关键词: 能量, 蛋鸡, FSH, LH, P4, 产蛋率

Abstract: The objectives of this study were to investigate the effects of diet energy on plasma folliclestimulating hormone (FSH), luteinizing hormone (LH), progesterone (P4) and laying rates of layers and to relate these hormone levels with the laying performance. Radiation immunity analysis was used to determine the plasma hormone concentration during prepubertal development and laying period. The results demonstrated that high energy level led to ahead of the day to first egg. Laying rates of high energy I and low energy Ⅱincreased slowly after first egg. With the decrease of energy level, the time to laying peak was delayed. The order of laying peak value from high to low was control group, low energy group and high energy group. Compared with other groups, laying rates in high energy groups descended rapidly. During sexual maturity, plasma FSH concentration increased with age，FSH concentrations were higher in high energy groups than that in low energy groups,plasma LH concentration increased with age，LH concentration was higher in high energy group than that in low energy groups. High energy I reached FSH level peak at 28 weeks, whereas other groups reached the peaks at 3340 weeks. High energy I，high energyⅡand control groups reached LH level peak at 27，34 and 30 weeks, respectively, whereas low energy I and low energy Ⅱ reached the peaks at 30 and 42 weeks; During laying period, control group had higher FSH level than other groups and higher LH level than low energy groups. Control group had higher laying rate than other groups. When FSH concentrations at peaks and during laying period were related to mean laying rates, a significant positive correlation and a significant positive correlation were obtained respectively. During sexual maturity, P4 concentration increased with age in all groups, P4 concentration was low before 18 weeks and increased at 22 weeks sharply, P4 concentrations in high energy groups were higher than that of low energy groups. During laying period, P4 concentrations and mean laying rates were higher in control and low energy groups than that in high energy groups. Significant positive correlations of P4 concentration at peak, after peak and during laying period with mean laying rate were obtained, respectively.

Key words: energy, layer, FSH, LH, P4, laying rate