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Browsing by Subject "Broiler"

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  • Allometric Growth and Morphometrics of Five Different Commercial Broiler Hybrids and their Relationship with Wooden Breast Presentation 
    Verastegui Castro, Karla Lucia (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.
  • Mechanical analysis of Wooden Breast muscle in broiler during chilled storage 
    Gao, Jingxian (2015)
    The literature review deals with different biochemical factors affecting texture changes of poultry meat during chilled storage. Proteolysis plays one of major roles in postmortem tenderization. The calpain system is activated by calcium and calpain is a key protease for cytoskeletal protein degradation. Different instrumental methods which are applied to measure meat texture were described. The aims of this study were to investigate mechanical properties of Wooden Breast and Normal muscles during 168 h of postmortem storage at 5˚C; both raw and cooked conditions were compared. Additionally, possible related changes in weight losses and myofibrillar proteins were examined. The results showed that raw Wooden Breast were significantly harder (p<0.05) than Normal muscles at 10 h postmortem. Raw Normal broiler breast muscles were homogeneous in texture. On the contrary, inhomogeneous texture profiles were observed within raw Wooden Breast muscles, and the hardness was mainly present in the surface layer. During chilled storage, raw Wooden Breast muscles became softer which mainly occurred during the first 3 days. At 168 h postmortem, there was no significant difference (p>0.05) in mechanical properties in 80% compression, between these two categories. Weight losses, SDS-electrophoresis and Western Blot pointed to a relationship between proteolytic activity and texture changes. However, Allo-Kramer shear force implied that cooking (75°C) diminished the difference in hardness between Wooden Breast and Normal meat, and that the tenderness of cooked meat increased during storage time.

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