Delayed ovarian resumption in Holstein lactating cows: association with elevated beta-hydroxybutyrate levels during early postpartum period

Abstract

The present study was aimed to investigate body condition, hepatic insulin-like growth factor (IGF)-1, IGF binding protein (BP)-1 and growth hormone receptor (GHR) mRNA abundance and specific energy metabolites in association with delayed ovarian resumption in Holstein lactating cows. Of 10 cows studied, 5 cows had normal ovarian resumption (NR group), whereas the remaining 5 cows had delayed ovarian resumption (AB group) within 7 wks after calving. No significant differences in mean BW and BCS between the two groups were observed (P > 0.05). In addition, mean hepatic IGF-1, IGFBP-1 and GHR mRNA abundance of the NR and AB groups was not significantly different (P > 0.05). Mean non-esterified fatty acid (NEFA) levels of the two groups were elevated, particularly at 1 wk after calving, but no significant differences between the two groups were observed (P > 0.05). In contrast, differences in mean beta-hydroxybutyrate (BHB) levels between the NR and AB groups were significant (P = 0.047) and mean BHB levels at 3 and 5 wks after calving of the AB group were higher than those of the NR group (P < 0.05). In conclusion, the effects of BW, BCS, hepatic IGF-1, IGFBP-1 and GHR mRNA abundance and NEFA levels were not observed, but a degree of negative energy balance (NEB), indicated by the elevated BHB levels during the early postpartum period, was associated with the occurrence of delayed resumption of ovarian activity in the Holstein lactating cows.