Effects of calcium soaps of fatty acids on postpartum reproductive function in beef cows.
Hightshoe R.B. | Cochran R.C. | Corah L.R. | Kiracofe G.H. | Harmon D.L. | Perry R.C.
Twelve multiparous Simmental cows (584 kg) were used to determine the influence of calcium soaps of fatty acids (CSFA) incorporated in a range supplement on postpartum reproductive characteristics. Cows were assigned randomly to receive a control [C; containing grain sorghum (GS) and soybean meal (SBM)] or CSFA-based (containing Megalac [a source of CSFA], GS, and SBM) supplement. Supplements plus prairie hay were individually fed. Diets were isonitrogenous and met the NEm requirement for heavy-milking beef cows in early lactation. Supplement feeding and daily blood collection began at parturition. Calves were removed permanently from cows at 25 +/- 2 d postpartum. Duration of first postpartum estrous cycles was determined by both visual observations and changes in concentrations of progesterone in serum. Concentrations of LH in serum (15-min intervals for 6 h) were determined 12 h before and 48 and 96 h after calf removal. Concentrations of progesterone and estradiol-17 beta in serum were determined daily. Cows receiving CSFA had higher (P = 0.06) mean concentrations of LH than those receiving C (1.47 vs 1.12 +/- 0.13 ng/ml). Concentrations of estradiol-17 beta were lower (P <.02) and serum progesterone were higher (P < 0.02) between d 6 and 8 of the induced cycle in CSFA-fed cows. Plasma cholesterol was greater (P < 0.01) in cows fed CSFA although plasma triglyceride concentrations were similar between treatments. Feeding CSFA enhanced (P < 0.05) growth of ovarian follicles into larger class sizes based on transrectal ultrasonography during the 5-d period before calf removal. Increased plasma cholesterol in cows fed CSFA was accompanied by decreased serum estradiol, enhanced follicle growth, increased LH, and greater progesterone during the luteal phase of the first postpartum estrous cycle.
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