Effect Of Alfalfa Saponins On Cholesterol Metabolism And Genes Expression Involved In Hepatic Cholesterol Metabolism In Laying Hens

This paper was conducted to investigate effect of adding different levels alfalfa saponins on growth performance, cholesterol content, serum biochemical indexes, bile acid and expression of liver m RNA, which is related to cholesterol metabolism of laying hens. The steps and results are as following:The objective of the study was to explore effects of dietary alfalfa saponins(AS) on the cholesterol and its regulation mechanism on some key genes involved in cholesterol metabolism in laying hens by feeding a high-cholesterol diet. A total of 200 Hy-Line Brown laying hens(56-week-old) were randomly assigned to five treatment groups and fed on diets supplemented with 0(control group), 0.5% cholesterol(high cholesterol group) and 0.5% cholesterol with 120, 240, 480 mg/kg AS(AS group) for a 8-week experimental period. Each treatment had five replicates with eight hens each. Total cholesterol(TC) and total bile acids(TBA) levels in liver and feces were measured. The TC, triglyceride(TG), high-density lipoprotein cholesterol(HDL-C) and low-density lipoprotein cholesterol(LDL-C) in serum were determined. Furthermore, the m RNA expression levels of ABCG5, ABCG8, ABCA1, ACAT2 and LXR in liver were investigated. The result showed compared to control group, no significant difference was found in the level of egg production(P > 0.05), the serum lipid levels in the hens were ameliorated by adding 0.5% cholesterol and AS(P < 0.05). TC and TBA had significant differences between trial groups and CK in liver and fences(P < 0.01). The m RNA expression levels of ABCG5, ABCG8, ABCA1 and ACAT2 in the liver of laying hens were remarkably up-regulated by 120- and 240-mg/kg AS administration(P < 0.01) and down-regulation by 0.5% cholesterol and 480 mg/kg AS administration(P < 0.01). However, LXR expression by adding AS or cholesterol was down-regulation or up-regulation respectively(P < 0.05). After 8 weeks of dietary supplementation, AS groups had significantly lower serum TC, LDL-C and TG, and increased HDL-C concentration than those of control group. Our present study indicated that AS had cholesterol-lowering effects and it can be used as an effective feed additive for the poultry.