Genetic parameters of white striping in relation to body weight, carcass composition, and meat quality traits in two broiler lines divergently selected for the ultimate pH of the pectoralis major muscle

Background: White striping (WS) is an emerging quality defect with adverse consequences for the sensorial, technological, and nutritional qualities of breast meat in broiler chickens. The genetic determinism of this defect is little understood and thus the aim of the study presented here was to estimate the genetic parameters of WS in relation to other traits of economic importance such as body weight, carcass composition, and technological meat quality in an experimental population consisting of two divergent lines selected for high (pHu + line) or low (pHu-line) ultimate pH (pHu) of the pectoralis major (p. major) muscle. Results: The incidence of WS in the whole population was 50.7 %, with 36.7 % of broilers being moderately and 14 % being severely affected. A higher incidence of moderate (p < 0.001) and severe (p < 0.0001) WS was observed in the pHu + line, and strong genetic determinism (h(2) = 0.65 +/- 0.08) was evidenced for WS in the studied lines. In addition, WS was significantly genetically correlated with body weight (r(g) = 0.33 +/- 0.15), and breast meat yield (0.68 +/- 0.06), but not with the percentage of leg or abdominal fat. Increased body weight and breast muscle yield were significantly associated with increased incidence and severity of WS regardless of the line. Significant rg were observed between WS and several meat quality traits, including breast (0.21 +/- 0.08) and thigh (0.31 +/- 0.10) pHu, and breast cooking loss (0.30 +/- 0.15). WS was also strongly genetically correlated with the intramuscular fat content of the pectoralis major muscle (0.64 +/- 0.09), but not with the lipid oxidation index of this muscle. Conclusions: This study highlighted the role of genetics as a major determinant of WS. The estimated genetic correlations showed that WS was more highly related to muscle development than to the overall growth of the body. The positive genetic association reported in this study between WS and muscle pHu indicated a possible relationship between the ability of muscle to store energy as a carbohydrate and its likelihood of developing WS. Finally, the strong genetic determinism of WS suggested that selection can be an efficient means of reducing the incidence of WS and of limiting its undesirable consequences on meat quality in broiler chickens.