The thirds experiment was conducted at the same commercial farm as the second experiment but instead targeting 18 week old broiler breeder females reared under either everyday feeding (ED) or skip-a-day (Skip) feeding regimens. The aim was to investigate whether those differences found between small and large broiler breeder females at 4 weeks were still present towards the end of the rearing phase. In order to do this a tonic immobility test and a social isolation test were carried out including 19 small and 19 large birds from each feeding regimen. Alongside the behavioural test daily home pen activity monitoring and activity monitoring around a manual restraint test was also carried out on 6 small and 6 large birds from each feeding regimen.