Endocrine changes during restoration of estrous cycles following induction of anestrus by restricted nutrient intake in beef heifers

Journal of Animal Science
K ImakawaJ E Kinder

Abstract

The working hypotheses in this experiment were: that ovarian estradiol would inhibit luteinizing hormone (LH) secretion in heifers that were anestrus as a result of restricted dietary energy intake and the responsiveness of LH secretion to estradiol negative feedback would decrease during the period when restoration of estrous cycles occurred following feeding of diets adequate in energy. Fifteen heifers weighing 341 +/- 12 (mean +/- SE) kg were fed a diet containing 50% of the energy required for maintenance until 40 to 50 d following cessation of estrous cycles. Heifers were assigned to intact control (C, n = 5), ovariectomized (OVX, n = 5) or ovariectomized-estradiol-17 beta-implanted (OVX + E2, n = 5) treatments. Heifers were subsequently provided a high-energy (HE) diet until termination of the study. Progesterone concentrations indicating cessation of corpus luteum function were detected after heifers had lost 71 +/- 8 kg body weight over 186 +/- 28 d. Control heifers re-initiated estrous cycles as indicated by increased progesterone concentrations in serum at 49 +/- 9 d after initiation of feeding the HE diet (360 +/- 18 kg body weight). Initiation of pulsatile LH secretion was observed in heifers by d 12 following OVX. ...Continue Reading

Citations

Feb 18, 2004·The Journal of Reproduction and Development·Tomomi TanakaYoshihiro Kaneda
Apr 1, 2014·Animal : an International Journal of Animal Bioscience·M A CroweE J Williams
Oct 16, 2002·Animal Reproduction Science·P M DawudaK D Sinclair
Jul 1, 1992·Domestic Animal Endocrinology·F N SchrickB B Plyler

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