Effects of dietary zeolite and vitamin A on tibial dyschondroplasia in chickens.

Four experiments were conducted to determine the effects of dietary zeolites on tibial dyschondroplasia in chicks. All studies used a practical-type corn-soybean meal diet and male broiler chicks from 1 day to 14 or 16 days of age. Vitamin A was added to the diet in the first experiment at levels of 0 or 45,000 IU/kg in addition to full or half required levels of vitamin premix, and in the second experiment at levels of 0, 11,250, 22,500 and 45,000 IU/kg in addition to full requirement levels of vitamin premix. This was done in order to determine if vitamin levels affected expression of tibial dyschondroplasia and, if so, if this expression could be influenced by 1.0% dietary zeolite. A high level of dietary vitamin A caused a lower incidence of tibial dyschondroplasia in Experiment 1 but had no effect in Experiment 2. Zeolite at graded levels of 0, .25, .50, and 1.0% in Experiment 3 and at the 1.0% level in all other experiments consistently caused a higher bone ash and a lower incidence and number of birds exhibiting severe tibial dyschondroplasia. The addition of zeolite to the diet generally had no effect on body weight or gain:feed ratio but reduced tibial dyschondroplasia scores in two of the four experiments. In Experiment 4, the addition of dietary zeolite increased 47Ca absorption but did not influence biological half-life.