The effects of high and low planes of nutrition on reproduction in rabbits

Abstract

Abstract Rabbits of an inbred strain with a high proportion of foetal atrophy were, when adult. put on High and Low planes of nutrition groups. During the pre-experimental period as well as during the experimental period conception rates and litter sizes were recorded. At the end of the experimental period the does were slaughtered at the 29th day of pregnancy and observations made on the reproductive organs. (1) The conception rate during the pre-experimental period was lower in autumn and summer than in winter and spring. Low plane of nutrition depressed the conception rate at all times of year but particularly so during the autumn and summer months, while High plane of nutrition raised the conception rate and reduced seasonal variation. (2) The average litter size during the pre-experimental period was highest in spring and summer and lowest in winter and autumn. In the High plane does, litter size was reduced. (3) The average number of normal young found in the uteri of High plane does (3.8) was lower than in the Low plane does (6.0) in spite of the fact that the ovulation rate was higher for the High plane (10.1) than for the Low plane (9.6). This was not due to foetal atrophy after attachment but to lack of fertilisation or death of the egg before attachment.