Manitoba Agriculture, Food and Rural Initiatives

Nutrition and Feeding Management to Maximize Sow and Boar Performance

Bob Goodband, Mike Tokach, Steve Dritz, and Jim Nelssen
Department of Animal Sciences and Industry
Kansas State University,
Manhattan, KS 66506-0201

Introduction

Recently, the swine industry has seen dramatic change in care and management of the breeding herd. These changes have dramatically increased the prolificacy of the sow and boar. Without question, research will continue to unlock the mysteries of reproduction as well as develop methodologies to influence finishing pig growth performance and carcass traits via gestation feeding and management. Yet in spite of all the tremendous potential to enhance sow performance, there are many day to day management considerations that producers need to remember. While feeding strategies to enhance fetal muscle cell formation may be important in the future, it’s the simple things like not over-feeding during gestation or under-feeding during lactation that have a huge impact on today’s bottom line. As producers and nutritionists, we need to "set a mark on the horizon", for where we plan to be in regards to breeding herd goals. However, we also need to keep one eye on the day to day management items to ensure we are able to maintain a viable business so we can achieve our goals. The objective of this paper is to briefly review some of the basics of breeding herd management and nutrition – items especially critical during periods of economic distress, as well as to discuss some of the research evaluating technology that may influence the breeding herd in the future.

Links:

Gestation Diets
Is the Pattern of Feed Intake Important During Gestation?
Lactation Diets
Boar Diets
Conclusion
 

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Gestation Diets

During gestation, the recommended feeding method for gilts and sows is limit feeding. Over-conditioned gilts and sows are common problems. The high energy (feed) intake: (1) is an unnecessary expense; (2) reduces feed intake during lactation; and (3) impairs mammary development.

The success of a limit-feeding program depends upon controlling the intake of each gilt or sow. Care must be taken to see that each female gets her share. Individual sow feeding stalls are an effective device for controlling boss sows. If sows are group fed, it is imperative that the feed be spread across a large area to reduce the amount of fighting and to ensure that all animals consume their feed allotment. Interval feeding during gestation is a possible alternative to limit-feeding.

Interval feeding is accomplished by feeding the sows every other or every third day. Of course, the amount fed is adjusted accordingly, For an example, instead of feeding 1.8 kg each day during gestation, 3.6 kg are fed every 2 days. With interval feeding, it is necessary to have sufficient feeder space. Research results have shown that a minimum of 2 to 6 hours out of every 72 hours is an adequate feeding time. Interval feeding is not recommended for gilts or during the last two weeks before farrowing.

What are the nutrient requirements during gestation?

Nutrient requirements during gestation can be divided into three different areas: (1) maintenance, (2) maternal growth, and (3) fetal growth. Basic energy and amino acid requirements can be determined using a factorial approach as will be demonstrated in the following sections. In addition, the pattern of intake is important due to influences on embryo survival, lactation feed intake, and, in recent literature, subsequent growth and lean deposition of the offspring.

Energy Requirements. Maintenance needs account for 75 to 80 percent of the energy requirement during gestation (Table 1). The maintenance energy requirement can be calculated as 106 kcal ME/kg⁷⁵. The requirement for maternal growth can be calculated by making assumptions about the composition of the gain and requirements to attain that composition (i.e. gain with a composition of 25 percent fat and 15 percent protein would have a requirement of approximately 4.85 Mcal ME/kg gain). The developing litter has a very small nutrient requirement and a high priority for nutrients. The requirement for conceptus growth is only about .2 Mcal ME/day. Using these values, you can easily calculate the energy requirement of sows in a thermoneutral environment.

Table 1. Energy Requirement of Gestating Sows

Item	Sow weight, kg
	113	150	200
Total weight gain, kg Fetal weight gain, kg Net weight gain, kg	52 22 30	43 22 20	34 22 12
Mcal ME/day
Maintenance Net weight gain Conceptus Total requires	3.75 1.24 .2 5.19	4.53 .87 .2 5.60 Feed/day, kg	5.58 .48 .2 6.26
	1.62	1.75	1.95
Assumptions: 1.45 Mcal ME/kg diet. Maintenance: 106 kcal ME/kg.75 . Net weight gain: 4.85 Mcal ME/kg gain (25% fat & 15% protein) x weight gain, kg/114 days. Conceptus: 2 Mcal ME/day. Sow in thermoneutral zone (.27 kg/day of feed required for each 5?C below 29?C).

Using the calculations described in Table 1, gilts and sows require about 5.2 to 6.3 Mcal ME/day during normal (spring/fall) weather conditions. This equates to 1.6 to 2.0 kg of a corn-soybean meal diet. This energy intake may need to be adjusted up or down depending on the condition of the sow and as the weather changes. This is usually accomplished by increasing or decreasing the amount of feed given to the sows daily. Sows require approximately .27 kg of extra feed for every 5?C below 18?C.

Another major component of the energy requirement is the desired weight gain during gestation. A sow should gain 35 to 45 kg and a gilt should gain 45 to 57 kg during gestation. Approximately 22 kg of the weight gain will be fetal growth and products of conceptus. The remaining 12 to 22 kg in sows and 22 to 35 kg in gilts is actual net weight gain. Sow condition is a critical indicator of performance, thus high-producing sows may require higher feeding rates to maintain adequate body condition. If sows lose considerable weight during lactation, additional feed must be provided during the subsequent gestation.

Amino Acid Requirements. Similar calculations to those for energy can be made to determine the requirement for protein (Table 2). Detailed estimates for each amino acid also can be calculated in a similar manner. The individual amino acid requirements are influenced greatly by the expected lean tissue gain during pregnancy. A mature sow gaining 20 kg from breeding to farrowing requires less than 9 g/d of lysine, similar to NRC (1988) requirement. Younger gilts bred at 130 kg with an expected gain of 30 kg would require 11 g/d of lysine. As the expected weight gain increases, the lysine need may increase to as high a 14 g/d in some first parity gilts. However, these levels can be achieved with a relatively low lysine diet (.55 to .65 percent), depending on the level of feed intake. Excessive protein intake during gestation unnecessarily increases feed cost. In one trial, high protein intake during gestation actually reduced feed intake during lactation.

Vitamin and Mineral Requirements. Recommended daily allowances for vitamins and minerals can be controversial. Relatively little information is available on some vitamins and trace minerals to make recommendations. Our suggested vitamin and mineral levels are shown in amount per day and amount per ton in Table 3. If feed intake is substantially greater or less than the 1.8 kg/day used in the calculations for Table 3, the diet should be adjusted accordingly.

Table 3. Recommended Daily Nutrient Levels During Gestation

Is the Pattern of Feed Intake Important During Gestation?

High or low feed intake during particular phases during gestation can cause deleterious effects or have specific advantages. Each stage of gestation is discussed below. These stages are depicted in Figure 1 as a proposed ideal feeding pattern.

Day 0 to 30. Several researchers have reported high intake before day 30 of gestation decreased embryo survival. The increased embryo mortality was attributed to a reduction in plasma progesterone concentration due to increased blood flow and hepatic clearance of progesterone caused by the high feed intake. Further research indicates the critical window to reduce feed intake to prevent embryo mortality may be during the first 48 to 72 hours after mating. Feed intake should be limited to less than 2.25 kg per day for at least the first 2 days after mating.

The body condition or energy state of the sow also influences the response to high levels of feed intake after mating. Embryo mortality is only increased when high levels of feed are provided to sows in good body condition. Embryo mortality is actually reduced by providing extra feed for the first 30 days after breeding to sows in poor body condition due to low lactation feed intake. Therefore, feeding according to body condition during the first 30 days of gestation is critical for minimizing embryo mortality. Recent unpublished data from Australia also credits high feeding during early gestation with increasing farrowing rate during the summer months when seasonal infertility is a problem.

Feeding level from day 2 to 30 is shown as a shaded area in Figure 1. The shading indicates the feeding level should be adjusted to match the body condition of the sow. The goal should be to have the sow at the body condition desired for farrowing by day 30 of gestation. In order to reduce the possibility that the higher feed intake will increase embryo mortality, feeding level from day 0 to 2 of gestation is shown at the baseline value (approximately 2 kg of a diet containing 3.2 Mcal ME).

Day 30 to 75. Current understanding of this period during gestation is poor. As shown in Figure 1, the general recommendation is to feed a constant level sufficient to meet the energy requirements of the sow and maintain body condition. However, the recent research indicates this is a critical period for muscle differentiation of the developing fetuses. A recent research trial demonstrated that doubling feed intake (2.5 versus 5 kg/day) from day 25 to 80 of gestation increased the number of secondary muscle fibers and improved growth rate and feed efficiency of the offspring during their growing period (day 70 to 130 of age). As further research identifies the specific nutrient(s) and time period to elicit the optimal response, stage feeding during gestation for muscle development of the fetuses may become an important part of commercial swine production.

Day 75 to 100. This period is critical for mammary development. Excessive energy intake during this period increases fat deposits and reduces the number of secretory cells, DNA, and RNA in the mammary gland. The result is lower milk production during lactation. Excess feed intake should be avoided during this time.

Day 100 to 112. Feed intake should be increased by 1 to 2 kg from day 100 to 112 of gestation to prevent sows from losing weight and backfat during this period of rapid fetal growth. Failure to increase feed intake during this period can result in sows in an extremely catabolic state at farrowing. The catabolic state contributes to gorging and sows "going off feed" during lactation.

Day 112 to 114. Feeding pattern during the last few days of gestation is a controversial area. We prefer to feed 1.8 kg or more from day 112 to 114. Field experience indicates that extremely low intake of 1 kg or less during this limits the producers ability to increase feed intake rapidly during early lactation. In extreme cases, ulcers can be created by the extended period of low intake around farrowing. After the long period without feed, sows often overeat if provided free access to feed. The sows will go off feed or have a noticeable dip in feed intake. Many people prescribe limit feeding as a cure for the sows going off feed instead of correcting the problem that originally caused the problem (the extended period of little or no feed intake prior to and immediately after farrowing).

Table 4. Recommended Nutrient Levels for Lactating Sows and Gilts^a

Nutrient	Amount/head/day Amount/ton
Crude protein Lysine Met & Cystine Tryptophan Threonine Valine Calcium Phosphorus Available phosphorus Salt Trace mineralsb	1,025 g 54 g 33 g 11 g 39 g 54 g 49 g 43.5 g 27 g 27 g	19% 1.0% .60% .20% .72% 1.0% .90% .80% .50% .50%
Copper Iodine Iron Manganese Seleniumb Zinc Vitamins	90 mg 1.6 mg 900 mg 216 mg 1.6 mg 900 mg	15 g .27 g 150 g 36 g .27 g 150 g
Vitamin A Vitamin D Vitamin E Vitamin Kc Riboflavin Niacin d-Pantothenic acid Vitamin B12 Folic acid Biotin Choline Pyridoxine	60,000 USP 9,000 USP 240 IU 24 mg 54 mg 300 mg 180 mg 0.24 mg 9 mg 1.2 mg 3,000 mg 82.5 mg	10,000,000 USP 1,500,000 USP 40,000 IU 4,000 mg 9,000 mg 50,000 mg 30,000 mg 40 mg 1,500 mg 200 mg 500,000 mg 13,750 mg
a Assumes 5.5 kg/day feed intake of a diet containing 1.0% lysine. b Trace minerals and vitamins levels added to the diet. c Menadione.

Lactation Diets

It is recommended that sows during lactation be full-fed in order to obtain maximum milk production. A sow will normally consume 4 to 7 kg per day. This intake will depend upon diet composition, sow’s condition, previous gestation feed intake, and environmental temperature of the farrowing facilities. For maximum milk production, it is recommended that the sow be maintained in an environment of 15? to 21?C. At higher temperatures, a reduction in feed intake will be evident. Recommended minimum nutrient levels are provided in Table 5.

Table 5. Dietary Lysine Level Based Upon Litter Weaning Weight and Sow Feed Intake

Feed ingredients with a high fiber content such as beet pulp, oats and wheat bran, may be used as laxatives to keep sows from becoming constipated. However, they also reduce the energy density of the diet and limit sow energy intake. If laxatives must be used, top dressing individual sows would be the preferred method of choice. Chemical laxatives, such as magnesium-potassium-, or sodium-sulfate, may be a preferred method of controlling constipation problems. The recommended level of magnesium sulfate (Epsom Salts) is .5 to 1% of the complete diet or a top dressing of about 1 to 2 tablespoons per feeding.

How do I determine the appropriate dietary lysine level for my sow lactation diets?

To customize lactation diets based on sow productivity, dietary lysine level can be calculated if a producer knows the average litter weaning weight and sow feed intake averaged over the entire lactation period. By dividing litter weaning weight by lactation length, daily litter weight gain can be calculated. Sows require approximately 11.9 grams of lysine per pound of daily litter weight gain. Table 5 can be used to determine the approximate lysine dietary level to accommodate the herd’s average milk production.

If the previous lactation diet being fed on the farm is higher in lysine than the recommended level from Table 5, it may be possible to reduce the dietary lysine level without sacrificing performance. If the previous lysine level being fed is lower or the same as the recommendation, the producer may want to increase the lysine (protein) level and reexamine performance records to determine whether litter weaning weight increases. This relatively simple approach allows the sow lactation diet to be customized to an individual farm.

Should the lactation diet contain added fat?

Adding fat to the lactation diet is an effective means of increasing the fat content of the milk and improving litter weaning weight. However, adding fat to the diet will not benefit sow reproductive performance. Producers should take all steps possible to increase lactation feed intake whether fat is added to the diet or not. As a general guideline, if it is economical to add fat to the late nursery diets, it will be economical to use 3 to 5 percent fat in the sow lactation diet.

Should sows be full fed or restricted during lactation?

Low feed intake during lactation will decrease litter weight gain and subsequent reproductive performance. Thus, sows should be allowed to consume as much feed as possible during lactation.

What is the best way to maximize the feed intake of lactating sows?

Many different feeding methods will work to obtain maximum feed intake. The most important facet of any feeding method is to ensure that the sow always has access to feed. Lactating sows should be fed three or four times per day to ensure that feed is always available. We would suggest using the procedure diagramed in Table 6 and outlined below to maximize sow feed intake:

Sows are fed 0, 1, or 2 scoops at each of three feedings during the day. If the feeder has feed left from the previous meal, no feed will be added to the feeder. If a small amount of feed is left, 1 scoop will be added. If the feeder is empty, 2 scoops will be fed.

The only deviation from this pattern is for day 0 to 2 after farrowing. During this time, the decision is to give 0 or 1 scoop at each meal. The sows should not receive 2 scoops at a single feeding during this period.

Table 6. Feeding Strategy for Lactating Sows

Following is an example of the decision process at each feeding.

Morning Feeding -- All sows are fed 1 scoop (2 kg) if small amount of feed is left in the feeder and 2 scoops if the feeder is empty.

Late Morning Feeding -- A second feeding is done later in the morning or immediately after lunch using the same scheme (1 scoop if a small amount of feed remains and 2 scoops if the feeder is empty). If no feed has been consumed since the morning feeding, the sow is then investigated to determine if she has a fever, retained pig, or other detectable reason for being off feed.

Evening Feeding -- A similar scheme is used for the evening feeding; however, some judgement will have to be used if there is some feed left in the feeder. The sows that have had good appetites throughout the day but some feed remaining should receive 2 scoops. Sows that appear to be reaching appetite receive 1 scoop, and again if the feed has not been touched since the last feeding, the sow is investigated to see if there is a detectable reason for being off feed.

Boar Diets

Boars can be fed a grain-soybean meal diet fortified similarly to a gestation diet. The daily feeding rate has to be changed to reflect differences of season, condition, and workload of the boar. Boars under heavy use should be fed 3 kg per head per day of that diet. Care should be taken to avoid underfeeding micronutrients and protein when limit feeding boars (<1.8 kg/day) with the sow gestation diet. A separate diet should be formulated for boars in a boar stud. Due to the relatively low cost of the boar diet and the importance of boar sperm production in the stud, we fortify the boar diet with higher levels of protein and vitamins. We must caution that few trials have been conducted to determine the nutrient requirements of boars. The diet in Table 7 is an example of a diet that has worked well in boar studs.

Table 7. Suggested Board Stud Diets

Ingredient, %                                                         Low energy                                     High energy
Corn Soybean meal, 46.5% CP Dehydrated alfalfa meal, 17% CP Monocalcium phosphate, 21% P Limestone Salt Vitamin premix Sow add pack Trace mineral premix	58.4 25.0 12.5 2.1 .65 .50 .35 .35 .15	65.6 30.0 __ 2.0 1.1 .50 .35 .35 .15
Total	100.0	100.0
Calculated analysis Lysine, % Met:lysine ratio, % Met & Cys:lysine ratio, % Threonine:lysine ratio, % Tryptophan:lysine ratio, % ME, kcal/kg Protein, % Calcium, % Phosphorus, % Available phosphorus, %	1.01 30 65 76 25 3,054 19.1 .90 .80 .53	1.07 29 64 75 23 3,263 19.8 .90 .80 .50

Conclusion

The two most important variables that contribute to the profitability of a swine business are feed costs and sow productivity. Too many producers tend to over-feed sows during gestation then limit- or under-feed sows during lactation. While gestation and lactation diets represent approximately 16% of the feed usage on a farrow-to-finish operation, it is important that these diets be correctly formulated to the productivity level of the herd and fed at the proper amounts. Improperly formulating or managing gestation and (or) lactation diets will negatively affect feed costs, but they will also affect profitability through decreased sow performance. Conversely, not only will excellent management improve breeding herd feed utilization, research suggests it may also impact efficiency of the offspring.