Evidence and role of phlebitis and lipid infiltration in the onset and pathogenesis of Wooden Breast Disease in modern broiler chickens

Abstract

Wooden Breast Disease (WBD), a myopathy that frequently affects modern broiler chickens, is a disorder that has been associated with significant economic losses in the poultry industry. To examine tissue changes associated with the onset and early pathogenesis of this disorder, a time-series experiment was conducted using chickens from a high-breast-muscle-yield, purebred commercial broiler line. Birds were raised for up to seven weeks, with a subset of birds sampled weekly. Breast muscle tissues were extracted at necropsy and processed for analysis by light microscopy and transmission electron microscopy. Histologic presentation indicated localized phlebitis with lipogranulomas in Week 1, focal single-myofibril degeneration in Week 2 preceding an inflammatory response that started in Week 3. Lesions in Week 4 were characterized by multifocal to diffuse muscle fibre degeneration, necrosis, interstitial oedema accompanied by increased lipid and inflammatory cell infiltration. Lesions in Weeks 5-7 revealed diffuse muscle degeneration, necrosis, fibrosis and fatty infiltration with lipogranulomas. Ultrastructural examination showed myofibrillar splitting and degeneration, irregular, displaced and degenerated Z-lines, mitochondrial degeneration and interstitial fibrosis with dense regular collagen fibres. This study, therefore, demonstrates that WBD exhibits an earlier onset in modern broilers than when detectable by clinical examination. Further, this study shows that the disease assumes a progressive course with acute vasculitis, lipid deposition and myodegeneration occurring in the earlier stages, followed by a chronic fibrotic phase.

Wooden‐Breast, White Striping, and Spaghetti Meat: Causes, Consequences and Consumer Perception of Emerging Broiler Meat Abnormalities

“…Several studies have been conducted to ascertain the possible factors involved in the occurrence of WS, WB, and SM in fast‐growing broilers (Table ). It is widely accepted that the incidence of breast abnormalities rises with increasing slaughter weight (Cruz et al., ; Lorenzi et al., ; Papah et al., ), growth rate (Kuttappan et al., , , ; Lorenzi et al., ), and genetic potential for breast meat yield (Alnahhas et al., ; Bailey et al., ; Livingston et al., ; Lorenzi et al., ; Petracci et al., ; Trocino et al., ) in agreement with strong genetic correlations found by Alnahhas et al. ().…”

“…(). This has been also confirmed by histological observations which evidenced that myodegeneration progress associated with the development of breast abnormalities is strictly related to age at slaughter (Griffin et al., ; Kawasaki et al., ; Papah et al., ; Radaelli et al., ; Sihvo et al., ) and breast growth pattern (Papah et al., ) (Table ; Radaelli et al., ). Recently, it was also demonstrated that egg storage duration before hatching as well as manipulation of embryonic development by egg incubation temperatures and chick weight at hatching can affect muscle morphology traits and related to occurrence of breast abnormalities (Clark, Walter, & Velleman, ; Livingston et al., ).…”

“…Concurrently, it has been found that metabolic waste products displacement might be impaired and associated to the development of phlebitis and perivascular lipid infiltration (Papah et al., ; Sihvo et al., ). Besides the veins, evidences of vascular pathology affecting the arteries, depicted by arteriosclerosis and atherosclerosis, has been observed by analyzing the genes differentially expressed between 3‐week‐old unaffected birds and WB cases (Papah et al., ).…”

“…A schematic representation of the underlying mechanisms leading to the progression of WS, WB, and SM abnormalities is shown in Figure . An early version of this illustration, reported in a previous review (Petracci et al., ), has been updated with findings from recent studies (Boerboom et al., ; Papah et al., , ; Sihvo et al., ).…”

“…This rigidity can be localized (the muscle presents focal rigid consistency, while other areas have normal consistency) or diffuse (extend throughout the breast meat) (Sihvo et al., ). Four categories can be attributed to WB (Papah et al., ; Petracci et al., ; Sihvo et al., ): mild (focally diffused and light firmness), moderate (focally diffused with extensive firmness of the breast), severe (>75% of the breast being extremely firm and with diffuse coverage) and extremely severe (firm breast). Although chicken breasts may present only symptoms from this myopathy, it is often reported to be associated with WS (Kuttappan et al., ; Soglia et al., ).…”