Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 3, 1998
Publication Date: N/A
Interpretive Summary: The relative ability of male and female turkeys to fight bacterial infection under stressful conditions was studied. Stress is known to decrease the ability to fight infection, and males of many different species have been shown to be more susceptible to disease than are females. At five weeks of age, turkeys were injected with a compound known to mimic the physical changes caused by stress before injecting their respiratory systems with very low levels of bacteria. The male turkeys had a much higher incidence of respiratory disease and mortality than did the females. The stress-inducing compound caused female birds to increase the number of blood cells involved in fighting infection, but there was no such increase in male birds. This study suggests that female turkeys may be more resistant to disease than male turkeys, especially under very stressful environmental conditions.
Technical Abstract: Five-week old male and female commercial turkeys were immunosuppressed with dexamethasone (DEX) and challenged by airsac inoculation with 100 CFU of Escherichia coli. Mortality and airsacculitis scores were significantly higher in challenged birds treated with DEX and in males as compared to females. Recovery of E.coli from blood and tissues was significantly higher rin challenged birds treated with DEX and marginally higher in males (P = 0.09). Body weights 2 wk post-challenge were significantly decreased by both DEX and E.coli challenge. Relative liver and heart weights were increased by both DEX and E. coli challenge, whereas bursal/spleen ratios were decreased by both treatments. Total leukocyte counts and relative heterophil counts from blood samples taken 24 h post-infection were significantly higher in DEX-treated birds and in unchallenged DEX-treated females as compared to males. DEX treatment resulted in significantly higher heterophil/lymphocyte ratios, but there was no difference between sexes. Males had significantly lower serum levels of uric acid, total protein, albumin, aspartate aminotransferase, and lactate dehydrogenase than did females. These data suggest that male turkeys may be more susceptible to colisepticemia than female turkeys, especially when under severe stress.