Identifying nutritional signals in sheep before and after mating
Kakar, M.A.(Adelaide Univ., Roseworthy (Australia). Dept. of Animal Science) | Maddocks, S.(Adelaide Univ., Roseworthy (Australia). Dept. of Animal Science) | Chawanakul, S.(King Monkut Univ. of Technology, Bangkok (Thailand). The Joint Graduate School of Energy and Environment) | Abbas, M.(Livestock and Dairy Development Dept., Quetta (Pakistan). Embryo Transfer Lab.) | Kleeman, D.O.(South Australian Research and Development Inst., Rosedale (Australia). Turretfield Research Centre) | Walker, S.K.(South Australian Research and Development Inst., Rosedale (Australia). Turretfield Research Centre)
Two experiments were conducted to investigate the effect of short-term (one cycle) changes in nutrition during the peri-conceptual period of the ewe, on blastocyst development and quality. In the first experiment 48 ewes were allocated to one of three dietary treatments as follows: high energy (H), moderate energy, low energy (L). Embryos from sheep fed L diet had significantly greater total cell numbers than sheep fed H diet. This increase appeared to result primarily from a significant increase in the number of trophectoderm cells in the embryo. In the second experiment 76 ewes were fed the same diets as in the first experiment but for different lengths of time. Although no significant differences were found in the number of embryos collected, the total number of cells that each embryo produced was significantly reduced for sheep receiving H ration for the whole trial period or after mating. A significantly higher proportion of these cells were trophectoderm cells in sheep fed L ration after mating than in sheep receiving H ration. Our results indicate that the timing of changes in feed allowances before mating does not affect embryo quality. On the contrary, these changes after mating are crucial for demonstrating the effect of nutrition on embryo quality.
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