It is well known that reduced protein diets in broiler chickens could lessen nitrogen excretion and environmental pollution. However, the successful strategy for broiler chicken production fed on reduced protein diets largely depends on both exact amino acids balance and sufficient quantity.
Currently ideal amino acids profile and absolute standardised ileal digestible lysine concentrations provide this recommendation on amino acids balance and quantity, respectively. In reduced protein diets, if any amino acid is deficient or limiting, ingestion of excess of other amino acids will result in accumulation of these amino acids in plasma, leading to the reduction in feed intake. Figure 1 clearly shows that when the reduced protein diet is deficient in Arginine, it will result in increased plasma lysine, methionine plus cysteine, threonine, Valine, and isoleucine concentrations, indicating these surplus essential amino acids could not be degraded for muscle growth.
Figure 1. The effect of Arginine deficiency on plasma amino acids concentration (log ug/ml)
Arginine is one of most versatile functional amino acids because it is a precursor of several molecules, such as creatine, ornithine, nitric oxide, citrulline, proline, and polyamines. Apart from protein synthesis, it can stimulate the release of growth hormone and insulin-like growth factor 1.
Arginine also acts as a trigger of target of rapamycin (TOR) signalling system activation for reducing protein degradation. Supplementation of L-Arginine has been approved significantly increase Nitric oxide and reduce ascites related mortality.
In recent updated amino acids profile recommended by Aviagen breeder company, the SID Arginine to SID Lysine ratio has been increased significantly, up to 110% in the finisher period. A 42 days broiler chicken trial conducted in the University of Sydney clearly showed that when SID Arginine to Lysine ratio increased from 107% to 113%, plasma Lysine, methionine plus cysteine, and threonine concentrations were significantly reduced (Figure 2).
Increasing SID valine to Lysine ratio from 76% to 81%, SID isoleucine to lysine ratio from 69% to 73%, and SID Arginine to lysine ratio from 107 % to 113%, increased breast meat by 59 grams.
Figure 2. Plasma lysine, methionine plus cysteine, and threonine concentrations in response to dietary SID Arg/Lys ratios.
Report by Redox Animal Nutritionists