Effects of Undernutrition on in Vitro Fertilization (ivf) and Early Embryonic Development in Sheep

Nutrition has been shown to influence several reproductive functions including hormone production, oocyte competence and fertilization, and early embryonic development. To determine the effects of maternal diet on in vitro fertilization (IVF) and early embryonic development, ewes (n=18) were divided into control and underfed groups and received 100% and 60% maintenance diet, respectively, for 8 weeks before oocyte collection. Once a week ewes were weighted and the body condition score (BCS) was determined. Estrous synchronization was performed using progestagen sponges for 14 days. Follicular development was induced in ewes by twice daily injections of follicle stimulating hormone (FSH) on day 13 and 14 of the estrous cycle. Oocytes were collected from all visible follicles on day 15 of the estrous cycle. After IVF, the rate of early embryonic development was evaluated throughout the 8 day culture period. An average initial body weight was 53.8 ± 1.2 kg and 49.4 ± 0.6 kg at the end of experiment weight was 55.4 ± 1.5 kg and 44.4 ± 0.9 kg for control and underfed ewes, respectively. An average initial BCS was 3.4 ± 0.04 at the end of the experiment BCS was 3.7 ± 0.1 and 3.1 ± 0.1 for control and underfed ewes, respectively. Both, the weights and BCS were different (P<0.01) for control and underfed ewes at the end of experiment. Undernutrition decreased (P<0.001) the number of blastocysts per ewe and the rate of blastocyst formation. However, number of visible follicles (large and small), the total number of oocytes, the number of healthy oocytes, the percentage of healthy oocytes and cleavage rates per ewe were similar for control and underfed ewes. These data indicate that undernutrition of donor ewes resulting in lower weight and BCS, has a negative effect on oocyte quality which results in a lower rate of blastocyst formation.