Effect of Condition of Animal on the Requirements of Energy for Maintenance of the Bovine

Summary Three sets of monozygous bovine animals (two sets of triplet bulls and one set of twin steers) were used to study the relationship between the feed energy required to maintain body weight and the condition (fatness) of the animal. The animals within each set were fed rations with different contents of energy but which were not limiting in their supply of other nutrients. The rations fed caused certain animals of each set to weigh more and be in higher condition than others in the set. Under these circumstances, the TDN required per unit weight for maintenance increased materially as weight and condition increased. Under the circumstance, where the animals of a set were at the same weight but differed in condition, the animal that was fattest required the most TDN per unit weight for maintenance. The effect of feeding 15 g. thyroprotein to one bull in a set of triplets caused maintenance requirements per unit weight for TDN to be greater than for the bull of the set maintained in very high condition. It was concluded that maintenance requirements for energy per unit weight increase as condition of the animal increases or as effective quantities of thyroprotein are included in the ration of the bovine animal.