IN THE U.S. CATTLE INDUSTRY, CALVES ARE PRODUCED THROUGHOUT THE COUNTRY WITH MANY OF THE CALVES BEING SHIPPED TO FEEDLOTS IN THE MIDWEST, WHERE THEY ARE FED GRAIN-BASED DIETS PRIOR TO HARVEST. DURING THIS PERIOD OF TRANSFER, CALVES (RECEIVING CATTLE) ARE EXPOSED TO A NUMBER OF STRESSORS THAT LEAD TO A SIGNIFICANT PORTION OF THE CALVES BECOMING SICK, LARGELY WITH RESPIRATORY DISEASES, AFTER THEY REACH THEIR DESTINATION. THIS RESEARCH WILL ADDRESS A DIETARY STRATEGY THAT COULD HELP TO REDUCE DISEASE INCIDENCE IN RECEIVING CATTLE, THEREBY IMPROVING BOTH ANIMAL WELFARE AS WELL AS THE EFFICIENCY OF BEEF PRODUCTION.SPECIFICALLY, THIS RESEARCH WILL EVALUATE METABOLISM OF METHYL GROUP-CONTAINING COMPOUNDS (VITAMIN-LIKE COMPOUNDS) AND THEIR EFFECTS ON IMMUNE FUNCTION, HEALTH, AND PERFORMANCE OF RECEIVING CATTLE. NOTABLY, WE WILL PREDICT THE ANIMALS' REQUIREMENTS FOR METHYL GROUPS, SUCH THAT THEY CAN BE SUPPLEMENTED TO DIETS IN AMOUNTS THAT WILL OPTIMIZE ANIMAL PERFORMANCE.THE PROPOSED RESEARCH WILL ADDRESS SEVERAL SPECIFIC ISSUES: 1) HOW ARE DIFFERENT SOURCES OF METHYL GROUPS METABOLIZED BY CATTLE? 2) HOW DOES THE METHYL GROUP STATUS OF CATTLE AFFECT IMMUNE FUNCTION? 3) WHAT IS THE ULTIMATE EFFECT OF METHYL GROUP SUPPLEMENTATION ON PERFORMANCE OF RECEIVING CATTLE? ULTIMATELY, MORE INFORMATION ABOUT METHYL GROUPS WILL BE USED TO IMPROVE THE PRODUCTION AND ECONOMIC EFFICIENCIES OF GROWING/FINISHING BEEF CATTLE.THE COST ASSOCIATED WITH TREATING RESPIRATORY DISEASE IN RECEIVING CATTLE CAN BE MORE THAN $200 PER CASE, WITH THAT COST REFLECTING COST OF TREATMENT, DEATH LOSS, AND REDUCED PERFORMANCE. THE SIGNIFICANCE OF APPROPRIATE IMMUNE FUNCTION IS DIFFICULT TO OVERSTATE FOR RECEIVING CATTLE, WHERE MORBIDITY (SICKNESS) RATES CAN EXCEED 60%. EVEN A MODEST 5 PERCENTAGE UNIT REDUCTION IN MORBIDITY REPRESENTS MORE THAN A $10 ADVANTAGE PER ANIMAL, WHICH ACROSS 20 MILLION CALVES THROUGHOUT THE U.S. WOULD TRANSLATE TO A YEARLY SAVINGS OF MORE THAN $200 MILLION. WITH A BETTER ASSESSMENT OF METHYL GROUP SOURCES AND EFFECTS OF THEIR SUPPLEMENTATION, IT MAY BE POSSIBLE TO PROVIDE NUTRITIONAL SUPPLEMENTS THAT ARE EFFECTIVE AND ECONOMICALLY FEASIBLE.