Understand calf digestive development

Cattle Chat Kansas State University

A calf’s digestive system is shaped by more than time. Diet, milk intake and early environmental exposure all influence rumen development.

On a recent episode of the Kansas State University Beef Cattle Institute’s Cattle Chat podcast, specialists discussed how differences in calf nutrition between beef and dairy systems affect herd performance.

Billy Brown, Kansas State University dairy cattle nutritionist, said dairy calves are introduced to grain from day one, even though they consume very little early on.

“We’re trying to get fermentable carbohydrates into the rumen early,” Brown said. “Fermentation produces volatile fatty acids, which stimulate the growth of rumen papillae, which is essential for nutrient absorption.”

Since dairy calves are weaned at six to eight weeks, their rumen must develop quickly. Those calves often eat five to eight pounds of grain daily by two months of age.

In contrast, beef calves develop slower due to different management strategies, according to Phillip Lancaster, Kansas State University beef cattle nutritionist.

Lancaster said, “Beef calves are on pasture, learning by watching their dams. They might nibble grass and hay, but usually only eat about a pound of forage per day at two months.”

Microbial colonization in the rumen begins within days of birth in both systems. Calves pick up microbes through their environment and dams, which jump-starts rumen activity. However, diet dictates how quickly the rumen matures.

Kansas State University veterinarian Bob Larson said milk production also affects solid feed intake.

Larson said, “A high-milking cow may delay the calf’s interest in solids, while a lower-producing dam may encourage earlier forage intake."

In dairy systems, early grain intake is essential to prepare calves for weaning. Without proper rumen development, a post-weaning slump can occur, Brown said.

Brown said, “Accelerated milk programs grow calves fast, but they may not eat enough grain before weaning, which can slow adjustment (from milk to grain)."

Though beef calves are typically weaned later — often at five to seven months — producers should monitor signs of rumen development, including behavior and pasture consumption.

Larson said, “Beef cows generally peak in milk between 30 and 90 days post-calving. That’s when calves get the most milk and may limit solid intake.”

Regardless of the production system, early digestive development is key to future performance.

Brown said, “Whether a calf is on pasture or in a hutch, getting the rumen working early supports better health and productivity."