The effect of route of administration on the anthelmintic efficacy of benzimidazole anthelmintics in sheep infected with strains of Haemonchus contortus and Trichostrongylus colubriformis resistant or susceptible to thiabendazole

Observations of erratic anthelmintic activity of fenbendazole against known standardised thiabendazole-resistant strains of Haemonchus contortus and Trichostrongylus colubriformis in sheep were investigated. Fenbendazole at a dose rate of 10 mg/kg body weight was administered by oral, intra-ruminal or intra-abomasal routes, and was most effective against both resistant strains following intra-ruminal administration. In addition thiabendazole, oxibendazole, fenbendazole, parbendazole and mebendazole plus two unrelated compounds, levamisole and morantel tartrate, were used at one and a half times their suggested or recommended therapeutic dose rate against thiabendazole-resistant strains of H contortus and T colubriformis in sheep; each drug being administered by the intra-ruminal or intra-abomasal routes. Fenbendazole was more effective against both strains following intra-ruminal administration. Parbendazole was more effective against the resistant strain of T colubriformis following intra-ruminal administration. At the dose rate chosen for the other benzimidazoles used against these resistant strains, there was no difference in anthelmintic efficacy due to route of administration. Levamisole was highly effective against both resistant strains, irrespective of the route of administration. In the groups treated with morantel tartrate, the results obtained were difficult to interpret due to mortalities and a highly variable response in the surviving sheep. Fenbendazole, thiabendazole and mebendazole when used at their suggested or recommended therapeutic dose rate in sheep, were highly effective against known thiabendazole-susceptible strains of H contortus and T colubriformis following both intra-ruminal or intra-abomasal administration.     

Survey of Toxoplasma antibodies among sheep in western United States

A survey was conducted to determine the prevalence of toxoplasma antibodies among breeding ewes and among lambs slaughtered for food in western United States. Each serum was tested by the indirect hemaglutination method, using microtiter technique. Agglutination (greater than or equal to 2 +) at the 1:64 dilution was considered to be a positive reaction. Of 2,164 ewes from 18 flocks tested in California, 523 (24%) were seropositive for Toxoplasma gondii, with prevalence rates among flocks ranging from 4 to 51%. In 9 of those flocks, 1,495 ewes were stratified by whether ewes had lambed or were barren. On an overall basis, the antibody prevalence was similar (about 25%) in both groups, but there was a significant difference (P less than 0.05) in 1 flock in which 30% of the nursing ewes were seropositive, compared with 21% of the barren ewes. Of 1,056 market lambs from 19 lots tested, 85 (8%) were seropositive. The antibody prevalence in lambs tested at slaughter in California, by state of origin, were: Oregon, 11/51 (22%); Nevada, 32/159 (20%); Idaho, 12/147 (5%), and California, 30/699 (4%).     

Planned control of reproduction processes in industrialized pig production

A planned process of concentration and specialisation in pig production has been introduced in the USSR, GDR, and other socialist countries in recent years and is likely to open up wider opportunities for the use of up-to-date technologies and latest findings of the biological sciences. Large-scale use of bio-engineering and methods of reproduction control is quite logical, in this context. This will provide a real chance for cyclogram control of all events important to management, planning, and follow-up of reproduction processes and for a planful implementation of industrialised production methods. Processes of cycle control are being increasingly applied to industrialised sow breeding units against the background of artificial insemination of pigs which is gaining widespread popularity after its emphasised introduction in the USSR. Research and field results regarding biological engineering in sow of oestrus, ovulation, pregnancy, and birth are reported in this paper and will, hopefully, help in determining mating and farrowing deadlines for breeding on the basis of artificial insemination and, consequently, contribute to widest possible programming of life cycles for the breeding animals concerned.     

Problems in the use of radioactively labelled bacteria in experiments. 2. Quantitative method for the evaluation of pathogens in the calf lung by means of labelled bacteria after aerosol or intratracheal administration

By means of two aerosol apparatures radioactive labelled Pasteurella-multocida-germs were given to calves via a respiratory mask. Labelling of Pasteurellae was done internal by using special nutritive media with Fe-59 or P-32. In a period of 10-25 minutes 5 X 10(9)-10(10) labelled bacteria were given to the animals for inhalation. Another animal group was injected intratrachealy with the same quantity of labelled germs. Immediately after termination of germ application the animals were killed and dissected. After solution or homogenization, respectively of the total lung tissue radioactivity was determined by liquid-scintillation-counting (Fe-59) or Cerenkov-measurement (P-32), respectively. The activities recovered from lung homogenates rendered is possible to calculate the received amount of bacteria. 40-80% of germs would be recovered in the lung after application by intratracheal injection while only 1-7% could be recovered after individual aerosol application lasting for 15-25 minutes.