Reza Salahi Moghaddam; Mohammad Hossein Shahir
Articles in Press, Accepted Manuscript, Available Online from 04 September 2021
Abstract
In order to evaluate the response of broiler chicks to different levels of dietary ideal protein (Ross 308 strain recommendation and 10% less) and digestible valine to lysine ratio (71, 74, 77, 80, and 83%) in the starter period (one to 10 days of age), a study was performed using 500-day-old male broilers ...
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In order to evaluate the response of broiler chicks to different levels of dietary ideal protein (Ross 308 strain recommendation and 10% less) and digestible valine to lysine ratio (71, 74, 77, 80, and 83%) in the starter period (one to 10 days of age), a study was performed using 500-day-old male broilers in a 2×5 factorial arrangements based on a completely randomized design including 10 treatments and five replications. The results showed that reducing dietary ideal protein level increased body weight, feed intake and improved feed conversion ratio (P<0.01). The percentage of bone ash and calcium content also increased significantly with decreasing dietary ideal protein (P <0.05). Reducing the dietary ideal protein level decreased serum cholesterol, glucose, total protein, albumin, globulin, calcium, and phosphorus (P<0.05). The highest average body weight at 10 day of age, weight gain, carcass and breast percentages and the lowest feed conversion ratio were observed at 74% of digestible valine to lysine ratio (P<0.05); while the highest average feed intake, thigh percentage, bone ash and calcium percentage were obtained at 77% of digestible valine to lysine ratio (P <0.05). No significant interaction was observed between the two experimental factors except for carcass percentage (P<0.05) and serum phosphorus concentration (P <0.01). In conclusion, based on the results of this study, a 10% reduction in dietary ideal protein levels is possible by maintaining ideal ratios of essential amino acids. The appropriate ratio of digestible valine to lysine is recommended to be 74% based on performance indices and carcass traits, and 77% based on bone traits.