Milk Production and Nutritional Requirements of Modern Sows

Milk Production and Nutritional Requirements of Modern Sows
Milk production levels of over 11 kg per day day can be achieved by today's sows in commercial situations, providing that specific needs are met for lysine and energy intake, according to Casey Neill and Noel Williams of PIC North America in a paper presented at the London Swine Conference 2010.

Introduction
The modern white line sow has been selected for large litters and milk production and the evidence is clear on sow farms. Many sow farms have been increasing total born and weaning large litters with heavier pigs. With litter size continuing to improve and lactation length increasing to around 21 days, the demand for milk production must continue to increase to meet the increasing demand of heavier pigs. Modern sows can produce 10 to 12 kg milk per day (Aherne, 2007) with day 21 of lactation being the peak of production. In fact, sows can produce more milk per kg of body weight than cows. If a 182 kg sow produces 11 kg of milk per day, that would be 0.06kg of milk per kilo of body weight. A 909kg cow can produce 45.5kg of milk per day that would be 0.05kg of milk per kilo of body weight (Goodband, personal communication).

Milk production by the mammary glands is influenced by genetics and nutrition (Tri-State Swine Nutrition Guide, 1998). To maximise milk production in sows, it takes many factors besides genetics and nutrition. Other factors include feed intake (frequency of feeding), environment (farrowing house temperature), length of lactation, body condition and water intake. One example of management that decreases milk production is restricting feed intake, which will decrease milk production in gilts and sows (Pluske et al., 2009).

With the correct selection of genetics, the right environment and management, there can be an increase in milk production and therefore heavier weaning weights.

Potential for Milk Production in Commercial Units
As sows have been selected for greater milk production and productivity levels have been improved in commercial units, both milk production and litter weaning weights have increased substantially. In USA, there are examples of units where sows are weaning total litter weaning weights of over 76kg on 20-day lactation (Table 1). With increased potential for milk production, management and nutritional factors must be changed to meet these demands for lactation.

Table 1. Commercial production for milk production (January–June 2007)a
a PIC Commercial Camborough 1070 Females located in Midwest USA. b Assumes 4g milk per gram of piglet growth
Nutritional Requirements for Optimum Milk Production
Sows can achieve and maintain high levels of milk production throughout their productive life if given adequate levels of energy and nutrients. The most critical nutrients for maintaining optimum lifetime milk productivity are energy and amino acids. Table 2 shows the predicted lysine needs of prolific first litter sows based on current estimated milk production potential.

Table 2. Predicted lysine need for first parity sowsa
a,b Adapted from Boyd et al., 2002 and Pettigrew, 1993
These estimates for lysine needs have been validated in a series of studies designed to validate amino acid needs of PIC sows in commercial research conditions (Srichana et al., 2007). In these studies, PIC C-22 sows in parities 1 through 4 were fed isocaloric (3.46 Mcal ME/kg) corn/ soybean meal lactation diets ranging from 0.95 to 1.35 per cent total lysine. Diets were given to sows from day 112 of pregnancy throughout the 19-day lactation period. Feed intake was recorded with a computerised feeding system that insured ad-libitum feed intake. Figure 1 demonstrates the estimated lysine requirement (per cent and g/day) and milk production (kg/day) for PIC C-22 sows in parities 1 through 4.

Figure 1. Lysine requirements of PIC sows
In summary of these sets of experiments, total lysine intakes of 70g per day or 62 grams of SID lysine per day optimise reproductive and milk production performance in PIC sows.

Because gilts eat 10 to 15 per cent less than sows, the percentage SID lysine in the lactation must increase compared to a mature sow herd. Because the target is 62g SID lysine per day, feed formulation must be done based on feed intake and not only percentage SID lysine. To prevent a parity 2 dip, the gilt must be fed properly and allowed full feed after farrowing. Firstly, the gilt loses more than 10 per cent of her body weight during lactation, then the subsequent litter will suffer with low production.

Figure 2. Impact of body weight loss on subsequent performance (Parity 1 gilts)

Figure 3. Effect of dietary lysine intake on piglet ADG (g/d) of gilt litters
Treatment effect P=0.0117, Linear response P=0.0004; SEM=7.84

Figure 4. SID lysine requirement of PIC lactating sows
In addition to lysine requirements, the maximum amount of synthetic lysine in lactation diets and the ideal ratios of other amino acids have recently been validated (Shrichana et al., 2007). Not only will this improve performance but lower diet cost. Table 3 shows reproductive and milk production response to increasing levels of dietary synthetic lysine.

Table 3. Maximum use of crystalline amino acids in lactating sows a
a Shrichana et al., 2007. 283 Primiparous PIC C22 Sows. Total Amino acid ratios used in diets: Methinone+Cystine: Lysine, 58%; Threonine:Lysine,Tryptophan:Lysine, 18%; Valine:Lysine, 71%.
These studies indicate that up to 0.30 per cent synthetic lysine can be added to primiparous sow diets without deleteriously affecting reproductive or milk production performance. This response has also been validated in older parity sows (Allee, 2007 personal communication).

With updated nutrition requirements we have included updated SID amino acid ratios (Table 4).

Table 4. SID amino acid ratios
Feeding Management Requirements for Optimum Milk Production
In addition to amino acid intake, proper energy intake is essential for maximising milk production in sows. Both the amount of and type of energy can influence milk production.

Several ways to increase feed intake have been evaluated in commercial sow production. Basic feeder design and feeding pattern have recently been evaluated in commercial conditions to evaluate methods to maximize feed intake and thus milk production.

Recently in the United States, various forms of self-feeders have been evaluated in order to maximise feed intake. PIC has collaborated on various trials to determine the efficacy of newly designed self feeders in commercial systems. Although there exists various options within the industry, the authors have most extensively evaluated the INTaK Ad-Lib Lactation Feeding System. Commercial field research has demonstrated an improvement of seven per cent in feed intake compared with hand-feeding systems, along with less labour required for feeding. Figure 5 represents an illustration of an automated feeder.

Figure 5. Illustration of self feeder
In addition to evaluation of self feeders, we have evaluated optimum feeding pattern for maximising lactation intake in commercial systems. In a recent study, the following feeding patterns were evaluated with self feeding systems (Tables 5 and 6 - Kummer, PIC Symposium 2007).

Data from Tables 5 and 6, demonstrate the mild restriction for 3 days followed by full feeding from day 4 through the end of lactation resulted in increased feed intake and reduced body weight loss. Based on these data, the recommendation for feeding PIC sows is to scale feed at 1.8, 1.8, and 2.7 kg for days 0,1, and 2, respectively of lactation followed by ad-libitum access to feed. These data also more fully illustrate the potential for feed intake and milk production for PIC females in parities 1 and 2.

Table 5. Evaluations of various lactation feeding patterns

Table 6. Response to lactation feeding patternsa
a Adapted from Kummer, 2007. 200 PIC Camborough P1 and P2 sows. b,c Means with different superscripts differ, P<0.05
Bump Feeding in Late Gestation
There is limited research data on increasing feed in late gestation. However, it is common practice to increase feed by 0.5 to 1.0kg the last two to three weeks of gestation to support the increased litter growth. When sows are in proper body condition, bump feeding is recommended. However, if sows and gilts are over condition, bump feeding is not recommended. With the increase in feed costs, many producers are questioning the importance of bump feeding as it could save $3.00 to 5.00 per sow in feed costs.

A recent trial conducted by Shelton et al. (2009), used 108 PIC Camborough gilt and sows for a bump feeding trial. The researchers increased feed by 0.90 kg at day 90 of gestation or did not increase feed. The birth weight of pigs from gilt litters that were bump fed had increased (P<0.01, Feed Level) weights. However there were no differences in birth weight from sows that were fed increased levels. The researchers concluded little response to bump feeding.

One area to point out is the amount of feed that was fed from day 35 to 90 of gestation. Table 7 shows that the sows were fed 2.60 kg per day of a corn-soybean meal diet. In most production systems sows are fed 2.0 kg from day 35 to 90 of a lower energy diet with wheat midds, soy hulls or DDGS. This may have caused some over conditioning.

If sows and gilts are being fed 1.8 to 2.0kg per day in gestation, then the recommendation is to bump feed at day 90. If gilts and sows are over conditioned then do not bump feed. More research is needed to better obtain a conclusion.

Table 7. Bump feeding in late gestation
Added Fat in Lactation
This is another area of limited research. An abstract from the 2010 Midwest Animal Science meetings by Rosero et al. (2010) used 337 sows (PIC Camborough) in Oklahoma during the months of July to September with added fat levels of 0, two, four and six per cent. The fat source was an animal-vegetable blend.

The researchers reported that when caloric intake was increased there were no beneficial effects on any measured criteria, except for improved litter gain in P3+ sows.

Another internal research trial was conducted with 1,020 PIC gilts and sows with two treatment levels of 0 and five per cent added fat. The weaning weight from pigs that nursed from gilts and sows fed five per cent added fat were 0.18kg heavier (P<0.001). However, the difference in weight was not maintained at 22 weeks after weaning. There were no differences in sow performance reported.

Conclusions
The modern sow has a tremendous capacity for milk production given proper nutrition and feeding management. Milk production levels of over 11 kg per day can be achieved in commercial situations. To achieve these levels, specific needs for lysine and energy intake must be achieved.

These levels are well defined for PIC females and are supported by commercial research. This paper serves as a guide for nutritional and feeding management for PIC sows.

References
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This paper was presented at London Swine Conference – Focus on the Future 32 on 31 March to 1 April 2010.