Fat Levels in Female White-Tailed Deer during the Breeding Season and Pregnancy

Abstract

Levels of stored body fat, based upon the kidney fat index, were measured for 238 pregnant white-tailed deer through the gestation period and 866 nonpregnant female deer through the breeding season. The deer were collected on the Savannah River Plant (SRP) near Aiken, South Carolina. The percentage of stored body fat of pregnant deer decreased significantly over the length of pregnancy. The rate of fat loss was significantly related to the number of in utero fetuses, conception date, and individual genic heterozygosity but not age, weight, or habitat (either swamp or upland). Greatest fat loss in pregnant deer was for females with two fetuses or females that conceived early in the breeding season. Among nonpregnant females, fat levels increased significantly from September through December. Nonlactating females gained fat during this period at a significantly greater rate than lactating ones. Fat levels of nonpregnant deer differed among age classes but rate of fat increase during the breeding season was not associated with age. Fat levels of nonpregnant deer from the swamp habitat of the SRP were related significantly to individual heterozygosity, with higher levels of stored body fat in heterozygous female deer throughout the breeding season. These results indicate an association between individual heterozygosity and levels of stored energy of white-tailed deer which, in turn, may be related to reproductive success.