Effects of Early Flock Assembly on Agonistic Behavior and Egg Production in Chickens ,

Abstract

Pullets from high and low social-dominance strains of the White Leghorn (W.L.) and Rhode Island Red (R.I.R.) breeds were assembled in 32 flocks at 6 weeks of age; eight flocks per strain. At 19 weeks all birds were moved to strange pens; four flocks per strain were kept intact as to membership, whereas the other four were reassembled within strains so as to maximize number of strangers.Data were collected and analyzed for agonistic behavior from 19 to 31 and from 52 to 56 weeks, age at sexual maturity, egg weights at 32 and 55 weeks, hen-day rate of lay, hen-housed production and mortality.Intra-flock variability was significantly greater for the W.L. high dominance strain for rate of lay and hen-housed production, whereas the W.L. low strain was more variable for age at first egg and egg weights. High dominance strain R.I.R. pullets were more variable for age at sexual maturity only.Analyses of variance, based on flock means, indicated pullets of the W.L. high strain to be significantly inferior in egg production, survival, and to have smaller eggs than the W.L. low strain. Within the R.I.R. breed, the high strain matured earlier.Age at final assembly of flocks had no long-term effects on agonistic activity levels. However, pullets in flocks reassembled at 19 weeks interacted at elevated frequencies from 19 to about 26 to 30 weeks of age. Productivity traits were not significantly influenced by final flock assembly at 6 as compared to 19 weeks of age.Results are discussed in terms of agonistic behavior, social stress and how both appear to relate to productivity traits.