Effects of different levels of black cumin seed in diets containing different levels of protein on performance, litter quality and tibia bone parameters of broiler chickens

This experiment was conducted to evaluate the effect of different levels of black cumin seed in diets containing different levels of protein on performance، litter quality and tibia bone parameters of broiler chickens. This experiment was performed in a completely randomized design with 2×3 factorial arrangement containing، 2 levels of protein (NRC، 1994 recommendation level and 87% of NRC،1994 recommendation level) and 3 levels of black cumin seed (zero، 1 and 2 percent in diet). Three hundred and thirty six day-old Ross 308 broiler chickens (mixed sex) were allocated to 6 experimental diets with 4 replicates of 14 chicks each. Results showed that the weight gain (WG) and feed conversion ratio (FCR) of birds fed diets containing NRC،1994 protein level were significantly better than those fed 87% of NRC،1994 protein level during the grower and whole period of experiment (P<0. 05). In the grower and whole period of experiment، using 1 and 2 % black cumin seed in diets containing 87% of NRC،1994 recommendation protein level led to relative increase in WG of birds. Litter nitrogen percent was insignificantly lower in birds fed NRC،1994 protein level than those fed 87% of NRC،1994 protein level. Tibia bone weight and bone external diameter was significantly (P<0. 05) higher in birds fed NRC،1994 protein level as compared to those fed 87% of NRC،1994 protein level. Use of 1 and 2% black cumin seed in diets of containing 87% of NRC،1994 protein level improved bone weight، tibia external and internal diameter in broilers، but no such effect was found in those fed NRC،1994 protein level. Based on the results of this experiment، use of black cumin seed in low protein diet can improve performance and some tibia bone characteristics of broiler chickens.