Breast muscle meat quality of broiler chickens fed diets with different digestible lysine/crude protein ratios

One hundred Cobb male broiler chickens with 42 days old were used to study the effect of different digestible lysine and crude proteins ratios on chemical composition and physical composition of the breast muscle meat. A completely randomized design and two hierarquic criteries of classification was used. The birds were raised and fed a basal diet until 21 days old and, from 22 to 42 days, they were fed a diet formulated with two crude protein (CP) levels (17.0 and 19.5%) and five digestible lysine and CP ratios, 5.9, 6.4, 6.9, 7.4 and 7.9% for ration with 17.0% CP and 5.3, 5.7, 6.1, 6.5, and 6.9% for ration with 19.5% CP, totaling 10 treatments with six replications. At 42 age days, two birds of each replicate were slaughtered for breast muscle meat sample collections. No effects were observed on breast muscle meat for the physical characteristics. In the chemical characteristics, effect in the 19.5% CP level was observed, in a way that the protein of the breast meat meat llinearly increased as the digestible lysine and CP ratio increases, not being evidenced differences for the others evaluated characteristic. The best ratio for protein deposition in the breast muscle meat in the 17.0% CP level was 5.9% (1.34% digestible lysine), and the worse in the 19.5% CP level was 5.3% (1.03% digestible lysine). However, as the others characteristic was not affected, the option to increase the digestible lysine content to improve the breast muscle meat protein deposition will depend on the cost of this operation. The protein level in the diet of broiler chickens in growth phase can be reduced up to 17.0% CP, with no effect on breast muscle meat quality of broiler chickens, by using an ideal protein concept.