Performance and adipose cellularity of female progeny of White Plymouth Rock dams and commercial broiler breeder sires

The study was conducted to compare performance and abdominal adipose cellul arity in broiler-type female progeny of commercial broiler breeder sires an d White Plymouth Rock (WPR) darns, and in the WPR females. Nine hundred and eighty three WPR and 816 crossbred (CB) female progeny were fed diets cont aining 13 MJ ME/kg(-1) and 20% CP ad libitum and body weight gain, feed int ake and feed conversion, breast angle, carcass weight, abdominal fat weight and adipose cellularity were determined at 58 days of age. Body weight gain and feed intake were significantly higher (P < 0.05) by 15 .3 and 18%, respectively, in the CB than in WPR progeny. Mean breast angle, carcass weight, abdominal fat weight and total lipid in abdominal fat pad were also 12, 13.5, 33 and 42.8%, respectively higher (P < 0.05) in CB than WPR progeny. The CB progeny had significantly more fat cells of 230 to 290 mu m in diameter than WPR progeny (0.31 x 10(7) vs 0.12 x 10(7)). Negative and highly significant (P < 0.01) correlations were observed betwe en abdominal fat cell size and total fat cell number in abdominal fat tissu e of WPR and CB progeny (r = -0.89 and -0.93, respectively) suggesting that adipocyte hyperplasia and hypertrophy were contributing factors to adipose tissue growth. Although the CB progeny outperformed WPR progeny, they howe ver accumulated more abdominal fat and total lipid and had more and larger adipocytes.