In order to study the marked variation of red blood cell sedimentation rate in some species of animals, the packed cell volume, volume percentage of erythrocytes in whole blood, was reshuffled of 20%, 40% and 60% using heteroplasma of chicken and goat, and the red blood cell sedimentation rate was measured in Westergren tubes at 27+-1 deg C and 8+-1 deg C. The values of packed cell volume (PCV) of goat and chicken were 40.7+-4.1% and 30.2+-2.2% respectively. The sedimentation rates of reshuffled red blood cell were settled faster at lower PCV than higher PCV, i.e. there was a reverse relationship between the sedimention rate and PCV. Red blood cells of chicken settled quickly, where as those of goat settled very slowly. Chicken red blood cell sedimented rapidly even in goat plasma, and goat red blood cell sedimented slowly in chicken plasma. These findings indicate that the plasma is not the only factor determining the rapid red blood cell sedimentation rate of chicken. The sedimentation rate of reshuffled red blood cell of chicken and goat were accelerated at higher temperature than lower temperature.

Three antigens were prepared from a type-3 avian strain of Pasteurella multocida, and their chemical and immunologic characteristics were studied. An antigen, designated 2.5S, was extracted with 2.5% NaCl solution and purified by chromatography. Lipopolysaccharide (LPS) was extracted with phenol-water, and a third antigen, designated FS, was extracted in 0.3% formalin solution containing 0.85% NaCl and purified by differential centrifugation. The 2.5S and the FS antigens consisted of 40% protein and 15% carbohydrate, whereas LPS did not contain a substantial amount of protein. A major protein component with a molecular weight of 44,000 was detected in the 2.5S antigen, as well as in the FS antigen. Of the 3 antigens, LPS had thehighest activity in mouse lethality and Limulus lysate tests. Antigenic cross-reactions among the 3 antigens were demonstrated by immunodiffusion tests. The 2.5S antigen was indistinguishable from the FS antigen, as both antigens contained the LPS component of approximately 45%. Treatments with various reagents indicated that the 2.5S and FS antigens contained at least 2 antigenic determinants. The first was a heat-stable protein sensitive to protease or phenol-water, and the second was a periodate-sensitive carbohydrate, which was an major antigenic determinant on the LPS antigen.

Clinical signs of respiratory tract disease were observed in chickens that were inoculated intratracheally with 1 x 10(6) oocysts of Cryptosporidium baileyi at 2 or 14 days of age (10 chickens/group), but not in chickens inoculated at 28 or 42 days of age (10 chickens/group). Orally inoculated chickens in all age groups (10 chickens/group) did not develop clinical signs of disease. Orally and intratracheally inoculated chickens in all age groups were infected, as determined by the finding of cryptosporidia in tissue sections of the trachea, bursa of Fabricius, and cloaca, and by the recovery of oocysts from their feces. Chickens inoculated at 2 and 14 days of age excreted oocysts for a longer period and had greater numbers of cryptosporidia in their tissues, compared with chickens inoculated at 28 and 42 days of age.

The respiratory tract of healthy chickens contain few free-residing phagocytic cells. Intratracheal inoculation with Pasteurella multocida stimulated a significant (P < 0.05) migration of cells to the lungs and air sacs of White Rock chickens within 2 hours after inoculation. We found the maximal number of avian respiratory tract phagocytes (22.9 +/- 14.0 x 10(6)) at 8 hours after inoculation. Flow cytometric analysis of these cells revealed 2 populations on the basis of cell-size and cellular granularity. One of these was similar in size and granularity to those of blood heterophils. Only this population was capable of generating oxidative metabolites in response to phorbol myristate acetate. The ability of the heterophils to produce hydrogen peroxide, measured as the oxidation of intracellularly loaded 2', 7'-dichlorofluorescein, decreased with time after inoculation. These results suggest that the migration of heterophils, which are capable of high levels of oxidative metabolism, to the lungs and air sacs may be an important defense mechanism of poultry against bacterial infections of the respiratory tract.

The minimum anesthetic dose (MAD) and the cardiopulmonary dose-response for halothane were determined in male chickens. The MAD for halothane was 0.85 +/- 0.09% (mean +/- SD), with a range of 0.75% to 0.98%. There was a significant (P less than 0.002) positive correlation between increasing concentrations of halothane and PaCO2, and significant negative correlations of halothane concentration with respiratory rate (P less than 0.04), arterial blood pH (P less than 0.008), and mean arterial blood pressure P less than 0.008). A significant correlation was not found between halothane concentration and heart rate or arterial blood bicarbonate concentration. It was concluded that the MAD for halothane in chickens is similar to values for minimum alveolar concentrations of halothane in mammalian species, and that there is substanial dose-dependent depression of cardiopulmonary function in chickens.

Ten-day-old chicken embryos were inoculated with isolates of myeloblastosis-associated virus that induced osteopetrosis of slow or rapid onset. Bursa of Fabricius, thymus, spleen, bone marrow, kidney, liver, and lung were examined at 15, 17, and 19 days in ovo and at 7 and 25 days after hatching by histologic and immunoperoxidase techniques. Tissues from 19-day-old in ovo embryos also were examined by electron microscopy. The lymphoid organs of embryos inoculated with all isolates manifested changes suggesting inhibited development. Virus was most often associated with macrophages, heterophils, and non-lymphoid stromal cells in these organs. Viral particles and antigen were abundant in tissues from embryos inoculated with slow-onset isolates, but cell necrosis was infrequent. The kidney and bursa had especially abundant viral particles and antigen. Conversely, viral particles and antigen were minimal in tissues from embryos inoculated with the rapid-onset isolate, yet intravascular cellular thrombi, substantial cell necrosis, and increased heterophils and hemocytoblasts were found.

Studies were undertaken to assess the chicken embryo and newly hatched chicken as models for studying the effects of bone-active agents. Initially, 1,25-dihydroxycholecaliferol (1,25[OH]2D3), sodium fluoride (NaF), parathyroid extract, epidermal growth factor, and prostaglandin E2, were tested for lethality over a broad dose range. One or 3 injections of 1,25(OH)2D3 into the yolk sac of chicken embryos resulted in death of embryos given greater than 0.1 ng/injection, whereas 0.01 ng was tolerated by the embryos. Administering 1,25(OH)2D3 intraperitoneally to newly hatched chickens as a single injection or weekly for 3 weeks resulted in no deaths at doses up to 50 ng. One or 3 IV injections of less than 400 micrograms were tolerated by the embryo. Giving chickens feed and water containing 2.4 g of NaF/kg was lethal but no deaths occurred when chickens were given feed containing less than 1.2 g of NaF/kg. Mortality associated with the administration of epidermal growth factor to embryos was inconsistent, in that death occurred in embryos given a single injection of greater than 250 ng, but no deaths occurred in embryos given 3 injections at similar doses. Parathyroid extract and prostaglandin F2 were not lethal when administered to embryos and chickens in a single-injection or multiple-injection regimen. Overall, lethality in chicken embryos given a particular agent reflected the dose of bone-active agent injected, rather than the number of injections. Three of the bone-active agents were selected to characterize their microscopic bone effects in chicken embryos and chickens. Administration of 1,25(OH)2D3 to embryos on day 14 at doses of 100, 10, 1, and 0.1 ng led to subperiosteal hyperosteoidosis in all 5 of the tibiotarsi examined from the high-dose (100 ng) group necropsied on day 18 of incubation. Three of 5 of the tibiotarsi from the 10-ng treatment group were similarly affected. Bone effects were noticed in chickens hatched from the aforementioned treatment groups or in chickens given 1,25(OH)2D3 intraperitoneally and examined at 3 and 6 weeks of age. Administration of NaF to chicken embryos on the 10, 12th, and 14th days of incubation via the IV route at doses of 160, 80, 40 and 20 micrograms/embryo led to subperiosteal hyperosteoidosis in tibiotarsi from 3 of 10 embryos (examined at 18 days of incubation) from the 2 high-dose groups. Tibiotarsi of chickens from this treatment group were microscopically normal at 3 weeks after hatching. When newly hatched chickens were given a diet containing NaF at dosages of 1.2 g/kg, 0.6 g/kg, and 0.3 g/kg, a dose-dependent increase in osteoid was seen at 3 and 6 weeks. In addition, cortical thinning and expansion of the medullary canal were observed only at 3 weeks. In contrast to the effects observed with 1,25(OH)2D3 and NaF, parathyroid extract caused no microscopic bone alterations when given to embryos or chickens. Overall, the bone alterations in the embryo were attributed to increased subperiosteal osteoid formation and defective mineralization. These findings were consistent with known effects of NaF and 1,25(OH)2D3 on bone, and they establish the chicken embryo as a sensitive model for studying bone-active agents.