Effects of high intensity step-up and low intensity step-down lighting programs on the incidence of leg abnormalities...

Two trials were conducted to determine if a high intensity (20 lx) step-up lighting program would decrease the incidence of leg abnormalities in turkeys. The step-up lighting regimen was compared to a low intensity (2.5 lx) step-down lighting program. Toms were used in Trial 1 and both sexes were employed in Trial 2. Body weight, feed/gain ratio, and mortality of toms of Trial 1 did not differ significantly between lighting regimens. The incidence of leg deformities and the length of the tarsometatarsal bone were significantly decreased, whereas plasma androgen and testes weights were increased for toms of Trial 1 in the high intensity step-up lighting. The same trends were apparent for toms of Trial 2 with the exceptions that feed/gain ratios were adversely affected and testes weights were significantly lower for toms of the high intensity step-up lighting program. The performance of hens in the high intensity step-up lighting program of Trial 2 was affected adversely; however, incidence of leg abnormalities and length and width of the tarsometatarsus responded in the same manner as with toms. The results of this study indicate that a high intensity step-up lighting program can significantly reduce leg weakness problems in turkeys. Possible explanations for light stimulation reducing the incidence of leg abnormalities are through increased exercise and shortening of long bones.