Effect of high stocking density and dietary nano-zinc on growth performance, carcass yield, meat quality, feathering score, and footpad dermatitis in broiler chickens

In this study, effect of dietary nano-Zn and stocking density on performance, carcass yield, meat quality, and feathering score of broiler chickens was assessed at 42 d of age. Experimental treatments consisted of a 2 x 2 factorial arrangement of stocking density (low = 12 broiler/m(2) and high = 18 broiler/m2) and dietary Zn form (inorganic or nano). Four hundred eighty 1-d-old male broiler chickens were randomly assigned to 4 treatments with 8 pens in each treatment having 15 chickens per pen. Corn-soybean meal diets were formulated for starter, grower, and finisher phases. The high stocking density (HSD) negatively affected body weight gain (BWG) and feed intake (FI) of broiler chickens at 24 to 42 and 0 to 42 d of experiment (P < 0.05) but did not affect feed conversion ratio (FCR). The BWG (d 10 to 24, d 24 to 42, and d 0 to 42) and FI (d 10 to 24 and d 0 to 42) were negatively affected by dietary nano-Zn whereas, FCR was poor at 10 to 24 d only (P < 0.05). Dietary nano-Zn lowered the BWG at d 24 to 42 (P = 0.028), and FI of LSD and HSD treatments at d 24 to 42 and 0 to 42 (P = 0.019 and P = 0.028, respectively) compared to broiler chickens of LSD group fed inorganic Zn. Neither HSD nor nano-Zn had any effect on the relative yields of carcass, breast, and thigh. Meat quality traits were not affected by either HSD or nano-Zn. There were no differences between groups about back feathering score. However, HSD negatively affected wing feathering score (P < 0.05), and the worst score was observed in HSD dietary inorganic Zn group (P < 0.01). The HSD increased the footpad dermatitis (FPD) scores of chickens at d 24 and 42 (P < 0.01). Dietary nano-Zn reduced the FPD scores on d 24 (P < 0.05) but did not affect FPD on d 42. In conclusion, HSD negatively affected growth performance, wing feathering score, and FPD score in broiler chickens. Dietary nano-Zn suppressed the growth performance of broiler chickens subjected to HSD and did not affect the feathering, however, reduced the FPD score in broiler chickens.