The relationship between trough height, feather cover and behaviour of laying hens in modified cages

Abstract

The feather condition and behaviour of laying hens in modified cages with elevated (28 cm above floor) and conventional (6 cm above floor) height feed troughs was measured at 32–34 and 56–59 weeks of age. Feather cover was generally better at the younger age than the older, and in cages with the elevated trough as opposed to the conventional height trough. The differences in feather condition could not be attributed to different feeding patterns from the two troughs as neither feeding duration nor the number of bouts varied significantly between treatments. Increased feather damage was noted in cages with conventional height troughs compared with cages with elevated troughs and was likely to be due to hens stepping on each other's backs more in the former (medians 2.28 and 0.78 steps/bird/h, respectively, P<0.001). The elevated trough discouraged hens from stepping from the perch onto the backs of hens feeding and from dustbathing beside the food trough, both of which are likely to account for the better back feather condition as compared with conventional trough height cages. Feather pecking was similar between treatments at the younger age and the elevated trough treatment at the older age, but was considerably higher in cages with conventional height troughs at the older age. It is suggested that feathers damaged by cage-mates stepping on the back of hens promotes feather pecking in cages with conventional height troughs. A positive feedback loop of feather pecking triggered by the rate of feather deterioration is proposed to account for the poorer feather condition for all body parts for hens in cages with conventional as compared to elevated height troughs. It is concluded that an elevated trough enhances welfare of laying hens in modified cages by discouraging activities that cause feather damage.