Distribution of immunoglobulin-containing cells in calves inoculated orally with ruminal Bacteroides succinogenes and Selenomonas ruminantium

Distribution of immunoglobulin(Ig)-containing cells was investigated in calves inoculated orally with live organisms of both Bacteroides succinogenes and Selenomonas ruminantium. Pathological changes and many Ig-containing cells were observed in calves which inoculated three times at 2, 3 and 26 days of age. Follicular germinal center was increased in number and size of the lymph nodes associated with the forestomach, suggesting activation of lymph apparatus. In the associated lymph nodes, IgG-containing cells were predominant and were located in both cortex and medulla, mainly in the medullary cord, B lymphocyte areas. Only a few IgA- and IgM-containing cells were observed in the lymph nodes. Accordingly, the inoculated bacteria may stimulate IgG-containing B lymphocyte populations. A few IgG-containing cells were detected in the mucosa of the forestomach. Ig-containing cells, predominantly IgG, were observed in the mucosa of the abomasum and intestine, and in the mesenteric lymph nodes. However, number of the cells in the mesenteric lymph nodes was smaller than that of the forestomach associated lymph nodes. The results suggest that the intraorally inoculated bacteria may stimulate the maturation of IgG positive lymphocytes in the lymph nodes associated with the forestomach.     

Comparative distribution of immunoglobulin-containing cells in stomach, intestine and associated lymph nodes of cattle

Immunoglobulin (Ig)-containing cells were investigated immunohistochemically in the stomach, intestine and associated lymph nodes of clinically normal calves, cows and fetuses to examine mucosal immune responses in the forestomach to rumen microbial flora. IgG-containing cells were observed in the mucosal propria of the forestomach of a 32 day-old, a 37 day-old, two 90 day-old calves, and of all 5 cases of cows. However, no IgA- and IgM-containing cells were observed. Further, no Ig-containing cells were detected in the associated lymph nodes of all calves and cows. Various numbers of Ig-containing cells, predominantly IgG, were observed in the mucosal propria of the abomasum, small intestine and cecum, and in the mesenteric lymph nodes of aged calves and all cows. No Ig-containing cells were observed in any tissues of fetuses. The results suggest that the development of mucosal immune responses in the forestomach may be incomplete as compared with that of the intestine.     

Enteric campylobacter infection in gnotobiotic calves and lambs

Gnotobiotic calves and lambs were infected orally with Campylobacter jejuni, C coli or C hyointestinalis to assess pathogenicity. All animals were successfully colonised and excreted mucoid faeces but showed no other clinical signs. Campylobacters colonised the large intestine better than the small intestine, in which bacterial numbers decreased with time after infection. Campylobacters were found occasionally in the lumen of crypts in close proximity to epithelial cells and included in a mucus-like material. Lesions were mostly in the large intestine in calves whereas in lambs they were present in the ileum. In animals inoculated with C jejuni or C coli scattered crypt abscesses, focal inflammatory infiltrates in the lamina propria and goblet cell discharge were found. In lambs inoculated with C hyointestinalis only minor changes were found in the small intestine. Serum antibody response was either absent or present at a low level only from the 19th day after infection.     

Bovine ileal dome lymphoepithelial cells: endocytosis and transport of Brucella abortus strain 19

Ligated ileal loops of calves were inoculated with Brucella abortus and examined at 2, 4, 6, 10, and 24 hours post-inoculation. B. abortus was identified by light and electron microscopy using immunoperoxidase and antibody-coated colloidal gold techniques. B. abortus was detected in vesicles, phagolysosomes, and large vacuoles of lymphoepithelial cells. Numbers of intracellular bacteria decreased with time after inoculation. B. abortus was also seen between and below lymphoepithelial cells and free in the dome interstitium and intestinal lymph vessels. Neutrophils and macrophages in both epithelium and lamina propria contained intact or degraded bacteria within phagosomes, phagolysosomes, and multivesicular bodies. These studies showed that (1) transepithelial migration of B. abortus occurred principally by dome lymphoepithelial cell endocytosis and transport, and (2) B. abortus was degraded by macrophages and neutrophils of the gut-associated lymphoid tissue.     

Direct inoculation of Mycobacterium avium subspecies Paratuberculosis into ileocecal Peyer's patches results in colonization of the intestine in a calf model

The objective of this study was to develop an intestinal model of Mycobacterium avium subspecies paratuberculosis (Map) infection in the calf for evaluation of mucosal pathology and local and systemic immunologic responses. Map was inoculated into Peyer's patches of young calves using a right flank surgical approach in standing calves to exteriorize the ileocecal junction. Inoculum doses ranging from 10(3) to 10(9) colony-forming units of strain K10 Map were injected through the serosal surface into Peyer's patches of the distal ileum near the ileocecal valve. Fecal samples were collected for culture from each calf weekly until termination of the study. Calves were necropsied at 7, 30, 60, and 90 days after infection, when inoculation sites, lymph nodes, spleen, and peripheral blood were collected for evaluation. Ileocecal lymph nodes were consistently colonized by Map in the 10(5) to 10(9) groups. The ileocecal valve was also colonized in 10(7) and 10(9) groups. This correlated with fecal culture results as infected calves intermittently shed Map in their feces throughout the study. Granulomatous lesions with giant cells and acid-fast bacilli at the ileocecal junction, ileocecal lymph nodes, and lamina propria of high-dose animals (10(7) and 10(9)) were identified from each time point. Flow cytometry was used to detect antigen-specific production of interferon-γ and interleukin-4 locally (ileocecal lymph node) and systemically (peripheral blood mononuclear cells), which defined distinct immunologic profiles in low-dose and high-dose calves. This study demonstrates intestinal Map infection via Peyer's patch inoculation, a novel model with many shared features of natural Map infection.     

Inoculation of neonatal gnotobiotic dogs with a canine rotavirus

Neonatal gnotobiotic dogs were inoculated orally with a rotavirus isolated from a pup with fatal diarrhea, and in the gnotobiotic dogs, diarrhea was observed between postinoculation hours (PIH) 20 and 24. The diarrhea persisted through PIH 154, and inoculated pups had clinical signs of dehydration after PIH 24. Negative-contrast electron microscopy of the feces from inoculated pups revealed rotavirus particles from PIH 12 through 154. Using an indirect-fluorescent antibody test, serum rotavirus antibody was detected in inoculated pups by PIH 96. In the duodenum, jejunum, and ileum of inoculated pups, group-specific rotaviral antigen was observed within absorptive villus epithelial cells and mononuclear cells in the villus lamina propria with an indirect-fluorescent antibody test. Fluorescence was seen in the small intestine of inoculated pups killed by PIH 12 and was present in intestines of pups killed through PIH 154. Rotaviral antigen was also seen in the mesenteric lymph nodes of a few inoculated pups killed at PIH 48.     

Isotype-specific antibody-secreting cells in systemic and mucosal associated lymphoid tissues and antibody responses in serum of conventional pigs inoculated with PEDV

An enzyme-linked immunospot (ELISPOT) has been developed to detect porcine epidemic diarrhea virus (PEDV)-specific antibody secreting cells (ASC) in gut associated lymphoid tissues (duodenum and ileum lamina propria and mesenteric lymph nodes) and systemic locations (spleen and blood) of conventional pigs so as to characterise the mucosal and systemic antibody response generated by the infection with PEDV. A total number of 28 eleven-day-old conventional pigs were orally inoculated with the field isolate of the PEDV strain CV-777. Diarrhea was observed in 32% of the pigs and virus shedding was demonstrated in 100% between postinoculation day (PID) 1 and 8. Serum IgG and IgA antibodies to PEDV were detected by isotype ELISA from PID 12 and 15, respectively, reaching maximum values at PID 32 (IgG) and 21 (IgA). PEDV specific IgM ASC occurred in all the tissues between PID 4 and 7, with the strongest response in the intestinal lamina propria. IgA and IgG ASC responses were evident in the intestinal lymphoid tissues from PID 21, the highest number of specific ASC corresponded to the duodenum lamina propria. In the systemic lymphoid tissues the number of IgG and IgA ASC detected were lower than in the mucosal tissues, however, in the blood, presence of IgA ASC was constantly detected from PID 14 until the end of the experiment. Memory antibody response to the PEDV was also studied by secondary in vitro stimulation of the mononuclear cells (MNC) isolated from mesenteric lymph nodes, spleen and blood. The memory B cell response was prominent at PID 21 and 25 and consisted in IgG and IgA ASC. To our knowledge, this is the first report to research into the presence and distribution of specific ASC in different locations of the systemic and the gut associated lymphoid tissues after a PEDV infection as well as the presence of memory B cells.     

Ruminant forestomach and abomasal mucormycosis under rumen acidosis

Spores of Absidia corymbifera were inoculated orally into sheep with ruminal acidosis produced by feeding barley. Lesions, which developed in forestomachs of all four inoculated cases, included desquamation of superficial layers of the mucosae and focal necrosis from lamina propria to muscular layers. Granulomatous lesions were in the submucosa of three sheep. Lesions in the abomasum (two sheep) included focal necrosis, diffuse hemorrhages, and infiltration of neutrophils. All lesions were accompanied by mycotic proliferation. These results show that A. corymbifera can invade forestomach mucosae through degenerate epithelium resulting from ruminal acidosis.     

Studies on the pathogenesis of Salmonella heidelberg infection in weanling pigs

Experiments were conducted to define the pathogenic potential of Salmonella heidelberg in weanling pigs. Oral inoculation with S heidelberg resulted in severe catarrhal enterocolitis with accumulation of large amounts of fluid in the small intestine and colon. Salmonella heidelberg was demonstrated, with fluorescence microscopy and bacteriologic cultural techniques, to colonize the ileum, to invade ileal mucosal enterocytes, and to reach mesenteric lymph nodes and extraintestinal tissues by 8 hours. In 5 pigs, intestinal loops were surgically prepared and inoculated with S heidelberg (to determine its invasiveness). Microscopically, there were atrophy of villi, erosion of enterocytes, and neutrophilic infiltration in the lamina propria. Ultrastructurally, intracellular bacteria were demonstrated in villous and cryptal enterocytes, as well as in macrophages of the lamina propria. Bacteria were morphologically intact, occurred free and membrane-bound and caused no detectable cytotoxic effect to the cell.     

Ultrastructural changes in the small intestine of neonatal calves with enteric colibacillosis

The small intestines of calves inoculated orally with the enteropathogenic strain of Escherichia coli 0101:K'B41',K99 were examined by electron microscopy at 3, 6, 12, 16, 21, 36, 69, 70 and 72 hours after inoculation. The challenge organism adhered to the mucosa of the distal small intestine from six hours post-inoculation. Bacteria were separated from the microvillous brush border by a gap of 200 to 300 nm in which bacterial fimbriae and the microvillous glycocalyx were seen. Bacteria never were found in epithelial cells but were present in macrophages in the lamina propria from 12 hours. At three and six hours, cytopathic changes were not seen in the small intestine, but from 12 hours epithelial cells on affected villi had blunt and thick microvilli and contained cytoplasmic inclusions. Epithelial cells were seen frequently in the process of extrusion from the villi, either singly, in small groups, or as ribbons of cells. Intervillous bridges, characteristic of villous fusion, were seen frequently from 69 hours.     

Experimental induction of bacterial gastritis and gastric ulcer disease in gnotobiotic swine inoculated with porcine Helicobacter-like species

OBJECTIVE: To determine whether 2 isolates of recently isolated swine-origin Helicobacter pylori-like bacteria are pathogenic in pigs and compare the signs of gastric disease induced by these isolates with those detected in H pylori- and Helicobacter heilmannii-infected pigs. ANIMALS: 36 neonatal gnotobiotic pigs. PROCEDURE: Groups of separately housed pigs were inoculated orally with swine-origin Helicobacter-like isolates 2662 or 1268, H pylori (human gastric pathogen), or a gastric homogenate from gnotobiotic swine containing H heilmannii. Noninoculated pigs were used as control animals. Clinical signs and development of homologous and heterologous antibodies against Helicobacter organisms were assessed. After euthanasia, gastric tissues were examined grossly and microscopically; Helicobacter organisms were detected by use of Warthin-Starry and immunohistochemical stains. RESULTS: Both porcine Helicobacter-like isolates colonized the stomachs of swine. Isolate 2662 was highly pathogenic; in 13 isolate 2662-inoculated pigs, gastroesophageal ulcerations developed in 9 and ulceration of the gastric glandular mucosa was detected in 5. Histologically, inflammatory gastritis consisting of multifocal to diffuse lymphocytic and plasmacytic cellular infiltrates and lymphoid follicle formation in the gastric lamina propria accompanied bacterial colonization of the gastric compartment. In contrast, H heilmannii was minimally pathogenic in that only modest inflammatory cell infiltrates were seen. Gastroesophageal or mucosal ulcers were not evident in pigs inoculated with H heilmannii. CONCLUSIONS AND CLINICAL RELEVANCE: These data indicate that swine-origin H pylori-like bacteria can be pathogenic in pigs and suggest that porcine gastric disease may be mediated, in part, by colonization of the stomach by swine-origin H pylori-like bacteria.     

Enteritis associated with Yersinia pseudotuberculosis infection in a buffalo

SUMMARY: A week after transport a 4 month old buffalo calf developed diarrhoea. Its condition gradually deteriorated and it died. Necropsy revealed acute haemorrhagic enteritis and enlarged mesenteric lymph nodes. Haemorrhages and numerous microabscesses were detected in the lamina propria of the small intestine associated with colonies of Gram negative bacteria. Yersinia pseudotuberculosis was isolated from the small intestine and from mesenteric lymph node. Enteritis caused by Y pseudotuberculosis does not appear to have been reported previously in buffalo in Australia.     

Intestinal lesions in specific-pathogen-free lambs associated with a cryptosporidium from calves with diarrhea

Small and large intestines of seven specific pathogen-free lambs infected with cryptosporidia from calves with diarrhea were examined by scanning and transmission electron microscopy and by light microscopy. The small intestine was infected in all the lambs, and the cecum and colon in three. Small intestinal alterations were severe villous atrophy and dilatation of the crypts of Lieberkühn. Epithelial cross-bridging between contiguous villi caused much villous fusion. Epithelial cells constituting the bridges were connected by desmosomal junctions, and were continuous with the epithelial coverings of the associated villi. The lamina propria was heavily infiltrated with neutrophil leukocytes. Infected crypts in cecum and colon were dilated and devoid of mucus-secreting cells, while the ridges between crypts were hypertrophied, and the lamina propria was infiltrated by neutrophils. Cell vegetations with adherent bacteria were present in the surface intestinal epithelium of two lambs infected for 11 and 14 days, respectively. No adherent bacteria were seen in any site in lambs killed up to six days post-inoculation.     

Observations on the alimentary tract of gnotobiotic lambs.

Seventeen gnotobiotic lambs were reared up to 21 weeks of age on cows' milk followed by sterile solid diets similar to diets fed to conventional lambs. Seven were inoculated with limited defined populations of rumen bacteria, seven were left uninoculated and three were dosed with rumen contents from conventional sheep ('conventionalised'). Seven naturally-born lambs were reared for purposes of comparison. As with other species of gnotobiotic animals, both the inoculated and the uninoculated gnotobiotic lambs had small, poorly developed lymph nodes, soft colon contents and thin intestinal walls. Unlike other species the caeca of gnotobiotic lambs were of normal size. The overall size of the reticulo-rumen including contents relative to body weight was similar in gnotobiotic and conventional lambs. However, macroscopically, the musculature of the rumen seemed to be poorly developed and histological studies showed hypoplasia of the muscle tissue of both the rumen and reticulum. Rumination was noted only infrequently in gnotobiotic lambs. The epithelium of the rumen and reticulum of the uninoculated gnotobiotic lambs was similar to that of neonatal lambs, but there was normal development of papillae in gnotobiotic lambs inoculated with limited defined populations of rumen bacteria and in conventionalised lambs. Degenerative changes were observed histologically in some of the organs of gnotobiotic lambs which were consistent with nutritional deficiencies.     

Synergistic influence of Ostertagia ostertagi and Trichostrongylus axei on Ostertagia ostertagi larval inhibition and abomasal lesions in cattle

Parasite-free 4-month-old calves were inoculated with Ostertagia ostertagi and/or Trichostrongylus axei followed 6 weeks later by increasing doses of O ostertagi for 8 weeks. Clinical signs of parasitism, fecal egg counts, and plasma pepsinogen concentrations were monitored, and gross lesions and parasite burdens were determined postmortem. Clinical signs of parasitism were not observed and weight gains were not affected in experimentally infected calves. In calves infected with O ostertagi, mean plasma pepsinogen concentrations were greater than for control calves and were diagnostically significant 4 weeks after inoculation and during the last 4 weeks of serial inoculations with O ostertagi. In calves that were given O ostertagi and T axei, abomasal pH was significantly increased, and abomasal lesions were more pronounced than in control calves or in calves inoculated with only O ostertagi or T axei. Abomasal lymph nodes were enlarged in all parasitized calves; other lymph nodes in the calves inoculated with both O ostertagi and T axei were usually smaller than in calves inoculated with only O ostertagi or T axei. Numbers of O ostertagi-inhibited larvae were small in all inoculated calves, but the percentage inhibition was significantly greater in calves inoculated with both O ostertagi and T axei. The percentage inhibition was 3.53% for the O ostertagi-inoculated calves and 7.07% for calves inoculated with both O ostertagi and T axei. These percentages indicated a synergistic effect of concurrent abomasal parasitism, whereas a synergistic effect on T axei worm burden was not observed. The low percentage of larval inhibition indicated that factors other than host resistance are involved in naturally occurring pretype II ostertagiosis.     

Histological development and histochemical localization of enzymes in rumen and reticulum in bovine fetuses

Thirty Holstein fetuses from 100 to 251 d after conception were utilized to study prenatal anatomical development of the epithelium of the rumen and reticulum. Four calves at birth were included in the study for comparison. Tissue sections were frozen and stained to locate specific enzymes. At 100 d, the epithelial layer of the rumen was differentiated into a thin basal zone and a thickened superficial zone of undifferentiated cells. The basement membrane was straight, and in both zones cells were perpendicular to it. At 120 to 141 d, low, primary undulations were detected in the basal zone, basement membrane and underlying lamina propria. At 150 to 166 d, secondary undulations and incipient papillae began to resemble the papillae of mature mucosa. In rumen papillae of 192-d to 215-d fetuses, shallow furrows began to separate papillae apexes from the mass of epithelium. In fetuses 244 to 251 d, the papillae began to be a separate entity. At birth, the basal position of the papillae still remained fused. An incipient separation between the papillae was seen. Several dehydrogenase enzymes, including those associated with the Krebs cycle and reductase associated with energy transformation, were observed in both ruminal and reticular tissue. Alkaline phosphatase activity was localized in the stratum corneum and in blood vessels. Development of the honeycomb configuration of reticular epithelium was evident in the 100-d fetus and progressed rapidly with age.     

Effects of protozoa on methane production in rumen and hindgut of calves around time of weaning.

Effects of the presence or absence of ciliate protozoa on methanogenesis in the rumen and hindgut were investigated in young calves during a 7-week period. Ten Holstein calves, aged 7 days, were divided in two groups (n = 5) and fed an increasing amount of a commercial milk replacer and small amounts of a calves starter. One group was inoculated with ciliate fauna on two occasions, week 5 and 6, while the second remained ciliate-free. The absence of protozoa in the rumen decreased rumen empty weight (-23%, P < 0.01), and rumen pool size of N (-36%, P < 0.01) and crude fat (-37%, P < 0.05). Rumen bacteria of non-faunated calves contained a higher proportion of total amino acid-N per 16 g N (+3%, P < 0.01) and D-alanine-N per 16 g N (+13%, P < 0.05) compared to faunated calves. Further results contain a reference for a higher bacterial mass in the ciliate-free rumen with an increased number of bacteria adherent to rumen mucosa. The CH4 production in the rumen increased exponentially with the increase in protozoa population size (R2 = 0.68). In presence of 46 x 10(4) protozoa per ml rumen fluid, the in vitro CH4 production of rumen fluid per mol total VFA was about 34% higher in faunated than in non-faunated calves (P < 0.001). Hydrogen (2H) recovery of rumen fermentation was positively correlated (R2 = 0.55) to the CH4 production rate. Methanogens were attached on rumen mucosa. Methanogenesis, induced by rumen mucosa attached bacteria, was stimulated by ruminal protozoa. In the absence of protozoa in the rumen, the acetate-propionate ratio and butyrate proportion of VFA were reduced. In vivo, in the absence of protozoa not only the whole animal CH4 production (-30%, P < 0.05) but also the digestibility of carbohydrates (-4%, P < 0.05) was reduced. Thereby no difference was observed in the intake of ME per kg DM between the groups. In conclusion, the methanogenesis in the rumen, but not in hindgut, is associated with the development of the ruminal protozoa population. The level of methanogenesis (mol/mol VFA) in the hindgut amounts to 20% of the ruminal methanogenesis.     

Effect of antibiotics in milk replacer on fecal shedding of Escherichia coli O157:H7 in calves

The objective of this study was to compare the concentration and duration of fecal shedding of Escherichia coli O157:H7 between calves fed milk replacer with or without antibiotic (oxytetracycline and neomycin) supplementation. Eighteen 1-wk-old Holstein calves were orally inoculated with a strain of E. coli O157:H7 (3.6 x 10(8) cfu/calf) made resistant to nalidixic acid (NA). Rectal samples were obtained three times weekly for 8 wk following oral inoculation. Fecal shedding of NA-resistant E. coli O157:H7 was quantified by direct plating or detected by selective enrichment procedure. Eight weeks after inoculation, calves were killed, necropsied, and tissues (tonsils, retropharyngeal and mesenteric lymph nodes, and Peyer's patches) and gut contents (rumen, omasum, abomasum, ileum, cecum, colon, and rectum) were sampled to quantify or detect NA-resistant E. coli O157:H7. The percentage of calves shedding NA-resistant E. coli O157:H7 in the feces in the antibiotic-fed group was higher (P < 0.001) early in the study period (d 6 and 10) compared with the control group fed no antibiotics. There was no difference between treatment and control groups in the concentration of E. coli O157 in feces that were positive at quantifiable concentrations. A comparison of the duration of fecal shedding between treated and untreated calves showed no significant difference between groups. At necropsy, E. coli O157:H7 was recovered from the rumen and omasum of one calf in the control group and from retropharyngeal lymph node and Peyer's patch of two calves in the antibiotic group. Supplementation of milk replacer with antibiotics may increase the probability of E. coli O157:H7 shedding in dairy calves, but the effect seems to be of low magnitude and short duration.     

A Disease Resembling Paratuberculosis (Johne’S Disease) in Roe Deer (Capreolus Capreolus L.) an Aetiological and Patho-Anatomical Study

A disease in wild living roe deer (Capreolus capreolus L.) caused by acid-fast bacteria is described.The morphological and cultural properties of these bacteria agree closely with corresponding properties of Mycobact. johnei.Enlarged lymph nodes, especially mesenteric lymph nodes with greyish-yellow necroses, were the most prominent macroscopic lesions. No intestinal lesions were present.The histopathological picture of the lymph nodes resembled mostly lesions which can occur in paratuberculous sheep and goats. The epithelioid cells contained masses of acid-fast bacteria. Such rods were also demonstrated in the intestinal villi.The acid-fast bacteria could be isolated from the mesenteric lymph nodes, spleens, bone marrow, mammary gland and also from the lymph nodes of other organs.The organism did not produce tuberculosis in guinea pigs. Intravenous injections into hens and rabbits resulted in miliary nodules resembling those of tuberculosis in the livers and spleens of the hens, and in joint and tendon sheath lesions in the rabbits. Microscopically the lesions mostly resembled those in paratuberculosis.One of the strains which was inoculated intravenously into two calves caused no lesions. The results of the allergy tests and serological blood tests in one animal indicate that infection with Mycobact. johnei cannot be excluded.A goat which was inoculated in the same manner and with the same strain as the calves died after six weeks. Miliary epithelioid cell granulomas in the liver, spleen, kidneys, bone marrow of long bones and in the submucosa of the ileum, as well as patchy infiltration of epithelioid cells in, among others, the mesenteric lymph nodes were observed on microscopic examinations.By intravenous infection the disease could be reproduced in a roe deer (fawn) (Gapreolus capreolus L.). The animal died nine weeks after the infection, and during the last two days before death it had a profuse diarrhoea. Masses of short acid-fast bacteria in clumps were present in the faeces. Nor in the experimental animal did macroscopic intestinal lesions occur. Enlarged villi infiltrated with epithelioid cells containing acid-fast bacteria were demonstrated by histological examination.The acid-fast bacteria could be recovered, but only on the Taylor/ Finlayson medium, from all experimental animals except the guinea pigs. Concerning the experimental calves, acid-fast bacteria were recovered from only one of them and then nearly three years after the infection.The acid-fast bacteria did not reduce nitrate. They showed positive neutral red reactions and were sensitive to isoniazid in a concentration of 2.5 µg per ml medium after three weeks’ incubation.The possibility that the isolated acid-fast bacteria and the lesions caused by them might be avian tubercle bacilli and avian tuberculosis has been discussed by the author. He does not, however, find any relevant reason for such an assumption. The author considers that the bacteria and the lesions exhibit the greatest similarity to Mycobact. johnei and paratuberculosis (Johne’s disease).On account of the organism’s pathogenicity for hens and rabbits, and necroses in the course of the disease, the author suggests that these bacteria possibly constitute a variety of the classic bovine Mycobact. johnei, different from the pigmented and the Icelandic varieties.     

DAP-decarboxylase activity and lysine production by rumen bacteria.

The last step of pathway of lysine biosynthesis by rumen bacteria was tested. The first measurements of DAP-decarboxylase activity and of lysine production by Megasphera elsdenii, Selenomonas ruminantium, Clostridium spp., Butyrivibrio fibrisolvens and Bacteroides succinogenes as well as the first attempts to increase the lysine production by ruminal streptococci by mutation are described. The highest values were measured in Selenomonas ruminantium (DAP-decarboxylase activity = 146 micrograms DAP.min-1.mg-1 protein and lysine production was 390 micrograms.mg-1 protein) and the lowest values were ascertained in Butyrivibrio fibrisolvens (DAP-decarboxylase activity = 27 micrograms DAP.min-1.mg-1 protein and lysine production was 32 micrograms.mg-1 protein). DAP-decarboxylase activity was increased by mutation especially in Streptococcus bovis, the lysine production in both of tested ruminal streptococci. The potential use of lysine-excreting mutants in calves in future is suggested.