1 © 2008 Universities Federation for Animal Welfare The Old School, Brewhouse Hill, Wheathampstead, Hertfordshire AL4 8AN, UK Animal Welfare 2008, 17: xxx-xxx ISSN 0962-7286 Welfare implications of nipple drinkers for broiler chickens E Houldcroft, C Smith, R Mrowicki, L Headland, S Grieveson, TA Jones and MS Dawkins* Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK * Contact for correspondence and requests for reprints: marian.dawkins@zoo.ox.ac.uk Abstract Commercially reared broiler chickens are commonly supplied with drinking water through lines of nipple drinkers that are positioned above the birds’ heads to avoid water leaking and spoiling the litter underfoot. This means that the birds have to peck upwards to obtain water, an action that is very different from the ‘scoop’ action of natural drinking seen when birds drink from troughs or puddles. In this study we investigate the welfare implications of this unnatural drinking behaviour imposed by nipple drinkers. We show 1) that chickens have no apparent aversion to the taste of tap water, 2) that they prefer bell drinkers and troughs over nipple drinkers, 3) that the stereotyped ‘scoop’ action is seen even when birds are drinking from bowls of different heights, 4) that chickens have a strong preference for drinking from nipples that are lower rather than higher and, 5) that when offered a choice between bowls and nipples of the same height, the chickens are indifferent to the method of water presentation. We conclude that the height at which water is presented to chickens is more important to them than whether they can drink with the natural ‘scoop’ action. While this might suggest that chicken welfare could be improved by lowering the drinker lines, wet litter causes welfare issues of its own through its effect on hock burn and pododermatitis. We suggest that drinker systems should be designed so that both aspects of welfare (birds able to drink in their preferred way and clean litter) are possible. Keywords: animal welfare, broiler chickens, drinking behaviour, litter quality, nipple drinkers, preference Introduction Commercially reared broiler (meat) chickens (Gallus gallus) are frequently supplied with drinking water through lines of nipple drinkers, which the birds have to peck or press to release water (Appleby et al 1992). To avoid spillage and the consequent spoiling of the litter underneath, the nipple line is positioned above the birds’ heads and gradually raised as the birds grow so that, at all ages, they have to stretch upwards (Ross 2002; Figure 1[a]). This means that the water drips down into the birds’ throats but it also means that the action of taking in water is very different from the natural drinking behaviour of chickens (Lott et al 2001). In particular, the ‘scoop’ action, in which the bird lowers its head, takes water into its bill and then raises its head again (Dawkins & Dawkins 1973; McLelland 1979; Ross & Hurnik 1983; van der Leeuw et al 2001) is completely missing. Bell drinkers (Figure 1[b]), which are sometimes used as an alternative to nipple drinkers (Appleby et al 2004), allow birds to drink more naturally but are also much more liable to spillage which can have an impact on air and litter quality (Jones et al 2005). As wet litter is thought to be a major contributor to health problems such as pododermatitis and hockburn (Martrenchar et al 2002; Broom & Reefman 2005), nipple drinkers are much more widely used, despite evidence of lower daily water consumption from nipple drinkers than bells (May et al 1997) and of increased weight gain in birds supplied with open drinkers as opposed to nipples (Lott et al 2001). Nipple drinkers (particularly with small cups underneath each nipple to catch drips [Appleby et al 2004]) may be the most spillage-free method of providing water for chickens but it is not clear that the present design is the best way of doing so in terms of health, welfare or even production (Michel et al 1998). Chickens kept on commercial, free-range farms are also commonly provided with water through nipple drinkers inside their houses but are free to drink from puddles outside (Figure 1[c]). Puddles are likely to be contaminated with Campylobacter and other organisms that are potentially hazardous to the health of chickens and humans (Pearson et al 1993; Leclerc et al 2002; Cools et al 2003; Bull et al 2006; Kijlstra & Eijk 2006), therefore ‘persuading’ chickens not to drink from them, by providing a more attractive alter- native, could make a major contribution to bird health and human food safety in organic and free-range systems. From many points of view, therefore, it would be desirable to develop new methods of providing clean drinking water to chickens that 1) allow birds to drink adequate quantities of water, 2) are sufficiently preferred by the chickens them- selves that it discourages free-range birds from drinking from contaminated puddles and 3) do not waste water or spill it onto litter. To aid the development of such systems, Universities Federation for Animal Welfare Science in the Service of Animal Welfare