Metabolic characteristics associated with normal or abnormal progesterone profiles during the postpartum period of dairy cows

Abstract

AbstractPrevious studies have shown that 35 — 40 % ofmodern dairy cows experience ovarian disturbances during early lactation. Even though negative energy balance (NEB) has been implicated as a regulator of ovarian function, the exact metabolite(s) or hormone(s), which mediate this effect is still not clear. In this study, we investigated the relationship between blood metabolites (NEFA, BHB and glucose) and plasma insulin like growth factor-I (IGF-I) and ovarian dysfunction. Thirty three Holstein-Friesian cows were fed a lactational ration ad libtium and were inseminated at observed oestrus starting from 56 days post calving. Three times weekly milk samples and weekly blood samples were collected from cows from calving until confirmed pregnant. Cows were placed into “NORMAL” or “ABNORMAL” categories of ovarian activity based on their milk progesterone profiles. The days to first service were 71 ± 2 in “NORMAL” and 78 ± 6 in “ABNORMAL” animals. The calving to conception interval (days open) was shorter in the “NORMAL “ than the “ABNORMAL” group (90 ± 8.7 vs 119 ± 15.2 days). IGF-I levels were significantly lower in the “ABNORMAL” group from 2 until 7 weeks after calving (P<0.02) and NEFA concentrations were higher in the “ABNORMAL” cows in the early postpartum period (P<0.03). There was no significant difference in either plasma BHB or glucose. This study confirms that elevated plasma NEFA concentrations are associated with “ABNORMAL” ovarian activity. The most significant difference was in plasma IGF-I concentrations, which stayed lower for nearly 2 months in the “ABNORMAL” animals.