Reliability of a White Striping Scoring System and Description of White Striping Prevalence in Purebred Turkey Lines

Abstract

To efficiently meet consumer demands for high-quality lean meat, turkeys are selected for increased meat yield, mainly by increasing breast muscle size and growth efficiency. Over time, this has altered muscle morphology and development rates, which are believed to contribute to the prevalence of myopathies. White striping is a myopathy of economic importance which presents as varying degrees of white striations on the surface of skinless breast muscle and can negatively affect consumer acceptance at the point of sale. Breeding for improved meat quality may be a novel strategy for mitigating the development of white striping in turkey meat; however, it is crucial to have a reliable assessment tool before it can be considered as a phenotype. Six observers used a four-category scoring system (0–3) to score severity in several controlled rounds and evaluate intra- and inter-observer reliability of the scoring system. After sufficient inter-observer reliability (Kendall’s W > 0.6) was achieved, 12,321 turkey breasts, from four different purebred lines, were scored to assess prevalence of the condition and analyze its relationship with important growth traits. Overall, the prevalence of white striping (Score > 0) was approximately 88% across all genetic lines studied, with most scores being of moderate-severe severity (Score 1 or 2). As was expected, increased white striping severity was associated with higher slaughter weight, breast weight, and breast meat yield (BMY) within each genetic line. This study highlights the importance of training to improve the reliability of a scoring system for white striping in turkeys and was required to provide an updated account on white striping prevalence in modern turkeys. Furthermore, we showed that white striping is an important breast muscle myopathy in turkeys linked to heavily selected traits such as body weight and BMY. White striping should be investigated further as a novel phenotype in future domestic turkey selection through use of a balanced selection index.

Describing the relationships among meat quality traits in domestic turkey (Meleagris gallopavo) populations

“…Within each line, unfavorable correlations were observed between production and meat color with increased production (e.g., higher body weight, breast weight) associated with meat that is lighter, more yellow and more red (increased L*, b*, a*). Studies of the genetic and phenotypic correlations between growth and turkey meat quality traits also report positive correlations between body weight and particularly L* and b* ( Aslam et al, 2011 ; Vanderhout et al, 2022 ). This unfavorable relationship between growth and meat color could be due to the faster pH decline reported in some studies of fast-growing turkey lines ( Berri et al, 2001 ; Werner et al, 2008 ).…”

“…The age of the turkeys at slaughter was between 20 and 24 wk. All birds were reared under similar housing and management conditions and were processed at the same commercial poultry abattoir under identical conditions ( Vanderhout et al, 2022 ; Leishman et al, 2022 ). The turkeys were electrically stunned and exsanguinated, then scalded, defeathered, and eviscerated before being water chilled (2 h) and moved onto ice in refrigerated storage for 22 h.…”

“…However, an alternative strategy is to use genetic selection targeting meat quality traits ( Bailey et al, 2020 ). The presence of noticeable physical changes in the meat caused by myopathies (e.g., white striping, woody breast) or other conditions (e.g., PSE, DFD) have been noted to be connected to the intensive selection for larger body weight and breast meat yield ( Berri et al, 2001 ; Fernandez et al, 2001 ; Vanderhout et al, 2022 ). The impact of this intensive selection has also been proven to be a driving factor in the progression of myopathies and meat quality attributes ( Werner et al, 2008 ; Zampiga et al, 2020 ).…”

Genetic Parameters of White Striping and Meat Quality Traits Indicative of Pale, Soft, Exudative Meat in Turkeys (Meleagris gallopavo)

“…All fillets were also photographed (Hero 6, GoPro, San Mateo, CA, United States) approximately 24 h post-mortem. Photographs were used to evaluate WS on a 0–3 scoring scale ( Kuttappan et al, 2016 ; Vanderhout et al, 2022 ).…”

“…In addition to the rise in PSE meat observed in the poultry industry over the past decades, an increase in the incidence of the growth-related myopathy white striping (WS) has been observed in the turkey industry ( Mudalal, 2019 ; Vanderhout et al, 2022 ). This myopathy presents itself as thin white striations on the surface of the muscle running parallel to the muscle fibers.…”