Experimental infections enabled to study susceptibility to M. avium and disease pathogenesis in the turkey and guinea fowl. After intramuscular implantation of M. avium suspension macroscopic tuberculous lesions were observed at the spot of puncture in turkeys in 35 days, and miliary tuberculosis of liver and spleen in 55 days. Cultivation demonstrated mycobacteria in various organs and tissues since day 12 after infection. The guinea fowl showed macroscopic lesions at the spot of puncture in 28 days, and miliary tuberculosis of liver and spleen in 42 days. Cultivation of most tissues gave positive results since day 14 with prevailing massive growth of mycobacteria. After infection with feed contaminated with the liver of the tuberculous fowl isolated tuberculous lesions in liver, spleen and lungs were observed in the turkey in 133 days, and in the intestine in 163 days. Cultivation was successful enough to demonstrate sporadic mycobacteria in spleen and lungs in 106 days. The guinea fowl showed isolated tuberculous lesions in liver, spleen and intestines in 160 days. Cultivation after 160 days also gave positive results, particularly the presence of mycobacteria in liver, spleen and lungs was proved to be massive. After contacts with the tuberculous fowl, the turkeys showed isolated tuberculous lesions in the liver, spleen and lungs since day 218. Cultivation gave positive results since day 218. Isolated tuberculous lesions in liver were observed in the guinea fowl in 180 days, as well as in spleen, lungs and intestines in 270 days. Cultivation demonstrated smaller numbers of mycobacteria in the infected tissues.(ABSTRACT TRUNCATED AT 250 WORDS)