Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/19/2005
Publication Date: 2/1/2006
Citation: Huff, G.R., Huff, W.E., Rath, N.C., Balog, J., Anthony, N.B., Nestor, K. 2006. Stress induced colibacillosis and turkey osteomyelitis complex in turkeys selected for increased body weight. Poultry Science. 85:266-272. Interpretive Summary: Three genetic lines of turkeys were compared for their responses to bacterial challenge in two stress models, Dexamethasone (DEX) 1.Bacterial injection following treatment with a compound that mimics stress or 2. Bacterial injection 8 days before being transported in a truck for 12 hours. The turkey lines were a slow growing line selected for increased egg production (Egg line), a fast growing line selected for increased body weight (F line), and a fast growing commercial line (Comm line). At 2 weeks post challenge, all birds were sexed, scored for signs of disease and bacteria were isolated from knee tissues. Mortality was unaffected by sex, and was increased by treatment with the DEX compound. Both treatments increased respiratory disease. A condition called turkey osteomyelitis complex (TOC), which includes bone infections and arthritis, was increased by the compound only. There was no TOC in Egg line birds while male birds of both the F line and the Comm line had increased TOC. Males had twice as much TOC as females. Bacteria were isolated from more knee cultures of both fast-growing lines as compared to the Egg line. Isolation was increased by the DEX compound and was higher in male birds. The differences between these lines in their disease resistance in two stress models suggests that increasing selection for body weight of turkeys changes the response to stress that causes an increase in bacterial disease.
Technical Abstract: Two stress models were used to induce colibacillosis and turkey osteomyelitis complex (TOC): Escherichia coli challenge following dexamethasone injection (DEX) and E. coli challenge preceding transport stress (TRANSPORT). A total of 160 birds from 3 lines of turkeys: a slow growing line selected for egg production (Egg line), a line selected for 16 wk BW (F line), and a commercial line (COMM), were studied in a 3 X 3 X 2 (Line X Treatment X Sex) factorial design. At 14 wks, the DEX group was treated with 3 injections of 2mg Dex/kg BW followed by airsac challenge with 100 cfu of E. coli. The TRANSPORT group was given 5000 cfu of the same E. coli, and 8 d later was transported for 3 h and held an additional 9 h in the transport vehicle. Controls of each line were neither stressed nor challenged with E. coli. Birds were necropsied 2 wk post challenge. All birds were sexed, scored for airsacculitis (AS) and TOC, and knee synovia was cultured for E. coli. Mortality was unaffected by Sex, was increased by the DEX treatment and was higher in DEX-treated male COMM line birds and Dex-treated female F-line birds as compared to their respective non-challenged controls. Both treatments increased AS scores and scores of DEX treated male COMM line birds and female F-line birds were also higher as compared to their respective controls. Male COMM birds under TRANSPORT had higher AS scores as compared to non-challenged males and challenged females. TOC incidence was increased by DEX only. There was no TOC in Egg line birds while TOC incidence approached significance in both COMM and F lines as compared to the Egg line (P = 0.06). Males had twice as much TOC as females and this approached significance in the F line (P = 0.06. DEX-treated male birds of both the F line and COMM line had a higher incidence of TOC compared to non-challenged controls. E. coli was isolated from more knee cultures of both large lines as compared to the Egg line. Isolation was increased by DEX and was higher in male COMM line birds and both male and female F-line birds relative to their controls. The difference in disease resistance between these lines suggests that selection for fast growth of turkeys may affect the stress response, resulting in increased chronic bacterial disease.