Nutrition: Can spray-dried plasma help sow feed intake during lactation?

Monday, February 4, 2008

Experiments in Indiana suggest that young lactating sows fed spray-dried plasma in summer had increased feed intake and reduced weaning-to-estrus interval, whereas mature sows had lower feed intake and heavier litter weights without compromising days to estrus

by JANICE MURPHY

A tremendous amount of time and energy goes into the selection and management of breeding females in a swine herd. Attrition of young sows has a significant impact on a production unit's ability to achieve sow longevity targets. Ultimately, a breeding female must produce enough offspring to offset her purchase price and maintenance costs within the herd so that any offspring produced above and beyond that represent profit.

There are many reasons why sows are culled from a herd. Usually at the top of the list are reproductive failure (which covers a whole range of issues, including anestrus and poor conception rates) and feet and leg problems.

What does this have to do with nutrition? Research has shown that the odds of culling a sow before her next farrowing decreased 30 per cent with every one-kilogram increase in average daily feed intake during lactation. This underlines how important adequate lactation intake is in carrying the sow through to the next reproductive cycle.

Reduced lactation feed intake results in decreased litter weight gain, increased maternal tissue loss and an increase in the probability of a prolonged weaning-to-estrus interval in primiparous sows. Conserving protein stores in lactating sows will minimize the weaning-to-estrus interval and increase subsequent litter size. Heat stress can also have a negative impact on lactation feed intake.

Researchers in Indiana recently proposed that feeding spray-dried plasma could enhance lactation feed intake and so improve sow and piglet performance. Spray-dried plasma has been shown to have immunological effects on various species, including pigs and rats, resulting in improved growth and feed intake in young pigs specifically. However, this has never before been tested in sows.

In four separate experiments, more than 2,000 sows were used to determine the effect of spray-dried plasma in lactation diets on such things as average daily feed intake (measured as feed disappearance), sow body weight, fetal and placental loss, litter size at weaning, litter weight at weaning and average days from weaning to first estrus.

Three of the experiments were conducted during summer months, when the effect of heat stress was expected to be a factor, and the remaining experiment was conducted during fall and winter. The first experiment used only parity 1 and 2 sows. The fourth experiment used only mature (more than two parities) sows, whereas the second and third experiments used the whole array of parity groups.

The objective of the initial two experiments was to compare the effect of zero and 0.25 per cent spray-dried plasma in lactation diets on sow feed intake, sow body weight, fetal and placental loss from day 110 of gestation to weaning, weaning-to-estrus interval, percentage of sows within the weaning-to-estrus interval category, pigs weaned per litter, litter weight and average pig bodyweight at weaning. A total of 265 parity 1 and 2 sows were used in the first experiment, farrowed during the months of August and September. In the second experiment, 410 multiparous (parity 1 to parity 10) sows farrowed from September to December were used.

Sows fed spray-dried plasma in the first experiment had significantly higher feed intake and a tendency for reduced fetal and placental loss and weaning-to-estrus interval (Table 1, page 28). Meanwhile, in the second experiment, spray-dried plasma tended to increase sow body weight at weaning and reduce fetal and placental loss, whereas other variables were not different between diets.

Armed with this information, the researchers set out to assess the effect of zero and 0.5 per cent spray-dried plasma in lactation diets on sow feed intake, weaning-to-estrus interval, percentage of sows within the weaning-to-estrus interval category, number of pigs weaned per litter, percentage survival of pigs at weaning, and subsequent farrowing rate and number of pigs born alive per litter.

The third experiment was conducted with 894 sows between August and September with a commercial sow herd in Oklahoma that used parity segregated management. In this herd, parity 1 sows were housed in one quadrant, parity 2 sows at another, and mature sows (more than two litters) were housed in the remaining quadrants at the sow site, all within a two-kilometre radius.

The parity 1 and 2 sows fed spray-dried plasma in this experiment had increased feed intake, but this was in contrast to mature sows fed spray-dried plasma which had reduced feed intake. Pig survival and litter size at weaning for all parity groups did not differ between diets.

The weaning-to-estrus interval for parity 1 sows fed spray-dried plasma was reduced and tended to be reduced for mature sows fed spray-dried plasma, but was not different between diets for parity 2 sows. More parity 1 sows fed spray-dried plasma were detected in estrus four to six days after weaning, and fewer were detected in estrus six days after weaning compared with control parity 1 sows.

The final experiment set out to determine the effect of zero and 0.5 per cent spray-dried plasma in lactation diets for mature sows on feed intake, number of pigs weaned per litter, number of marketable pigs at weaning (pigs > 3.6 kilos of body weight or without physical defects), survival of all pigs and marketable pigs at weaning, litter weight at weaning and average pig body weight at weaning. This experiment involved 554 mature sows farrowed during the month of July at the same site as well as the mature sows that were involved in the third experiment, the year after that particular study was completed.

In the fourth experiment, mature sows fed spray-dried plasma had significantly lower feed intake (Table 2, this page). However, interestingly enough, litter weight and average pig body weight at weaning was higher, with more marketable pigs weaned per litter.

This series of experiments is the first to evaluate the impact of relatively low inclusion rates of spray-dried plasma for lactating sows. Overall, lactation feed intake of sows farrowed during summer months, when heat stress would be a factor, increased for young sows and decreased for mature sows fed diets containing spray-dried plasma. For sows that farrowed during fall and winter months, feed intake of young and mature sows was not different between diets.

Even though the genetics of the sows used in the first experiment differed from the genetics of sows used in the remaining experiments, the feed intake response to spray-dried plasma, regardless of inclusion rate, was similar for sows farrowed during summer months.

Despite the fact that mature sows fed spray-dried plasma during summer months consumed less feed, there was no negative impact on the weaning-to-estrus interval, with the added bonus of increased litter weight, average pig body weight, and number of marketable pigs at weaning. The researchers hypothesized that this improved performance response in the offspring could be related to improvements in the efficiency of nutrient utilization.

The reduced feed intake of mature sows fed 0.5 per cent spray-dried plasma may be related to the ability of spray-dried plasma to maintain gut barrier function during stressful situations, like heat or antigens, therefore improving nutrient utilization and reducing metabolic demands for nutrients needed to support increased maintenance requirements or to mount an immune response.

The results of these studies are unique in that young lactating sows fed spray-dried plasma during the summer months had increased feed intake and reduced weaning-to-estrus interval, whereas mature sows had lower feed intake, improved number of marketable pigs at weaning, and heavier litter weights without compromising days to estrus.

The researchers, although pleased with the results to date, are quick to suggest that further research is needed to understand the mechanisms by which spray-dried plasma affects sow and litter performance and the potential impact on the longevity of young sows in the breeding herd. BP

Source:
Crenshaw, J.D., Boyd, R.D., Campbell, J.M., Russell, L.E., Moser, R. L., and Wilson, M. E. 2007. Lactation feed disappearance and weaning to estrus interval for sows fed spray-dried plasma. J. Anim. Sci. 85:3442–3453.

Janice Murphy is a former swine nutritionist with the Ontario Ministry of Agriculture, Food and Rural Affairs, who now lives and works in Prince Edward Island.