PSIX-3 Fast-growing and slow-growing broiler breeds had different response to feed energy level

An experiment was carried out to investigate the effects of feed energy on the fast-growing and slow-growing broilers. A total of 1080 1-d-old WOD168-1 and -2 broilers breeding by Yukou Poultry of both gender were assigned to 8 groups. A 2×2×2 factorial arrangement of treatments was used in a randomized complete block design to study the effects of breeds (fast-/slow-growing breeds), feed energy (LOW: 2920, 3020 kcal/kg; HI: 3020, 3120 kcal/kg diet for 0–21 d and 22-42d, respectively), and gender (male and female), and the interactive effects. A corn-soybean meal basal diet was formulated to meet nutrient requirements of both breeds. Body weight (BW), feed intake (FI), and feed to gain ratio (F/G) were determined on d 21 and 42, and carcass compositions were determined on d 42. Results from d 0 to 21 indicated that BW, FI and F/G of both breeds decreased as feed energy increased; fast-growing breeds had higher BW and FI, and lower F/G when compared with slow-growing breeds. High feed energy had decreased BW of both breeds on d 42. While F/G from d 0 to 42 showed interactive effects between breeds and feed energy: high feed energy and fast-growing breeds had lowered F/G; while F/G of fast-growing breeds fed with increased feed energy decreased less than slow-growing breeds. Carcass composition measured on d 42 showed different results between breeds and feed energy. Semi-eviscerate rate was increased in fast-growing breeds, but decreased in slow-fasting breeds. In conclusion, different breeds of broilers had different response toward feed energy level.