Intensity of the biostimulatory effect of bulls on resumption of ovulatory activity in primiparous, suckled, beef cows.

摘要: Abstract Two experiments were conducted to evaluate postpartum resumption of ovulatory cycles in primiparous, suckled beef cows exposed close physical contact or limited, fenceline with mature bulls. The hypotheses tested that proportions cycling and intervals from the start exposure did not differ among contact; Angus×Hereford assigned randomly be (experiment 1 (Exp. 1), BE; n =14); 2, BEFL; =22); (Exps. NE; =37) bulls beginning 59 days 1) 68 2) after calving (day 0 each experiment, respectively). In Exps. anovular biostimulatory stimuli for 35 42 days, respectively. An increase progesterone concentrations exceeded 1.0ng/mL three consecutive samples was used as evidence luteal function Exp. 1. presence a corpus luteum an ovary, assessed by ultrasonography, function. Percentage resumed activity end greater ( P 0.05) BE than NE cows, whereas BEFL >0.10) between 2. Interval period shorter cows. We conclude response anovular, primiparous effect may depend on intensity (frequency exposure, duration quantity stimuli) pheromonal produced