White striping (abbreviated WS) is a condition in
poultry
Poultry () are domesticated birds kept by humans for the purpose of harvesting animal products such as meat, Eggs as food, eggs or feathers. The practice of animal husbandry, raising poultry is known as poultry farming. These birds are most typ ...
where white
fat
In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food.
The term often refers specif ...
deposits replace
muscle
Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...
in stripes along muscle fibers. It is considered a type of
myopathy
In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. ''Myopathy'' means muscle disease ( Greek : myo- ''muscle'' + patheia '' -pathy'' : ''suffering''). This meaning implies that the primary defec ...
, primarily of the
Pectoralis major muscle. There does not appear to be direct harm to birds specifically from white striping. However, some scientists and
animal welfare
Animal welfare is the quality of life and overall well-being of animals. Formal standards of animal welfare vary between contexts, but are debated mostly by animal welfare groups, legislators, and academics. Animal welfare science uses measures ...
groups have called its presence indicative of the industry's use of fast-growing birds, who have higher rates of health issues and welfare concerns such as
hock burns.
Using fast-growing birds is linked to overall higher rates of white striping.
Prevalence
Over the last decade, the rates of white striping have increased substantially. In 2012, multiple studies averaged around 5% of birds showing signs of white striping. In 2018 and 2019, studies averaged above at least 90%. In 2021, one group found that it showed up around 99% of all farmed birds in the US, with 70% being moderate to severe.
The condition is not limited to the United States. In Italy, France, Spain, and Brazil, up to 50% of chicken breasts contained white striping according to research from 2014 to 2016. While data is not always available for every country, researchers suggest it is likely to appear at a higher prevalence in countries with fast-growing birds. It is also suggested that prevalence of white striping is likely higher than what the industry reports.
Cause
The exact cause is not fully known. It is hypothesized that
hypoxia and
oxidative stress
Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal ...
play a role in the emergence of the condition. Other hypotheses include higher calcium levels in the tissue between cells and the muscle fibers changing type.
It is known that birds genetically selected to grow faster show higher rates of white striping, regardless of their diet. Compared to a more moderately growing bird, the fast-growing Ross 308 shows an 11-25 times increase, and the
Cobb 500 shows a 24–28 times increase. The exact mechanism behind that connection is still an area of open research.
Effects
In severe cases of white striping, one study found it results in 223% higher fat and a 9% reduction in the
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
of chicken. Moderate cases result in 87% higher fat and a 3% reduction in protein. Additionally, birds with white striping show worsened quality of protein.
See also
*
Woody breast
References
{{Poultry
Poultry farming