Enhancement of Ovulatory Follicle Development in Maiden Sheep by Short-term Supplementation with Steam-flaked Corn
2008
Letelier, C. | Gonzalez-Bulnes, A. | Hervé, M. | Correa, J. | Pulido, R.
The effect of a short-term nutritional supplementation with steam-flaked corn on metabolism and folliculogenesis was evaluated in 14 maiden sheep. Oestrus was synchronized with two prostaglandin F₂α doses given 10 days apart. From day 11 to 15 of the oestrous cycle induced with prostaglandins, half of the ewes (group 2M) were supplemented with steam-flaked corn, double the daily maintenance ration of the control sheep (group 1M). Body weight and condition remained unaffected, but the energetic supply increased plasma concentrations of glucose (3.6 ± 0.1 vs 4.3 ± 0.1 mmol/l, p < 0.0001) for the first 4 days and 3-hydroxybutyrate (0.323 ± 0.58 vs 0.582 ± 0.04 mmol/l, p < 0.005) from day 2 to 4. The profile of insulin secretion was also affected by the treatment, increasing in group 2M to reach significant differences on days 13 and 14 (p < 0.05). From similar values at the start of the food supply, the treatment induced a higher follicular development in group 2M (1.1 ± 1.2 vs 7.4 ± 1.06 total follicles in day 15, p < 0.05), as evidenced by the lineal increase in the number of larger follicles (>4 mm, p < 0.005). Then, the number of follicles >4 mm in size in 2M was around 60% higher on day 16 (7.86 ± 0.45 vs 4.86 ± 0.63, p < 0.005). Thereafter, the mean number of corpora lutea per ewe was around 30% higher in group 2M (1.43 ± 0.2 vs 1.10 ± 0.1, although differences were not found to be statistically significant). These data suggest that the use of diets containing high starch sources, like the steam-flaked corn, increases folliculogenesis and ovulation rate in sheep and can be applied in short-term feeding practices.
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