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The biostimulatory effect of bulls on the hypothalamic-pituitary-adrenal and ovarian axes and on temporal aspects of resumption of ovarian cycling activity in primiparous, postpartum, anestrous, suckled, beef cows: Author: Tauck, Shaun Austin; Date: 2008-12-15; Program: Animal and Range Sciences; Abstract: Exposing cows to bulls or excretory products of bulls stimulates resumption of ovarian cycling activity in postpartum, suckled, anestrous cows. This biostimulatory effect may be mediated by pheromones produced by bulls that stimulate physiological changes in the hypothalamic-pituitary-ovarian (HPO) and/or -adrenal (HPA) axes of cows. In Experiment 1, the hypothesis tested was that the biostimulatory effect of bulls is associated with adrenal regulation and/or function in anestrous cows. The biostimulatory effect of bulls was associated with mean concentrations of cortisol in postpartum cows. E...; Download File | View full details

Changes in temporal leptin concentrations and other metabolic factors in primiparous, postpartum, anestrous, suckled, beef cows exposed to bulls: Author: Olsen, Jesse Riley; Date: 2009-08-15; Program: Animal and Range Sciences; Abstract: Exposing cows to bulls or excretory products of bulls stimulates resumption of ovarian cycling activity in postpartum, suckled, anestrous cows. This biostimulatory effect may be mediated by pheromones produced by bulls that stimulate physiological changes in metabolic regulation of the hypothalamic-pituitary-ovarian (HPO) axis of cows. In Experiment 1, the hypotheses tested were that concentrations of glucose, NEFA, thyroxine (T4), tri-iodothyronine (T3), and T3:T4 ratios do not differ between cows exposed to bulls or steers. The biostimulatory effect of bulls was associated with lower mean co...; Download File | View full details

The biostimulatory effect of bulls on postpartum follicular wave development in postpartum, anestrous, suckled beef cows: Author: Wilkinson, Jarrod Robert Charles; Date: 2009-08-15; Program: Animal and Range Sciences; Abstract: The objective of this experiment was to determine if bull exposure influences follicular wave dynamics in primiparous, postpartum, anestrous, suckled, beef cows exposed to bulls. In Experiment 1, cows were exposed (continuously 24 h/d), (EB; n = 5) to bulls or not exposed to bulls (NE; n = 5) throughout the experimental period. In Experiment 2, cows were exposed to bulls for either 12 h, (EB12; n = 15), 6 h, (EB6; n =14) or not exposed to bulls (NE; n = 10) from the start to the end of the experimental period. In Experiments 1 and 2, cows were 67 d ± 3.8 (mean ± SE)...; Download File | View full details