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.     

Effect of the polyether antibiotic "monensin" on fattening and slaughtering performance as well as protein and energy retention in bulls

In an individual feeding experiment (150-500 kg live weight) the influence of the polyether antibiotic Monensin on the fattening, slaughtering and retention performances of crossbreeding dairy bulls (genotype 31) and fattening hybrids (genotype 61) was ascertained. The supplementation of the polyether antibiotic on average resulted in a decrease by approximately equal to 11% of the dry matter and energy expenditure per kg weight gain due to a lower feed intake and a higher live weight gain. The slaughtering parameter investigated and the chemical composition of the empty body remained uninfluenced. The daily nutrient retention values were positively influenced by the Monensin supplementation since the fattening bulls of the test group required 30 days less to achieve the attempted fattening weight. The additional retention of protein, fat and energy per animal and day in the dairy bulls approximately equal to 10.9; 13.5 and 16.4% and in the fattening hybrids 1.9; 3.2 and 2.6%. Due to a higher energy retention at a lower level of feed and energy intake after Monensin supplementation an average of approximately equal to 11.3 and 15.4% resp. more of the consumed digestible protein and the digestible energy resp. were retained in the empty bodies. One can conclude that Monensin improved the utilisation of feed energy; obviously the effect of the polyether antibiotic is due to its influence on processes in the rumen or directly or indirectly on metabolism.