Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2002
Publication Date: N/A
Interpretive Summary: Vitamin D supplemented in drinking water was previously shown to decrease disease in stressed turkeys infected with bacteria. This study attempted to increase the level of disease protection by feeding turkeys diets supplemented with more chemically active metabolites of vitamin D. At 5 weeks of age half of the turkeys were treated with a compound that mimics the effects of stress in the body. Half of the treated and half of the untreated birds were given a respiratory challenge with bacteria. At 9 weeks and at 12 weeks of age survivors were again treated with the compound. While vitamin D had previously prevented disease after the second treatment with the compound, supplementation with the more active vitamin D metabolites tended to increase mortality and respiratory disease and decrease body weights of the birds challenged with the compound and bacteria. The number of birds with TOC lesions was, however, decreased by supplementation with the active vitamin D metabolites after the second treatment. There were never any negative effects of supplementation of diets with the vitamin D metabolites on the birds which were not treated with the compound or challenged with bacteria. Supplemented birds had increased bone strength. It was concluded that supplementation with the more active vitamin D compounds caused a shift in the immune response of the birds, which together with similar immune changes caused by both treatment with the stress-mimicking compound and the bacterial challenge, caused an increase in the level of disease.
Technical Abstract: The objective of this study was to determine the effects of supplementation of turkey diets with either 10ug of 1,25 dihydroxyvitamin D3 (1,25D) /kg feed or 99ug of 25-hydroxyvitamin D3 (25-D)/kg feed on disease resistance in a dexamethasone (DEX) - Escherichia coli model of turkey osteomyelitis complex (TOC). Birds were fed the supplemented diets continuously and ad libitum. At 5 wks of age half of the birds were treated with DEX and half of both the the DEX-treated and the untreated birds were challenged with E.coli. At 9 and 12 wks all of the DEX or E.coli treated birds were given another DEX treatment. After the first DEX treatment, mortality was increased in the 25D supplemented birds which were given both the DEX treatment and the E.coli challenge. After the DEX treatment, the main effect mean BW was significantly lower in birds given 1,25D as compared to both controls and 25D supplemented birds. Mortality was higher in 1,25D supplemented birds which were challenged with E.coli at 5 wks and treated with DEX at 9 wks, as compared to 25D supplemented birds. The 1,25D treated birds which were treated with DEX at both 5 wk and 9 wk and challenged with E.coli at 5 wks had higher mortality and airsacculitis scores as compared to both controls and 25D birds. The main effect mean mortality was significantly higher in birds given 1,25D as compared to controls and 25D birds. The percentage of birds with TOC lesions was decreased from 27% to 0 by both 25D and 1,25D in the groups given 2 DEX treatments and E. coli challenge. After the 3rd DEX treatment, BW of 1,25D suppplemented birds was decreased and mortality and airsacculitis scores were increased. Bone strength was generally increased by supplementation with both metabolites, however 1,25 supplementation had a greater effect.