Data from an experiment in China indicate that increasing supplemental vitamin D3 has favourable effects on walking ability and welfare status of broilers kept at high stocking density; there was no effect on their performance.

Z.W. Sun from the China Agricultural University in Beijing and co-authors there and at New Hope Liuhe Co. Ltd. and Shandong Agricultural University explain in the current issue of Poultry Science that they conducted a study to evaluate the effects of varying dietary vitamin D3 and stocking density on growing performance, carcass characteristics, bone biomechanical properties and welfare responses in Ross 308 broilers.

Experimental diets, containing one, 10 or 20 times the NRC recommended level of vitamin D3 (200IU per kg), were formulated with low-, medium- or high-vitamin D3 levels for three growing phases. Two stocking densities were 10 and 16 birds per square metre. Day-old hatchlings (1,872 males) were randomly assigned to six pens in each treatment.

Results showed that high stocking density decreased feed intake, bodyweight gain (P<0.01), breast muscle yield (P=0.010) and tibial development (P<0.01). However, high stocking density increased feed conversion ratio (P<0.001) and the scores of gait, footpad and hock burn, and abdominal plumage damage (P<0.01), particularly toward the age when birds attained their market size.

Increasing dietary vitamin D3 improved the birds’ walking ability and tibial quality (P<0.05) and reduced the development of footpad or hock dermatitis and abdominal plumage damage (P<0.01), some aspects of which were age-dependent and appeared to vary with stocking density.

Reference

Sun Z.W., L. Yan, Y.Y. G, J.P. Zhao,, H. Lin and Y.M. Guo. 2013. Increasing dietary vitamin D3 improves the walking ability and welfare status of broiler chickens reared at high stocking densities. Poult. Sci. 92(12):3071-3079. doi: 10.3382/ps.2013-03278