Pathological changes associated with white striping in broiler breast muscles

Abstract

White striping is a condition in broiler chickens characterized grossly by the occurrence of white striations, seen parallel to the direction of muscle fibers, on broiler breast fillets and thighs. Based on visual evaluation of the intensity of white striping, breast fillets can be categorized into normal (NORM), moderate (MOD), and severe (SEV) categories. This study was undertaken to evaluate the details of changes in histology as well as proximate composition occurring in the fillets with respect to the 3 degrees of white striping. In experiment 1, representative breast fillets for each degree of white striping (n = 20) were collected from 45-d-old broilers, approximately 2 h postmortem. From each fillet, 2 skeletal muscle samples were obtained and fixed in 10% neutral buffered formalin. To identify and differentiate the histological changes, slides were prepared and stained using hematoxylin and eosin, Masson's Trichrome, and Oil Red O stains. In experiment 2, samples with 3 degrees of white striping were collected from 57-d-old birds for conducting proximate analysis. Major histopathological changes observed in the MOD and SEV samples consisted of loss of cross striations, variability in fiber size, floccular/vacuolar degeneration and lysis of fibers, mild mineralization, occasional regeneration (nuclear rowing and multinucleated cells), mononuclear cell infiltration, lipidosis, and interstitial inflammation and fibrosis. Microscopic lesions were visually scored for degeneration and necrosis, fibrosis, and lipidosis. The scale used to score the samples ranged from 0 (normal) to 3 (severe). There was an increase (P < 0.05) in mean scores for degenerative or necrotic lesions, fibrosis, and lipidosis as the degree of white striping increased from NORM to SEV. The results from the histopathological study were supported by the findings from proximate analysis confirming that the fat and protein contents of muscle increased (P < 0.05) and decreased (P < 0.05), respectively, as the degree of white striping increased. In conclusion, the histopathological changes occurring in white striping indicate a degenerative myopathy that could be associated with increased growth rate in birds.

Effect of White Striping on Chemical Composition and Nutritional Value of Chicken Breast Meat

“…Severe white-striped meat showed lower myofibrillar protein concentration at almost all molecular weights (Figure 3). Degeneration of myofibrils (Kuttappan et al, 2013a;Petracci et al, 2013c;Sihvo et al, 2013), which coincided with an increase in the levels of some serum enzymes like creatine kinase and alanine transaminase (Kuttappan et al, 2013b), can explain the disparity in the pattern of sarcoplasmic and myofibrillar proteins as well as the differences in the concentration for both types of proteins between normal and severe white-striped fillets.…”

“…Some studies have pointed out the presence of different histological changes in the breast of modern chicken hybrids like increased eosinophilia, floccular/vacuolar degeneration and lysis of fibers, mild mineralisation, occasional regeneration (nuclear rowing and multinucleated cells), mononuclear cell infiltration, lipidosis and interstitial inflammation and fibrosis (Kuttappan et al, 2013a;Petracci et al, 2013c;Sihvo et al, 2013). Hence, these modifications explain the increase of intramuscular lipids (e.g.…”

“…A recent survey has estimated that incidence of white-striped breast fillets was around 12% (Petracci et al, 2013b). The causes of WS are still unknown and no sign of systemic infections was found, but the histological evaluations showed that WS usually coupled with muscle degeneration and myopathic changes beneath the striation area (Kuttappan et al, 2013a;Petracci et al, 2013c;Sihvo et al, 2013). Occurrence of WS on the surface of chicken breasts impaired visual appearance and reduced the consumer willingness to buy this type of meat (Kuttappan et al, 2012b).…”

Implications of white striping and wooden breast abnormalities on quality traits of raw and marinated chicken meat

“…In this context, several studies have shown that breast muscle fibres of fastgrowing strains showed a shift towards glycolytic metabolism and are characterised by a larger diameter, lower capillaryto-fibre ratio, greater intercapillary distance and lower rate of protein degradation compared with unselected breeds (Sosnicki and Wilson, 1991;Mahon, 1999;Schreurs, 2000). All these changes have contributed to the appearance of different structural and metabolic abnormalities within muscle that are usually accompanied by myodegeneration and subsequent regeneration (Dransfield and Sosnicki, 1999;Sandercock et al, 2009;Petracci and Cavani, 2012) Recently, abnormalities have also been observed in breast muscles characterised by degenerative myofibrillar proteins that impair the functionality of cell membranes (Kuttappan et al, 2013a;Sihvo et al, 2014). This myodegeneration can be explained by the increased rate of growth of muscles, which exceeds the physiologically sustainable growth rate, leading to muscle damage (Wilson, 1990;Mahon, 1999).…”

Role of proinflammatory cytokines and growth factors in skeletal muscle regeneration

“…Badane mięśnie cechuje twardość (potoczna nazwa tej miopatii -"drewniana pierś"), a w obrazie histopatologicznym stwierdza się liczne ogniska degeneracji i regeneracji włókien mięśniowych oraz białe prążkowanie spowodowane nagromadzeniem tkanki łącznej i limfocytów (52). W innym badaniu wykazano dodatkowo zmienną wielkość włókien mięśniowych, łagodną mineralizację tkanki, zapalenie i lipidozę (35).…”