Effect Of Photoperiod On Procreation Morphology, Production And Haemal Biochemical Parameters

The laying performance of poultry is not only influenced by the development of the follicle,but also by the breeds,management measures,environment and so on,among which temperature,lighting and feed have the most significant influences on the reproduction.This study tried to investigate the effect of photoperiod on the laying hens, including the changes of oviduct and ovary in the anterior and latter laying period respectively,laying performance throughout laying period and biochemical parameters of latter laying period.Photoperiod from 10 to 20wk were 8L:16D.At the age of 20 week,320 laying hens were selected and allotted randomly 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,were achieved according two approaches abruptly increscent and slowly increscent.At the beginning of 29wk,four hens from each treatment was selected, weighted and randomly placed in individual,illuminated,standard laying cages.The egg-laying condition and time were respectively observed and recorded.The results showed as follows:1.Oviduct and ovary:Photoperiod did not significantly affect oviduct and ovary before laying(P＞0.05),but had a significant effect inthe latter laying(P＜0.05),the changes of oviduct and ovary in 11L:13D were more than other groups,whose weight were 63.65g and 73.52g.Photoperiod significantly affect total follicle number,primary follicle number, secondary follicle number and the atretic ratio of secondary follicle(P＜0.05),with the largest number of total follicle,primary follicles,secondary follicle of 47604.0, 42220.0,5383.9 respectively and the highest atretic ratio of secondary follicle of 5.26%in the group 11L:13D;Photoperiod had a great significant effect on the SVF number(P＜0.01),with the largest number of SVF of 11.25 and 12.00 respectively in the group of 13L:11D and 15L:9D.Increscent patterns did not significantly affect oviduct and ovary(P＞0.05).At the rate of laying 50%,the abruptly increscent patterns had much more secondary follicles,but in the latter laying period,the slowly increscent patterns had much more total follicles,The groupⅡandⅢhad much less total follicles.At the rate of laying 50%,the plica of magnum was much shorter,thinner and looser of the group ofⅢ,Ⅳ,ⅦandⅧ.In the latter period,the group ofⅦandⅧhad much looser plica than other groups.The plica developed well in all groups,the plica of groupⅣwas thinner,but whose density was higher,in the latter laying period the plica of groupⅢandⅦarrayed orderly.2.Egg-Laying time:Different photoperiod had a great effect on the egg-laying time,and a proportion of eggs was laid before the lights came on when day was less than 17 hours long.When the daylength decreases,the proportion of eggs laid during the night should distinctly increase.The group ofⅠlaid 38.35%eggs during night.3.Performance:Different photoperiod did not significantly affect rate of feed and egg,feed intake and mortality(P＞0.05),but had an effect on the different laying period.The feed intake of 17L:7D was significantly lower than 13L:11D in the initial laying(P＜0.01), which were 91.42g and 95.01g respectively,but the largest group of feed intake in the peak and post-peak were 17L:7D and 13L:11D(P＜0.05),which were 131.28g and 139.46g respectively;The rate of feed and egg of 15L:9D and 17L:7D were significantly lower than other groups,which were 2.237 and 2.239 respectively;Egg weight was significantly affected throughout laying period(P＜0.05),with the heaviest weight of 62.95g in the group 11L:13D;Different photoperiod had a most effect on the rate of lay throughout laying period(P＜0.01),with the highest level of 87.04%in the group 17L:7D;Different photoperiod significantly affected the egg quality in the peak period,there were very significantly different about egg yolk color between 15L:9D and 13L:11D(P＜0.01), which were 8.38 and 7.88 respectively;The thickness of eggshell of 13L:11D was significantly higher than 15L:9D(P＜0.05),which were 0.335cm and 0.308cm respectively; The egg yolk color of 11L:13D was significantly higher than 17L:7D in the latter laying(P＜0.05),which were 9.27 and 8.79 respectively.The carcass parameters to the depletion age were significantly different(P＜0.05):The live weight of 17L:7D was significantly higher than 15L:9D(P＜0.05),which were 2140.0g and 1876.0g respectively.The ventral fat rate of 13L:11D was significantly higher than other groups(P＜0.05),which was 11.28%.Increscent patterns did not significantly affect performance(P＞0.05)except egg form index to the peak laying period(P＜0.05).4.Biochemical parameters:Increscent patterns did not significantly affect biochemical parameters(P＞0.05),but different photoperiod had a significant effect on the total protein and globin(P＜0.05),with the highest total protein of 41.787g/dL and the highest globin of 39.664g/dL in the group 17L:7D.