Effect of Different Levels of Sunflower Meal and Niacin on Performance, Biochemical Parameters, Antioxidant Status, and Egg Yolk Cholesterol of Laying Hens

This study was conducted to evaluate the effect of different levels of sunflower meal (SFM) and niacin on laying hens performances, biochemical parameters, antioxidant status, and egg yolk cholesterol concentration. A total of 960, White Leghorn (Hy-Line W-36) commercial layers were randomly assigned to 12 groupsof 8 replicates with 10 hens each. Hens were allocated to diets 1 through 12 in a 3 × 4 factorial design and the dietary treatments included 3 levels of SFM (0, 10 and 15%) and 4 levels of niacin (0, 175, 225 and 275 mg/kg) fed to the birds for 10 weeks. Feed consumption was not affected (P>0.05) by niacin, SFM and SFM × niacin interaction. Dietary supplementation of 15% of SFM significantly (P<0.05) reduced egg weight, egg production and consequently egg mass. However, dietary addition of 275 mg of niacin/kg of diet increased (P<0.05) egg production and egg mass. Egg weight was not affected (P>0.05) by dietary addition of niacin. Feed conversion ratio was affected (P<0.05) by dietary addition of SFM and was not affected (P>0.05) by dietary incorporation of niacin and the SFM × niacin interaction. In fact, dietary supplementation of 15% of SFM significantly increased (P<0.05) FCR from 2.12 to 2.14. With the exception of shell thickness, all other parameters were not affected (P>0.05) by dietary addition of niacin. Dietary supplementation of 15% of SFM reduced (P<0.05) egg shell thickness from 0.29 to 0.28. However, only egg shell strength was affected (P<0.05) by dietary incorporation 275 mg of niacin/ kg of diet. Egg yolk cholesterol content was affected (P<0.05) by dietary addition of SFM and niacin. Our data also showed that serum concentration of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and triglycerides (TG) levels were not affected (P>0.05) by dietary incorporation of SFM, niacin, and their interaction. By contrast serum concentration of total cholesterol (TC) were affected (P<0.05) by dietary addition of SFM, niacin and their interaction. There were no effects (P>0.05) of the experimental diets on total antioxidant capacity (T-AOC), total superoxide dismutase (TSOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) serum concentration.