Physical and Chemical Properties of Meat in Relation to Wooden Breast Myopathies in Male Broiler Chickens Raised in Evaporative Cooling Systems

Background: There are few scientific reports of the occurrence of wooden breast (WB) in Thailand. This study aimed to evaluate the incidence and effect of WB on the physical and chemical properties of meat from chickens reared under an evaporative cooling system (EVAP). Methods: A total 124 broiler chickens (BW = 2721.27±273.40 g) were selected from a group of 588 male broiler chickens (at 36 days of age). The WB meat (left site) score of each chicken was identified as being normal, moderate or severe. In order to compare the effect of the WB score on meat quality, based on the number of chickens in the normal group, the number of chickens in the moderate and severe groups were equalised (19 birds/group). The effects of the WB score on pH, colour, drip loss, thawing loss and cooking loss of the meat were observed. Result: The body weight of normal meat, moderate WB and severe WB was 2525.26±221.49, 2683.53±273.17 and 2883.78±211.90 g, respectively. The severe WB score occurred when the body weight (g) was heavier than the normal meat group for 14.19% (P less than 0.01). At 24 hours, the pH, drip loss, cooking loss and water content of the severe WB group was significantly higher, while the protein content in the severe WB group was lower than the normal meat group (P less than 0.01). Moreover, the severe WB group presented higher lightness, redness and yellowness values compared to the normal meat group (P less than 0.01). In conclusion, a larger body of broiler chickens, greater than 14% of the strain’s recommendation induced a severe WB score, which caused poor meat quality.