Induction of luteolysis in goats with prostaglandin F2 alpha.

On day 10 of each estrous cycle, 19 cycling does were given (IM) 1 of 3 dosage levels of prostaglandin F2 alpha (PGF2 alpha) or saline solution. After injections, goats were observed twice daily for behavioral estrus, and serum concentrations of progesterone (P4) were determined from daily blood collections to measure response to treatment. Every dose of PGF2 alpha (0.0165 mg/kg of body weight, 0.0275 mg/kg, and 0.0385 mg/kg) was administered during 20 estrous cycles, and 0.25 ml of saline solution was administered during 12 estrous cycles. Fourteen of 20, 15 of 20, 20 of 20, and 0 of 12 does exhibited signs of behavioral estrus within 96 hours of injections of 0.0165 mg of PGF2 alpha/kg, 0.0275 mg of PGF2 alpha/kg, 0.0385 mg of PGF2 alpha/kg, and saline solution, respectively. A decline in mean concentrations of peripheral P4 from 3.6, 3.8, 4.4, and 4.3 ng/ml to less than 1 ng/ml within 24 hours was observed in 15 of 20, 16 of 20, 20 of 20, and 0 of 10 does after injections of 0.0165 mg of PGF2 alpha/kg, 0.0275 mg of PGF2 alpha/kg, 0.0385 mg of PGF2 alpha/kg, and saline solution, respectively. The dosage level of 0.0385 mg of PGF2 alpha/kg (1.75 mg of PGF2 alpha/45.36 kg) was effective for induction of estrus in 100% of the does.