Dairy producers frequently add clay as a feed supplement to reduce the symptoms of aflatoxin and subacute ruminal acidosis (SARA) in lactating cows. In a new study from the University of Illinois, researchers show that clay can also improve the degradability of feedstuffs.
"Farmers are giving this clay, but they want to know if the corn silage or hay the cow is eating is affected. We found that yes, the clay is changing the way the cow degrades feedstuffs," says Phil Cardoso, associate professor in the Department of Animal Sciences at Illinois and co-author of the Animal Feed Science and Technology study.
Cardoso and his team tested the degradability of six feedstuffs -- dried alfalfa hay, grass hay, wet brewer's grains, ground corn, corn silage, and soybean meal -- along with no added clay, 1%, or 2% of dietary dry matter.
The researchers placed the feedstuffs into mesh bags and inserted them directly into the rumen through a cannula or fistula, a surgically installed portal that allows the contents of the rumen to be sampled for research purposes. The bags were then drawn out at multiple time intervals (two hours to four days) and analyzed.
"There were some differences in how the feedstuffs degraded over time. When clay was added to grass hay at 2% of dietary dry matter, the digestibility and usage of the fat in that material was maximized. It's better. And we didn't see a decline in degradability of the other feedstuffs, either," Cardoso says. "Overall, to maximize the benefits of clay, we'd recommend adding it at 1 to 2% of dietary dry matter."