Dustbathing by broiler chickens: a comparison of preference for four different substrates

Abstract

Leg abnormalities leading to lameness in broiler chickens are a serious welfare problem. Previous work in our laboratory demonstrated that providing broiler chickens with the opportunity to exercise by performing more natural behaviors (such as perching, walking up and down inclines and dustbathing) can improve their ability to walk normally [J.A. Mench, J.P. Garner, C. Falcone, Behavioral activity and its effects on leg problems in broiler chickens, in: H. Oester, C. Wyss (Eds.), Proceedings of the Sixth European Symposium on Poultry Welfare, World’s Poultry Science Association, Zollikofen, Switzerland, 2001, pp. 152–156]. With the long-term goal of stimulating dustbathing to improve leg condition, the aim of this study was to determine the dustbathing substrate preferred by broiler chickens. We conducted a dustbathing choice test experiment using four different bedding types (pine wood shavings, rice hulls, construction grade sand, and a recycled paper animal bedding product). Four different broiler chickens were tested each week for 6 weeks starting when the chicks were 1 week old. They were selected from two groups of broiler chickens housed in large home pens bedded with wood shavings. Selected birds were tested in smaller pens where they were deprived of all loose bedding material except during testing, which was carried out for 1 h each day for three consecutive days per week. During an observation, each corner of the test pen was filled with a different bedding type, and the behavior of the focal chick recorded. Vertical wing shakes (VWS) were used as the primary measure of dustbathing activity. Broilers performed significantly more VWS per hour in sand ( F 3,36=13.52, P<0.0005) and spent a greater proportion of their total time in sand ( F 5,60=5.15, P=0.001) than in the rice hulls, paper, or wood shavings. They also visited the sand significantly more often than the paper or the wood shavings ( F 5,60=96.47, P<0.0005). There were no dustbaths in the rice hulls. The latency to enter sand was significantly shorter than the latency to enter any of the other three substrates ( F 3,15=5.24, P=0.0113). Ground pecking generally precedes a dustbathing bout, and the rate of pecking and the proportion of the total time budget spent pecking were also highest for sand ( F 3,51=24.49, P<0.0001 and F 3,51=15.28, P<0.0001, respectively). The preference for sand was apparent in the first week, and was stable with age. The results of this study suggest that sand is attractive to broiler chickens and is a potent stimulus for dustbathing. Further work is needed to determine if stimulating broiler chickens to dustbathe by providing sand can improve their leg condition, and thus their welfare.