Changes in ovarian function and gonadotropin secretion preceding the onset of nutritionally induced anestrus in Bos indicus heifers

Biology of Reproduction
F M RhodesJ E Kinder

Abstract

The aim of this study was to monitor endocrine and ovarian changes immediately preceding the onset of nutritionally induced anestrus. Daily blood samples were obtained from 14 postpubertal heifers for one estrous cycle (initial estrous cycle). Subsequently, heifers designated "restricted" were given a limited diet (n = 9), and daily blood samples were obtained for approximately 21 days preceding onset of anestrus (anovulatory cycle). Controls were allowed ad libitum dietary intake (n = 5), and daily blood samples were collected for a complete estrous cycle during a time period that coincided with that preceding onset of anestrus in restricted heifers. Plasma samples were assayed for LH, FSH, progesterone, and estradiol-17 beta. The ovaries of all heifers were examined daily using transrectal ultrasonography from the initial until the final or anovulatory estrous cycles to determine changes in growth of follicles and corpora lutea. Anestrus was defined as failure of ovulation of the dominant follicle following luteolysis. When anovulatory and initial estrous cycles in restricted heifers were compared, mean concentrations of LH were lower (p < 0.01), and diameters of dominant follicles were smaller (p < 0.01); mean concentrations...Continue Reading

Citations

Jun 24, 2003·Animal Reproduction Science·G A BóM F Martínez
May 6, 2003·Reproduction, Fertility, and Development·F M RhodesG A Verkerk
Oct 1, 2009·Reproduction in Domestic Animals = Zuchthygiene·M Maquivar, C S Galina
Jan 15, 2009·Journal of Animal Physiology and Animal Nutrition·L O FiemsD L De Brabander
Jul 24, 2004·Animal Reproduction Science·G P Nogueira
Aug 25, 2017·Zygote : the Biology of Gametes and Early Embryos·Davide RondinaRegiane R Santos
Feb 18, 2004·The Journal of Reproduction and Development·Tomomi TanakaYoshihiro Kaneda

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