Effects of dietary dihydropyridine on laying performance and lipid metabolism of broiler breeder hens

The experiment was conducted to investigate the effects of dihydropyridine supplementation on the laying performance and lipid metabolism of broiler breeder hens. A total of 720 forty-five-week old broiler breeder hens were randomly divided into four experimental groups, each group consisting of six replicates of 30 birds. For 10 weeks the birds were fed a maize-soybean meal diet containing 0, 100, 200, 300 mg dihydropyridine/kg, in the respective treatment groups. The daily egg weight and daily feed intake were not affected by dihydropyridine supplementation, but the laying rate and feed efficiency were significantly increased. The percentage of abdominal fat and percentage of liver fat were significantly decreased by dietary dihydropyridine. A level of 100 mg dihydropyridine/kg had no effect on hormone-sensitive triglyceride lipase (HSL) activity in the liver or abdominal fat, though higher levels of dietary dihydropyridine (200 mg/kg or 300 mg/kg) increased HSL activity in the liver and abdominal fat. The concentration of cyclic adenosine monophosphate (cAMP) and superoxide dismutase activity were significantly increased by dihydropyridine, but the malondialdehyde content decreased. The apolipoprotein B concentration was increased at levels of 100 and 200 mg dihydropyridine/kg, but the 300 mg level had no effect on apolipoprotein B, compared with the control group. The triiodothyronine concentration was significantly increased by dietary dihydropyridine. It is concluded that supplementing dihydropyridine in the diet has a beneficial effect on the laying performance and regulates the fat metabolism of broiler breeder hens. The results suggest that the supplementation of 200 mg dihydropyridine/kg diet is the optimal dose for broiler breeder hens.