Total versus digestible amino acid requirements for growth and nutrient utilization of naked neck broilers during finishing phase

A study was conducted to compare the performance of Naked neck broilers (n=288) when fed 12 isocaloric diets (2×3×2 factorial design) formulated on either total or digestible amino acids basis (2 variables), three levels of amino acids (115, 100 and 85% of NRC, 1994 requirements) and with (FM) or without animal (VM) protein source (2 variables) during 4–6 wks period. The 6^th wk body weight, 4–6 wk body weight gain and FCR did not differ due to total or digestible amino acids basis. Better 6^th wk BW, 4–6 wk BWG and FCR were recorded in groups fed high (115%) and medium (100%) levels of amino acids. However, higher feed intake was recorded in the lower AA level. Efficiency of ME utilization was better (P<0.001) in high and medium AA diets. Whereas, better CP efficiency was recorded in low (85%) AA diets. Diets having higher levels of AA recorded increased N retention and decrease in N loss in birds. Lower N loss (P<0.001) was recorded in FM based diet than all VM diet. It may be concluded that the broilers fed diets formulated on digestible AA basis had similar performance, but better N-retention and lower N-loss than those fed diets of total amino acid groups. The optimum critical AA requirement for naked neck broiler during finisher phase might be 100% amino acid level of NRC (1994). Animal or vegetable protein source diets did not alter performance in the broiler during finishing period.