Enhancing Calf Immunity through Nutrition

Dairy calves are extremely susceptible to gastro-intestinal disease during the preweaned period. The risk for disease decreases as the calf ages; therefore, I think it is important to break the pre-weaned period up into at least 2 distinct phases that likely need to be managed differently, early life (1 and maybe the 2 week of life) and the remaining time the calf is fed fluid (milk or milk replacer). When a calf is born they have never been exposed to any microorganisms and some aspects of their immune system are not fully developed. Since the calf in utero received its nutrients from the cow through placental transfer, the calf has never had any nutrition orally. After birth, the calf is now in a microbial world and expected to receive all its nutrients orally from its mother’s milk. The gastro-intestinal tract of the calf is naïve and develops rapidly during the first few days to weeks. The cells that make up the gastro-intestinal tract are the first line of defense of the immune system; therefore, until the cells are more adult-like the calf is at an increased risk for developing gastro-intestinal diseases. Future research needs to focus on how much, the frequency of feeding, and composition of fluid fed to a calf during this period. Currently, the primary strategies to improve the resistance to gastro-intestinal diseases during this period is focused on decreasing the interaction of potential pathogens with the cells of the calf’s gastro-intestinal tract. The uses of prebiotics, probiotics, and hyper-immunized egg protein have all been shown to decrease the incidence of gastro-intestinal diseases and improve the growth of preweaned calves. It is important to note that not all research has shown improvements, but no studies have reported adverse effects with their inclusion in the diet. Calves where the bacteria get into the bloodstream are at an increased risk of becoming septicemic and consequently have a greatly increased risk of death. The high risk of death is associated with an aggressive inflammatory response. Data, in other animal models as well as calves, indicate that supplementing omega-3 fatty acids decreases the inflammatory response and improves survival of septicemic animals. Therefore, supplementing the fluid of calves may improve the survival of septicemic calves. Lastly, the plane of nutrition that calves are fed during the pre-weaned period was reported to improve future lactational performance and emerging data suggests that it may improve the resistance to gastro-intestinal diseases. Further the effect appears to persist past the pre-weaned period. Nutrition can influence disease resistance of calves in many ways, both directly by supplying specific nutrients and indirectly by influencing the exposure to microorganisms. 1 Contact at: Department of Animal and Food Sciences, Texasd Tech University, Lubbock, TX 79409; Phone: 806-742-2805 ext. 251; Email: [email protected]