ISSUE FOCUS 36 FEED & ADDITIVE MAGAZINE July 2025 ARGININE IN BROILERS: ENHANCING GROWTH, IMMUNITY, AND HEAT STRESS RESILIENCE Dr. Xiaoli Dong Animal Nutrition Technical Manager CJ BIO China "L-Arginine is a basic amino acid and serves as the most abundant nitrogen carrier in tissue proteins. In mammals, it is considered a conditionally essential amino acid. However, poultry are unable to synthesize arginine on their own, making it an essential amino acid that must be supplied through the diet. The dietary requirement for arginine in broilers varies with the season. During the summer, the requirement increases to support optimal growth under heat stress conditions, so higher levels of arginine should be included in the diet." ARGININE IS AN ESSENTIAL AMINO ACID FOR BROILERS Uric acid is the vehicle for nitrogen excretion in poultry metabolism. It originates from the purines which derive their nitrogen from amino acids. Therefore, arginine would not be expected to function in nitrogen transfer to the extent that it does in animals with an ornithine cycle (Figure 1). Klose (1938) and Leveille (1959) studied that arginine is essential for the growing chick as well as the adult bird. Arginine could not be replaced by ornithine and citrulline. Tamir and Ratner (1963) found that carbamyl phosphate synthetase has not been detected in any tissue, while ornithine transcarbamylase, argininosuccinate synthetase, and argininosuccinase lyase have been found in the kidney but not in the liver. Small amounts of argininosuccinate lyase activity were also presented in the spleen, pancreas, and intestinal tract. Jones et al. (1961) studied the enzymes of arginine metabolism in rats. Compared to the enzymes in rats, it can be concluded that arginine is essential for broilers because they lack carbamyl phosphate synthetase. NUTRITIONAL EFFECT OF ARGININE IN BROILERS The Requirements of Arginine in Broilers Arginine is an essential amino acid for broilers. The requirement of arginine in broilers is affected by many factors such as breed, environment, etc. Moreover, Corzo (2020) indicated that the ratio of dArg/ dLys increased as the birds’ age increased. The optimum dArg/dLys value to optimize BW gain and FCR from 1-14d was 106 for both parameters, however, it was determined to be 129 and 116 from 25 - 42d, respectively. The arginine requirement also increased in broilers fed diets without antibiotics. Ruan et al. (2020) demonstrated that growth performance of Qingyuan partridge chickens, which belong to the yellow-feathered broilers, was improved by increasing dietary Arg from 8.5 to approximately 12.0 g/kg in antibiotic-free diets. The study also showed that
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