Co-segregation of behaviour and production related traits in an F3 intercross between red junglefowl and White Leghorn laying hens

In poultry breeding, selection for production traits may cause side-effects on the physiology and behaviour of the birds with a potential influence on animal welfare. Genetic associations between phenotypic traits can be studied in an intercross of two divergent breeds. In advanced generations, traits controlled by the same genes or by genes located close to each other will co-segregate. Our aim was to study if behavioural styles expressed by red junglefowl (n=26) and White Leghorn (n=26) in a social vs. exploration motivation test as well as breed-differences in contrafreeloading (CFL), an energy demanding feeding strategy, would co-segregate with production related traits in their F3 intercross progeny (n=78). The results revealed Leghorns to maintain closer social contact in the test, whereas junglefowl, which according to previous studies have also a higher degree of CFL, were more active and explorative. Furthermore, these behavioural differences correlated with several production related traits, such as growth and residual feed intake (RFI), in the F3 generation. F3 birds with higher levels of production related traits behaved in a fashion resembling Leghorns more than junglefowl. Both in parental animals and the F3 birds, the above effects were clearest among females. The results, thereby, suggest that selection for high production in fowl may simultaneously have side-effects on sociality and foraging. This could further influence the general capacity of birds to cope with environmental challenges such as exploring a novel environment. The genetic mechanisms underlying this co-segregation remain to be investigated.