This study was conducted to investigate the effects of garlic powder on the performance, egg traits and blood parameters of laying hens. One hundred and sixty-two SHSY-type brown layers aged 21 weeks were chosen at random from a large flock. They were allocated to three dietary treatments. Each treatment comprised six replicates of nine layers in groups of three. The diets were supplemented with 0, 5 and 10 g kg −1 garlic powder. The experimental period lasted 22 weeks. Garlic powder addition did not significantly affect body weight, egg production, feed consumption, feed efficiency, egg shell index, egg breaking strength, egg shell thickness, egg albumen index, egg yolk index, egg Haugh unit, egg yolk weight and serum protein concentration. Egg weight increased (P < 0.01) with garlic powder supplementation. There was a significant (P < 0.01) reduction in egg cholesterol concentration as mg g −1 yolk when the dietary level of garlic powder was increased from 0 to 10 g kg −1 . Hen serum triglyceride (P < 0.05) and total cholesterol (P < 0.01) concentrations decreased with garlic powder supplementation. This study demonstrated that garlic powder addition increased egg weight and decreased egg yolk cholesterol concentration (mg g −1 yolk) and serum triglyceride and cholesterol concentrations without adverse effects on performance and egg traits.
INTRODUCTIONGarlic (Allium sativum) and its products are known to have potential hypolipidemic/hypocholesterolemic, hypotensive, hypoglycemic, hypothrombotic and hypoatherogenic properties. 1 -4 Garlic contains a variety of organosulfur compounds such as allicin, ajoene, S-allylcysteine, diallyl disulfide, S-methylcysteine sulfoxide and S-allylcysteine sulfoxide. 5 Despite the fact that the mechanisms primarily responsible for the hypocholesterolemic action of garlic are uncertain at present, the composition and quantity of the sulfur components of different garlic preparations used in various studies could account in part for the inconsistent findings. 6 Other contributing factors may include subject recruitment, duration of experiment, dietary control, lifestyle and methods of lipid analysis. 3,4 S-Methylcysteine sulfoxide 7,8 and S-allylcysteine sulfoxide 8 had a potent antihypercholesterolemic effect on cholesterol-fed rats. However, previous studies with laying hens and broilers showed controversial results on the hypocholesterolemic effect of garlic. 9 -13 In experiments with diets containing garlic paste at 38 g kg −1 or solvent fractions or garlic oil equivalent to 38 g kg −1 garlic paste, the activity of hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase decreased by 50-69% in 12-week-old