Performance, Livability, and Carcass Yield of Slow- and Fast-Growing Chicken Genotypes Fed Low-Nutrient or Standard Diets and Raised Indoors or with Outdoor Access
2008
Fanatico, A.C. | Pillai, P.B. | Hester, P.Y. | Falcone, C. | Mench, J.A. | Owens, C.M. | Emmert, J.L.
Two experiments were conducted to assess the effect of genotype, production system, and nutrition on performance and livability of meat chickens for niche markets. Slow-growing (SG) and fast-growing genotypes (FG) were raised for 91 and 63 d, respectively, in experiment 1 (females) or 84 and 56 d, respectively, in experiment 2 (males). In each trial, SG were placed before FG to achieve a similar BW at processing. In experiment 1, each genotype was assigned to 8 pens of 20 birds each, with 4 pens within each genotype raised indoors in a conventional research facility or in a small facility with outdoor access. All birds were fed a low-nutrient diet. In experiment 2, genotype assignment to pens was as in experiment 1; however, 4 pens within each genotype were fed a low-nutrient diet or a conventional diet, and birds were raised indoors. Birds were gait-scored and commercially processed; legs were examined for tibial dyschon-droplasia lesions and scanned for bone mineral density. In experiment 1, FG gained more weight than SG (P < 0.05) even though they were placed later. Outdoor access increased feed intake, and feed efficiency was poorer (P< 0.05). Fast-growing genotypes had higher breast meat yield, whereas SG had higher wing and leg yields (P < 0.05). In experiment 2, the low-nutrient diet reduced (P< 0.05) gain of the SG; FG increased feed intake of the low-nutrient diet such that their gain was unaffected (P> 0.05). For FG, the low-nutrient diet resulted in a poorer (P < 0.05) feed efficiency. Although weight gain of the FG was maintained on the low-nutrient diet, breast yield was reduced (P < 0.05). Genotype affected bone health in both experiments, with SG having better gait scores and less tibial dyschondroplasia (P < 0.05). Outdoor access and the low-nutrient diet also resulted in better gait score (P < 0.05). These data indicate differences among genotypes and provide information about the efficiency and potential for alternative poultry systems.
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