Effect of level of dietary energy and protein on embryo survival and progesterone production on day eight of pregnancy in Rasa Aragonesa ewes.

摘要

In mid-October, 29 Aragonese ewes were fed to provide 1.5 X maintenance energy requirements (H), 0.5 X maintenance (L) or 0.5 X maintenance + 7.44 g crude protein/MJ metabolizable energy (LP) from 14 days before synchronized mating (day 0) onwards.There was a significant effect of nutrition on ovulation rate (2.22±0.16, 1.50±0.16 and 1.88±0.12 corpora lutea for H, L and LP respectively; P<0.05). On day 7, L ewes had the highest mean plasma LH level (P<0.01), while H ewes had the lowest mean LH concentration and the highest mean plasma progesterone concentration (P<0.01). Laparotomies were performed on 6 ewes from each group on day 8 to determine the effect of nutrition on embryo development. Embryos recovered from L and LP ewes were at the morula, early blastocyst and expanded blastocyst stage while all embryos from H ewes were expanded blastocysts (P<0.001). The ratio of blastocysts to corpora lutea was higher in H ewes (0.86) compared with a pooled value for L and LP groups (0.57; P<0.05). Mean progesterone concentration in the ovarian vein was 800-fold higher than mean jugular venous levels, with no differences between groups. Samples from ovarian veins contralateral to corpus luteum-bearing ovaries had a lower mean progesterone concentration than samples opposite to the corpus luteum (ipsilateral, 1037.84±138.45; contralateral, 30.4±11.22 ng/ml; P<0.001). Mean progesterone concentration in the uterine vein was approximately 30-fold higher than that in the jugular vein and was similar in the 2 uterine horns and among treatments. No effect of nutrition on pregnancy rate was observed (89, 92 and 100% for H, L and LP respectively).