Effect of intermittent administration of neurokinin 3 receptor agonist on luteinizing hormone secretion, estrus, and ovulation in feed-restricted goats

Abstract The aim of this study was to determine the short-term effects of feed restriction on follicular dynamics and hormone secretion patterns in goats, and to examine the effect of senktide, a neurokinin 3 receptor agonist, under the feed-restricted condition. Goats were administered 2 mg of dinoprost in the luteal phase of the estrous cycle, and an intravaginal progesterone device (CIDR) was inserted for 10 days. Feed was provided at the level of 50% (feed-restricted, n  = 12) or 100% maintenance (control, n  = 5) for 15 days, beginning on the day of CIDR insertion. At 12 h after CIDR withdrawal, feed-restricted goats were intravenously administered with 200 nmol of senktide ( n  = 6) or saline ( n  = 6) at 4-h intervals for 24 h. Fifteen days of feed restriction caused 12.4 ± 5.5% body weight loss. On the day of CIDR withdrawal, feed-restricted goats had fewer follicles with smaller diameter than control goats. Feed restriction caused anestrus and anovulation in one case, and all the other goats in the control and feed-restricted saline-treated groups showed estrus and ovulated within normal ranges. Therefore, there was no significant influence of feed restriction on the timing of these events and related hormone profiles. In senktide-treated goats, there was a rapid increase in luteinizing hormone (LH) after each injection, which was followed by an increase in plasma estradiol concentration. In the senktide-treated group, 5/6 goats did not show estrus, and 3/6 goats ovulated 2 days after treatment, while most goats ovulated 3 or 4 days after treatment. These results suggest that feed restriction negatively affects follicular development and that senktide can enhance pulsatile LH secretion and thereby accelerate the ovulatory process.