EFFECTS AND INTERACTIONS OF DIETARY LEVELS OF VITAMIN-A AND VITAMIN-EAND CHOLECALCIFEROL IN BROILER-CHICKENS

Four experiments were conducted to determine the effects and interacti ons of feeding different levels of vitamins A, cholecalciferol (vitami n D-3), and E on broiler chicks. In Experiment 1, chicks were fed marg inal vitamin D-3 (500 IU/kg) and increasing dietary levels of vitamin A (5,000, 10,000, 20,000, 40,000, 80,000, and 160,000 IU/kg). Bone ash was reduced by 10,000 IU/kg of vitamin A in the diet and at vitamin A levels above 20,000 IU/kg of diet body weight was reduced. In Experim ent 2, two levels of vitamin A (1,500 and 15,000 IU/kg) and six levels of vitamin E (10, 500, 1,000, 2,500, 5,000, and 10,000 IU/kg) were ad ded to the basal diet. High levels of vitamins A and E significantly ( P < 0.001) reduced bone ash. The vitamin A x E interaction was signifi cant (P less than or equal to 0.05) for rickets. In Experiment 3, the same two levels of vitamin A as Experiment 2 and six levels of vitamin D-3 (500, 1,000, 1,500, 2,000, 2,500, and 3,000 IU/kg) were added to the basal diet that contained 10,000 IU/kg of vitamin E. Body weight a nd bone ash were increased by increasing vitamin D-3 with a correspond ing reduction (P less than or equal to 0.05) In rickets. In Experiment 4, three levels of vitamin A (1,500, 15,000, and 45,000 IU/kg), three levels of vitamin D-3 (500, 1,500, and 2,500 IU/kg), and three levels of vitamin E (10, 5,000, and 10,000 IU/kg) were added to the basal di et. Significant negative responses (P less than or equal to 0.05) to i ncreasing dietary vitamin A were observed for bone ash, rickets, and p lasma and liver vitamin E. A significant (P < 0.001) increase in bone ash and plasma calcium with a corresponding reduction in rickets was o bserved by increasing vitamin D-3. Increasing dietary vitamin E advers ely affected (P less than or equal to 0.01) bone ash, plasma calcium, and plasma and liver vitamin A concentrations. These results indicate the need for making feed with the proper ratios of vitamins A, D-3, an d E.