Nutrition Influences the Health of Dairy Calves

Dairy calves are extremely susceptible to gastro-intestinal disease during the pre-weaned period. The risk for enteric disease decreases as the calf ages; therefore, it is important to break the pre-weaned period up into at least two distinct phases that likely need to be managed differently, early life (first couple weeks of life) and the remaining time the calf is fed milk or milk replacer. When a calf is born they have been exposed to very few if any microorganisms and some aspects of their gastrointestinal immune system are not fully developed. After birth, the calf is now in a microbial world and exposed to a greater quantity and diversity of microorganisms. This adaptation is abrupt and dramatic and is a major stressor to a newborn calf. The gastrointestinal tract of the calf is naïve and develops rapidly during the first few days to weeks of life. The cells that make up the gastrointestinal tract are the first line of defense of the immune system; therefore, until the cells are more adult-like the calf maybe at an increased risk for developing gastro-intestinal diseases. My laboratory recently tested the hypothesis that feeding greater quantities of milk solids during the first week of life would increase the percentage of dietary nutrients that were neither digested nor absorbed by the calf, which would increase the risk of scours. The data indicated that dairy calves during the first few weeks of life digest and absorb nutrients well, and when fed a greater plane of nutrition the