DIETARY LEVELS OF METABOLIZABLE ENERGY AND CRUDE PROTEIN FOR CORNISH CHICKS

One hundred eighty hybrid broiler chicks of the Peterson x Hubbard lin e, in 18 groups of 10, were used to compare six diets (three replicati ons). The diets consisted mainly of maize, soybean and fish meals, and vegetable oil, and varied in levels of metabolizable energy (kcal/kg) and protein (g/kg) as follows: (A) 3,000/230, (B) 3,200/230, (C) 3,40 0/245, (D) 3,400/260, (E) 3,600/260, and (F) 3,800/260. Mean values pe r chick at wk 4 for treatments A to F, respectively, were as follows: weight gain, 994; 1,053; 1,105; 1,055; 1,063; and 943 g; and feed conv ersion, 1.81, 1.71, 1.57, 1.55, 1.48, and 1.48 g/g. Weight (g) and yie ld (%) of carcass at wk 4, respectively, were 693 (66.7), 740 (67.4), 774 (67.3), 725 (66.0), 740 (67.0), and 653 (66.0). Sample evaluation of these carcasses and of locally produced and imported carcasses show ed percentage of breast to be highest in the imports (30.8) and in tre atment C (30.6). In the objective criterion of conformation [weight (g )/pectoral muscle area (cm(2))], carcasses of C (19.8) and 5 (18.7) we re highest. Percentages of water and of protein in the dry matter (DM) were highest in imported carcasses (70 and 52, respectively). In perc entage fat in the DM, those of A and C and local commercial carcasses were highest (42), and those of F (32) and the imported (35) were lowe st. Diets C and E, which promoted rapid, efficient growth and desirabl e carcasses, are recommended for use with ''Cornish'' chicks.