Fearful behavior by caged hens of two genetic stocks

Abstract

Two White Leghorn stocks (Y 1 and Y 2) and sire families within each were compared for nervousness scores and for latencies to feed and to return to “normal” activity after being subjected to fear-inducing stimuli, involving either a metronome or the cage being struck by a human observer. Information on feather damage and loss, age at sexual maturity, and part-year egg-mass production was also collected. Strain differences were clearly evident for nervousness score, duration of fearful behavior, and feather loss. The strain having more nervous and fearful hens also suffered greater feather damage and loss. Sire-family differences were erratically present for the same traits. Correlation coefficients calculated within strains for latency data obtained by 2 observers, working independently, indicated significant repeatability in 5 of 8 comparisons ( r values from 0.50 to 0.91). Correlations of latencies within strains obtained by the use of 2 kinds of fear-inducing stimuli also indicated significant repeatability in 4 of 8 comparisons ( r values from 0.35 to 0.88). Further intra-strain correlation analyses indicated that fearful behavior, as measured by latencies, tended to be associated with number of hens per cage, but was relatively independent of neighbors' behavior. Greater nervous and fearful behavior of caged groups tended to be significantly associated with greater feather loss and non-significantly associated with earlier sexual maturity and lower egg-mass production of 30 – 40-week-old pullets.