Nutritional strategies to improve gastrointestinal health of dairy calves
Dairy calves are extremely susceptible to gastrointestinal disease during the pre-weaned period. The gastrointestinal immune system of the calf is naive 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 may be at an increased risk for developing gastrointestinal diseases. Gastrointestinal health can be improved either by hastening the maturation of the intestinal immune system or by controlling infections in the intestines until the local immune system fully develops. Various nutritional strategies may function through 1 or both of these mechanisms and include yeast cell wall extracts, probiotics, other fermentation products, hyper-immunized egg protein, and spray-dried plasma proteins. In addition to various nutritional additives, the quantity and quality of milk solids that are fed to neonatal calves can influence not only the pre-weaning health, but have effects that persist later into life. Nutrition of neonatal calves is as important to calf health as any other management strategy.