Sustainable and Cost-effective Field-level Therapeutic Strategy for Managing Repeat Breeding in Dairy Cattle

Abstract

Repeat breeding in bovines is a multifactorial reproductive disorder, often exacerbated by subclinical endometritis (S.E) and ovulatory dysfunction namely Delayed Ovulation (D.O), particularly under field conditions. This study was conducted to evaluate the effectiveness of a field-level therapeutic strategy targeting these two major contributors. The trial was implemented in six villages under the jurisdiction of the Veterinary Dispensary, Vedullapalli, involving 80 apparently healthy and well-nourished repeat breeding buffaloes. All selected animals exhibited normal clinical parameters and reproductive tract morphology upon per rectal and vaginal examination. Uterine discharges were clear, devoid of pus cells, leukocytes, or blood, and demonstrated a normal fern pattern on microscopic evaluation, indicating the absence of overt endometrial pathology. These were the selection criteria of repeat breeding animals for this study. On the onset of estrous, a single intramuscular dose of long-acting oxytetracycline dihydrate (20 mg/kg body weight) was administered. 6 Artificial inseminations (A.I) were performed at 12-hour intervals over three consecutive days, beginning 24 hours post-antibiotic administration. This is the Test-therapeutic protocol (TTP). Pregnancy diagnosis was conducted on Day 90 post-A.I by per rectal palpation for those animals that hadn’t come to heat. A total of 200 repeat breeding buffaloes, selected based on the criteria previously described, were enrolled in the study and randomly allocated into 4 equal groups (n = 50) Group A, Group B, Group C and Group D. One more group of 50 animals was chosen randomly without any selection criteria and was named as Random Group (R.G). For Group R.G and A, single A.I was done in their estrous period as per standard protocol. Group A serves as control group. For group B, 6 A.I were done, for Group C oxytetracycline dihydrate injection and single A.I was done, for Group D TTP protocol was followed in their estrous periods. Pregnancy diagnosis was performed via per rectal palpation on the 90th day post-A.I. Conception rate in Group R.G is 40%, Group A is 0%, Group B is 22%, Group C is 76% and group D is 92%. Conversely, all non-conceived animals in all groups returned to estrus within 21 to 22 days post-insemination, indicating failure of conception. The results clearly proved that TTP protocol has highest conception rates in Group D when compared to that of other protocols in remaining groups, by resolving the repeat breeding condition, due to both S.E and D.O, in group D animals. These findings suggest that a single-dose long acting oxytetracycline-based intervention, coupled with multiple doses of A.I, can serve as a sustainable, field-appropriate and cost-effective strategy for improving conception rates in repeat breeder bovines, particularly in resource-limited rural settings.