Myopathies are gaining the attention of poultry meat producers globally. White Striping (WS) is a condition characterized by the occurrence of white striations parallel to muscle fibers on breast, thigh, and tender muscles of broilers, while Woody Breast (WB) imparts tougher consistency to raw breast fillets. Histologically, both conditions have been characterized with myodegeneration and necrosis, fibrosis, lipidosis, and regenerative changes. The occurrence of these modern myopathies has been associated with increased growth rate in birds. The severity of the myopathies can adversely affect consumer acceptance of raw cut up parts and/or quality of further processed poultry meat products, resulting in huge economic loss to the industry. Even though gross and/or histologic characteristics of modern myopathies are similar to some of the known conditions, such as hereditary muscular dystrophy, nutritional myopathy, toxic myopathies, and marbling, WS and WB could have a different etiology. As a result, there is a need for future studies to identify markers for WS and WB in live birds and genetic, nutritional, and/or management strategies to alleviate the condition.

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.

Due to the numerous proposed cardiovascular benefits associated with consumption of omega-3 fatty acids, marketing of an egg enriched by omega-3 fatty acid may benefit the egg producer. Effects on yolk composition of a standard laying hen diet enriched with 3% menhaden oil (test diet), versus an isocaloric (control) diet containing no added fat, were evaluated for 18 wk. Dietary menhaden oil did not alter egg production, egg weight, total yolk fat, or yolk cholesterol. However, yolk contents of omega-6 and omega-3 fatty acids were influenced by diet. Arachidonic acid decreased and eicosapentaenoic acid increased in eggs from hens fed the test diet following 1 wk of dietary treatment. Docosahexaenoic acid and linolenate increased in eggs from hens fed the test diet at 2 and 3 wk of the trial, respectively. These alterations in yolk composition resulted in a decrease in the ratio of omega-6 to omega-3 fatty acids from 18 for eggs from hens fed the control diet to 3 for eggs from hens fed the test diet. At Weeks 14 and 18, hens (n = 10 per diet) were killed and necropsied. No change in gross scoring of hepatic lipidosis was observed. Histologically, significantly greater scores for hepatocellular lipid infiltration were recorded for liver sections from hens fed menhaden oil than for control hens. Increased microscopic hepatic lipid infiltration observed with dietary omega-3 administration may have significance for flocks predisposed to fatty liver syndrome and may also provide a unique system in which to study the effects of dietary omega-3 fatty acids on liver lipid metabolism.

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White striping (WS) and woody breast (WB) are 2 poultry meat quality defects that affect the acceptance of raw breast fillets as well as properties of cooked and further processed products. The present study was intended to evaluate the incidence of these conditions in broilers at different ages and to compare the properties of fillets with different degrees of WS and WB. For this study, 1,920 birds were processed, at 6 and 9 wk of age, in a standard commercial inline processing system. After chilling, carcasses were deboned and butterfly fillets were collected and weighed. Individual fillets were scored for normal, moderate, severe, and very severe degrees of WS and WB, and for petechial hemorrhagic lesions (PHEM, 0 - no lesion to 2 - severe lesion). Representative fillets with NORM-WS/WB, SEV-WS, SEV-WB, and SEV-WS/WB were selected and stored at 4°C. After 24 h, fillet length, width, cranial height, and caudal height, as well as pH, color, and drip loss were recorded. There was an increase in incidence of severe and very severe WS and WB conditions at 9 wk compared to 6 wk of age. The relationship between fillet weight and the myopathies plateaued at 9 wk of age with more fillets showing a higher score. Mean PHEM scores were higher (P < 0.05) in SEV-WS, SEV-WB, and SEV-WS/WB compared to NORM-WS/WB birds, both at 6 and 9 weeks. NORM-WS/WB birds had lower (P < 0.05) live and breast weight, breast yield, and cranial and caudal heights, as well as b* value (yellowness) compared to SEV-WS/WB. NORM-WS/WB had lower (P < 0.05) pH while NORM-WS/WB and SEV-WS samples showed lower (P < 0.05) drip loss when compared to SEV-WB and SEV-WS/WB. The results from this study showed that the severe degrees of WS and WB are associated with heavier and older birds, and thicker breast fillets. Occurrence of severe degrees of WS and/or WB can affect various raw meat quality factors, mainly color and water holding capacity.