METHYL GROUP EFFECTS ON IMMUNE FUNCTION AND HEALTH OF NEWLY RECEIVED CATTLE

The long term goals of the proposed research are to improve the efficiency of the beef cattle industry by developing new information about methyl group metabolism and effects of methyl group supplementation on health and immune function. With better understanding of methyl group metabolism and effects on cattle health, we will be better able to match nutrient supplies with animal requirements. Notably, the opportunity exists to expand nutrient assessments to include estimated requirements for methyl groups, such that deficiencies could be predicted and supplied in a fashion similar to that used for amino acids.The proposed work will consider methionine (a frequently limiting amino acid), choline (a vitamin-like compound that can improve performance of feedlot cattle and is often supplemented to transition dairy cattle), and betaine, a methyl group source produced from oxidation of choline and used for synthesis of methionine from homocysteine.Our objectives are to determine:Are the various metabolic pathways of methyl groups in cattle sufficiently interconnected to allow all methyl group sources to be similarly effective, or do responses differ among methyl group sources? In other words, are different methyl groups sources quantitatively interconvertible?How does the methyl group and methionine status of cattle affect immune function when assessed indirectly and under ex vivo conditions?How does the methyl group and methionine status of cattle affect immune function as measured by disease status of receiving cattle?How does the methyl group and methionine status of cattle affect performance of receiving cattle?Answers to these questions will allow production of growing beef cattle to be more economically efficient, while reducing nitrogen excretion by the beef industry to the environment. Insights into methyl group metabolism in cattle may provide insight into health and efficiency of lactating dairy cattle, although this is not the key focus of the proposed work.