Use of vitamin D to reduce lameness in broilers reared in harsh environments

Abstract

In tropical poultry-producing countries, poultry houses usually have little environmental control. This study investigated the effect of dietary vitamin D on the incidence of leg abnormalities of a fast-growing broiler strain reared under harsh conditions. In this study, 300 one-day-old male broilers were distributed in two treatments with three replicates of 50 birds each. One group was fed a placebo and the other group was fed 25-hydroxycholecalciferol (25-OH-D3) in a soluble form. The environmental variables were weekly recorded during until birds were 49 days old. Birds were weekly gait scored, and their walking speed and vertical force while walking were assessed. Post-mortem examination was performed and skeletal lesions were assessed. Control birds presented more leg problems than those that ingested 25-OH-D3. These results suggest that dietary vitamin D is effective in decreasing the severity of lameness by reducing tibial dyschondroplasia and other leg abnormalities. INTRODUCTIONIt has been reported that the low locomotor activity of broilers coupled to their high initial growth rate of broilers results in leg problems and gait abnormalities. Long times spent sitting on wet litter may cause breast and leg skin lesions, which may contribute for the deterioration of the flock well-being (McGeown et al., 1999;Vestergaard & Sanotra, 1999;Weeks et al., 2000;Bokkers & Koene, 2004;Bessei, 2006). A causal interrelationship between the rapid growth broiler strains, low locomotor activity and leg problems has been discussed in current literature (Julian, 1998;Vestergaard & Sanotra, 1999;Kestin et al., 2001;Sanotra et al., 2001;Bokkers & Koene, 2003). However, the influence of environmental and management-related factors, such as heat stress, light intensity, age, stocking density and diet on the incidence of leg abnormalities in broiler flocks has also been reported (Edwards Jr., 2000;Edwards Jr., 2003;Dawkins et al., 2004;Bessei, 2006).The most common skeletal problems that cause leg weakness in broilers are tibial dyschondroplasia, chronic painful lameness, chondrodystrophy or angular bone deformities, valgus-varus deformities, spondylolisthesis, rickets, femoral head necrosis, curled toes, and ruptured gastrocnemius tendon (Angel, 2007). Lameness in broilers with poor gait scores significantly improved after treatment with analgesic and anti-inflammatory drugs, which has led to the assumption that the leg problems in broilers are painful (McGeown et al., 1999;Danbury et al., 2000;Weary et al., 2006;Nääs et al., 2009). Several attempts have been made to determine the broilers' locomotor deficiencies (Dawkins et al., 2004) and to increase the walking ability of the birds (Corr et al., 2007).Among the studies to reduce lameness in broilers, some are related to the use of feed additives (Rath et al., 1998)

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