19. Some turkey parent stock, and the majority of turkeys grown for Christmas on small farms, are reared in pole barns. Consequently, pole barns accommodate a small proportion of the UK turkey population but on a relatively large proportion of the production units. The systems of environmental control within pole barn housing are rudimentary. Turkey poults intended for housing in pole barns are usually reared in brooder houses (similar to conventional turkey housing) until they are 6 weeks of age, by which time they do not need additional heat. Once in the pole barn, the birds are subject to natural daylight (which may be supplemented during the winter months with electric light) and there is often little control of temperature or ventilation. The labour requirement in pole barns is higher and the stocking density lower than in conventional (enclosed) housing. Injurious pecking can be a problem and is usually controlled by beak-trimming. In an attempt to provide a better environment and reduce injurious behaviour some growers provide vegetable material or other objects for the turkeys to investigate and manipulate.