| Lighting may be the most critical of all environmental factors to birds. Compared to temperature, moisture factors, little research of the effect of lighting on physiological and reproduction character was given. This experiment tried to investigate Effect of Photoperiod on Carcass, Reproduction Morphology, Biochemical Parameters and Hormone Changes. This study had three experiments.Experiment 1: Photoperiods from 10 to 20wk were 8L:16D. At the age of 20wk, two pullets from each replicate were selected, weighed and randomly placed in individual, illuminated, standard laying cages. The portable cage units consisted of 8 cages. The two cages units were placed into four rooms with different photoperiods of 17L:7D, 15L:9D, 13L:11D, 11L:13D. The results showed as follows:①Age of first egg, the 17L:7D group was 5.7d earlier than 11L:13D group(P＜0.05).②Different photoperiods were not significantly affect liver weight, lipid and protein content of liver, protein, lipid, ash, water content of carcass, length, weight, protein and lipid content of oviduct, first egg weight, F1(Follicle in the Oviduct) weight(P＞0.05).③There were significant difference between 17L:7D group and 11L:13D group on the weight and percentage of ovary(P＜0.05). Stroma weight between 11L:13D group and 13L:11D, 15L:9D, 17L:7D groups showed significantly different (P＜0.05).④The numbers of LYF in 13L:11D group were more than 17L:7D, 15L:9D, 11L:13D groups, but not significantly different(P＞0.05). The protein content of LYF, between 11L:13D group and 13L:11D group showed significantly different(P＜0.05).Experiment 2: The experiment was conducted using 320 20-wk-old laying hens to investigate the effects of photoperiod on hormone changes by studying the FSH, LH, P4, E2. Birds were randomly allotted to 8 treatments, each treatment represented by 4 replicates of 10 birds each. Photoperiods, which had four levels: 11L:13D, 13L:11D, 15L:9D, 17L:7D, according two approaches abruptly increscent and slowly increscent were achieved. At the beginning of 29wk, one hen from each replicate were selected, and placed in individual, standard laying cages. The plasma were collected every 2 hours. The results showed as follows:①The increscent patterns were not showed significantly different on the concentrations of FSH, LH, P4 and E2 (P＞0.05).②Photperiods had effect on the concentrations of FSH and LH(P＜0.01), concentration of FSH and LH in 11L:13D group were higher than other groups, but photperiod did not show significantly different on the concentrations of P4 and E2(P＞0.05).③Interect effect of increscent patterns and photoperiods were exist on the average concentrations of FSH, and LH, concentrations of FSH and LH in 11L:13D group with slowly increscent were higher than other groups. Interect effect of increscent pattern and photoperiod did not affect the concentrations of P4 and E2.④FSH cooperate with LH, could accelerate ovum to maturate, arose ovary secreting E2 and P4. 11L:13D with slowly increscent, surge level of FSH and LH were higher than other groups. The regulation of higher hormone secretion was not related to longer photoperiod.⑤Under different photoperiods, the ovulation surges of FSH, LH, P4 were similar, furthermore, appearance of P4 surge was later or at the same time to LH surge. According to the time of P4 surging level, could predict the laying time, aider appearing the surge level of P4, 2～4h later would lay.Experiment 3: The design of this experiment was the same like experiment 2. At the end of 29wk, one hen from each replicate was selected for collecting serum. The results showed as follows: Different increscent patterns did not show significantly different on the concentrations of glyceryl ester, glucose, protein, albumin, globulin, calcium, phosphorus, urea nitrogen, AKP, GPT(P＞0.05). Different photoperiods showed significantly different on the concentration of glucose, with the higest level of 376.8mg/dL in the group of 17L:7D; Different photoperiods showed significantly different on the concentration of protein, with the higest level in the group of 11L:13D; Different photoperiods showed significantly different on the concentration of globulin, with the higest level in the group of 13L:11D;Different photoperiods showed significantly different on the concentration of phosphorus, with the higest level of 2.06mg/dL in the group of 15L:9D; Different photoperiods showed significantly different on the concentration of GPT, with the higest level of 192.9U/dL in the group of 17L:7D (P＜0.05). Different photoperiods did not show significantly different on the concentrations of glyceryl ester, albumin, calcium, urea nitrogen, AKP (P＞0.05).
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