Physiological and biochemical response of broiler chickens to amino acids administration

Abstract

The main objective of this study was to evaluate the effect of amino acids supplementation to drinking water of meat-type broiler chickens on their blood parameters and productive traits. A total of sixty one day old, unsexed broiler chicks were obtained from a local hatchery. They were divided into three treatment groups: control group, and two treatment groups supplemented (via drinking water) with amino acids preparation (Amino-2500 USA Premium Nutrition) at 0.5 and 1.0 g/L, respectively. All chicks were fed a commercial low protein diet containing 19% crude protein and 2900 kcal metabolizable energy per kilogram of the diet. Chicks of the control group was fed the recommended (standard) diet containing 23%crude protein and 3000 kcal of ME/Kg. The duration of the experiment was five weeks. The criteria of productive and physiological responses were live body weight, weight gain, blood plasma protein fractions, plasma lipids (cholesterol, triglycerides, high density lipoprotein (HDL) and low density lipoprotein (LDL). Transaminase (ALT and AST) activity indicative of liver function was measured. Kidney function test in terms of plasma creatinine, urea nitrogen and uric acid were also determined. Results showed that live body weight and weight gain of broiler chickens were significantly increased by AA administration either at three or five weeks of age. At marketing age (5 weeks), birds from the 3rd and 2nd groups achieved heavier body weigh by 32.3 and 26.8% more than the control chickens. Blood plasma total protein, albumin and globulin levels were significantly increased in the AA treatment groups for T3 and T2, respectively as compared to the control chicks. Addition of AA resulted in an obvious increase in the activity of ALT and AST indicative of negative influence of excess AA on livers function-related enzymes, especially with the higher dose of AA (T3).This was also observed for plasma uric acids and creatinine concentrations as end products of protein metabolism. The histological sections from lymphoid organs revealed better histological appearance indicative of better immunity and bird's health. It is concluded that excessive AA administration for broilers fed on low protein diet, could be used to increase live body weight, enhance protein metabolism without negative impacts on blood biochemistry, and improve their immune response. However, further study is needed to assess the cost and the net revenue from AA supplementation.