column A represents a finishing facility that removes pigs over a three-week period for slaughter, with an average sale weight of 275 lb. Column B represents the same facility, but all pigs remain until they are sold at one time.

Average daily gain and feed conversion are slightly worse, due to crowding, when pigs are not sold over a three-week period.

Final market weights (289 lb.) in column B are higher because the heaviest pigs, which would have been removed at desirable market weights, remain in the facility. Those pigs also have a slightly lower overall diet cost because a larger share of the finishing group is being fed the lowest-cost diet.

Death loss in column B pigs is increased slightly to reflect more days on feed. This does not necessarily suggest that death loss increases in facilities where pigs are “dumped” or marketed all at one time.

Finally, the average price received was lowered to the point where the net returns for column B equaled the returns from column A. This becomes an estimate of how much lower the average price received can be when dumping vs. “topping” pens (selling pigs when they reach the desired weight), due to the large increase in sale weight.

In short, this suggests there is no one-size-fits-all formula that meets the needs of grow-finish facilities. The amount of grow-finish capacity a production system needs is ultimately based on the variation in pig flows from the farrowing site, the expected performance of the pigs in the facility, and the delivery requirements of the slaughterhouse as expressed in the payment grid.

Table 1. Selling Strategies
Slaughter Management Option
Input Three-Week Period All At Once
Number of pens 40 40
Pen size (sq.ft.) 190 190
Pigs/pen 26 26
Space/pig (sq.ft.) 7.3 7.3
Initial weight, lb. 55 55
Final weight, lb. 275 289
Avg. daily gain 1.75 1.72
Market period, days 21 0
Days to clean/turn 5 5
Feed: gain 2.90 2.92
Vet/med., $/hd. $1.50 $1.50
Death loss, % 4.00% 4.10%
Feeder pig price, $/hd. $48.00 $48.00
Net Market price, $/cwt. $44.00 $42.92
Feed price, $/ton $140.00 $139.50
$/facility/yr. Contract fee $36,000 $36,000
Throughput Comparison
Turns/year 2.58 2.59
Pigs purchased 2,688 2,691
Pigs sold 2,581 2,581
Income Expenses $312,251.24 $320,140.06
Pigs $129,029.44 $129,182.92
Feed $114,048.58 $121,769.69
Vet/med. $4,032.17 $4,036.97
Contract fee $36,000.00 $36,000.00
Total Expenses $283,110.19 $290,989.57
Net $29,141.05 $29,150.48
Difference vs. column A $9.44

Animal Welfare Flow Considerations

A recent variant in the pig-flow/throughput discussion is the impact that animal welfare constraints have on production systems. While there has been considerable discussion already in the industry regarding gestation crates vs. loose sow housing, an emerging discussion with major implications for facility throughput is space allocation in grow-finish facilities.

Research has shown that as we give pigs less space during the grow-finish period, average daily feed intake and average daily gain decrease. For most producers, the balancing point between average daily gain and facility expense has been a space allocation of less than 8 sq. ft./pig to slaughter weight.

In fact, a recent industry survey on the space allocation debate suggests that the average pig density in fully-slotted finishing facilities in the United States is 7.2 sq. ft./pig. The survey was part of an evaluation funded by the National Pork Board.

This reality contrasts with the industry's recommendation of 8 sq. ft./pig from 150 lb. to slaughter weight, contained in the Swine Care Handbook. That manual provides the basis of proper pig space allocation under the National Pork Board's Swine Welfare Assurance Program (SWAP).

The challenge of relating space allocation to pig welfare comes down to the fact that pig size within a fixed facility (pen size) is constantly changing. The question becomes: “How many pigs per pen of given size?”

For instance, pens in fully-slotted facilities that measure 10 ft. wide by 19 ft. deep are routinely stocked with 23 pigs/pen (8.3 sq. ft./pig) up to 28 pigs/pen (6.8 sq. ft./pig).

While this method of defining space allocation by square foot per pig reflects the realities of pig numbers and facility space, it doesn't take into account the known effect of pig size.

Redefining Pig Space Needs

A more recent method of defining the space needs of pigs is to express pig size as a function of body weight and relate that to space. This allometric equation is most often written as:

A = kBW.667, where A is the area per pig expressed in square meters/pig, k is a constant, and BW is body weight in kilograms.

A recent analysis of published literature on the effects of space allocation on pig performance was led by Harold Gonyou, a research scientist in ethology from the Prairie Swine Centre in Saskatchewan, Canada. Funded by pork checkoff, the analysis suggests that average daily feed intake and average daily gain for the entire grow-finish period are maximized when k is approximately 0.0335 for both fully-slotted and partially-slotted facilities. Any increases in space allocation beyond this constant generally did not produce any improvement in performance.

Table 2. Estimate of Pig Space Allocation that Does Not Result in a Decrease in Average Daily Gain or Feed Intake (K= 0.0335)
Weight, lb. Sq. ft./pig
200 7.33
210 7.57
220 7.81
230 8.04
240 8.27
250 8.50
260 8.73
270 8.95

However, for each 3% decrease in space allocation, average daily gain and average daily feed intake decreased 1%, with no significant overall effects on feed conversion.

These results support the earlier observation that producers have generally stocked facilities at a rate that resulted in a decrease in average daily gain vs. stocking at a rate that maximized individual pig performance. The net effect of this overstocking or crowding has been increased pounds of gain/unit of floor space and lowered costs of production.

Animal Welfare Production Standard

To understand the impact of an animal welfare standard that might be based on space allocations that maximize pig performance, let's first look at how the allometric equation defines space when k is 0.0335.

Table 2 is the estimated space allocation at which pig performance would not be impacted. Note that this table predicts that in order for performance to not decrease due to space allocation restrictions, grow-finish pigs require 8.27 sq. ft./pig when the average weight of all pigs in the pen is 240 lb. This is a 15% increase in space when compared to the current industry standard of 7.2 sq. ft./pig.

Critical Weight Evaluation

When considering the issue of pig space and throughput, it is important to determine the critical weight that defines when space allocation is limiting performance. There are two possible answers — the average weight of all pigs in the pen on the day the first pig is removed, and the weight of all pigs delivered for slaughter.

Critics of the industry would like to use the sale weight of all pigs, since it is generally taken on a certified scale.

Yet, as was discussed earlier, the reality is that pigs are removed from a facility over a three- to four-week period.

Weight Estimates

One way to estimate pig weight at the time of first removal is to use Table 3. Typically, pigs within 10 days of age at placement that are housed in AIAO facilities have coefficient of variation (CV) for pig weight in the range of 10-13% when the first pig is removed.

Table 3. Expected Percentile Distribution of Pig Weights When Pigs Are Reasonably Healthy
Standard Liveweight Percentile
CV1 Deviation 10 20 30 40 50 60 70 80 90
10% 20.0 174 183 190 195 200 205 211 217 226
10% 21.5 187 197 204 210 215 220 226 233 243
10% 23.0 200 211 218 224 230 236 242 249 260
10% 24.5 214 224 232 239 245 251 258 266 276
10% 26.0 227 238 246 253 260 267 274 282 293
10% 27.5 240 252 261 268 275 282 289 298 310
Standard Liveweight Percentile
CV Deviation 10 20 30 40 50 60 70 80 90
11% 22.0 172 181 188 194 200 206 212 219 228
11% 23.7 185 195 203 209 215 221 227 235 245
11% 25.3 198 209 217 224 230 236 243 251 262
11% 27.0 210 222 231 238 245 252 259 268 280
11% 28.6 223 236 245 253 260 267 275 284 297
11% 30.3 236 250 259 267 275 283 291 300 314
Standard Liveweight Percentile
CV Deviation 10 20 30 40 50 60 70 80 90
12% 24.0 169 180 187 194 200 206 213 220 231
12% 25.8 182 193 201 208 215 222 229 237 248
12% 27.6 195 207 216 223 230 237 244 253 265
12% 29.4 207 220 230 238 245 252 260 270 283
12% 31.2 220 234 244 252 260 268 276 286 300
12% 33.0 233 247 258 267 275 283 292 303 317
1Coefficient of variation

If 20% of the pigs are marketed at the time of first removal, and they average 265 lb. live weight, the average pen weight is very close to 230 lb., assuming a 12% CV. In Table 3, the 90th percentile value represents the estimated average weight of the top 20% of the pigs in the pen (265 lb.) when the pen averages 230 lb. for all the pigs in the pen (50th percentile).

This suggests that if pig performance becomes a welfare criteria, space allocations will need to be even greater than the 8 sq. ft./pig currently listed in the Swine Care Handbook.

If space allocation becomes a production standard in the United States, how will the industry react?

Options for pork producers include building more facilities, selling pigs at lighter weights or farrowing fewer pigs. All of these options will increase production costs.

In the end, it's doubtful that pigs will be sold at lighter weights, especially if grain prices remain low and slaughter plants don't do a major revision of their payment grids.

Farrowing fewer pigs dramatically ramps up costs as the entire production chain must absorb the inefficiencies associated with under-utilized production facilities.

Even adding more finishing facilities has added costs, which includes the cost of community resistance. That raises the question of whether rural communities will allow more production facilities to be constructed if consumers (generally urban residents) require more space/pig as part of a welfare requirement.


Throughput is not as simple as maximizing output for a given set of inputs. Increasingly, throughput includes consideration of non-traditional restraints in the production decision-making process.

For now, these non-traditional restraints may include animal welfare.

In the future, these restraints may include standards for air emissions and land application, as well as standards for community resistance.

Successful pork producers will be those who can best anticipate and plan for these unexpected restraints.