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Several types of muscle abnormalities are present in the poultry industry as a result of genetic selection, leading to decreased quality of meat and consequent economic loss. The appearance of thin (moderate) to thick (severe) white striping (WS) striations parallel to muscle fibers on the surface of broiler breast fillets is one of the most troubling issues in the poultry industry. White striping also has unfavorable implications on visual acceptance, nutritional value, and processing traits of breast meat. The aim of this survey was to assess the influence of market class (medium and heavy birds) and genotype (standard- and high-breast yield hybrids) on the incidence of WS in broiler chickens raised under commercial conditions in Italy. The incidence of WS for both medium and heavy broilers was high (43.0%), with 6.2% of samples considered severe. Heavy flocks had significantly higher percentages of both moderate (46.9 vs. 25.8%; P ≤ 0.001) and severe (9.5 vs. 2.7%; P ≤ 0.001) WS than medium flocks. Considering the effect of genotype, high-breast yield hybrids exhibited a higher incidence of both moderate (40.2 vs. 33.2%; P ≤ 0.001) and severe WS (7.2 vs. 5.0%; P ≤ 0.001) compared with standard-breast yield birds. In addition, within the medium class, the occurrence of WS reached higher levels in flocks of males. The heavy class consisted of male flocks separated into 2 slaughter weight categories. Birds that reached higher slaughtering weights (3.8–4.2 kg) exhibited higher incidence of WS than flocks slaughtered at lower weights (3.0–3.8 kg) at a similar age. In conclusion, the main broiler genotypes used for commercial production were affected by a high rate of WS; hybrids selected for higher breast yields were more prone to the WS abnormality. In addition, severe cases of WS are even more prevalent at higher slaughter age and weight, although reduced growth rate is associated with a lower incidence and severity of WS. [ABSTRACT FROM AUTHOR]