Search

Turkey, broiler breeder, and layer cases submitted for necropsy in 1986 to the University of Georgia were categorized by diagnosis, grouped by clinical features, season, age, and presenting history, and evaluated for statistically significant patterns. The most commonly diagnosed diseases were: fowl cholera in turkeys, 64 cases (34.4% of cases; 26.2% of diagnoses); staphylococcal arthritis/synovitis (SA/S) in broiler breeders, 35 cases (20.7%; 17.7%); and osteomalacia in layers, 17 cases (21.0%; 15.6%). In turkeys, fowl cholera, colibacillosis, and aspergillosis were significantly more common in the fourth, second, and third quarters of the year, respectively; enteritis and viral enteritis were more common in early grow-out, and osteomyelitis, SA/S, and synovitis were greatest in late grow-out. Overall, musculoskeletal problems in turkeys were more common in the third quarter and were less common in the first and fourth quarters. Erysipelas occurred most frequently in turkeys 50 to 112 days of age. In both broiler breeders and layers, SA/S was more common in the second quarter, and a history of musculoskeletal problems was less common in both post-peak-production broiler breeders and layers. Fowl pox was more common in the fourth quarter and in late-production broiler breeders. In layers, osteomalacia and Marek's disease were more common in the first and fourth quarters, respectively.

Turkeys developed a high level of protective immunity and serum anti-Pasteurella multocida antibody when vaccinated with the Clemson University (CU) strain of P. multocida via the following routes: wing-web puncture with the recommended dosage or 1:10 dilution of this dosage, subcutaneous, crop injection, cloacal perfusion of the bursa of Fabricius, and intratracheal. The development of immunity after vaccination via the wing-web puncture and subcutaneous routes was dose-dependent: the lower dosages induced less serum antibody and protective immunity. Immunity was greatest 3 weeks after vaccination via wing-web puncture, although immunity was evident as early as 4 days after vaccination. A high level of antibody and protective immunity with no adverse reactions was induced by vaccinating twice, either by the drinking water followed by a similar dosage parenterally or by a parenteral route followed by the drinking water; these regimens were similar to one vaccination in the drinking water. Vaccination via wing-web puncture and possibly subcutaneous injection and bursal perfusion could be used for flocks with a history of a high mortality after vaccination with the CU vaccine in the drinking water and suspected of being immunosuppressed.

Unvaccinated laying breeder hens and semen-producing toms were susceptible to the CU strain of Pasteurella multocida and highly susceptible to a virulent strain of P. multocida. Laying breeders vaccinated with CU strain when environmental temperatures were low ceased egg production during the first week after vaccination and had 29% mortality, whereas those vaccinated when temperatures were moderate had only a 25% decrease in egg production and 17% mortality. Comparable nonlaying breeders vaccinated during moderate temperatures did not die. Although few semen-producing toms died postvaccination and the quantity and quality of semen was not affected, 21.7% developed torticollis. Laying breeders were protected against CU vaccine and challenge with virulent P. multocida if vaccinated every 4 weeks beginning when 7 weeks old. Potential breeders vaccinated before laying with combinations of 3 vaccinations via drinking water, wing-web puncture, or inoculation into the air spaces of the head through the auditory tube were protected against challenge after the onset of laying. However, vaccination via wing-web puncture at 25 weeks of age resulted in abscesses that failed to resolve. The combination of vaccinations most effective in protecting laying breeders was vaccination in the drinking water at 7 and 11 weeks and inoculation into the air spaces of the head at 15 weeks.

Turkeys surgically bursectomized, irradiated, and/or injected with cyclophosphamide at 1 day were vaccinated with the live Clemson University (CU) strain of Pasteurella multocida. Bursectomized turkeys vaccinated via drinking water or wing-web puncture at 7 weeks and challenged at 11 weeks had a significantly (P less than 0.05) lower survival rate after challenge than unbursectomized controls. Bursectomized and unbursectomized turkeys vaccinated via drinking water at 7 weeks, revaccinated via the auditory tube at 11 weeks, and challenged at 15 weeks had similar survival rates. The vaccinated bursectomized turkeys had significantly (P less than 0.05) lower levels of serum anti-P. multocida antibody than vaccinated unbursectomized controls. Radiation had no immunosuppressive effect. The immunosuppressive effect of cyclophosphamide was dosage-dependent. Bursectomy and injection of cyclophosphamide in the same turkey were complementary. It was concluded that in young turkeys, the development of immunity to the avirulent CU vaccine is highly dependent upon the bursa of Fabricius, but that as they grow older the bursa is of less importance, particularly if they were vaccinated via a parenteral route, such as in the air spaces of the head.

Nine isolates of Pasteurella multocida serotype 3,4 were isolated from turkeys that had been vaccinated against fowl cholera but that subsequently experienced outbreaks of fowl cholera. These isolates were compared with the CU vaccine strain. Characteristics examined were antimicrobial susceptibility profiles; carbohydrate fermentation; production of bacteriocin, siderophore, and hemolysin; resistance to serum complement; membrane proteins; enzyme activities; presence of plasmids; transferability of R-plasmids; and pathogenicity. Differences were observed between the CU strain and virulent isolates of P. multocida serotype 3,4 for resistance to serum complement, presence of plasmids, hemolysis, membrane proteins, and pathogenicity. Other parameters compared did not differ significantly between the two groups. The presence of plasmids and resistance to the lytic action of complement of the isolates of P. multocida serotype 3,4 correlated with the mortality rates caused by these bacteria.

Disease prevalence in turkeys was estimated by totaling the flock size of necropsy cases submitted to the University of Georgia in 1986 for each disease reported and comparing it with the population at risk. Fowl cholera was the most prevalent disease in both commercial tom flocks (18.0%) and breeder hen flocks (14.7%). Prevalence of colibacillosis was 15.9% in commercial tom flocks, and prevalence of aspergillosis was 8.5% in commercial tom and 4.9% in breeder hen flocks.