Contributing factors to repeat breeding and postpartum anestrus and pregnancy rate subsequent to hormonal intervention in crossbred dairy cows

A cross-sectional study was conducted from January to July 2021 to determine the prevalence and contributing factors to repeat breeding  (RB) and postpartum anestrus (PPA) in crossbred dairy cattle in the central highland of Ethiopia. Furthermore; a retrospective study was  used to collect data on the occurrence of RB and PPA and the associated risk factors. The pregnancy rate was determined by rectal  palpation on day 60 after hormonal therapy using double PGF2α and GnRH in combination with PGF2α. (Ovsynch). The prevalence of RB and PPA was 33.85% and 30.73%, respectively. Body condition score, parity, milk yield, herd size, abortion, and mastitis all revealed a  statistically significant association (p < 0.05) with the prevalence of RB and PPA. Cows with a previous history of abortion were 2.58 times  at risk of repeat breeding than those without. Similarly, cows with a previous history of mastitis were 2.63 times more at risk of RB than  cows that didn’t encounter the disease. Previously aborted and older cows with greater parity numbers were 2.89 and 1.23 times more  affected by PPA, respectively. Moreover, endometritis and retained fetal membrane showed significant association (p<0.05) with  postpartum anestrus. The pregnancy rates in cows treated with double PGF2α and GnRH + PGF2α (Ovsynch) were 41.46% and 29.17%,  respectively. It is concluded that the occurrence of RB and PPA in the research area was influenced by parity, body condition, and daily  milk yield of the cow. Reproductive health problems including abortion retained fetal membranes, endometritis, and mastitis affected the  prevalence of RB and PPA. Although the use of double PGF2α or in combination with GnRH has resumed cyclicity in RB and PPA dairy  cows, the pregnancy rates are yet low. Hence, a study that utilizes detailed hormonal assay profiles and reproductive-related blood  metabolites should be done.