Effects Of Polysavone On Cholesterol Metabolism And Its Related Gene Expression Of Laying Hens

There was a significant practicial effect on high production performance under normal body weight and physique by regulating the fat metabolism of laying hens, especially in cholesterol metabolism.The experiment was carried out to evaluate the effects of polysavone on growth performance, egg egg quality, cholesterol content, lipid metabolism parameters of serum and liver of laying hens. The expression of m RNA which is related to cholesterol metabolism also was measured. The mechanism of polysavone through nutrition and molecular biology was studied. The results as follows:Exp.1: Effects of polysavone on cholesterol metabolism of laying hens.A total of 540 26-week-old Brown Nick laying hens were randomly divided into 5groups consisted of 6 replicates of 18 birds each pen. During the 10 weeks experiment periods,laying hens in control group were fed with corn-soybean basal diet, and other groups were provided with the basal diets supplemented with 300, 600, 900, 1200 mg/kg polysavone,respectively. The pre-test lasted for 7 days, and the experiment lasted for 70 days. The results showed that:(1) Laying rate of 900 mg/kg polysavone group was significantly higher than the control group(P<0.05). Feed/egg ratio of all treatment groups were lower than that of control group, and egg weight and feed consumption had no change(P>0.05). All treatment groups had no effect on external egg quality of laying hens. The albumen height of 300, 600, 900mg/kg polysavone groups and the harrington unit in 600 mg/kg polysavone group were significantly higher than the control group(P<0.05).(2) Cholesterol content of the yolk of600 mg/kg polysavone group decreased by 9.09% on day 56(P<0.05), and cholesterol content of the egg of 900 mg/kg polysavone group decreased by 8.52% on day 70(P<0.05).Cholesterol content of the yolk could be decreased by 600 and 900 mg/kg polysavone groups,while cholesterol content of the egg could be decreased by 600, 900, 1200 mg/kg polysavone groups in the whole experimental period. The percentage of abdominal fat of 1200 mg/kg polysavone group was significantly lower than the control group( P<0.05). Cholesterol content of the liver in 600, 900, 1200 mg/kg polysavone groups significantly decreased by13.92%、13.91%、16.19%(P<0.05), and TBA in excrement of 900 mg/kg polysavone group significantly increased by 57.12%( P<0.05).(3)HDL-C levels in serum of 900 mg/kg polysavone group was higher than that of control group(P<0.05). LDL-C levels in serum of600 and 900 mg/kg polysavone groups were lower than that of control group on day 35(P<0.05). HDL/LDL of 900 mg/kg polysavone group was higher than that of control group(P<0.05).There were no significant difference between the TC and TG levels in serum(P>0.05).Exp.2: Effect of polysavone on m RNA levels of HMGCR、SREBP-2、Apo-VLDL-Ⅱ、CETP、CYP7A1 in the liver and OVR in the ovarian follicleExperimental design of Exp.2 is the same with Exp. 1. Compared with the control group,the m RNA levels of HMGCR in 600, 900, 1200 mg/kg Polysavone groups significantly decreased by 64.42%、62.5%、48.08%(P<0.05). The m RNA levels of CETP in 600 and 900mg/kg polysavone groups significantly decreased by 34.71%、38.02%(P<0.05). The m RNA levels of CYP7A1 in 900 and 1200 mg/kg polysavone groups significantly increased by61.73%、69.14%(P<0.05). No significant differences(P>0.05)in the m RNA levels of SREBP-2, Apo- VLDL-Ⅱin the liver and OVR in the ovarian follicle were observed among the whole groups.Conclusions:These studies show that polysavone can improve the internal egg quality which may be related to the biological activity of polysavone. The possible mechanism of cholesterol lowering effects could result from reducing endogenous synthesis of cholesterol and more cholesterol reverse transport and cholesterol excretion. The suitable polysavone requirement of laying hens of 26~35 weeks is 900 mg/kg.