[The spread of enzootic bovine leukemia via the seminal fluid in certain breeds of bulls]. / Razprostranenie na enzootichnata levkoza po govedata sus semennata technost ot niakoi porodi bitsi.

Studied was the occurrence of enzootic bovine leukosis as dependent on the use of semen of leukosis-affected bulls for the artificial insemination of cows and heifers and their offsprings in the F1 generation on 16 farms. Semen was used of a total of 30 bulls of the Holstein-Friesian, American Brown, and European Black-and-white breeds. The agar gel immuno-diffusion test was employed to establish antibodies to the bovine leukosis virus in the sera of the bulls. On 9 farms with 2,997 cows and heifers that were negative for leukosis antibodies a total of 800 female calves (F1) were born. Serologic investigations of both dams and calves, aged 2 to 5 years revealed no leukosis antibodies. On other 7 farms with 1,717 cows and heifers, among which sporadic carriers of BLV-antibodies were discovered, 713 female offsprings (F1) were born. Seventeen (2.38 per cent) out of these responded positively for BLV antibodies. Twenty-two (3.0 percent) of the dams following calving also showed a positive reaction. Over the 1981-1985 period a total of 1,593 female calves were born as the offsprings of 4,714 cattle on all 16 farms. The percent of the positively responding to leukosis was 1.06, resp., 1.38. These results were considered indicative in ruling out the transmission of enzootic bovine leukosis with semen in the artificial insemination of cows and their F1 offsprings.

[Comparative studies of the properties of Br. ovis strains 03, 303 and 100671 to those of local strains for the production of antigen]. / Sravnitelni prouchvaniia na kachestvata na shtamove Br. ovis 03, 303 i 100671 s mestni shtamove za poluchavane na antigen.

Colorimetric analysis, biochemical methods, and the complement-fixation test were employed to study 3 Australian and 5 Bulgarian strains of Brucella ovis. Determined were some biochemical manifestations, the adaptation capacity with regard to aerobic conditions of cultivation without serum, the amount of polysaccharides contained in the strains, and the properties of the antigens obtained as checked via CFT. Milanov's method was employed for antigen production. Three of the Bulgarian strains showed definite advantages in the commercial production of antigens for the serologic diagnosis of the Brucella ovis infection in sheep.

[Atypical course of cholera in poultry]. / Prouchvane na atipichno protichashta kholera po ptitsite.

Atypically developing chicken septicemia was studied at 3 farms in Bulgaria. In one of the observed centers of chicken septicemia infection no pathologic anatomical changes were evident while in the other two centers of infection serofibrinose and serofibrinose vitelline peritonitis, as well as pleurisy were present. In the bacteriological investigation carried out on 2969 samples 233 strains of chicken septicemia were isolated. Identification of 84 of them by the aid of the specific bacteriophage P. multocida 115 and of sugar and alcohol fermantation revealed that they can be classified as P. multocida. They are lyzated by a phage but do not reproduce it. Chicken septicemia cultures are virulent for white mice. In intramuscular injections of pullets these cultures prove not virulent, but their intravenous application kills the pullets in 5--10 days and the initial strain is isolated from all inner organs. The biological test on pullets is suitable for determining chicken septicemia culture virulence.