Influence of diet on photoperiod-induced gonadal regression in female hamsters

Introduction of a seed/nut mixture (Lyric) to the diet of female golden hamsters was found to stimulate growth as well as to effect a delay in the reproductive response to a short photoperiod. In a series of experiments we found that 1) growth rates of hamsters offered the Lyric diet alone or in conjunction with the standard rodent diet exceeded those of hamsters offered only the standard rodent diet. 2) Hamsters fed the standard rodent diet for eight weeks, followed by the Lyric diet for four weeks remained reproductively functional in a short photoperiod; however, 3) most hamsters that were fed the Lyric diet or the standard rodent diet continuously for 12 or 16 weeks experienced reproductive atrophy in short photoperiods; 4) The presence of a vitamin/mineral supplement in the Lyric diet did not affect the incidence of reproductive degeneration in hamsters fed this diet continuously for 12 weeks; however, 5) the vitamin/mineral supplement in this experiment did influence weight gain in hamsters exposed to short photoperiods. We conclude that the Lyric diet, offered as a novel food source after eight weeks on a standard rodent diet, acts to delay the onset of reproductive atrophy in hamsters exposed to short photoperiods. The mechanism for such an effect is not known at this time.