Effect of Supplementary Dietary L-carnitine and Yeast Chromium on Lipid Metabolism of Laying Hens

Two hundred and eighty-eight 21-week-old Hyline Brown laying hens were randomly allotted to 9 treatments, 32 birds for each treatment. A 3${\times}$3 (chromium${\times}$L-carnitine) factorial experiment was designed to investigate the single and interactive effects of adding yeast chromium (0, 400 and 600 ${\mu}g/kg$) and L-carnitine (0, 50 and 100 mg/kg) to corn-soybean diets on lipid metabolism of laying hens for 7 weeks. The results showed that 600 ${\mu}g/kg$ chromium or 100 mg/kg L-carnitine had significant effects on most indices of lipid metabolism (p<0.05 or 0.01). There were significant interactions on the concentration of liver triglycerides, egg yolk cholesterol, abdominal fat percentage between chromium and L-carnitine (p=0.0003-0.0500). Adding 400 ${\mu}g/kg$ chromium and 100 mg/kg Lcarnitine simultaneously was the best for reducing egg yolk cholesterol and adding 400 ${\mu}g/kg$ chromium and 50 mg/kg L-carnitine at the same time was the best for reducing abdominal fat percentage. There was no side effect on production performance of laying hens while chromium or (and) L-carnitine reduced liver lipid, abdominal fat and egg yolk cholesterol.