A. H. Jensen

Influence of Ambient Temperature Stress on Response of Pregnant Rats to Dietary Protein Levels

E XPOSING the nonpregnant animal to cold stress has been shown to alter nitrogen metabolism. The endogenous urinary nitrogen excretion of rats was increased after an exposure to a cold environment (Treichler and Mitchell, 1941). Similarly, men consuming low-nitrogen-low-energy diets were in negative nitrogen balance during and for several days after exposure to 8 ~ C. (Issekutz et al., 1962). Klain et al. (1962) using growing rats showed that cold exposure overcame the decreased food intake associated with amino acid imbalanced diets. Subsequently, the irabalancing amino acids were found to be metabolized more rapidly than other dietary amino acids (Klain and Winders, 1964). However, rats at 7 or 23.5 ~ C. both rejected an amino acid imbalanced diet in favor of a nitrogen-free diet (Harper and Rogers, 1966). The dearth of information regarding the nutrition of pregnant animals maintained under temperature stress led to the trials reported herein. The objective of these trials was to assess the influence of dietary protein levels on the reproductive performance of rats maintained at one of three different ambient temperatures.