Effect of long-term or short-term supplementation of high energy or high energy-protein diets on ovarian follicles and blood metabolites and hormones in ewes

- Feeding program affected double ovulation rate and serum metabolites of cyclic ewes.
- High energy diets change blood levels of glucose, insulin and oestradiol of ewes.
- The period of diet treatment could be reduced to 6 days just before ovulation time.
- High energy-protein diets had adverse effect on ovulation rate and serum metabolites.

This study was conducted to compare the effect of high energy or high energy-protein diets in long-term (16 days, flushing) or short-term (6 days, focus feeding) supplementation period on ovarian performance and serum metabolites and hormones of ewes. For this purpose 40 cyclic Naeini ewes (40 ± 1 kg BW and 2-3 years of age) were randomly assigned to experimental groups: 1-Control (CON), 2-long-term high energy diet (LE), 3-short-term high energy diet (SE), 4-long-term high energy-protein diet (LEP), and 5-short-term high energy-protein diet (SEP). Ewes were housed in the individual pens with free access to food and water. The estrous cycle of ewes was synchronized with insertion of intravaginal progesterone sponges for a 12-day period. Follicular development was observed by ultrasound four days before to one day after sponge removing (−4 to +1) and blood was sampled once a day during this time. Results showed that LE and SE groups had more large-size (>5 mm) follicles (P < 0.05) than those the other group on day +1. Double ovulation rate was high in ewes fed with high energy diets. The LE and SE groups had higher (P < 0.05) serum glucose, cholesterol and insulin, but lower urea concentration compared to the other groups. Feeding high energy caused low serum oestradiol before the sponge removing. However, the LE and SE groups had the highest (P < 0.05) oestradiol concentration before the estrus time. Results of the present study revealed that change in dietary energy levels for a short-term or long-term period just before ovulation could improve the blood metabolites and reproductive performance of the ewes.