WATER IS AN ESSENTIAL NUTRIENT FOR BEEF CATTLE, YET WATER REQUIREMENTS OF BEEF CATTLE OFTEN RELY ON DATA COLLECTED IN THE 1950S OR EARLIER. BEEF CATTLE HAVE CHANGED CONSIDERABLY IN BODY SIZE AND PRODUCTION CHARACTERISTICS OVER THE LAST 60-70 YEARS. OUR OVERARCHING HYPOTHESIS IS THAT WATER REQUIREMENTS VARY AMONG ANIMALS BASED ON THEIR BODY WEIGHT, AGE, CLIMATIC FACTORS, AND GENETICS. SPECIFICALLY, WE AIM TO (1) ESTIMATE WATER REQUIREMENTS OF BEEF CALVES AND YEARLINGS AT DIFFERENT AGES, BODY WEIGHTS, AND CLIMATIC FACTORS, AND (2) IDENTIFY GENES ASSOCIATED WITH THIRST IN BEEF CALVES. WE EXPECT TO ESTIMATE UPDATED WATER REQUIREMENTS IN BEEF CALVES THAT CAN BE USED BY BEEF PRODUCERS TO PREDICT WATER NEEDS OF THEIR HERD. WE ALSO EXPECT TO IDENTIFY GENES IMPORTANT FOR THE THIRST RESPONSE IN CATTLE. IDENTIFICATION OF THESE GENES WILL BE AN IMPORTANT FIRST STEP TOWARDS UNDERSTANDING GENETIC VARIATION OF WATER REQUIREMENTS OF OUR BEEF HERD. THIS RESEARCH WILL IMPACT THE BEEF INDUSTRY BY HELPING PRODUCERS UNDERSTAND GENETIC AND ENVIRONMENTAL EFFECTS THAT AFFECT WATER INTAKE OF CATTLE.