July 31, 2012

Predicting milk yield in sows to meet nutrient requirements

Photo from National Hog Farmer

A study published in the July issue of the Journal of Animal Science aims to help pork producers determine nutrient requirements in sows during the lactation period. Researchers at the University of California, Davis compared data from multiple studies to see how factors like litter size and piglet weight gain affected milk production in sows.

Researchers were looking for a more accurate way to model milk yield. Current models only predict average milk yield, but milk yield changes throughout lactation. A sow’s nutrient requirements also change during lactation. Because of this relationship between lactation and nutrition, it is important to have reliable milk yield predictions.

Previous studies of sow lactation had focused on average milk yield and composition. For this study, the researchers analyzed data to get more comprehensive results.

“The milk composition is easy to measure, because you only need a sample of the milk, whereas, it is very difficult to measure the daily milk production since you cannot milk a sow like a dairy cow,” said Anja Hansen, a research at the University of California, Davis and coauthor of the study.

Sows utilize energy during lactation, often in the form of stored body fat. Researchers are examining new ways to adequately meet energy requirements, not only to reduce excessive loss in body weight during lactation but to also improve sow health and longevity.

In the study, researchers found that larger piglet litters lead to more milk production in sows. Increased litter size can also increase piglet weight gain because more mammary glands are used during feeding. Researchers reported that sows that had already given birth to previous litters tended to have larger litters later.

After studying how variations in litter size affect milk production, the researchers found that many nutrient requirement recommendations for sows are either underestimated or overestimated.

“The common practice today is that the sows are fed the same diet during the entire lactation period, but maybe she should be fed more energy or nutrient-dense diet during the first week, because she cannot eat enough to cover the requirement. These new feeding strategies could provide piglet growth and longevity of the sow and thereby the economy of the producer,” said Hansen.

Hansen said new feeding strategies could improve piglet growth and help sows live longer. Better growth and longevity could also make farms more economically sustainable.

The Journal of Animal Science paper comes with a tool that could be useful for pig producers. The researchers have included an excel spreadsheet that allows producers to enter the litter size and average litter gain to see the milk production curve that would aid in nutrient requirement calculations. Hansen said a limiting factor may be the ability for producers to realistically feed sows multiple diets.

This study is titled “Predicting milk yield and composition in lactating sows: A Bayesian approach” by A.V. Hansen, A.B. Strathe, E. Kebreab, J. France, and P.K. Theil. It can be read in full at the Journal of Animal Science.

Scientific contact:

Anja Varmloese Hansen, University of California, Davis, avhansen@ucdavis.edu