Effect of Dietary Energy, Protein, and Lysine Content on Performance and Yields of Two Strains of Male Broiler Chicks

In a factorial arrangement of treatments Arbor Acres and Ross male broiler chicks were given four diets with 3,200 kcal ME/kg and four diets with 2,880 kcal ME/kg, two CP levels per energy level (23.1 and 33.6% in the high-energy diet and 21.0 and 29.7 in the low-energy diet) and two Lys levels per CP level per energy level (1.20 and 1.36% per CP level in the high-energy diets and 1.08 and 1.22% per CP level in the low-energy diets). The diets were given to 8 wk of age. Weight gain of Arbor Acres chicks was significantly higher (P less than .05) than that of Ross chicks at 6 and 7 wk of age, but feed to gain ratios were also significantly higher (P less than .05) at 6, 7, and 8 wk of age. Weight gain and feed to gain ratios were significantly better (P less than .05) on the high-energy diets than on the low-energy diets at 6, 7, and 8 wk of age. With equal Lys content, the normal-CP diets gave significantly higher gains (P less than .05) than the high-CP diets at 6, 7, and 8 wk of age. With equal CP content, the high-Lys diets gave significantly more gain (P less than .05) than the normal-Lys diets at 6, 7, and 8 wk of age. Oven-ready and breast meat yields of Ross chicks were significantly higher (P less than .001) compared with those of Arbor Acres chicks at 6, 7, and 8 wk of age and yields of edible organs, skin and fat, and remaining carcass were significantly lower (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)