Serum and plasma metabolites associated with postpartum ovulation and pregnancy risks in suckled beef cows subjected to artificial insemination1

Abstract

Two experiments were conducted to determine relationships of blood metabolite concentrations, BW, BCS, and rump fat depth with postpartum ovulation and pregnancy risks, as well as their utility in predicting those outcomes in suckled beef cows. In experiment 1, plasma glucose collected 10 and 3 d before AI of suckled beef cows at seven locations did not differ between cows that had resumed estrous cycles (ovulated) before AI compared with anovulatory cows, whereas plasma glucose 3 d before AI was greater (P < 0.01) in cows that became pregnant compared with nonpregnant cows. Serum beta-hydroxybutyrate (BHB) tended (P = 0.09) to be less in ovulatory cows compared with anovulatory cows 10 d before AI, but was unrelated to pregnancy status. Receiver-operator derived true-positive (sensitivity) and false-positive (1-specificity) risks were determined for plasma glucose and serum BHB as predictors for postpartum ovulation and pregnancy status. Serum BHB 3 d before AI produced true-positive and false-positive risks of 82% and 37%, respectively, when predicting ovulatory status before AI. Serum BHB 10 d before AI produced a true-positive and false-positive risks of 92% and 25%, respectively, when predicting pregnancy status. In experiment 2, blood was collected weekly for 12 wk from multiparous suckled beef cows to assess blood metabolite concentrations in addition to concurrent weekly assessments of BW, BCS, and rump fat. When blood metabolites and physical measures were normalized to parturition reflecting changes occurring during the first 6 wk after calving, we observed reduced (P < 0.05) concentrations of serum BHB and NEFA, and greater (P < 0.05) rump fat and BCS in cows that ovulated before first AI, whereas reduced (P < 0.05) plasma glucose was characteristic of cows that became pregnant. When blood metabolites and physical measures were normalized to the onset of the AI program reflecting changes during 6 wk before AI, ovulatory cows had increased (P < 0.05) BCS and lower (P < 0.05) NEFA from 3 to 6 wk before the onset of the AI program compared with anovulatory cows. With all predictor variables in regression models, some multiple correlation coefficients (R2) exceeded 50% when predicting postpartum ovulatory status, but those for predicting pregnancy risk were less than 25%. Although measures of BCS and BHB during 6 wk after calving were related to postpartum ovulation risk, rump fat, glucose, BCS, and NEFA were associated with cows that were ovulatory and pregnant.

Body status and blood metabolites profiles during resumption of postpartum ovarian activity in yak (Poephagus grunniens)

“…In this study, the subcutaneous back fat tended to be higher in all the cyclic animals as compared to cystic and acyclic yaks. These findings are supported by earlier studies that the back‐fat values decrease considerably after calving for animals that are not pregnant and non‐cycling (Diaz et al., 2018; Hill et al., 2018). It is well established that cows overconditioned at calving will exhibit decreased appetite (lower dietary intake) and develop more severe NEB than the cows in the moderate condition (Garnsworthy & Topps, 1982; Treacher et al., 1986).…”

Comparison between the 5-day cosynch and 7-day estradiol-based protocols for synchronization of ovulation and timed artificial insemination in suckled BOS taurus BEEF cows

“…Cows that maintained BCS during the postpartum period had a shorter interval to estrus, greater levels of basal LH and enhanced response to GnRH induced LH release [48].A study including 3,269 cows in seven different studies reported a linear increase of 18 % in the number of cyclic cows for each unit of BCS increase from ≤ 3.5 to ≥ 6.0 of a 1 (thin) to 9 (fat) scale [45].Rump fat and BCS were greater and serum concentration of BHB and NEFA reduced during the six weeks after parturition in cows that ovulated before first AI and become pregnant [49].…”

Two melatonin treatments improve the conception rate after fixed‐time artificial insemination in beef heifers following synchronisation of oestrous cycles using the CoSynch‐56 protocol

“…Melatonin treatment has successfully been used to initiate ovarian cyclicity in anoestrous buffalo heifers 11 and increase plasma concentrations of GnRH and gonadotropins, promoting follicular growth and ovulation 12, 13 . The conception rate following AI is usually between 30% and 70% 14–22 . Early embryonic development may be negatively affected by insufficient progesterone (P4) production, with pregnancy failure attributed to insufficient luteal P4 production during early embryonic development 23 …”