Mating behaviour of male rats following pre- and early postnatal undernutrition: a comparison of two outbred stocks.

Developing rats of two outbred stocks (Lister and Wistar) were either well-nourished or were undernourished by feeding their mothers a restricted quantity of food during pregnancy and lactation. All rats were fed ad lib from 25 days. Beginning at 14 months, the mating behaviour of males was investigated in five tests at weekly intervals using ovariectomised females brought into behavioural oestrus using injections of oestradiol and progesterone. Lister males were tested with Lister females, and Wistar males with Wistar females. Early life undernutrition reduced the numbers of non-penetrative mounts and shortened the latency to ejaculate in rats of the Lister but not the Wistar stock. Mount latency was reduced by early undernutrition in the Wistar stock, but was unaffected in the Lister stock. These results indicate that the effects of early life undernutrition on male mating behaviour differ in detail from one stock of rat to another. In general, however, the results suggest that infantile undernutrition facilitates, rather than impairs, the sexual behaviour of male rats in "middle-age."