The Deposition Rule And Gene Expression Involved In Yolk Cholesterol In Different Layer Breeds

360 chickens which were good health and 20 weeks old,were choosed for experiments,90 chickens of Brown shell Roman layer, White shell Roman layer, Silky fowl layer and Green shell Lushi layer respectively. Each strain comprised 6 repetitions with 15 layers. Experiment was undertaken by the same condition from 21 weeks to 51weeks. In this experiment, it was the effect of different strains and different ages on the content of cholesterol in yolk, and the effect of different strains and different ages on serum biochemical indexes and related gene expression that we study for.Experiment 1 The deposition law of yolk cholesterol in different breedsThree eggs were collected from each repetition to determine the content of cholesterol in yolk. The result showed that there were diffenece among the different strains in the content of cholesterol in yolk (P<0.05). The order of content of cholesterol in yolk is Silky fowl layer, Brown shell Roman layer, White shell Roman layer, and Green shell Lushi layer; while the order of content of cholesterol in egg is changed to Silky fowl layer, Green shell Lushi layer, White shell Roman layer, and Brown shell Roman layer. There were diffenece among the different ages in the content of cholesterol in yolk (P<0.05).The deposition law of the content of cholesterol in yolk was increasing in 21week to 31 week, and decreasing in 31 week to 51 week.Experiment 2 Correlation analysis of serum biochemical parameters and content of cholesterol in yolkOne chicken selected from each repetition was used for determining the serum biochemical paramenrs.The result showed that breed significantly affected TC, HDLC, FSH, LH, E2, LPL, Apo-B(P<0.05). Age significantly affected HDLC, FSH, LH, E2, CYP7A1, LPL, Apo-B, Apo-II (P<0.05). There were significant postive correlation between the content of cholesterol in yolk and the content of LDLC in serum, FSH, LH, HMGR, LPL, Apo-II (P<0.05); while there were significant postive correlation between the content of cholesterol in yolk and CYP7A1, Apo-B (P<0.05). The content of cholesterol in yolk and LDLC levels serum were significantly positively correlated (P<0.05). TG levels in serum and TC, LDLC and VLDLC were significantly positively correlated (P<0.05). TC levels in serum and HLDC, LDLC and VLDLC level in serum were significantly positively correlated (P<0.05); while TC levels in serum and Apo-B levels were significantly negatively correlated (P<0.05). HDLC levels in serum and FSH levels were significantly negatively correlated (P<0.05). LDLC levels in serum and VLDLC level in serum were significantly positively correlated (P<0.05); while LDLC levels in serum and CYP7A1 activity and Apo-B levels were significantly negatively correlated (P<0.05). CYP7A1 activity and Apo-B level, LPL activety and E2 level, AND E2 level and Apo-II level were significantly positively correlated (P < 0.05).Experiment3 Study on the expression of HMGR, Apo-II and VLDLR gene in different layer breedsOne chicken which was selected from each repetition was used for collected liver and ovary to determine the expression of chicken HMGR, Apo-II and VLDLR gene. The result showed that there were diffenece among different breeds in the expression of HMGR in liver (P < 0.05); The expression of HMGR in liver of Brown shell Roman layer, is significantly higer than Green shell Lushi layer. There were diffenece among the different breeds in the expression of Apo-II in liver and VLDLR in ovary (P > 0.05). There were diffenece among different ages in the expression of HMGR, Apo-II in liver and VLDLR in ovary (P < 0.05). The trend of expression of HMGR and Apo-II in liver was increased in 51 week. The trend of expression of VLDLR in ovary was increase in 21week to 51 week.