Dairy producers know early nutrition for young calves has far-reaching impacts, both for the long-term health and productivity of the animals and for farm profitability. With the goal of increasing not just body weight but also lean tissue gain, a new University of Illinois study found enhanced milk replacer with high crude-protein dry starter feed is the winning combination.

“Calves fed more protein with the starter had less fat in their body weight gain, and more protein was devoted to the development of the gastrointestinal system, compared with the lower starter protein,” said James Drackley, U of I Department of Animal Sciences professor and study co-author. “Our results say producers who are feeding calves a more aggressive amount of milk for greater rates of gain should be feeding a higher protein starter along with that.”

Drackley and his co-authors started two-day to three-day-old calves on one of three experimental diets: a low rate of milk replacer plus conventional starter (18% crude protein, as-fed basis); a high rate of milk replacer plus conventional starter; and a high rate of milk replacer plus high crude protein starter (22% crude protein, as-fed basis). Additional protein in the high-protein starter was provided by soybean meal, compared with conventional starter, which was a mixture of wheat middlings, soybean meal and corn, among other ingredients. The calves were weaned at six weeks of age and were harvested at five or 10 weeks to determine body composition.

“After weaning, the weights of the digestive system and liver were greater with the higher protein starter,” Drackley said. “It might be part of the reason why a slump in growth is often seen right around the time of weaning when calves are fed a conventional starter. The calves just don't have the developed digestive system to be able to keep things going as they change from the milk diet to the dry feed diet.”

He added that calves fed the higher rate of milk replacer grew more rapidly and had more lean tissue with less fat.