|Cheng, Heng wei|
Submitted to: International Society of Applied Ethology
Publication Type: Abstract only
Publication Acceptance Date: 7/19/2005
Publication Date: 8/15/2005
Citation: Marchant Forde, R., Jefferson, L., Cheng, H., Muir, W.M. 2005. Genetic related differences in response to chronic stress in laying hens. International Society of Applied Ethology. p. 68. Interpretive Summary:
Technical Abstract: The objective of this research was to examine genetic differences in behavioural and physiological response to chronic stress (increased group size combined with a higher stocking density) in three strains of hens: Kind gentle birds (KGB) birds selected for high productivity and survivability; control birds (C) with poorer productivity and survivability; and Dekalb-XL (D) birds, a highly cannibalistic commercial strain. At 17-wks of age, 112 birds per strain were allotted to standard four bird (K4, C4, D4, 213cm2/bird) or 10 bird (K10, C10, D10, 170cm2/bird) cages and behaviour was recorded weekly for 14 weeks. At 30-wks of age, two birds/cage were sedated and blood sampled before being feather scored and euthanized. Total body weight (BW) as well as individual organ weights (heart, liver, spleen and adrenals) were obtained. The total time and number of bouts of postural, consummatory and aggressive behaviours were determined. Blood was assayed to evaluate circulating corticosterone, adrenaline, noradrenaline and dopamine. Overall, K4 and C4 birds were less active than all other strain X group size (SXGS) combinations (p<0.05). D4 and D10 birds were most active (p<0.05). Activity levels in K10 and C10 were intermediary. Aggressive pecking was affected by genetics (K=0.27±0.05; C=0.33±.08; D=0.73±0.17 p=0.016) but there were no notable effects of SXGS interactions. Other behaviour parameters did not differ significantly between strains or SXGS. Likewise, there were few consistent differences in behaviour across SXGS at the individual week level. D4 & D10 birds exhibited the heaviest BW and spleen weights, but the lowest adrenal/BW ratio and poorest feather condition score (all p<0.05). Lastly there were few effects of strain or SXGS on the hormones or neurotransmitters measured. Genetic and stress related differences seen in bird behaviour were not evident in the physiological indices observed in this study. Further work is necessary to elucidate the regulatory interrelationships between these parameters in poultry.