title: The influence of vitamin A on the utilization and amelioration of toxicity of cholecalciferol, 25-hydroxycholecalciferol, and 1,25 dihydroxycholecalciferol in young broiler chickens.
abstract: Three experiments were conducted to determine the influence of vitamin A on the utilization and amelioration of toxicity of cholecalciferol (vitamin D3), 25-hydroxycholecalciferol [25-(OH)D3], and 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] in young broiler chicks. Two levels of vitamin A (1,500 and 45,000 IU/kg or 450 and 13,500 microg) were fed in all experiments. In Experiment 1, chicks were fed six levels of vitamin D3 (0, 5, 10, 20, 40, and 80 microg/kg). High dietary vitamin A decreased bone ash (P < 0.001), and increased the incidence of rickets (P < or = 0.02). Linear and quadratic responses to vitamin D3 levels were significant (P < 0.01) for body weight, bone ash, incidence and severity of rickets, and plasma calcium. In Experiment 2, six levels of 25-(OH)D3 (0, 5, 10, 20, 40, and 80 microg/kg) were added to the basal diet. Adding 25-(OH)D3 increased (P < 0.001) body weight, bone ash, and plasma calcium, and decreased rickets and plasma vitamin A. Adding 25-(OH)D3 overcame the reduction in bone ash produced by high dietary vitamin A showing a significant (P < 0.02) interaction. In Experiment 3, six levels of 1,25-(OH)2D3 (0, 2, 4, 8, 16, and 32 microg/kg) were added to the basal diet. High dietary vitamin A increased (P < 0.01) the incidence and severity of rickets. Adding 1,25-(OH)2D3 increased (P < 0.01) body weight, bone ash, plasma calcium, and reduced rickets and plasma and liver vitamin A. Adding 1,25-(OH)2D3 overcame the reduction in bone ash, and the increase in rickets produced by high vitamin A was significant (P < or = 0.05). These results indicate that high dietary vitamin A (45,000 IU/kg) interferes with the utilization of vitamin D3, 25-(OH)D3 and 1,25-(OH)2D3, increasing the requirement for each of them. Moreover, 45,000 IU/kg of dietary vitamin A ameliorated the potential toxic effects of feeding high levels of vitamin D3, 25-(OH)D3 and 1,25-(OH)2D3 to young broiler chickens. Further work is necessary to find the minimum levels of these vitamins needed to cause these effects.
authors.affiliation: Department of Poultry Science, University of Georgia, Athens 30602-2772, USA.
authors.forename: A
authors.initials: A
authors.lastname: Aburto
authors.forename: H M
authors.initials: HM
authors.lastname: Edwards
authors.forename: W M
authors.initials: WM
authors.lastname: Britton
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D002112:Calcifediol / Q000378:metabolism / Q000633:toxicity*; D002117:Calcitriol / Q000378:metabolism / Q000633:toxicity*; D002645:Chickens / Q000502:physiology*; D002762:Cholecalciferol / Q000378:metabolism / Q000633:toxicity*; D015331:Cohort Studies; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D015994:Incidence; D008297:Male; D011201:Poultry Diseases / Q000178:diet therapy / Q000453:epidemiology; D012279:Rickets / Q000178:diet therapy / Q000453:epidemiology / Q000662:veterinary; D014801:Vitamin A / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D014801:Vitamin A; D002762:Cholecalciferol; D002117:Calcitriol; D002112:Calcifediol