Genetic variation in reproductive responses to a high-energy diet in mice

Effects of a high-energy diet on reproduction were studied in 300 mice from lines selected for litter size and(or) 6-wk BW (L+, increased litter size; W+, increased body weight; L+W-, increased litter size and decreased body weight; L-W+, decreased litter size and increased body weight; and K, randomly selected control). Mice received a high-energy diet (HED; 3.8 kcal/g of ME) or a standard diet (STD; 3.3 kcal/g of ME) from 8 to 11 wk of age and were then mated and evaluated for ovulation rate and embryo survival through 17 d of gestation. The HED increased ovulation rate in all lines (P less than .05). The line x diet interaction was significant, with increased ovulation rate due to HED ranging from 9.9% in W+ to 24.2% in L-W+. Within-line regression coefficients of ovulation rate on ME intake (kilocalories from 10 to 11 wk) varied from .08 +/- .04 (P less than .05) in L+W- to .177 +/- .05 (P less than .01) in L+. In contrast, nonsignificant increases were observed in litter size (live fetuses at 17 d of gestation) due to HED. Effects of HED on embryo survival rate were significantly negative in L+ and L+W-; the decrease in L+ was a result of preimplantation losses, and the decrease in L+W- was due to postimplantation losses. The line x diet interaction was significant for postimplantation embryo survival. The results indicate significant genetic variation in reproductive responses to a high-energy diet in mice.