Fertilization and blood levels of progesterone and LH in beef heifers on a restricted energy diet.

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

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. Fifte...

Effects of Nutritional Level and Biological Type on Gonadotropin-releasing Hormone-induced Luteinizing Hormone Release and Plasma Progesterone, Estrone and Estradiol Concentrations in Pre- and Post-partum Beef Heifers1, 2

Forty-six beef heifers (16 to 23 mo) of two biological types (small = Red Poll-sired, large = Charolais-sired) were individually fed from d 90 of gestation through parturition to evaluate the effects of nutritional restriction on plasma LH and steroid hormone concentrations. Heifers were allotted to one of two nutritional treatments to achieve a BW reduction (loss, fed at 1% of BW/d) or to main...

The effect of acute nutritional change on follicle wave turnover, gonadotropin, and steroid concentration in beef heifers.

The effects of acute nutritional change on endocrine and ovarian characteristics were studied in cyclic (intact; n = 20) and long-term ovariectomized (ovx; n = 18) heifers being fed 1.2 x maintenance (1.2M). On d 7 of an 8-d progesterone and estradiol treatment, intact and ovx heifers were randomly allocated to diets providing .4, 1.2, or 2.0M until emergence of the second follicular wave after...

Samson Gombe and William Hansel Heifers on Restricted Energy Intakes Plasma Luteinizing Hormone (LH) and Progesterone Levels in 1973, 37:728-733

Circulating gonadotrophins during a period of restricted energy intake in relation to body condition in heifers.

Beef heifers, 13 months old, were fed to achieve high (7.6 +/- 0.2 units) or low (3.9 +/- 0.1 units) body condition by feeding them one of two diets for 20 weeks. During week 17 of the growth phase, all heifers were ovariectomized. From week 20 to week 27 (restriction phase), all heifers were fed a daily diet containing 0.071 MJ metabolizable energy kg-1 body weight. At weekly intervals through...