HISTROTROPHIC NUTRITION AND EARLY EMBRYO DEVELOPMENT
Histrotrophic nutrition was manipulated in adult Merino ewes during the course of a single reproductive cycle. From 18 days before until 6 days after ovulation. The effect of his relatively short-term exposure to high feed intake (H: 1.5 × maintenance ration), maintenance intake (M: 1× mainrenance ration) or low feed intake (L:0.5 × maintenance) was examined on embryo development, composition of oviductal fluid and pregnancy outcome in the ewes that either ovulated naturally or were induced to superovulate. Live weight was significally (p<0.05) reduced in sheep on L-compared with a M- or H- feed intake regime. The mean number of embryo collected, the mean number of corpora lutea (CL), and the proportion of embryos/CL recovered, was not influenced significally by differences in feed intake. However,embryos from sheep with an L feed intake during the peri-conceptional period consistently contained a significally (P<0.05) increased number of cells, resulting from a specific increase in the number of trophectoderm (TE) cells. Manupulating feed intake across the pre- vs.post-ovulatory periods revealed that exposure to a low feed inake in the 6-days post-ovulatory period caused this increase in the number of TE cells.
Overall, these studies indicate that short-term changes in feed intake can significantly alter embryo development with potential consequences for subsequent fetal development. The way in which these short term changes influences development has not been resolved, but a number of exciting avenues are presented for further investigation. The findings are relevant to both human and animal and to improving our understanding of basic development process in reproduction.