The effect of crude aflatoxin (AF) on the growth, performance, and immune response of turkeys and broilers was studied. Crude AF, produced from a natural outbreak of Aspergillus flavus on corn, was ground and mixed in rations to contain either 0, 100, 200, 400, or 800 ppb of aflatoxin B1 (AFB1). Turkeys (Experiment 1) and broilers (Experiment 2) were used in identical experimental designs. In each, 200, 14-day-old birds were divided equally by sex into five groups of 40 and were fed one of five AF diets for 35 days. In Experiment 1, crude AF greater than or equal to 400 ppb was highly toxic to turkeys. These levels produced signs and lesions of aflatoxicosis as well as a significant decrease in weight gain and feed conversion during 5 weeks. In addition, microscopic lesions, indicative of aflatoxicosis, were evident as low as 100 ppb, and significant decreases in cell-mediated immunity were noted in the 200 ppb group birds. Experiment 2 indicated that chickens were less susceptible to crude AF than turkeys. Neither morbidity nor mortality occurred in broilers. Gross lesions consistent with AF toxicity were evident in birds given 800 ppb and microscopic lesions were observed in birds given 100 ppb. Feed conversion was significantly increased in the 800 ppb broilers only. Cell-mediated immunity, measured by a delayed hypersensitive skin test, was significantly decreased in broilers receiving AF at 200 ppb or greater. Neither humoral immunity nor the development of the acquired immunity to Newcastle disease or fowl cholera vaccination were decreased in turkeys or broilers given AF.

Streptococcus agalactiae is a major bacterial pathogen that is the cause of serious economic losses in many species of freshwater, marine and estuarine fish worldwide. A highly efficacious S. agalactiae vaccine was developed using extracellular products (ECP) and formalin-killed whole cells of S. agalactiae. The vaccine efficacy following storage of S. agalactiae ECP and formalin-killed S. agalactiae cells at 4 degrees C for 1 year was determined. The stored ECP containing S. agalactiae formalin-killed cells failed to prevent morbidity and mortality among the vaccinated fish, and the relative percentage survival was 29. Serum antibody responses of the stored ECP and freshly prepared ECP against soluble whole cell extract of S. agalactiae indicated that significantly less antibody was produced in fish immunized with stored ECP and S. agalactiae cells than in those fish immunized with freshly prepared ECP and S. agalactiae cells at day 31 post-vaccination. Silver staining of sodium dodecyl sulphate-polyacrylamide gels and immunostaining of Western blots with tilapia antiserum to S. agalactiae revealed that predominant 54 and 55 kDa bands were present in the freshly prepared ECP fraction. The 55 kDa band was absent from the stored ECP and new bands below 54 kDa appeared on the Western blot. The results of this study on S. agalactiae ECP provide evidence for a correlation between protection and antibody production to ECP and for the importance of the 55 kDa ECP antigen for vaccine efficacy.

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