Increasing sperm production per breeding male has economic significance with increasing use of artificial insemination. Manipulations to increase sperm production in livestock will only be useful if libido and sperm fertilizing capacity are not adversely affected. Reducing endogenous estrogens in the postnatal interval increases the number of Sertoli cells and hence testicular sperm production capacity. These experiments were designed to evaluate the effects of reducing endogenous estrogens on libido and sperm fertilizing capacity. Boars were treated with an aromatase inhibitor, letrozole, to reduce testicular estrogen production between 1 and 6weeks of age or between 11 and 16weeks of age, and the littermates to these boars were treated with the canola oil vehicle. Letrozole treatment did not affect time to first mount at 22weeks of age, regardless of whether the treatment occurred from 1 to 6weeks of age (118seconds vs. 233seconds, SEM=161 for letrozole-treated and vehicle-treated boars, respectively) or from 11 to 16weeks of age (107seconds vs. 67seconds, SEM=63 for letrozole-treated and vehicle-treated boars, respectively). Similarly, sperm fertilizing ability and invivo fertility were equivalent in letrozole-treated boars and their vehicle-treated littermates. Surprisingly, the increase in Sertoli cell numbers observed in the letrozole-treated boars at 20weeks of age (5.8 vs. 4.3 billion, SEM=0.5; P<0.05) was not maintained to 40weeks of age in their letrozole-treated littermates. Reducing endogenous estrogen production neonatally or prepuberally had no detectable adverse effect on libido or sperm fertilizing capacity.
|Original language||English (US)|
|Number of pages||9|
|State||Published - Sep 1 2014|
ASJC Scopus subject areas
- Animal Science and Zoology
- Food Animals
- Small Animals