铬对产蛋鸡生殖激素分泌的影响

为探讨铬元素对产蛋鸡生殖激素分泌的影响及其机制，在基础日粮（含Cr5.09mg/kg)中分别添加铬0，5和50mg/kg饲养4个月，观察其产蛋性能，检测血浆雌二醇（F2），孕酮（P），促黄体生成素（LH）水平，并于试验结束时进行卵泡细胞的离体培养，结果表明，添加5mg/kg铬有利于产蛋率的提高及产蛋高峰期（＞90％）的持久，不同铬日粮对血浆中上述激素水平无显著影响，但在组间产蛋率出现显著差异时，试验P，LH水平也相应地比对照组高，离体试验表明，铬可以通过直接对卵泡发生作用促进E2的合成与分泌（P＜0．01），对P分泌也有促进趋势。

Effects of Dietary Chromium on the Egg Yield and Reproductive Hormone Secretion of Laying Hens

Seventy two laying hens, 25 weeks of age, were randomly allocated into 3 groups and fed with diets containing 5.09,10.09,55.09 mg/kg chromium respectively for 4 months. Egg yield was observed. Estrodiol(E 2), progesterone(P) and luteinizing hormone(LH) were determined by radioimmunoassay ( RIA).Follicular cells were cultured with pituitary cells or hypothalamus extracts. Different dosages of chromium were added to the culture medium to observe the influence of chromium on concentrations of E 2 or P secreted by in vitro cultured follicular cell F 3 and F 1 respectively. The results showed that the rations containing 10.09 mg/kg chromium suited the hens better and enhanced egg productive ratio so as to prolong the laying peak period (>90%) . Proper concentration of chromium could directly affect the secretion of E 2 by follicular cells to a significant extent ( P <0.01) .The mechanisms concerning how chromium affected the endocrine activity of laying hens as well as the association with the metabolism of glucose and lipids were also discussed.