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

peer-reviewedThis is the author's version of a work that was accepted for publication in Journal of Dairy Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Dairy Science, 2006, 89 (8), 2938-2951. DOI:10.3168/jds.S0022-0302(06)72566-8Mature 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.USDA regional project NE-161Teagas