Synchronization of estrus with an intrauterine infusion of prostaglandin F2α and an intramuscular injection of LH-releasing hormone (LH-RH) in cows
1976 Volume 21 Issue 4 Pages 141-146
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1976 Volume 21 Issue 4 Pages 141-146
Prostaglandin F2α (PGF2α) and two synthetic LH-RH preparations; i.e. pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2 (LH-RH) and its analog [Des-Gly-NH210, Pro-ethylamide9]-LH-RH (LH-RH-I), were used for the estrous synchronization in the grazing cows, and the occurrence of estrus, ovulation after the treatments and the fertility at the first synchronized estrus were investigated.
A total of 61 cows (48 Holstein and 13 Japanese Shorthorn) in the luteal stage of the estrous cycle were alloted to three experimental groups; i.e. Group A including 16 cows received a single intrauterine infusion of 3 mg or 4 mg of PGF2α and an intramuscular (i.m.) injection of 200 μg of LH-RH, Group B including 13 cows received the same PGF2α treatment as in Group A and an i.m. injection of 200 μg of LH-RH-I, and Group C including 32 cows received the PGF2α treatment alone. Each dose of PGF2α dissolved in 0.75 ml or 1.0 ml of aq. distillata was deposited through the cervix into the uterine horn ipsilateral to the corpus luteum. LH-RH and LH-RH-I preparations dissolved in 5.0 ml of aq. distillata was injected during the period between 52 and 56 hr after the PGF2α treatment.
Estrus occurred in 10 (62.5%) of 16 cows in Group A, 10 (76.9%) of 13 cows in Group B and 26 (81.3%) of 32 cows in Group C during the period of 3772 hr after the PGF2α treatment. Estrus did not occur during the period of 73108 hr in all cows of three groups except two (6.2%) in Group C. Quiet ovulation was observed in 6 cows (37.5%) in Group A, in 3 cows (23.1%) in Group B and in 1 cow (3.1%) in Group C within 132 hr after the treatment. The remaining 3 cows in Group C exhibited estrus between the period of 11 and 15 days.
Ovulation occurred in 12 (75.0%) of 16 cows during the period of 7396 hr in group A, in 11 (84.6%) of 13 cows during the period of 6184 hr in Group B and in 17 (58.6%) of 29 cows during the period of 85108 hr in Group C. The interval elapsing from the treatment to the time that ovulation being detected in more than 80% of cows in Group A and B were shortened by 24 hr and 12 hr, respectively, as compared to that in Group C.
In the cow that exhibited behavioral estrus, the conception rates were 66.7% (6 of 9 cows) in Group A, 60.0% (6 of 10 cows) in Group B and 75.0% (21 of 28 cows) in Group C by the insemination during 35 days of the post treatment period. Whereas, the cow which occurred quiet ovulation in Group A, B and C conceived in 0 of 4, 1 of 3 and 1 of 1, respectively.
These results suggest that an intramuscular injection of synthetic LH-RH preparations following an intrauterine infusion of PGF2α during the luteal stage of the estrous cycle may be applicable to the synchronization of ovulation in cows. However, the cause of the occurrence of quiet ovulation and the low fertility of the cow which showed dull estrus followed by the treatments must be futher-more investigated.
