Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 10, 2003
Publication Date: February 1, 2004
Citation: Rath, N.C., Balog, J.M., Huff, W.E., Huff, G.R. 2004. Comparative efficacy of different dithiocarbamates to induce tibial dyschondroplasia in poultry. Poultry Science. 83:266-274. Interpretive Summary: Meat-type poultry often suffer from leg problems one of which is tibial dyschondroplasia (TD) where the ends of certain leg bones remain soft and cartilaginous which cause pain, fracture, and bone infection. We wanted to find what causes this condition and the failure of the bone formation. Therefore, we developed an experimental model so that we can understand the mechanism of the disease. We fed young broiler chicks with three different chemicals for 1-7 days. Our results show that young chickens fed thiram, a common agricultural chemical, would induce severe leg problems as seen in naturally occurring disease. The artificially induced TD showed similar changes in the tissues as the naturally occurring disease. Thiram also reduced body weight and induced stress in the chickens. We suggest that this experimental model of inducing TD may be useful to determine what nutritional supplements may prevent the disease in chickens.
Technical Abstract: Tibial dyschondroplasia (TD) is a metabolic cartilage disease in poultry the natural etiology of which is not known. In the absence of biomarkers to monitor the initiation and progression of the naturally occurring disease, experimentally induced TD can provide a suitable venue to study the mechanism of its pathogenesis. Therefore, the objective of this study was to establish a streamlined experimental protocol to induce TD using dithiocarbamates and to determine a time course of its progression. Three different dithiocarbamates, dimethyldithiocarbamate (DMTC), pyrrolidine dithiocarbamate (PDTC), and tetramethylthuram thiuram disulfide (thiram), were tested with respect to their abilities to induce TD and affect different physiological parameters. Our results show that chickens fed thiram during the first 2 wk of age showed a maximum TD index. Thiram appeared to be the most potent of the three dithiocarbamates with DMTC having the least ability to induce TD, and PDTC showing an intermediate potency. A transient exposure to thiram for a day or two was sufficient to markedly increase the incidence of TD and produce a lasting damage as determined by the presence of severe lesions in a high percent of birds at 2-3 wk after the treatment. Thiram affected the chondrocyte morphology of maturing zone cartilage evident by nuclear shrinkage, and emptied chondrocyte lacunae during later times with involutions of capillary vessels. Such changes were not seen in prehypertrophic zone chondrocytes of the same growth plates. Thiram reduced the BW, increased blood heterophil to lymphocyte ratios and elevated serum corticosterone concentrations indicating physiological stress. However, there was no change in relative liver weights or blood clinical chemistry including the serum concentrations of Ca, P, and Cu in thiocarbamate fed chickens. Induction of TD in young chickens with a short feeding protocol with thiram may be useful to study the mechanisms of pathogenesis of TD and to identify micronutrients that can provide protection against this disease.