Reproduction Abstracts

The aim of this study was to determine the effect of feed restriction on follicular dynamics and hormone secretion patterns in goats, and to examine the effect of neurokinin B analog (senktide) under this experimental setting. Goats were administered 2 mg of dinoprost during the luteal phase, and CIDR was inserted for 10 days. Feed was provided at the level of 50% (feed-restricted; n=9) or 100% maintenance (control; n=4) for 15 days, beginning on the day of CIDR insertion. At 12 h after CIDR withdrawal, feed-restricted goats were administered 200 nmol senktide (n=4) or saline (n=5) at 4 h intervals for 24 h. Feed restriction caused 13.9±5.1% body weight loss, accompanied by lowered glucose and increased non-esterified fatty acid levels in plasma. On the day of CIDR withdrawal, feed-restricted goats had fewer follicles (2.6±0.9 vs 3.8±1.9 follicles), with smaller diameter (3.5±0.3 vs 3.9±0.5 mm) than control goats. However, occurrence of estrus, ovulation rate, and related hormone profiles in the feed-restricted goats were similar to those in the control goats. In senktide-treated goats, there was a rapid increase in LH after each injection, followed by an increase in plasma estradiol. Three of four goats treated with senktide did not show estrus. The interval from the beginning of treatment to ovulation tended to be shorter in senktide-treated goats (60.0±24.0 h) than in saline-treated goats (86.4±13.1 h). Maximal diameters of ovulatory follicles in senktide-treated goats were smaller than those in the control group (4.4±0.8 vs 5.1±0.6 mm). These results showed that 50% feed restriction negatively affected follicular development and that senktide could enhance LH secretion and accelerate the ovulatory process.