Effects of stocking density and group size on thermoregulatory responses of laying hens under heat challenging conditions

A. R. Green, H. Xin

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Sectors of the US cage layer industry have begun adopting practices of reduced stocking density (i.e.. increased cage floor space) and varying group sizes. This study was conducted with 24 groups of 48 W-36 laying hens (39 to 46 weeks old) to assess the effects of cage floor space or stocking density (SD) (348, 387, 465, or 581 cm2/bird; 54, 60, 72, or 90 in 2/bird) and group size (GS) (8 or 16 birds/cage) on the ability of the hens to cope with heat challenge. Data were collected at thermoneutral (24°C or 76°F) and warm conditions (32°C or 90°F and 35°C or 95°F). No differences in core body temperature (CBT) of the hens were observed among the treatment regimens at 24°C. In general, mean CBT increased with heat exposure duration (P<0.0001) but leveled offafter the 32°C phase. At 32°C, CBT was higher for GS of 16 vs. 8 (42.3 vs. 42.1°C, P=0.05); higher for SD of 348 and 387 cn2/bird than for 465 or 581 cm2/bird (42.4 and 42.2°C vs. 41.9 and 42.1°C, respectively, P=0.009). Bird body mass decreased as heat exposure duration increased (P<0.0001), but no differences were observed among the treatments. No mortalities were observed during the thermoneutral period, and the mortality rate increased with heat exposure duration. The results indicate that, while CBT was lower for lower stocking density, the increased space was not sufficient to offer a clear benefit for coping with heat challenge of 32°C or 35°C.

Original languageEnglish (US)
Title of host publicationLivestock Environment VIII - Proceedings of the 8th International Symposium
Pages569-575
Number of pages7
StatePublished - Dec 1 2008
Event8th International Livestock Environment Symposium, ILES VIII - Iguassu Falls, Brazil
Duration: Aug 31 2008Sep 4 2008

Publication series

NameLivestock Environment VIII - Proceedings of the 8th International Symposium

Other

Other8th International Livestock Environment Symposium, ILES VIII
CountryBrazil
CityIguassu Falls
Period8/31/089/4/08

Keywords

  • Cage layer
  • Core body temperature
  • Heat stress
  • Production
  • Welfare

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Animal Science and Zoology

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