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Feeding for Sow Reproductive Efficiency

Feeding for Sow Reproductive Efficiency
One of the keys to this achievement — first and foremost — is to have the right people in the production system. Having talented staff who are dedicated to production and a standard operating protocol that is followed to the letter is easily the number one factor to achieving the 30-P/MF/Y target.

As recently as five years ago, many in the U.S. pork industry felt the prospects of achieving 30 pigs/mated female/year (P/MF/Y) was a dream. Today, the 30-P/MF/Y goal can be and is being achieved on some select farms (see “Sow & Pig Care to the Max,” Aug. 15, 2011, National Hog Farmer, p. 6).

One of the keys to this achievement — first and foremost — is to have the right people in the production system. Having talented staff who are dedicated to production and a standard operating protocol that is followed to the letter is easily the number one factor to achieving the 30-P/MF/Y target.

Genetics and herd health are also very high on the priority list. Those topics are covered elsewhere in this issue.

As Figure 1 shows, the total number of pigs born and the number born alive has steadily increased since 2002. This improvement has been a result of selection pressure to produce highly prolific sow lines and the swine veterinary corps’ efforts to improve swine health — controlling porcine reproductive and respiratory syndrome (PRRS) being the greatest challenge. Without excellent health, making the jump to 30 P/MF/Y is going to be next to impossible.

Common-Sense Diets

As a swine nutritionist, I would like to say that diet formulation ranks up there with those big three essentials to hit the 30-P/MF/Y mark but, unfortunately, it does not.

There are no magical ingredients or silver bullets that can be economically justified. Solid, well-formulated diets are important; however, items such as laxatives or specialty products to enhance the immune system or feed intake are not essential to achieving high productivity. That’s not to say these products shouldn’t be evaluated, but they need to be tested side-by-side in an experiment in a common facility, not in one barn vs. another.

Much more important and not to be overlooked is feeding management. Getting the right amount of feed to the gilt or sow at the right time is often overlooked or sometimes misguided. Therefore, I hope to cover some key nutritional issues that can help producers who are striving for 30 P/MF/Y.

Start with Gilt Development

From a reproductive efficiency standpoint, excellent sow production starts with a good gilt development program. A year ago, I authored an article for the Oct. 15, 2010 Blueprint edition entitled “Feeding for Success.” (See

To summarize, a nutrition and management program for replacement gilts that allows for moderate levels of growth performance from birth to selection will positively affect reproductive performance and longevity. As a target, gilts should weigh at least 300 lb. and have 0.63 in. of backfat depth at breeding and weigh at least 400 lb. with 0.67-0.75 in. last rib backfat depth at farrowing.

If we are to ensure a long breeding life, it is apparent that gilts should enter the breeding herd with greater tissue reserves (protein) and should be fed to ensure that these reserves are not significantly reduced in lactation. Table 1 provides an example of a well-balanced diet for developing gilts. The primary difference between gilt developer and growing-finishing diets is the high concentrations of calcium (Ca) and phosphorus (P) in the former.

Nutrition in Gestation

Sows should be full-fed from weaning to breeding. In most cases, the amount will exceed the capacity of a full drop box; therefore, additional feed should be hand-fed throughout the day, as much as their appetites will allow. The goal during this period is to have feed available 24 hours a day. One special consideration for sows housed in a row of stalls is to provide water through a nipple drinker vs. the feed trough, as water cannot flow through a trough containing feed.

Gilts moved directly from the developer barn to the gestation barn can be fed the regular gestation diet for a period of time at 4 to 4.5 lb./day and then “flushed” by feeding 6 lb./day from approximately 190 days of age to breeding (~ Day 210). Providing an extra 2 lb./day for two weeks before breeding, commonly known as flushing, has been shown to increase litter size as much as one pig per litter.

After breeding, feed intake for sows and gilts in good body condition should be reduced to 4 or 4.5 lb/day or the level they will be fed throughout gestation. Thin sows should be fed at the level required to return them to the desired body condition.

When designing a feeding program for ges­tating sows, overall goals for the nutri­tion program include:

  1. Preparing sows to be in proper body condition at farrowing, approximately 0.67-0.75 in. last rib backfat depth;
  2. Maximizing reproductive performance (farrowing rate, litter size); and
  3. Meeting the daily nutrient requirements at the lowest possible cost (measured as cost/sow/day).

The two most important factors determining a sow’s feed requirements during gestation are body weight and desired weight gain.

Body weight determines the sow’s maintenance requirement (Figure 2), which represents approximately 90% of her energy requirements up until the last two to three weeks of gestation. Using typical corn-soybean meal-DDGS-based diets, a base gestation feeding level for most young sows is 4 lb./day (Table 2). For older sows, the base level might increase to 4.5 to 5 lb./day.

Remember, the amount of gestation diet is selected to meet the maintenance requirement. For thin sows that need to gain weight or fat sows that need to lose weight, appropriate adjustments must be made. Adjust drop boxes up or down from the base amount according to body condition with a goal of bringing thin sows into condition within 30 days of gestation, normally the Day-30 pregnancy check. If necessary, recheck body condition on subsequent pregnancy detection days.

Most thin sows should be able to regain body condition by Day 30 to 45 of gestation if drop boxes are set to approximately 8 lb./day. Fat sows’ drop boxes should be set at a minimum of 3.5 to 4 lb./day to help reduce condition. Once a sow is in condition, set her drop box back to the base setting.

To minimize sows stealing each other’s feed, try putting all the thin sows in a row next to each other in one location and the fat sows in another location. Remember, for heavier, older-parity sows, base feed allowance may be up to 5 lb./day to hold their body condition steady.

The best method of feeding to achieve ideal sow body condition varies. Some sow managers use only visual evaluation; others may use the weight tape and backfat method. A combination of the two approaches is gaining favor in the field — using the flank-to-flank tape measurement (Figure 3; see photo, page 29) to estimate sow weight and, hence, the maintenance feed allowance, and combining this with a visual evaluation of body condition, with feed adjustments made accordingly.

In a well-managed gestation barn, about 80% of the sows should have ideal body condition, with 10% thin sows and 10% fat sows.

Another strategy, called “bump-feeding,” provides 2-3 lb. of extra feed for 2-3 weeks before farrowing to increase pig birth weight. Two recent research studies suggest that for Parity 2 or older sows in good condition, there is no benefit to bump feeding. The data did suggest that thin sows and gilts may benefit from added feed from Day 100 of gestation to farrowing, but feed settings for fat sows should not be increased.

Full-Feed in Lactation

It is well known that lactating sows need maximum intake of a good-quality diet to opti­mize sow and litter performance. However, whether intentional or not, the feed intake for many lactating sows is limited. Low feed intake in lactation results in decreased milk production and excessive loss of sow weight and backfat, which can impair subsequent reproductive performance.

The three main goals of the nutrition program for lactating sows are:

  1. Maximize intake of a prop­erly formulated diet;
  2. Match the amino acid and other nutrient levels to the level of feed intake that is achieved; and
  3. Maintain a reasonable feed cost per weaned pig.

Achieving excellent lactation feed intake starts with proper body condition. If sows are too fat coming into the farrowing house, they will eat less in lactation, lose weight and have poor subsequent reproductive performance.

Figures 4 and 5 show the effects of backfat depth on feed intake as sows enter the farrowing house. Sows with greater than 0.83 in. of backfat ate significantly less than their counterparts with 0.83 in. or less backfat. Because sows did not eat as much in lactation, they lost proportionally more backfat as a percentage of body weight, which resulted in a smaller litter size in the subsequent farrowing (Figure 5).

People also affect feed intake; some intentionally, some not. This can result from not feeding multiple times during the day or, more commonly, the long-held belief that sows must be gradually brought up to full feed over time so as not to have them go off feed later (mid-lactation).

This philosophy is wrong. Sows need to be brought up on feed as quickly as possible and have feed in front of them at all times. To accomplish this, many producers are moving toward automatic or ad-libitum sow feeding. While feed intake will vary from day to day during lactation, ad-libitum feeders, either purchased or homemade, are the best way to keep feed in front of sows during lactation. Not only will sows lose less weight with increasing lactation feed intake, but research has shown that farrowing rate and subsequent litter size will improve, while days to estrus will decline.

One method to calculate your lactation feed intake is to use one of the equations below.

Total feed delivery
# of crates × days in the period

Total feed delivery
# of litters × lactation length

The first equation will generally underestimate lactation feed intake because it assumes that the farrowing crates are full of lactating sows. The second equation will generally overestimate lactation feed intake because it assumes the feed provided prefarrowing is actually a part of lactation intake. The actual lactation feed intake lies in between these two values, and we typically average them to estimate lactation feed intake.

Taking a six-month rolling average of feed intake will also take out some of the month-to-month variation in feed deliveries made at the end of the month. A simple spreadsheet for calculating lactation and gestation feed intake can be found at

The sow’s lysine requirement during lactation is influenced by energy intake and litter growth rate. To account for differences in ingredient amino acid digestibility, we have moved from expressing requirements on a total lysine basis to standardized ileal digestible lysine, or SID lysine.

Formulating on a digestible amino acid basis has become especially important with the increased use of DDGS and crystalline amino acids in lactation diets. Recent research for high-producing sows suggests a SID lysine requirement of 55 to 65 grams/day to maximize litter weaning weights and reduce sow weight loss. That equates to a 1.1% SID lysine diet with an average lactation feed intake of 11 to 13 lb./day (Table 2).

And don’t forget, there are other amino acids besides lysine, but the use of DDGS actually helps maintain high ratios of other amino acids relative to lysine. DDGS are relatively low in lysine and tryptophan, yet high in other essential amino acids. Therefore, when adding DDGS to gestation or lactation diets, crystalline lysine can be used to offset the low lysine concentration in DDGS, yet still provide enough of the other essential amino acids. Because DDGS are low in tryptophan, it will likely limit the amount of crystalline lysine added to lactation diets.

Research on the tryptophan requirements of lactating sows is scarce, but based on the National Research Council (NRC, 1989) and the National Swine Nutrition Guide, the ratio of SID tryptophan to lysine should not be less than approximately 19% of lysine. However, more research on amino acids relative to lysine needs to be conducted.

Nutritional Foundation

Nutrition may not be as important as sow husbandry, herd health or genetics, but striving for 30
P/MF/Y requires a solid nutritional foundation for the breeding herd. This foundation is based on proper feeding management and practical diet formulation.

Feeding management means getting the right amount of feed to each sow in gestation so the majority of the herd stays between 0.67-0.75 in. last rib backfat depths. In lactation, it means keeping feed in front of the sows at all times. Ad-libitum lactation feeders can help. Finally, for diet formulation, there are no magical ingredients or additives.

Although it’s pretty hard to beat a properly formulated corn-soybean meal-based diet, alternative ingredients such as DDGS can be used when diets are properly formulated.