Aggressive pecking by males in breeding groups of Japanese quail (Coturnix japonica).

1. Head injuries caused by aggressive pecking are an important welfare problem in quail farming. The aim of experiments one to three was to reduce the rate of aggressive pecking in breeder groups. 2. The quails were housed in pens containing litter, nest boxes and a dustbathing box. The experimental groups consisted of 2/14, 3/14, 5/15 or 5/35 (males/hens) quails which were introduced into the experimental pens at the age of 4, 6 or 7 weeks. 3. None of the 5 factors that varied between the pens (visual barriers, age of introduction into the pens, number of hens per 5 males, number of males per 14 hens and light intensity) had a significant effect on the rate of aggressive pecking interactions between males. 4. Because of serious head injuries 20%, 17.5% and 12.5% (experiments 1, 2, 3) of the males had to be removed from their groups. 5. In single-male groups containing 8, 12, 16 and 20 hens (experiment 4) the percentages of fertilised eggs were 92%, 84%, 77% and 69% (medians, n = 4 pens per group size). No males were seriously injured in these groups. 6. It is concluded that for welfare reasons multi-male breeding groups of Japanese quail cannot be recommended. Given the satisfactory fertility observed in groups with a sex ratio of 1:8 or 1:12, single-male groups are also of interest for economic reasons: food costs are reduced.