Dietary Guidelines for The Breeding Herd
The updated National Swine Nutrition Guide is a helpful resource.
By David Meisinger
The National Swine Nutrition Guide (NSNG) is a sensible, easy-to-use source of nutrition information and recommendations. Its companion piece, the Diet Evaluation and Formulation Software DVD, is also very user-friendly and has the flexibility for producers to custom-build their rations based on feedstuffs available, their own nutrient analyses of feedstuffs and their own desires as far as the final nutrient makeup of the diet is concerned.
The breeding herd is divided into considerations for gestating and for lactating sows. For gestating sows in early stages of gestation, successful conception and embryo survival are the most important factors to success. For mid-gestation, growth and development of the fetuses and increasing or replenishing body nutrient stores is critical. In late gestation, the emphasis is on fetal growth and mammary development. We want large, vigorous litters of pigs at farrowing from sows equipped to produce large quantities of milk. The ultimate goal is to have females that can have long productive lifetimes at a reasonable economic cost.
Gestation feed intake inversely affects lactation feed intake. To maximize lactation feed intake and sow performance, gestation feed intake must be limited. Over-feeding of gestating sows compromises mammary development, depresses feed intake during lactation and increases birthing difficulties. Under-feeding of gestating sows can cause failure to recycle, lower conception rates, smaller subsequent litter size and even fatigued-sow syndrome. The three components of nutrient requirements of gestating sows include maintenance, fetal growth and maternal weight gain.
Productive sows have special needs
The primary challenge of feeding highly productive sows involves minimizing the negative nutrient balances that often occurs during lactation in order to minimize shortterm and long-term reproductive performance problems. Lactating sows need energy and other nutrients to maintain body tissues and support milk production, a particular challenge with today's more prolific females.
Excessive body-weight nutrient loss (high negative nutrient balance) can lead to:
- Short-term reproductive problems, such as extended wean-to-estrus interval and smaller subsequent litter size
- Long-term problems, including a high culling rate of the sow herd that results in low average parity, reduced pigs weaned per reproductive lifetime and higher genetic cost per pig produced
Factors affecting feed intake
Understanding the different factors that affect nutrient requirements and feed intake can assist in developing a successful lactating sow feeding program. Because maximizing daily nutrient intake during lactation is so important to minimize nutrient drain from body tissues, a brief discussion of the different factors that affect feed intake is necessary:
Parity: Lactating-sow feed intake increases from the first to the sixth parity, with the biggest increase occurring between the first and second parity (15 - 20 percent).
- Sow lactation feed intake is often not enough during parities 1 and 2 to meet maintenance and milk production needs
- Research has shown if these sows mobilize more than 15 percent of their protein mass during lactation, subsequent reproductive efficiency and litter weaning weight are reduced
- First-parity sows are still growing and thus may have lower body stores of fat, protein and minerals from which to draw
Sow condition: Over-conditioned sows consume less feed during lactation, while mammary development may be compromised, resulting in reduced milk production
Level of dietary protein: Reducing the crude protein level of the diet from 16 or 18 percent to 12 or 14 percent has been shown to reduce feed consumption. Consequently, sows will experience increased weight loss over the lactation period, as well as reduced piglet weaning weights. Particular care must be taken if formulating lower-protein diets to ensure essential amino acid requirements are met. Otherwise, delays in subsequent wean-to-estrus period and poorer subsequent conception rates may occur, especially in first-parity sows.
Feeding frequency: Feed diets at least twice daily (preferably three or four times) to lactating sows in order to keep feed fresh and encourage increased voluntary feed intake. The value of increased sow observations and the need to remove wet or spoiled feed cannot be stressed enough.
Diet form and feeder design: There appears to be no appreciable improvement in litter weight gain, sow feed intake, or sow weight loss by feeding pelleted diets compared to ground mash, although feed wastage may be considerably reduced. The additional cost of pelleting must be compared to estimated reductions in feed waste to determine if pelletting is economically feasible. Improper feeder design may restrict the sow's ability to consume maximal levels of feed, and can also lead to increased feed wastage. Bars, rods or other types of items in feeders tend to restrict access, as well as overall size. Generally, the larger the feed pan, the better. Average particle size of feed should be around 700 microns to provide optimum sow performance (utilization of nutrients in the feed is greater with smaller particle size). This particle size also allows adequate feed processing efficiency and feed flow ability while minimizing the occurrence of ulcers due to finely ground feed.
Water: Quality and quantity of water must never be restricted; otherwise reductions in feed intake and associated performance parameters will occur. A lactating sow can consume up to 7 gallons of water daily. A water-flow rate of 1.5 to 2 pints per minute is recommended for nipple waterers, which need to be checked periodically.
Environmental conditions: High farrowing room temperatures (above 70 degrees fahrenheit) will depress voluntary sow feed intake. Utilize zone heating and minimize drafts to keep piglets warm and allow room temperatures to be reduced to the 65 to 70 degree F range.
Wet versus dry feed: Wetting of sow feed at feeding can increase intake by 2 lbs./sow/day during hot weather, but requires extra time and attention, both for getting the feed wet and cleaning up uneaten feed.
Feed access: Make sure sows have access to feed over the evening/nighttime periods during hot weather; when temperatures are cooler, lactating sows will consume 20 to 25 percent more feed.
Feeding methods: Regardless of feeding method, the goal is to maximize total feed intake during the lactation period.
Many farms choose to gradually ramp-up feed allowance during the first week post-farrowing before providing feeding levels. Compared to more aggressive feeding systems that challenge sow intake within the first few days post-farrowing, these restricted feeding systems can reduce sow feed intake by up to 15 percent during the first week of lactation. Concern is often that sows will go off feed mid-lactation due to early overfeeding. Data indicates 10 to 30 percent of all sows will exhibit a dip in feed intake during the second week of lactation, irrespective of early feeding level. Thus, the goal should be to maximize feed intake as soon as possible following farrowing and throughout lactation to minimize sow body weight loss, maximize growth rate and optimize subsequent reproductive performance.
Much more information
The NSNG is a very dynamic source of information with several updates planned over the next few years, as more information becomes available on alternative feedstuffs, on immunological castration, on improved genetics, etc. The Guide is available for viewing or ordering on the U.S. Pork Center of Excellence website at www.usporkcenter.org.