University of Illinois study explores best feeding strategy for artificially reared piglets

When piglets don’t get enough milk in the first weeks of life, the chances of them thriving dramatically decline. In the US pork production system, piglets with limited access to their mothers’ milk are typically “cross-fostered” with other sows. But in the EU, a different solution is gaining ground. In certain circumstances, underfed piglets are artificially reared with milk replacer, mimicking feeding setups used in biomedical research.

A new study at the University of Illinois Urbana-Champaign asks a deceptively simple question: what is the best way to feed artificially reared pigs? The answer has implications not just for agriculture, but for biomedical research where pigs are used to study different aspects of human medicine. 

“The main driving factor for this study was to bridge the gap between the agriculture and biomedical worlds,” said lead study author Kaitlyn Sommer, a doctoral researcher in the Department of Animal Sciences, part of the College of Agricultural, Consumer and Environmental Sciences at Illinois. By testing different feeding strategies, researchers can better understand how nutrition early in a pig’s life can affect their growth, metabolism, behavior, and overall welfare. 

In this study, 85 piglets were weaned at two days of age and reared individually with a nutritionally complete milk replacer. Half of the piglets were able to drink milk freely (known as ad libitum or free choice feeding), while the other half received carefully measured doses based on body weight, mimicking the frequency and quantity a piglet would get from a sow. Over the 15-day feeding study, the team tracked everything from the piglets’ body weight, insulin concentration, behavior, and even soft tissue composition.

The results were striking. “Ad libitum pigs drank more milk overall and gained more weight,” Sommer said. However, there were no significant differences in the soft tissue composition between the two groups at the conclusion of the study. Researchers found that the body fat and muscle protein content were comparable between the ad libitum and “prescribed feeding” piglets. The main distinction was in how quickly they grew.