Effects of dietary lysine and methionine supplementation on Ross 708 male broilers from 21 to 42 days of age (II): breast meat quality

In a previous companion study, we found that broiler growth performance and meat yield were improved by the feeding of increased levels of dietary lysine (Lys) and methionine (Met). In the current study, dietary Lys and Met supplementation were evaluated for their effect on the breast (pectoralis major) meat quality of male Ross x Ross 708 broilers. A completely randomized block design with a 2 x 4 factorial arrangement of treatments was applied (10 blocks and 8 treatments/block). The diets, including 2 Lys levels (1.013 and 1.216%) and 4 Met levels (0.304, 0.380, 0.456, and 0.532%), were fed from 21 to 42 d of age in the form of pellets, and broilers were processed at 42 d of age. Data were analyzed by 2-way ANOVA using the MIXED procedures of SAS 9.2. Lysine supplementation yielded breast meat with increased sarcoplasmic protein (soluble protein) solubility (P = 0.007) and pH (less protein denaturation; P < 0.0001), and decreased cooking loss (higher cooking yield; P = 0.0009), shear force (increased tenderness; P = 0.035), and lightness (associated with higher muscle pH and cooking yield; P < 0.0001). Dietary Lys and Met interacted to affect cooking loss, in that breast meat from birds fed the highest Lys and Met levels showed the lowest cooking loss (P = 0.02). In addition, overall consumer acceptability was slightly higher for the breast meat of birds belonging to the Lys (1.216%) and Met (0.532%) treatment group when compared to those in the 1.013% Lys and 0.380% Met treatment. In conclusion, supplemental dietary Lys and Met increased growth rate and meat yield without having any adverse effects on the meat quality parameters tested. Furthermore, the supplementation of diets with Lys and Met slightly improved some meat quality parameters.