Minisymposium: Effect of Partitioning Agents on Nutrient Requirements Impact of Somatotropins on Nutrient Requirements in Domestic Animals1

Somatotropins increase nitrogen reten tion, decrease carcass fat and increase lean/fat ratio in growing ruminants and swine. However, responses are much more variable in growing ruminants. Maintenance requirements in both ruminants and swine are increased slightly with somatotropin treatment in conjunction with increased lean mass. This is associated with in creases in partial efficiency of protein accretion, re sulting in increased efficiency of growth. Additional in formation is required to accurately assess effects of somatotropin on nutrient requirements for growing ru minants and swine. Future studies should target de- gradable and nondegradable protein requirements for growing ruminants and the impact of somatotropin on these requirements; definition of dose, pattern and for mulation of somatotropin for both ruminants and swine and interaction of somatotropin with other factors af fecting feed intake in swine and ruminants. J. Nutr. 122: 855-860, 1992.