Galenia africana L. poisoning in sheep and goats: hepatic and cardiac changes.

Lesions in 4 field cases (3 sheep and 1 goat) of 'waterpens' or water belly, caused by the plant Galenia africana, are described. The clinical pathological and pathological findings in 7 sheep which were drenched with toxic plant material are also reported. Inappetence, ruminal stasis and apathy as well as tachycardia were noticed in some of the sheep towards the end of the dosing period. The most prominent clinical pathological change in the experimental animals was an increase in the activity of gamma-glutamyltransferase which in some animals occurred within days after commencement of dosing. This indicates liver involvement in the early stages of the intoxication, and at this stage no heart abnormalities were detected clinically, clinical pathologically or with cardiac function tests. Decrease in cardiac function were recorded in 2 sheep towards the end of the dosing period. Liver and heart lesions were present in all the animals. In some cases hepatic changes were mild and characterized by dilation of central veins and sinusoids and, less commonly, centrilobular fibrosis. More advanced lesions included centrilobular fibrosis and bridging between neighbouring lobules with adjacent areas of coagulative necrosis, lysis and ballooning degeneration of hepatocytes. Myocardial changes occurred in the free ventricular walls and interventricular septum and comprised hypertrophy of myocytes with consequent degeneration and necrosis and fibrosis. In cases of longer duration myocytes were diffusely atrophic with scattered groups of remaining hypertrophic fibres. The clinical pathological and pathological features suggest that G. africana is primarily hepatotoxic with myocardial involvement occurring only in the terminal stages of the intoxication.     

Field evaluation of an experimental albendazole pulse release bolus in the control of parasitic gastroenteritis in first-season grazing calves

A field experiment is described which evaluates the use of an experimental albendazole pulse release bolus (E-bolus) on gastrointestinal parasitism. The bolus was administered at turnout to 9 first-season grazing calves and 9 animals were kept as controls on a separate pasture. Dry summer observed. The E-bolus introduced at the start of the grazing season provided moderate control of gastrointestinal parasitism. The beneficial effect of the treatment was demonstrated by lower strongyle egg counts and significant differences in ELISA extinctions for Ostertagia, Cooperia and Dictyocaulus. However pepsinogen values were elevated in the bolus-treated group, probably because of the long interval (31 days) between the pulsed treatments. Although not significant there was a trend for the bolus-treated group to gain more weight than the controls.     

Studies on the replacement policies in dairy cattle. III. Influence of variation in reproduction and production

The optimum policy of insemination and replacement of dairy cows was determined by the dynamic programming technique. The model used in the previous study was extended to allow variation in time of conception. From 2 to 7 months after calving three alternatives were considered for an open cow namely (a) inseminating the cow, with a calculated probability of success, (b) leaving her open, and (c) replacing her immediately. When it was profitable to leave a cow open, the optimum time for replacement during the lactation period was determined.The minimum production level for insemination to be the optimum choice depended on the stage of lactation and the parity of the cow. In the optimum situation the average calving interval was 371 days, while 13% of the cows had an interval of 14 months or longer.The optimum policy was greatly affected by changes in the replacement heifer price. Changes in the probability of conception and persistency of milk production had significant but smaller effects. In herds with a smaller decline in production after the peak, insemination should be continued for longer than in herds with a larger decline.The relation between production and calving interval that resulted from the optimum policy was determined. When a measure of milk production was used that was not affected by gestation, the average correlation was 0.09. The correlation increased to 0.35 when the total 305-day production was used.     

Infectivity virulence and immunogenicity of Anaplasma centrale live blood vaccine

Cross-bred Bos taurus calves, aged between 6 and 8 months, were inoculated with the Onderstepoort Anaplasma centrale live blood vaccine. One group of 15 calves were inoculated once only, while a 2nd group of 15 were revaccinated 6 months later. All the animals were challenged with approximately 1 X 10(10) Anaplasma marginale parasites of a known virulent strain 8 months after the first vaccination. The results of blood smear examination and the card agglutination test indicated that only 20 out of 30 animals vaccinated contracted A. centrale infections after the first attempt, and 3 out of 5 after the second. The vaccine conferred only partial immunity to challenge with a virulent A. marginale strain.     

Isolation and characterization of the heat stable enterotoxin from a pathogenic bovine strain of Escherichia coli

A heat-stable enterotoxin secreted by a pathogenic strain of Escherichia coli of calf origin was purified to homogeneity by a procedure involving acetone fractionation, DEAE cellulose chromatography, Biogel P2 chromatography and size exclusion high pressure liquid chromatography. The purity of the product was ascertained by amino-acid analyses and amino acid sequence using manual degradation with 4-N, N dimethylaminoazobenzene-4' isothiocyanate (DABITC) and an automatic gas phase sequenator. The following amino acid sequence is proposed: Asn-Thr-Phe-Tyr-Cys-Cys-Glu-Leu-Cys-Cys-Asn-Pro-Ala-Cys-Ala-Gly-Cys-Tyr. It is identical to a similar active peptide isolated from strains of porcine origin. Antibodies to ST were successfully produced in rabbits using a conjugate with bovine serum albumin. The ultraviolet absorption and circular dichroism spectra of the active product were recorded and discussed.     

The Results of Using Faecal Culture as Confirmation Test of Paratuberculosis‐seropositive Dairy Cattle

A total of 15 822 cattle aged 3 years and older, belonging to 378 randomly selected herds, were tested for paratuberculosis using an absorbed enzyme‐linked immunosorbent assay (ELISA); 3.3% tested positive. This percentage was lowest for the group of cattle aged 3–4 years (2.3%) and highest for cattle with the age of 5–6 years (4.5%). The mean Sample to Positive (S/P) ratio of seropositive cattle vaccinated against paratuberculosis was higher (0.75 ± 0.33) than that of seropositive, non‐vaccinated cattle (0.58 ± 0.26). Faecal samples of 422 ELISA‐positive cattle were cultured for the presence of Mycobacterium avium subsp. paratuberculosis, 12% of these were contaminated. The percentage of non‐contaminated samples with positive culture results was 17.3%, with a substantial difference between vaccinated (1.7%) and non‐vaccinated cattle (20.2%). Of the positive cultures, the number of colonies varied from 1–10 (22% of cultures), 11–100 (22%), to more than 100 (55%). The percentage of ELISA‐positive, non‐vaccinated cattle tested culture‐positive was positively correlated with the magnitude of the S/P ratio. This percentage varied from 12% (S/P ratio 0.3–0.5) to 58% (S/P ratio > 1.1), a result that might have implications for interpretation of the test. In this study, the percentage of ELISA‐positive cattle with positive faecal culture results was limited and these individuals were mostly moderate to heavy shedders.     

Effects of diet formulations containing proteins from different sources on intestinal colonization by Campylobacter jejuni in broiler chickens

The objective of this study was to compare the effects of 3 diet formulations containing different protein sources (animal, plant, and a combination of animal and plant) on the colonization of Campylobacter jejuni in the gastrointestinal tract of broiler chickens. A freshly isolated strain of C. jejuni (biotype IV, serotype HS O:21, O:29, HL untypable) from a broiler chicken was used to infect 3-day-old chicks that had been free of C. jejuni; 0.5 mL of an inoculum containing 10⁸ colony-forming units was administered orally. Shedding of the organism was studied, and C. jejuni in the ceca, jejuni, and crop were enumerated by quantitative culture. The isolates recovered from the birds during the study period of 35 d were characterized and confirmed as C. jejuni by the use of standard methods and underwent biotyping, serotyping, antimicrobial susceptibility testing by disk diffusion and the E-test, and flagellin gene typing. A cyclical pattern of shedding of C. jejuni was observed in all the birds. Colonization was highest in the ceca. The ceca of birds receiving plant-protein-based feed had significantly less colonization then the ceca of birds receiving the other types of feed, whereas the differences in colonization of the jejuni and crops were not significant. Characterization by biotyping, serotyping, and flagellin gene typing showed that 95% of the recovered isolates were identical to the strain used for infecting the chicks. However, with the Lior-HL typing scheme, 74% of the recovered isolates were HL untypable. Antimicrobial resistance testing did not reveal significant differences between the infecting strain and the recovered isolates among the different feed groups.     

A Stenosis of the Isthmus Aortae Concurrent with Multiple Defects in a Calfheart An Attempt at an Embryological and Phylogenetical Explanation

The findings in a calfheart with multiple ventricular septum defects and an isthmus stenosis in an aorta with its origin in the right ventricle have been described and discussed. The anomalies are explained embryogenetically as well as phylogenetically. No choice could be made between the theories. The author states: The phylogenetic theory needs more attention in future comparative studies of anomalies of the heart.     

OSTEOCHONDROSIS LESIONS OF THE CANINE SHOULDER: CORRELATION OF POSITIVE CONTRAST ARTHROGRAPHY AND ARTHROSCOPY

In this study the correlation between positive contrast arthrography and arthroscopy was evaluated in a series of 20 shoulder joints (12 dogs) with radiographic and clinical evidence of osteochondrosis. The joints were consecutively examined by arthrography and arthroscopy. In 12 joints arthrography revealed the presence of a cartilage flap, and this finding was confirmed by arthroscopy. In 3 out of 8 joints where arthrography failed to demonstrate rupture of the cartilage, arthroscopy revealed the presence of a distinct fissure line. In 2 joints arthroscopy demonstrated a lesion comparable with chondromalacia and in 3 only a dimple in the articular cartilage was found. In 2 joints arthroscopy revealed the presence of small joint mice not detected by arthrography. Kissing lesions on the surface of the glenoid cavity opposite to cartilage flaps could be demonstrated as well. Evaluation of synovial inflammation, judged by the aspect and pattern of the synovial villi, correlated well with histologic findings. These results indicate that arthroscopy is a complementary examination in painful joints where arthrography fails to demonstrate rupture of the articular cartilage. It could be the procedure of choice if diagnostic and surgical arthroscopy can be combined. However, arthrography remains the technique of choice to demonstrate joint mice within the bicipital tendon sheath.