title: Effect of free-range days on a local chicken breed: growth performance, carcass yield, meat quality, and lymphoid organ index.
abstract: An experiment was conducted to evaluate the effect of free-range days on growth performance, carcass yield, meat quality, and lymphoid organ index of a local chicken breed. In total, 1,000 one-day-old male Suqin yellow chickens were raised for 21 d. On d 21, 720 birds with similar BW (536 ± 36 g) were selected and randomly assigned to free-range treatment at 21, 28, 35, and 42 d of age (assigned to free-range treatment for 21, 14, 7, and 0 d, respectively). Each treatment was represented by 5 replicates (pens) containing 36 birds (180 birds per treatment). All the birds were raised in indoor floor pens measuring 1.42 × 1.42 m (2 m(2), 18 birds/m(2)) in conventional poultry research houses before free-range treatment. In the free-range treatment, the chickens were raised in indoor floor houses measuring 3 × 5 m (15 m(2), 2.4 birds/m(2)). In addition, they also had an outdoor free-range paddock measuring 3 × 8 m (24 m(2), 1.5 birds/m(2)). The BW of birds after being assigned to free-range treatment for 7 d decreased significantly compared with that in the conventional treatment (P < 0.05). However, there was no effect of the free-range days on the BW at 42 d of age (P > 0.05). The daily weight gain, feed per gain, daily feed intake, and mortality from 21 to 42 d of age were unaffected by free-range days (P > 0.05). At 42 d of age, the breast yield increased linearly with increasing free-range days (P < 0.05), whereas the thigh, leg, thigh bone, and foot yields decreased linearly (P < 0.05). The lung yield showed a significant increasing and then decreasing quadratic response to increasing free-range days (P < 0.05). The water-holding capacity of the thigh muscle decreased linearly with increasing free-range days (P < 0.05), whereas there was no significant difference in the meat color, shear force, and muscle pH (P > 0.05). The absolute thymus weight and thymus:BW ratio showed a significant increasing and then decreasing quadratic response to increasing free-range days (P < 0.05). The findings of this study suggest that increasing free-range days advantageously affects breast yield, but decreases thigh, leg, thigh bone, and foot yields as well as the water-holding capacity of thigh. No evidence was found that increasing free-range days caused changes in growth performance, meat quality, and lymphoid organs except for changes in water-holding capacity and thymus.
authors.affiliation: Poultry Institute, Chinese Academy of Agricultural Sciences, 225125 Yangzhou, Jiangsu, P. R. China tonghb@163.com jlu283845846@163.com.
authors.forename: H B
authors.initials: HB
authors.lastname: Tong
authors.affiliation: Poultry Institute, Chinese Academy of Agricultural Sciences, 225125 Yangzhou, Jiangsu, P. R. China.
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Poultry Institute, Chinese Academy of Agricultural Sciences, 225125 Yangzhou, Jiangsu, P. R. China.
authors.forename: J
authors.initials: J
authors.lastname: Lu
authors.affiliation: Poultry Institute, Chinese Academy of Agricultural Sciences, 225125 Yangzhou, Jiangsu, P. R. China.
authors.forename: J M
authors.initials: JM
authors.lastname: Zou
authors.affiliation: Poultry Institute, Chinese Academy of Agricultural Sciences, 225125 Yangzhou, Jiangsu, P. R. China.
authors.forename: L L
authors.initials: LL
authors.lastname: Chang
authors.affiliation: Poultry Institute, Chinese Academy of Agricultural Sciences, 225125 Yangzhou, Jiangsu, P. R. China.
authors.forename: S Y
authors.initials: SY
authors.lastname: Fu
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D002681:China; D006799:Housing, Animal; D008221:Lymphoid Tissue / Q000737:chemistry*; D008297:Male; D008460:Meat / Q000032:analysis*; D011897:Random Allocation; D013997:Time Factors
keywords: carcass yield; free range; lymphoid organ index; meat quality; performance