Submitted to: American Society for Bone and Mineral Research
Publication Type: Abstract only
Publication Acceptance Date: 9/23/2005
Publication Date: 9/23/2005
Citation: Rath, N.C., Huff, W.E., Huff, G.R., Horst, R.L. 2005. Evaluation of the efficacy of vitamin D3 and its metabolites to prevent thiram-induced growth plate dysplasia in chickens [abstract]. American Society for Bone and Mineral Research. Available: http://www.asbmr.org/meeting/abstracts.cfm. Interpretive Summary:
Technical Abstract: Tibial dyschondroplasia (TD) is a metabolic disorder in rapidly growing broiler chickens and turkeys that is characterized by the failure of growth plate cartilage to be replaced by bone. Although the natural etiology of the disease is not understood, it has been suggested that diets supplemented with certain vitamin D metabolities could ameliorate TD in birds that were induced TD feeding Ca: P imbalanced diets. We have currently developed an experimental model of TD using tetramethyl thiuram disulfide (thiram), a dithiocarbamate pesticide, which when included in the diet at a concentration of 100 ppm between 1-3 week of age induces TD in more than 90% of chickens. Using this model the objective of our study was to evaluate the ability of vitamin D3 or its selective metabolites to prevent TD in chickens. Groups of broiler chickens were fed control or diets supplemented with vitamin D3 or its different metabolites over and above the content of vitamin D3 in the control diet. The study consisted of birds that were fed ad libitum (a) control non supplemented feed, (b) vitamin D3, 4,000 IU cholecalciferol/kg, (c) HYD**TM, a 25 (OH)2 D3, 63 ug/kg, (d) low dose 1,25 (OH)2 D3: 1 ug/kg, and, (e) high dose 1,25 (OH)2 D3: 5 ug/kg, starting from day of hatch. On day 7 feed was withdrawn for a period of 12 h after which each group was divided into two sub groups of 25 birds each. One received its assigned diet whicle the other received the same diet containing 100 ppm thiram for a period of 48 h. At the end of experimental thiram feeding, all birds in each group received their assigned diets until the day of necropsy on day 15. The birds were weighed, bled prior to necropsy and the tibial growth plates were evaluated for TD index (incidence times severity score) (scores: 0 = normal, 1 = growth plate width increased more than 2 times, and 2 = growth plate size increased more than 3 times). Some growth plates were processed for histological evaluations. In all birds that received thiram treatment, regardless of vitamin D treatment, the body weight was significantly reduced (p </= 0.005) and the TD index remained high (>/= 1.7) as compared to </= 0.2 in birds that did not receive thiram. Thiram caused chondrocyte apoptosis and blood capillary atrophy in the hypertrophic zone. It is concluded that extra supplementation of vitamin D or its metabolites do not protect birds against thiram-induced TD.