补喂来曲唑对种公牛血浆和精浆激素水平及精液品质的影响

Effects of supplement with letrozole on the hormone level in plasma,seminal plasma and semen quality of bulls

[目的]给西门塔尔种公牛补喂不同水平的来曲唑(LE),探究其用于提高西门塔尔种公牛精液品质的可能性。[方法]选取体质量相近、健康状况良好的西门塔尔种公牛35头。采用单因子多水平试验设计,将35头种公牛随机分为5组:对照组、试验Ⅰ组、试验Ⅱ组、试验Ⅲ组、试验Ⅳ组,各组在饲喂基础日粮同时,分别添加0、50、100、150和200 mg·d-1的来曲唑。每日18:00将来曲唑与精料混合一次性饲喂,试验期100 d。[结果]补喂不同水平来曲唑均可提高血浆及精浆中雄激素水平,降低雌激素水平,其中,雄烯二酮和睾酮水平极显著提高(P<0.01),雌酮和雌二醇水平极显著降低(P<0.01),但促卵泡素及促黄体素水平无显著变化(P>0.05)。各试验组种公牛射精量及精子活力与对照组相比均有所提高,且试验Ⅱ组种公牛的射精量及精子活力极显著提高(P<0.01)。[结论]补喂100 mg·d-1的来曲唑可显著提高种公牛的精液品质。

[Objectives] In this experiment, different levels of letrozole was supplied on Simmental bull, and the possibility of using letrozoie to improve semen quality of Simmental bull was determined. [ Methods] By the single-factor-multi-level test design,35 healthy Simmental bulls were randomly divided into 5 groups：control group, experimental groupI, experimental group If, experimental group Ⅲ, and experimental group Ⅳ. Beside the basal diet,the bulls in each group were supplied with 0,50,100,150,200 mg·d^-1 letrozole. The tetrozole was mixed with concentrate feeding stuff and supplied to bulls at 18：00 each day. The trial duration was 100 days. [ Results] The androgen levels increased and estrogen levels reduced in plasma and seminal plasma of those bulls supplement with different levels of letrozole. In the androgen,the content of androstenedione and testosterone levels increased significantly（P〈0.01 ）. In the estrogen, the content of estrone and estradiol decreased significantly（P〈0.01 ）. However, there was no significant effect on the content of follicle- stimulating hormone and luteinizing hormone （ P 〉 0.05 ）. In addition, by supplement with different levels of letrozole, the ejaculate volume and sperm motility of bull in each experimental group were improved than those in control group, while the ejaculate volume and sperm motility of bull in experimental group Ⅱ were improved extremely significantly （ P〈0.01 ）. [ Conclusions ] The semen quality of Sinunental bull could be improved by supplied with 100 mg·d^-1 letrozole in diet.