The future of veterinary medicine in poultry production.

The poultry industry is a highly complex food-animal production system. Its success is dependent upon sophisticated techniques and systems to ensure disease prevention and product quality. Poultry veterinarians play a key role in the overall business and are typically the only individuals within poultry companies who are involved in the entire production process, including production management, health management, product quality, nutrition, and economics. Preparing veterinarians to work effectively in the poultry industry can no longer be accomplished within the DVM instructional program. Post-DVM training programs specializing in poultry medicine are now producing the veterinarians entering the North American poultry industry. Regionalization of training in poultry medicine has already taken place. These training programs are very important to food animal production in North America; in the future, they must be nurtured and supported in order to remain able to supply the veterinary workforce for our dynamic poultry industry.

Comparative efficacy of enrofloxacin, oxytetracycline, and sulfadimethoxine for the control of morbidity and mortality caused by Escherichia coli in broiler chickens.

The purpose of the present study was to compare the ability of enrofloxacin, oxytetracycline, and sulfadimethoxine to reduce morbidity and mortality caused by Escherichia coli (colibacillosis) in broiler chickens. The chickens were raised in 80 pens (20 birds per pen) with 20 pens representing each treatment group under simulated commercial conditions that produced a colibacillosis challenge scenario. Each group of 20 randomized pens (replicates) was given one of four water treatments. Chickens that received enrofloxacin had significantly less mortality (P < 0.01), lower average gross pathology (colibacillosis) scores (P < 0.01), and better feed-conversion ratios (P < 0.05) than did chickens that received either oxytetracycline or no medication. Chickens that received enrofloxacin had significantly less mortality and lower pathology scores than those that received sulfadimethoxine and numerically lower feed conversion than the sulfadimethoxine group. Results from the present study show that enrofloxacin is superior to oxytetracycline and sulfadimethoxine for the control of morbidity and mortality caused by E. coli in broiler chickens. Our findings will help veterinarians choose and prescribe the most efficacious antimicrobial when treating colibacillosis.

Mild infectious laryngotracheitis in broilers in the southeast.

During 2001, a mild infectious laryngotracheitis virus (ILTV) infection occurred in broiler flocks in the southeastern United States. Clinical signs included mild tracheitis, swollen sinuses, and conjunctivitis, with no increased mortality and minimal serologic response. Infrequent intranuclear inclusion bodies with or without syncytial cell formation were observed in eyelid, trachea, and larynx and in the chorioallantoic membrane of infected embryos. Immunohistochemistry and a nested infectious laryngotracheitis polymerase chain reaction (ILT PCR) were utilized to confirm the presence of ILTV nucleic acid in fixed tissues. In addition, 2-wk-old specific-pathogen-free (SPF) birds inoculated with field material exhibited the mild signs observed in broilers in the field. Tracheal swabs and tissues taken from these SPF birds were also positive by nested ILT PCR. Restriction fragment length polymorphism analysis of ILT PCR products indicated that ILT virus associated with mild respiratory disease in the southeast is related to the chicken embryo origin vaccine type strains.

Evaluation of the effect of heating an oil-emulsion Pasteurella multocida bacterin on tissue reaction and immunity.

Killed vaccines in oil emulsions are critical components of breeder and layer vaccination programs. Current vaccination sites are limited, and each has inherent problems. Oil emulsion vaccines are associated with increased condemnations of spent fowl when vaccines are injected intramuscularly into the breast. In an attempt to reduce tissue reaction when injected into the breast muscle, a commercially available Pasteurella multocida bacterin was heated to 41 C (100 F) for 5 hr prior to administration. A second treatment group was injected with the same bacterin at room temperature, 25 C. The vaccine was injected into the breast muscle at 10 and 18 wk of age into white Leghorn hens. Seroconversion was evaluated using P. multocida enzyme-linked immunosorbent assay (ELISA) at 10, 18, and 24 wk. Treatment and control groups were euthanized and lesions scored at 24 wk of age. One replicate was challenged with type 1 P. multocida at 24 wk of age. Lesion scores for the heated vaccine group were significantly lower than the room temperature vaccine. ELISA titers were not significantly different at 24 wk between the two treatment group; however, a significant rise in antibody titer was observed at 18 wk in the group that was injected with the heated vaccine. Survivability to challenge was improved in birds injected with the heated vaccine. Results suggest that heating of a P. multocida bacterin reduces local tissue reaction without having a deleterious effect on immunity as measured by ELISA and challenge.

Cellulitis in Japanese quail (Coturnix coturnix japonica).

A case of cellulitis was observed in Japanese quail (Coturnix coturnix japonica) reared for commercial meat production. This condition in Japanese quail has not been reported in the literature. This incident was the first, and to date only, occurrence of cellulitis in this processing plant. The cellulitis lesions were localized to the subcutis overlying the breast and inner thigh. Carcasses of processed birds and live birds from the affected farm were presented to the Poultry Diagnostic and Research Center, University of Georgia. Escherichia coli was cultured from the lesion. The affected live birds displayed lameness and had osteomyelitis. Pasteurella multocida serotype 3,4 was cultured from the liver and bone marrow of affected birds. Approximately 4.61% of the processed carcasses from the flock were condemned because of cellulitis. This represented a 10fold increase from the typical condemnation rate. Further investigation revealed birds were placed in higher than normal density; therefore, we theorize that the concurrent pasteurellosis and increased placement density resulted in the cellulitis condition.