Abstract
Fertility of postpartum cows is negatively influenced by anoestrus. The objective of the present research was to evaluate utero-ovarian conditions and the management outcome of postpartum anoestrus in crossbred cows. Transrectal ultrasonography and a structured questionnaire were used in the cross-sectional study to collect data on the prevalence, risk factors and effectiveness of treatments of synchrony programmes for anoestrus in crossbred cows at 60 or more days postpartum in smallholder farms in Bangladesh. The prevalence of anoestrus was 18.0% as reported by the farmers. Of the cows reported to be anoestrus, 62.1% suboestrus, 31.0% true anoestrus, 4.3% cystic ovaries and 2.6% pyometra were diagnosed. Odds ratio (OR) for being true anoestrus was 17.5 and 2.8 times higher (P < 0.05) in cows with poor (≤ 2.0) and excessive (≥ 4.0) body condition score (BCS), respectively, compared to those with optimal BCS (2.5 - 3.5). The OR was 2.8 times higher in suckled than non-suckled cows (P < 0.05), and 2.5 times higher in cows that calved during cold season than those calved during hot season (P < 0.05). OR for being anoestrus was 1.6 times higher (P < 0.05) in cows managed by an employee than those managed by the farmers themselves (P < 0.01), and 2.7 times higher (P < 0.01) in small farms (≤ 5 cows) than that of large farms (≥ 11 cows). The OR was 0.7 to 0.5 times lower in farms having a guaranteed market to sell milk than those with an uncertain traditional milk market (P < 0.05). Treatment of true anoestrus resulted in oestrus and conception, respectively in 81.8% and 63.6% of nutritionally supplemented cows, and in 50.0% and 40.0% of suckling restricted cows. Control anoestrus cows without any treatment did not show oestrus. The difference in rates of conception was significant (P < 0.05) between the treatment groups. In suboestrus cows, the size of the largest follicle at AI had a positive correlation with the size of the resultant CL at d 7 (r = 0.84, P < 0.01). The conception rates of the synchronised suboestrus cows were not different (x2 = 0.83; P > 0.05) among the Cosynch (GnRH-PGF2a-GnRH+TAI, 54.1%), PG programme (one shot PGF2a, 63.3%) and Control (64.7%) groups. The follicle in cows that subsequently became pregnant was larger (P < 0.05) than that in the non-pregnant cows (15.8 ± 2.0 mm vs. 14.6 ± 2.3 mm), and was smaller (P < 0.01) in cows those experienced embryonic mortality (12.3 ± 1.0 mm) than in cows those successfully maintained pregnancy (15.8 ± 2.0 mm) or did not conceive (15.6 ± 2.7 mm). The embryonic mortality was 12.0% in the cows between d 28 and d 42. The overall pregnancy rate was 52.4% and did not differ (x2 = 1.56; P > 0.05) among the groups (Cosynch 45.9%; PG programme 56.7%; Control 58.8%). In conclusions, maintaining good BCS of cows, improved oestrus detection, and development of a market linkage for the farmer to sell milk would increase the number of cows presented for first breeding by 60 days postpartum. Nutritional supplementation to true anoestrus cows and close monitoring for oestrus with selective administration of PGF2a to suboestrus cows under veterinary supervision using ultrasonography would be an effective tool for improvement of fertility.