Occurrence and Characterization of Pale,Soft,Exudative-Like Broiler Muscle Commercially Produced in China

Pale, soft, exudative-like （PSE-like） broiler muscle is a growing problem for meat industry all over the world. However, limited studies have been made to assess broiler meat quality in China. The aim of this study was to investigate the characteristics and incidence of PSE-like broiler muscle commercially produced in China. A total of 1 274 Pectoralis muscles of Arbor Acre broiler were randomly obtained from the processing line to determine the commercial incidence of PSE-like muscle based on color. Furthermore, broiler Pectoralis muscles selected from the 1 274 muscle samples were classified as PSE-like muscle （L＊〉53, n=33） and normal muscle （L＊〉48 and L＊=53, n=33） to assess meat quality. It was determined that PSE-like muscle had lower muscle pH values, lower water-holding capacity （WHC）, lower sarcoplasmic protein solubility, and lower total protein solubility than the normal muscle did. SDS-PAGE profile also showed that bands of approximate 96 and 24 kDa in sarcoplasmic protein and myofibrillar protein varied between these two groups, suggesting partial denaturation of sarcoplasmic proteins and precipitation on myofillarments. Correlation analysis showed that L＊ values have significant correlation with WHC and protein solubility. Furthermore, the distribution of L＊ values exhibited a normal curve with range varying from 42.70 to 58.37. It was considered that approximately 23.39% of the population was PSE-like muscle. These results suggest that PSE-like meat can represent a significant portion of commercially processed broiler breast meat in China and that the L＊ value measurement could be used to sort broiler meat quality using a cut-off point.

Association of growth rate with hormone levels and myogenic gene expression profile in broilers

Background： The growth rate often varies among individual broilers of the same breed under a common management condition. To investigate whether a variation in the growth rate is associated with a difference in hormone levels and myogenic gene expression profile in broilers, a feeding trial was conducted with 10,000 newly hatched Ross 308 chicks in a commercial production facility under standard management. At 38 d of age,30 fast-, 30 medium-, and 30 slow-growing broilers were selected among 600 healthy male individuals. The levels of insulin-like growth factor-1（IGF-1）, triiodothyronine（T3）, thyroxine（T4）, and growth hormone in the serum or breast muscle were assayed by ELISA or RIA kits, and the expression levels of several representative pro-and anti-myogenic genes in the breast muscle were also measured by real-time PCR.Results： Results showed that both absolute and relative weights of the breast muscle were in linear positive correlations with the body weight of broilers（P 〈 0.001）. Fast-growing broilers had higher concentrations of IGF-1 than slow-growing broilers（P 〈 0.05） in both the serum and breast muscle. The serum concentration of T3 was significantly higher in fast-growing birds than in slow-growing birds（P 〈 0.05）. However, no difference was observed in growth hormone or T4 concentration among three groups of birds. Additionally, a decreased expression of an anti-myogenic gene（myostatin） and increased expressions of pro-myogenic genes such as myogenic differentiation factor 1, myogenin, muscle regulatory factor 4, myogenic factor 5, IGF-1, and myocyte enhancer factor 2B, C, and D were observed in fast-growing broilers（P 〈 0.05）, relative to slow-growing broilers.Conclusions： Collectively, these findings suggested that the growth rate is linked to the hormone and myogenic gene expression levels in broiler chickens. Some of these parameters such as serum concentrations of IGF-1 and T3 could be employed to breed for enhanced growth.