title: 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.
abstract: 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.
authors.affiliation: Center for Excellence in Poultry Science, University of Arkansas, Fayetteville 72701, USA.
authors.forename: A C
authors.initials: AC
authors.lastname: Fanatico
authors.forename: P B
authors.initials: PB
authors.lastname: Pillai
authors.forename: P Y
authors.initials: PY
authors.lastname: Hester
authors.forename: C
authors.initials: C
authors.lastname: Falcone
authors.forename: J A
authors.initials: JA
authors.lastname: Mench
authors.forename: C M
authors.initials: CM
authors.lastname: Owens
authors.forename: J L
authors.initials: JL
authors.lastname: Emmert
mesh_terms: D000821:Animal Feed; D000818:Animals; D002645:Chickens / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development* / Q000502:physiology; D005838:Genotype; D006128:Growth / Q000235:genetics; D006799:Housing, Animal; D008136:Longevity; D009753:Nutritive Value; D015430:Weight Gain