Effects of vision-restricting "polypeepers" on the behaviour of laying hens during adaptation, feeding, on general activity, agonistic behaviour and pecking damage.
Vision-restricting "polypeepers" have been reported to result in higher egg production with improved food utilisation in hens. In the present experiments behavioural explanations of these effects were sought. For detailed observations 128 White Leghorn X Black Australorp hens were used and for pecking damage comparisons a further 192 hens. Half were fitted with polypeepers. Birds were studied in individual cages, three-bird cages or deep litter pens by direct observation and cine-camera. Adjustment problems in feeding, stereotypic head shaking and protracted displacement neck preening occurred initially after fitting of polypeepers. Disappearance of these phenomena after about one month, however, indicated adaptation. The initial reduction of egg production associated with polypeepers, observed by others, coincided with the period of adaptation. Polypeepers resulted in less activity; birds in multiple cages and litter pens resting more, while in single cages body movement was reduced. Polypeepers caused faster eating and less wastage of both pellets and mash. In general, agonistic acts were greatly reduced in multiple cages, resulting in reduced feeding competition. Polypeepers reduced significantly the incidence of feather pecking, resulting in considerably less feather loss after three months, and more so after 14 months in lay. Over the study as a whole the reductions in activity, food spillage, agonistic behaviour and feather damage probably contribute to the lower food consumption and improved laying efficiency previously reported.