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Six groups of ten beef calves six to eight months of age were shipped from western Canada and observed untreated for one week after arrival. The following parameters were measured daily: body temperature, plasma fibrinogen, nasal bacterial mean colony counts of Pasteurella hemolytica and Pasteurella multocida, total and differential leukoyte counts, packed cell volumes and the following, twice during the week: serum and nasal antibody titres to P. hemolytica and parainfluenza-3 virus. The lungs from 44 of the calves were obtained at post mortem and given a numerical score based on the degree of pneumonia present. Animals were designated SICK and WELL according to body temperature and plasma fibrinogen. The SICK animals had higher nasal mean colony counts of P. hemolytica than the WELL animals. The SICK animals had lower levels of serum antibody to P. hemolytica than the WELL on day 1 but had a greater rise in titre over the week than did the WELL animals. Both groups were similar with regard to serum antibody to parainfluenza-3 virus and there was little change in these titres. The SICK animals had a much greater degree of pneumonia than the WELL. The values of some of the parameters were combined with the data of previously studied animals in order to provide a comparison of SICK and WELL with larger numbers of animals.

Two hundred and three isolates of Pasteurella haemolytica from cattle were studied. They originated from the nasal cavity of cattle in housed herds; the nasal cavity and pneumonic lungs of experimental feedlot calves and from pneumonic bovine lungs submitted for bacteriological diagnosis.To determine whether a single characteristic or combination of characteristics might be a feature of isolates collected from animals with pneumonic pasteurellosis (Shipping Fever), the following tests were made. Cultures were serotyped by indirect haemagglutination; the ability to produce beta-galactosidase was examined in the ortho-nitrophenyl-beta-D-galactopyranoside (ONPG) test and antibacterial sensitivity tests were done. None of these factors could be directly related to the role of P. haemolytica in "Shipping Fever".

The thoracic air sacs of poults at one day of age were examined to compare those of normal, saleable poults with those of sibs culled(1) at hatching at three stages in the laying season. Lesions of airsacculitis were recorded and the air sacs were cultured for mycoplasma. Impression smears of the thoracic air sacs were stained with rabbit anti-Mycoplasma meleagridis serum conjugated with fluorescein isothiocyanate and examined to determine the location and infection rate of the organism. M. meleagridis were observed closely associated with or within epithelial cells of the air sac; within mononuclear cells and as extracellular "microcolonies". The lesion and infection rate of cull poults in most hatches exceeded that of normal poults and infection with M. meleagridis was more often expressed (as a lesion) in cull than in normal poults.