Factors associated with abnormal resumption of ovarian activity after calving of Holstein-Friesian cows reared in northern Algeria

Abstract

The objectives of the present study were to identify the factors influencing the resumption of luteal activity, to describe the incidence of different categories of postpartum ovarian activity and to investigate the relationships among parity, calving season, body condition score (BCS) at calving, BCS loss from calving to 30 days of lactation (DIM), and abnormal resumption of ovarian cycles postpartum of 84 Holstein-Friesian cows in northern Algeria. Blood samples were collected on days 30, 42 and 54 after calving and serum progesterone concentrations were measured by enzyme immunoassay to determine the luteal activity (≥ 1ng/mL) and different types of luteal dysfunctions in cows. The luteal activity was estimated at 39% at 30 DIM, 57% at 42 DIM and 69% at 54 DIM. The onset of luteal activity was influenced by milk production at 30 DIM. Cows producing less than 3000 kg of milk per year were 1.43 times more likely to have early luteal activity. However, no significant influence was reported at 42 and 54 DIM. 38%, of cows had normal resumption and 62%, had abnormal cyclicity, where 31 had delayed first ovulation and 31%, presented prolonged luteal phase. Using multiple ordinary logistic regressions, significant associations between parity, calving season and abnormal ovarian cyclicity were identified. Primiparous cows were 6.6 times more likely to have delayed first ovulation as multiparous cows (OR=7.60, p<0.05). Calving in cold season increased significantly the risk for delayed of first ovulation (OR= 12.68, p<0.01) and prolonged luteal phase (OR=8.85, p<0.01). In conclusion, more than half of the cows presented abnormal resumption of ovarian cyclicity which was influenced by parity and calving season.