Estimating optimum dietary digestible arginine to lysine ratio for starter period in Arian broiler chickens at high altitude

In order to estimate the optimum dietary digestible arginine to lysine ratio for starter period at a high altitude (2100 m), 420 day-old Arian broiler chicks (210 male and 210 female) were used in a completely randomized design with seven treatments of six replicates. From 1 to 7 days of age, all chicks were fed with a standard diet. Dietary treatments with seven digestible arginine to lysine ratios (0.83, 0.93, 1.03, 1.13, 1.24, 1.34 and 1.44) were formulated and fed from 7 to 14 days of age. On day 14, feed intake and body weight gain (BWG) were recorded and feed conversion ratio (FCR) was calculated. The optimum ratio of arginine to lysine for BWG and FCR were estimated using quadratic regression (QR), linear broken line (BL), and quadratic broken line (BQ) models. The optimum ratios for BWG using QR, BL, and BQ models were estimated as 1.21, 1.08, and 1.22 (R2: 0.75, 0.70, and 0.69) respectively. Also, the optimum ratios for FCR using QR, BL, and BQ models were estimated as 1.22, 1.13, and 1.19 (R2: 0.77, 0.78, and 0.71) respectively. According to the obtained coefficients of determination (R2), it is concluded that in this study, the RQ model has more accurately estimated the arginine to lysine ratio for both BWG and FCR. Using this model, the obtained optimum ratio for both BWG and FCR in high altitudes is about 1.22 which is considerably more than the recommended ratio by the strain catalogue (1.08).