Tibial dyschondroplasia in broilers: comparison to dietary additives and strains

The effects of broiler strain and various additives to practical corn-soy diets on the incidence of tibial dyschondroplasia (TD) were studied using broiler chicks maintained in battery brooders. At the termination of each experiment, birds were killed and examined for TD by cutting longitudinally along the tibia. No significant difference in the incidence of TD was found among the nine broiler strains compared. While the incidence of twisted legs was higher than TD among the nine strains there was no apparent correlation between the two leg disorders. Studies conducted using the following additives did not significantly increase the incidence of TD in broilers when compared to controls: monensin, sodium chloride, copper sulfate, magnesium sulfate, potassium sulfate, roxarsone, gentian violet, erythromycin, vitamin K, or vitamin D3. However, dietary ammonium chloride (1.5 or 30%) did increase the incidence of TD, whereas adding various fermentation products at levels of 10 and 20% either in the absence or presence of ammonium chloride failed to reduce the incidence of the disease. The incidences of TD among broiler chicks fed high dietary fluoride were nonsignificant; no evidence of the disease was found in Leghorn chicks fed the same diets. Chicks maintained in battery brooders in these studies, generally had a lower incidence of TD than that reported for commercial flocks in the field. Furthermore, manipulation of feed additives or ingredients in practical rations for broiler chickens did not increase the incidence of the disease.