Doses of prostaglandin F 2α effective for induction of estrus in goats

Abstract

A total of 11 cycling does weighing between 24 and 50 kg were injected with varying dosages of prostaglandin F 2α (PGF 2α) between 7 and 10 days into each estrous cycle. Five injections each of 1.25, 2.5, 5.0, or 7.5 mg PGF 2α were alternated with five injections of 1.0 ml saline. Saline treated does served as controls. All does were teased twice daily with a buck and observed for signs of estrus for 5 days post-injection. Daily systemic concentrations of progesterone (P 4) were determined by radioimmunoassay. The mean (± S.E.) hours from injection to estrus was 47 ± 3.3, 42 ± 4.3, 44 ± 8.5, and 43 ± 5.5 for does receiving 1.25, 2.5, 5.0, and 7.5 mg PGF 2α, respectively. None of the does receiving saline exhibited estrus in the 5-day post-injection observation period. Mean (± S.E.) concentrations of systemic P 4 in all does on the day of injection was 4.22 ± 0.45 ng/ml. Concentrations 24 hours post-injection were 0.21 ± 0.02, 0.15 ± 0.05, 0.17 ± 0.04, 0.16 ± 0.04, and 4.5 ± 1.36 ng/ml for does receiving 1.25, 2.5, 5.0, and 7.5 mg PGF 2α, and 1.0 ml saline, respectively. The results suggested that 1.25 mg PGF 2α was effective for induction of estrus in the cycling goat.