Browsing by Subject "Wooden Breast"
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(2015)Genetic selection of broilers has produced heavier birds that grow faster, with consequent change in morphology and allometry (relative growth) of their body parts. Wooden Breast (WB) is a defect of the breast muscle that affects meat quality. Its cause is unknown, but heavy weight and/or rapid growth rate seem to be predetermining factors. The aim of this work was to study the differences in morphology and relative growth (allometry) between WB affected and unaffected birds. Random groups of a total of 350 male chickens of 5 hybrids were slaughtered at 7 different ages. Morphometric measurements of heart, liver, intestine, breast muscle, girth, coracoid, clavicle, keel and leg bones were analysed with a statistical software. Affected birds presented higher body weight, heavier, longer and thicker breasts and heavier livers than unaffected birds. On the other hand, unaffected birds presented longer legs, heavier intestines and hearts. Keel length, coracoid length and clavicle length did not present any difference between both groups. The comparison of allometric curves of affected and unaffected birds showed differences in almost all body parts, but the heart and liver. Clavicle was the only body part that presented a slower growth rate in unaffected birds, all the other body parts showed a higher growth rate. The relationship between breast thickness and clavicle, coracoid and keel lengths, had a great effect on the presentation of WB. Affected birds presented changes in morphology and growth, very similar to the ones caused by genetic selection. Genetic selection of broilers is very complex and dynamic and it may be possible that WB has several causes. It seems that one of them is the lack of support of the breast muscle, due to an impaired growth of its bone structure.
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(2015)Recently, a new muscular disorder has been reported in chicken M. pectoralis major called Wooden Breast that might be linked to intensive growth selection. The purpose of this study was to find the influence of Wooden Breast condition on protein composition of the breast muscle with special emphasis on myofibrillar and sarcoplasmic protein fractions. For fulfilling the aims of the study, a total number of 34 pectoralis major muscles from both Wooden Breast and normal chickens (Ross 508, Aviagen Ltd, Scotland) were used to evaluate protein composition, protein profile of sarcoplasmic and myofibrillar proteins and their changes, by doing one-dimensional SDS-PAGE analysis. M. Pectoralis major defected by Wooden Breast demonstrated significant decline in sarcoplasmic (P?0.001) and myofibrillar (P?0.05) protein content, in comparison with normal breast muscles. Furthermore, gel electrophoresis indicated significant changes in the intensity of 18 sarcoplasmic protein bands and 7 myofibrillar protein bands. Majority of affected sarcoplasmic proteins were glycolytic enzymes. Moreover, impacted myofibrillar proteins play a role in muscle fibre integrity (e.g. desmin) or calcium signalling. Results of the present study also revealed desmin overexpression with coexistence of a desmin fragment in Wooden Breast which was confirmed by Western-blot technique. In conclusion, the findings of this study indicated defected chicken breast with Wooden Breast contained less protein and the composition differed compared to normal chicken breast muscle, which proves the influence of Wooden Breast condition on protein characteristics of chicken breast muscle. Further studies are needed to interpret the protein changes in the Wooden Breast and the possible role of these changes on metabolic and structural status of the muscle.
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