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Influence of protein and energy intakes on boar reproduction
Abstract
Two experiments were conducted to investigate the effects of protein and energy intakes on adult boar libido, semen characteristics, and plasma hormone concentrations. In Exp. 1, 20 boars were fed either a low protein diet (6% CP) or a control diet (16% CP) with the same energy content. Semen was collected two times per week for 23 wk. In Exp. 2, 24 boars were allotted to one of three dietary treatments. Two protein levels (7.7 and 18.1 g/d lysine) and two energy levels (6.1 and 7.7 Mcal/d ME) were combined to create (1) low energy and low protein (ep), (2) low energy and high protein (eP), and (3) high energy and high protein (EP) treatments. Semen was collected two times a week for 27 wk. In Exp. 1, boars with low protein intakes required more time to ejaculation, had a shorter duration of ejaculation, and had reduced semen volumes compared to boars on the control treatment ($P <$.09). In Exp. 2, fewer EP and eP boars (0 of 8 and 2 of 8, respectively) than ep boars (5 of 8) consistently refused to mount the collection dummy ($P <$.05). The EP and eP boars had 33% longer durations of ejaculation and 60% greater semen and gelatinous fraction volumes than ep boars ($P <$.04). The EP boars had a 38% increase in sperm output over the ep boars ($P <$.1). Blood samples were collected at the end of each experiment. In both experiments, LH and testosterone concentrations were not affected by treatment ($P >$.1). In Exp. 1, boars fed the control diet had greater estradiol-17$\beta$ concentrations than boars fed the low protein diet ($P <$.08) and the concentration of estradiol-17$\beta$ was negatively correlated (r$\sp2$ =.72) with time to ejaculation. Although estradiol-17$\beta$ concentrations were not affected by treatment in Exp. 2 ($P >$.1), boars that refused to mount the collection dummy had lower ($P <$.03) estradiol-17$\beta$ concentrations than boars that continued to mount and produce an ejaculate. Boars with low protein intakes had decreased libido, semen volume, and sperm output. The reduction in libido may be a result of a decrease in concentration of estradiol-17$\beta$ circulating in the blood.
Subject Area
Livestock
Recommended Citation
Louis, Gary Francis, "Influence of protein and energy intakes on boar reproduction" (1992). ETD collection for University of Nebraska-Lincoln. AAI9314414.
https://digitalcommons.unl.edu/dissertations/AAI9314414