Pregnancy rates following cattle artificial insemination: The toll of late return to estrus, clarion call for reproductive health screening and possibly more

Abstract

Artificial insemination is an assisted reproduction technique that has been used for decades as a management tool to maximize reproductive efficiency and reduce the risk of disease spread in livestock production. The ensuing pregnancy rate, often used as a yardstick of successful insemination has not been consistent, variation occurring from farm to farm due to the multifactorial aetiologies of infertility. We report our observations, following artificial insemination of seventy-five apparently healthy cows from three different farms (n=25/farm) - FMA, FMB and FMC, that were subjected to ovulation synchronization protocol, along with the physical presence of owners on the farms (PPOF). Cows were treated using 100 μg Lecirelin^® (i/m on d0, d9) with 25 mg Lutalyse® (i/m on d7) and were inseminated at 8th and 16th hours after all treatments. A 60-day non-return to estrus was used as a tentative diagnosis of pregnancy which was confirmed via rectal examination on day 90 post-insemination. Between days 36 and 47 post-insemination, 36%, 100% and 20% of cows returned to estrus at FMA, FMB and FMC while 64%, 0% and 80% were pregnant at day 90, respectively. The differences between the proportions of cows that returned to estrus and pregnancy rates on FMA, FMB and FMC were significant (P<0.05). The difference between cows that returned to estrus (52%) and those pregnant (48%) in the study was not significant (P>0.05). The differences in PPOF in the study i.e. FMA (50%), FMB (25%) and FMC (100%) were significant (P<0.05). Findings indicate comparability and competitiveness between the incidence of late return to estrus and pregnancy rate suggesting the need for pre-breeding and prenatal reproductive health screening, and possibly more factors, even in apparently healthy cows, in order to improve pregnancy rate in livestock husbandry.