Xin Z, Silvia W J, Waterman D F, Hemken R W, Tucker W B
Department of Animal Science, University of Kentucky, Lexington 40546.
J Dairy Sci. 1993 Feb;76(2):437-44. doi: 10.3168/jds.S0022-0302(93)77364-6.
Two experiments were conducted to examine the effects of Cu status on neuroendocrine regulation of LH secretion in dairy steers. In Experiment 1, 18 Holstein steers were assigned randomly to treatment groups in a completely randomized design. Treatments consisted of basal diet alone (control) or supplemented with 5 ppm of Mo or with 20 ppm of Cu. At 8 and 16 wk, Cu concentrations in liver were higher in the group receiving Cu and lower in the group receiving Mo than in the control. Pulse frequencies of LH were not affected by any treatment. Serum LH concentration at 16 wk tended to be lower in the group receiving Mo than in either the control or the group receiving Cu. The ability of the pituitary gland to release LH in response to GnRH was not affected at 17 wk. Concentrations of LH in the pituitary glands were lower in the group receiving Mo than in that receiving Cu or in the controls. No differences in Cu or Mo concentrations were observed in pituitary, median eminence, or hypothalamic tissues. In Experiment 2, 12 Holstein steers were assigned to treatment groups receiving the basal diet supplemented with either 20 ppm or Cu or with 10 ppm of Mo. Spontaneous and GnRH-induced secretion of LH were not influenced by treatments after 8 mo of experiment. Reduction in Cu status has little effect on the endogenous secretion of LH in dairy steers.
进行了两项试验，以研究铜状态对奶牛促黄体素（LH）分泌的神经内分泌调节的影响。在试验1中，18头荷斯坦公牛被完全随机地分配到各处理组。处理方式包括单独给予基础日粮（对照组），或补充5 ppm的钼或20 ppm的铜。在第8周和第16周时，接受铜的组肝脏中的铜浓度高于对照组，而接受钼的组肝脏中的铜浓度低于对照组。任何处理均未影响LH的脉冲频率。在第16周时，接受钼的组血清LH浓度有低于对照组或接受铜的组的趋势。在第17周时，垂体对促性腺激素释放激素（GnRH）作出反应释放LH的能力未受影响。接受钼的组垂体中LH的浓度低于接受铜的组或对照组。在垂体、正中隆起或下丘脑组织中未观察到铜或钼浓度的差异。在试验2中，12头荷斯坦公牛被分配到接受补充了20 ppm铜或10 ppm钼的基础日粮的处理组。在试验8个月后，处理对LH的自发分泌和GnRH诱导的分泌均无影响。铜状态的降低对奶牛LH的内源性分泌影响很小。
