Criteria for evaluating husbandry practices to alleviate heat stress in broilers


Yalcin S. , OZKAN S. , CABUK M., SİEGEL P.

JOURNAL OF APPLIED POULTRY RESEARCH, vol.12, no.3, pp.382-388, 2003 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 12 Issue: 3
  • Publication Date: 2003
  • Doi Number: 10.1093/japr/12.3.382
  • Title of Journal : JOURNAL OF APPLIED POULTRY RESEARCH
  • Page Numbers: pp.382-388
  • Keywords: broiler, heat stress, relative asymmetry, heterophil-to-lymphocyte ratio, tonic immobility, TONIC IMMOBILITY REACTION, HETEROPHIL LYMPHOCYTE-RESPONSES, DEVELOPMENTAL STABILITY, DOMESTIC-FOWL, CHICKENS, STOCKS, RATIO, TEMPERATURE, INSTABILITY, ASYMMETRY

Abstract

This study was undertaken to investigate the effects of management techniques used under heat stress on growth as well as developmental instability, duration of tonic immobility (TI), and heterophil-to-lymphocyte ratios (H:L) of broilers. Three-hundred sixty cockerels obtained from a commercial hatchery were randomly assigned to 12 floor pens. When the cockerels reached 21 d of age, three pens were kept as controls. Broilers in the other nine pens were moved to a room heated from 32 to 35degreesC between 1000 and 1700 h each day from 21 to 42 d of age. Broilers in the heated room were randomized into three treatment groups consisting of 1) conditioned (chicks exposed to 36degreesC for 24 h at 5 d of age), 2) feed-restricted (during the heat stress, feed was withdrawn 2 h before the hot period, and chicks were fed between 1700 and 0800 h), 3) and heat-stressed only. Conditioned and feed-restricted broilers gained 3.2 and 2.8%, respectively, more BW than heat-stressed broilers. Relative asymmetry (RA) averaged across several bilateral traits for the prolonged heat stressor was more informative than the RA for a single bilateral trait. Corrrelations suggest that RA were not closely associated with duration of TI and H:L under the conditions of this experiment.