| Experiment I : Effects of copper and chromium and PUFA on lipid metabolism of laying hensEighty four 45-week-old Hyline brown hens were randomly allocatted into 7 groups fed different diets. Dietary treatments were as follows: linseed oil (LO) 3.0%, conjugated linoleic acid(CIA) 0.3%, Cu 150mg/kg, Cr 600u g/kg, LO 3.0%+CLA0.3%, Cu 150 mg/kg+Cr 600u g/kg and control dietary basal corn-soybean diet. The results indicated that the total cholesterol (TC) and triglyceride(TG) concentrations in blood were significantly reduced by Cu Cr Cu+Cr LO LO+CLA supplementation. Dietary CIA decreased the TC in blood (P=0.063) and TG concentration by 33.8%.The HDL-C level in blood was increased by CLA,Cu,Cr and LO+CLA compared with control. Copper treatment can increase the HDL-C in the largest extent. LDL-C concentrations in blood were also reduced by six treatments. The GSH-Px activity in liver was increased by adding Cr or Cu+Cr. There were no effects of six treatments on TSOD activity in liver. LO significantly elevated MDA level in liver compared with control. Yolk MDA level was increased by adding dietary LO or LO+CLA. Experiment II: Effects of copper and chromium on lipid metabolism in laying hens.In an experiment with 2X3 factorial arrangement ,ninty six 24-week-old Hyline brown hens were randomly allocatted into 6 groups fed different diets. Dietary copper levels were 0 and 150mg/kg, dietary chromium levels were 0,600 and 1000 u g/kg. Total cholesterol (TC) and triglyceride (TG) concentrations in liver, serum and yolk, hepatic glutathione (GSH) production and copper-zinc superoxide dismutase (Cu/Zn-SOD) ,seram lecithin-cholesterol acyltransferase (LCAT) and insulin (Ins) were determined at the end of the eighth week of experiment. The results indicated dietary 150 mg/kg copper increased egg production by 5.8% (P=0.048) , reduced TG and TC concentrations of liver, serum and yolk significantly compared to the control group. Hepatic GSH production and the activity of Cu/Zn-SOD were increased(P<0.01 ),serum insulin level was decreased( P<0.01) ,and LCAT activity was increased (P<0.01) .Dietary chromium supplementation significantly decreased feed intake(P<0.01), TC in liver, serum TG and TC, TC in yolk ,but increased Cu/Zn-SOD activity of liver ( P<0.05 ) .The activity of LCAT in hens fed with dietary chromium at 1000 u g/kg was reduced significantly (P<0.05) . Effects of negative interaction on feed intake and feed/egg ratio and positive interaction on serum TG and yolk TC were observed between copper and chromium.Experiment HI: Effects of dietary linseed oil and conjugated linoleic acid on lipid metabolism of laying hens.Sixty four 24-week-old Hyline brown hens were randomly allocatted into 4 groups.and fed basal diet or diet supplemented with LO 3.0%, CIA 0.3% or LO 3.0%+CLA 0.3%. The purpose of this study was to assess the effects of LO and CIA on lipid metabolism in liver, serum and yolk,including laying performance,concentration of total cholesterol ( TC ) and triglyceride (TG) ,copper-zinc superoxide dismutase (Cu/Zn-SOD) .hepatic glutathione (GSH) production and serum insulin (Ins) .The results indicated that feed intake and ratio of feed/egg mass were lower for the laying hens supplemented with three dietary groups than control group (P<0.0l) . Liver TG and TC concentrations were decreased significantly by dietary LO supplementation ( P<0.05 ) ,the activity of liver Cu/Zn-SOD was increased and LCAT,TG and TC in serum were decreased significantly by dietary LO , CLA or LO+CLA treatment (P<0.01) . Yolk TG and TC concentrations were reduced significantly by dietary supplementation LO or LO+CLA.Experiment IV: Interactive effects of dietary LO or CLA fed with high dose of copper chromium and on lipids metabolism of layers.Eighty 45 week-old Hyline brown hens were randomly allocatted into five groups. Experimental dietaries were control, Cu 150mg/kg+Cr 600ug/kg, Cu 150mg/kg+Cr 600ug/kg+ LO 3.0%, Cu 150mg/kg+Cr 600ug/kg+CLA 0.3% and Cu 150mg/kg+Cr 600ug/kg+LO 3.0%+ CLA 0.3% respectivel... |
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