ARS | Publication request: Strain variations in behavioral traits under heat stress in laying hens

Submitted to: International Society of Applied Ethology
Publication Type: Abstract Only
Publication Acceptance Date: April 10, 2011
Publication Date: N/A

Technical Abstract: Heat stress is a problem for welfare of animals including laying hens. This study examined whether hens’ responses and adaptation to heat stress are affected by their genetic strain. Ninety 28-week-old White Leghorns from two strains were used: DeKalb XL (DXL), a line of hens individually selected for high productivity, and KGB (kind gentle bird), a line of hens selected for high group productivity and survivability. The hens were randomly paired by strain at 2-bird/cage, providing 658 cm**2 floor space per hen, and assigned to heat (H) or control (C) treatment for 14 days (mean: C=24.3°C, H=32.6°C). Hens’ behavior was recorded at day 1, 2, 6, 11, and 13 during the treatment and examined using 10 min scan sampling for 2 x 2-h periods starting at 2 h for each, started at 2 h after lights on and 2 h before lights off, respectively. Data were analyzed using the mixed model procedure of the SAS program. Compared to the C hens, the H hens spent more time drinking and resting, displayed more wing-opening behavior, and less time sitting (P<0.05). Strain differences were also seen across the treatments. Compared to H-DXL hens, H-KGB hens rested less on day 1 (P<0.05), 11 and 13 (0.05<P<0.1); and tended to drink and eat more on both day 1 and 13 (0.05<P<0.1). In addition, H-KGB hens exhibited more panting behavior than H-DXL hens (P<0.05). The results indicate that, in general, hens have the capability to change their behavioral patterns in response to heat stress; the nature and intensity of the reactions are shaped by the genetic background of hens.