Effect of feed form, pellet diameter and enzymes supplementation on carcass characteristics, meat quality, blood plasma constituents and stress indicators of broilers
Abstract. Four hundred-twenty broilers were used in a factorial design (4×3) in which four feed forms (mash vs. pellet diet with diameter of 2 mm, 3 mm and 3.5 mm, respectively) and three enzymes treatments (unsupplemented, phytase, phytase+multi-enzyme) were used. Each treatment was replicated five times (7 broiler/replicate). Feed form had no effects on most of carcass traits and physical characteristics of meat, but pellet diets decreased the relative weight of gizzard and caecum length. Feeding 3.5 mm pellet diets increased abdominal fat compared to that of broilers fed mash diets. Pellet with 3 mm diameter increased and decreased respectively meat fat and moisture. Pellets with 3.5 mm diameter increased meat ash compared to broilers fed mash diet. Levels of plasma glucose and alanine aminotransferase of broilers fed 2 mm pellet, cholesterol of broilers fed 3 mm pellet and albumin/globulin ratio, monocytes and red blood cells of broilers fed 3.5 mm pellet were significantly higher than those of broilers fed mash diet. Haemoglobin, phagocytic activity, heterophils and heterophils/lymphocyte ratio were higher in groups fed mash diets and 2 mm pellet. Packed cell volume and phagocytic index were the highest in group fed mash diets. Phytase or multi-enzyme+phytase increased carcass yield, total edible parts and decreased inedible parts compared to broilers fed diet without enzyme supplementation. Enzyme supplementations significantly and similarly increased plasma glucose, total protein, triglycerides, red blood cells and phagocytic activity and decreased phagocytic index in comparison to the control group. However, phytase alone decreased cholesterol and increased monocytes by contrast with the control group. Multi-enzymes+phytase induced greater effect on white blood cells than phytase alone.