• Energy Balance, Metabolic Status, and the First Postpartum Ovarian Follicle Wave in Cows Administered Propylene Glycol

      Butler, Stephen; Pelton, Susanne H.; Butler, W.R.; USDA; Teagasc Walsh Fellowship Programme; NE-161 (American Dairy Science Association; Elsevier Inc., 2006-08)
      Mature Holstein cows were drenched daily with either 500 mL of water (CTL; n = 28) or propylene glycol (PPG; n = 28) from d 10 before parturition until d 25 postpartum. Follicular development was monitored thrice weekly by transrectal ultrasound. Blood samples were collected every 30 min from a subset of 10 cows per treatment on d 10, 2, and 25 to assess glucose and insulin response to treatments, and on d 10 postpartum, blood was collected every 10 min for 12 h to determine LH pulse profiles. Both insulin and glucose were elevated on d 2 and 25 following PPG administration, but only insulin was elevated on d 10. On d 10 postpartum the number of LH pulses, mean LH, and pulse amplitude were not different between CTL and PPG cows. The proportion of first postpartum dominant follicles that became ovulatory, atretic, or cystic was not different between CTL and PPG cows. Despite evidence of improved metabolic status, PPG failed to increase LH pulse frequency and failed to increase the proportion of first postpartum follicle waves resulting in ovulation. The dominant follicle of each cow was retrospectively categorized as being ovulatory (O; n = 17), non-ovulatory high estradiol (NH; n = 6), non-ovulatory low estradiol (NL; n = 24), or cystic (C; n = 8). Differences in dry matter intake and energy balance among cows in the different follicle categories were apparent as early as 3 wk before parturition. The NL cows had lower pre- and postpartum dry matter intake and energy balance compared with O cows. The NL cows also had postpartum metabolic hormone and metabolite profiles indicative of more severe negative EB.
    • Follicle stimulating hormone isoforms and plasma concentrations of estradiol and inhibin A in dairy cows with ovulatory and non-ovulatory follicles during the first postpartum follicle wave

      Butler, Stephen T.; Pelton, Susanne H.; Knight, Phillip G.; Butler, W.R.; USDA; Teagasc Walsh Fellowship Programme; regional project NE-161 (Elsevier Science Inc., 2008-07)
      Following parturition, all cows display a wave of ovarian follicular growth, but a large proportion fail to generate a preovulatory rise in estradiol, and hence fail to ovulate. Follicle stimulating hormone (FSH) exists as multiple isoforms in the circulation depending on the type and extent of glycosylation, and this has pronounced effects on its biological properties. This study examined differences in plasma FSH, estradiol, and inhibin A concentrations, and the distribution of FSH isoforms in cows with ovulatory or atretic dominant follicles during the first postpartum follicle wave. Plasma FSH isoform distribution was examined in both groups during the period of final development of the dominant follicle by liquid phase isoelectric focusing. Cows with an ovulatory follicle had higher circulating estradiol and inhibin A concentrations, and lower plasma FSH concentrations. The distribution of FSH isoforms displayed a marked shift toward the less acidic isoforms in cows with ovulatory follicles. A higher proportion of the FSH isoforms had a pI >5.0 in cows with ovulatory follicles compared to those with atretic follicles. In addition, cows with ovulatory follicles had greater dry matter intake, superior energy balance, elevated circulating concentrations of insulin and insulin-like growth factor-I, and lower plasma nonesterified fatty acids. The shift in FSH isoforms toward a greater abundance of the less acidic isoforms appears to be a key component in determining the capability for producing a preovulatory rise in estradiol, and this shift in FSH isoforms was associated with more favorable bioenergetic and metabolic status.