期刊
POULTRY SCIENCE
卷 93, 期 8, 页码 1883-1889出版社
ELSEVIER
DOI: 10.3382/ps.2013-03470
关键词
free range; performance; carcass yield; meat quality; lymphoid organ index
资金
- Scientific and Technical Support Program of the Twelfth Five-Year Plan [2012BAD39B04]
- Special Fund for Agro-Scientific Research in the Public Interest of Ministry of Agriculture [201003011]
- Scientific and Technical Support Program of Jiangsu Province, P.R. China [BE2012413]
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 x 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 x 5 m (15 m(2), 2.4 birds/m(2)). In addition, they also had an outdoor free-range paddock measuring 3 x 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.
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