Submitted to: Southern Poultry Science Society Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/1/2004
Publication Date: 1/24/2005
Citation: Huff, G.R., Huff, W.E., Balog, J.M., Rath, N.C., Anthony, N.B., Nestor, K.E. 2005. Hematological changes reflect stress response differences and disease susceptibility in lines of turkeys selected for increased body weight [abstract]. Southern Poultry Science Society. Available: http://www.poultryscience.org/psa05/abstracts/psabs104.pdf. Interpretive Summary:
Technical Abstract: Three genetic lines of turkeys were compared for their hematological responses to Escherichia coli challenge following dexamethasone injection (Dex) or E. coli challenge preceeding transport stress (Stress). The turkey lines were a slow growing line selected for egg production (Egg), a fast growing line selected for increased 16 wk BW (F-line), and a commercial Hybrid line (Hyb). At 14 wks of age, the Dex group was treated with 3 injections of 2mg Dex/kg BW followed by airsac challenge with 100 cfu of E. coli. The Stress group was given the same E. coli challenge without Dex treatment, and was subjected to transport stress, which included 12 hours of holding time in a transport vehicle, eight days after the challenge. All treated birds and untreated control birds were bled at the same time, which was 1 day after transport and 9 days after challenge with E. coli. The overall average total leukocyte counts (WBC) and the percentages of eosinophils (Eos) and basophils (Baso) were the same for all 3 lines, however the percentages of heterophils (Het) and monocytes (Mono) and the heterophil/lymphocyte ratio (H/L) were lower and the percentage of lymphocytes (Lym) was higher in the Egg line as compared to the two fast-growing lines. Both DEX and Stress increased WBC, Het, and H/L and decreased Lym in all three lines, however these effects were significantly greater in both fast growing lines as compared to the Egg line and were greater in the Hyb line as compared to the F-line. Mortality was significantly higher in the Hyb line as compared to the Egg line and was intermediate in the F-line. Sixteen week BW was unaffected by either treatment in the Egg line and was decreased by both treatments in the Hyb line and by the Dex treatment in the F-line. The differences between these lines in their physiological response to stress in two stress models suggests that increasing selection for body weight of turkeys is accompanied by changes in the stress response resulting in increased susceptibility to opportunistic bacterial infection.