title: Performance differences of Rhode Island Red, Bashang Long-tail Chicken, and their reciprocal crossbreds under natural cold stress.
abstract: OBJECTIVE
  The Bashang Long-tail chicken (BS), an indigenous Chinese breed, is considered cold tolerant. We selected BS, the Rhode Island Red (RIR), and their reciprocal crossbreds for the present study. The objectives were: i) to validate whether BS is cold tolerant and whether egg production and cold tolerance of crossbreds could be improved; and ii) to determine the physiological characteristics that underlie cold tolerance and favorable egg production performance in cold environments.
  
  
  METHODS
  A total of 916 chickens were reared in warm and natural cold environments (daily mean ambient temperature varied from 7.4°C to 26.5°C in the warm environment and from -17.5°C to 27.0°C in the cold environment). To investigate their adaptability to the cold environment, the egg production performance and body weight were monitored and compared between breeds and environments. The cloacal temperature and serum biochemical parameters were monitored to reveal the physiological characteristics underlie cold tolerance and favorable egg production performance in the cold environment.
  
  
  RESULTS
  The warm environment experiment showed that RIR had the highest egg production performance, and that the reciprocal crossbreds had a higher egg production performance than BS. While in the cold environment RIR had the lowest egg production performance, and the reciprocal crossbreds had a higher egg production performance than BS. In the cold environment BS and reciprocal crossbreds had higher triiodothyronine, tetraiodothyronine levels than RIR. At 35 and 39 wk of age, when the ambient temperature was extremely low (varied from -20°C to 0°C), serum glucose, follicle-stimulating hormone, luteinizing hormone, estradiol of BS and crossbreds were higher than RIR.
  
  
  CONCLUSIONS
  Bashang Long-tail chicken has a favorable cold tolerance ability. Crossbreeding with RIR and BS is an effective way to develop cold tolerant chickens with improved egg production performance.
authors.affiliation: National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Xie
authors.affiliation: National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Xukai
authors.initials: X
authors.lastname: Yang
authors.affiliation: National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Yahui
authors.initials: Y
authors.lastname: Gao
authors.affiliation: National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Jiao
authors.affiliation: National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Xinghua
authors.initials: X
authors.lastname: Li
authors.affiliation: National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Yajie
authors.initials: Y
authors.lastname: Li
authors.affiliation: National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Ning
keywords: Bashang Long-tail Chicken; Cloacal Temperature; Cold Stress; Egg Production Performance; Rhode Island Red; Serum Biochemical Parameters