Comparison between temporary weaning versus equine chorionic gonadotropin protocols after treatment with intravaginal progesterone for timed artificial insemination in Bos taurus indicus cows

Abstract

The aim of the study was to compare the reproductive efficiency of two protocols with temporary weaning (TW) of calves and one using equine chorionic gonadotropin (eCG), the synchronization of estrus and ovulation in timed artificial insemination (TAI) protocol. A total of 534 multiparous cows were distributed into three groups: temporary weaning on day 8 of the protocol group (TW8G; n = 225); temporary weaning on day 9 group (TW9G; n = 139) and equine chorionic gonadotropin group (eCGG, n = 170). TW8G received on day zero (d0) an intravaginal device with progesterone (P4; 0.558g) + estradiol benzoate (EB; 2mg, im). On d8, the device was removed with P4 + PGF (0.075mg, im) + estradiol cypionate (EC 0.5 mg, im) + removal of the calf for 48 hours. On d10, TAI was performed, and the calves returned to their mothers. The TW9G was subjected to the same protocol as the TW8G, except for the removal of the device with the P4, which occurred on the 9th, and on the d11, TAI was performed, and the calves returned to their mothers. eCGG was subjected to the same protocol as TW8G, except that on d8 it received eCG (300IU, im), on d9 estradiol benzoate and TAI on d10. The pregnancy diagnosis was made change for done at d45. The non-pregnant cows (post TAI) were re-inseminated under the observation for estrus observation (conventional AI). The remaining empty cows from conventional AI remained with the bull for another 45 days. PR after TAI was 47.1 (TW8G), 40.2 (TW9G) and 51.7% (GeCG), while PR after conventional AI was 19.3%; 31.3% and 26.8%. PR at the end of the breeding season resulted in 95.1, 90.6, and 92.3% respectively for TW8G, TW9G and eCGG. It was concluded that there was no difference in reproductive efficiency in the timed artificial insemination between the applied protocols; the use of TW or eCG can be implemented in the breeding season of beef cows.