Effect of chemotherapy on semen characteristics of Balami rams infected with Anaplasma ovis

Six intact Balami rams were experimentally infected with Anaplasma ovis. Another six were infected one month after splenectomy and six others served as controls. Clinical manifestations of the disease, first observed between 5 to 7 days post-infection, were more severe and prolonged in the splenectomised-infected than in the intact-infected group. There was progressive deterioration in semen quality, which was also significantly more severe and prolonged in the splenectomised than in the intact-infected rams. Following treatment with long-acting terramycine, clinical recovery occurred earlier in the intact-infected (1–4 weeks) than in the splenectomised-infected group (5–7 weeks). A similar pattern was observed in post-treatment improvement in the spermiogram. However, although the infected animals recovered clinically by 1–7 weeks post-treatment, restoration of the reproductive potential did not occur for 20 to 25 weeks. It appears that stress factors may aggravate the deliterious effects of anaplasmosis.     

Combined effects of fasting and diet on interferon production and virus replication in calves infected with a vaccine strain of infectious bovine rhinotracheitis virus

A study was undertaken to investigate the combined effects of fasting and different diets on interferon (IFN) production and virus replication measured in nasal secretions of calves inoculated with a vaccine strain of infectious bovine rhinotracheitis virus. Four groups of calves were inoculated intranasally with infectious bovine rhinotracheitis virus. Two groups were inoculated 24 hours after onset of a 3-day fast; upon refeeding, 1 group was fed a maintenance diet (M diet) of hay, and the other was fed a higher energy diet (HE diet) of hay and concentrate. Nonfasted control groups were fed the M diet or the HE diet. Overall IFN production was highest (P less than 0.01) in nonfasted calves fed the M diet throughout the study and lowest in nonfasted calves fed the HE diet. Fasted calves refed the HE diet produced consistently and significantly more IFN than did nonfasted calves fed this diet. Fasted calves refed the M diet, however, produced significantly less IFN, compared with control calves fed the M diet throughout the study. Overall mean virus excretion was similar in all groups; therefore, the amount of virus replication per se did not account for the differences in IFN production, nor did greater IFN production result in less virus excretion. Serum cortisol concentrations and immune responses were not significantly affected by fasting or diet.     

Influence of dietary niacin on volatile fatty acids in rumen liquid of sheep and rumen dry matter degradability of untreated and ammonia-treated wheat straw

Three rumen fistulated sheep were fed with roughage (1200 g artificially dried grass) or a concentrate/roughage diet (600 g concentrate, 400 g artificially dried grass per animal and day). The diets were unsupplemented or 0.5, 1 and 2 g niacin per animal and day were added. After a 14-day adaptation period samples of rumen liquid were taken 0, 1, 2, 3, 4 and 6 h after morning feeding. In a second experiment untreated and NH3-treated wheat straw were incubated in nylon bags for 6, 12, 24, 48 and 72 h in the rumen of 5 sheep fed with 1.2 kg artificially dried grass and unsupplemented or supplemented with 1 g niacin per day. Niacin did not significantly influence the total concentration of volatile fatty acids, acetate and branched chain fatty acids in both types of diet (P less than 0.05). 0.5 and 1 g niacin in the roughage and 0.5 g niacin in concentrate/roughage diet increased the propionic acid concentration and reduced the butyric acid concentration in rumen liquid of sheep (P less than 0.05). Niacin resulted in a small decrease (P greater than 0.05) of dry matter degradability in rumen. After 48 h incubation time, the dry matter disappearance of untreated and NH3-treated wheat straw amounted to 35.4 and 46.2% resp. The effects of niacin on rumen fermentation may be useful in avoiding ketogenic situations in dairy cows.     

Comparative serological evaluation of avian influenza vaccine in turkeys

Four- and six-week-old turkeys were vaccinated subcutaneously using avian influenza virus (AIV) A/Duck/613/MN/79 (H4N2) killed oil-emulsion vaccine. Sequential serological tests using agar gel precipitin (AGP), hemagglutination inhibition (HI), and enzyme-linked immunosorbent assay (ELISA) for measuring antibodies to AIV were performed up to 4 weeks postvaccination, when birds were challenged intranasally using A/Turkey/MN/80 (H4N2) live AIV. The ELISA was 25 to 1600 times more sensitive than the HI test and was able to detect antibody production earlier than the HI test. All turkeys with an ELISA titer of greater than or equal to 800 were protected against homologous challenge, as measured by virus recovery 3 days postchallenge. Four turkeys out of 20 serologically negative by AGP and HI tests but ELISA-positive were protected.     

A dot-immunobinding assay for infectious bronchitis virus

Common Whatman filter paper grade 1 and nitrocellulose membrane were compared for their sensitivity in a dot-immunobinding assay for detection of serum antibody titers to Arkansas avian infectious bronchitis virus (AIBV). For a blue to purple color detection, serum antibodies were bound to AIBV antigen adsorbed on the filter-paper discs or nitrocellulose membrane. Rabbit anti-chicken IgG horseradish-peroxidase (HRP) conjugate and hydrogen peroxide with 4-chloro-1-naphthol (HRP-color development reagent) were applied. The study indicates that very small amounts of antigen/antisera are needed for the dot-immunobinding assay. The test is sensitive, economical, and easy to run and can be completed within 6-8 hours.     

Spontaneous and mitogen-induced RNA synthesis by blood lymphocytes from bovine leukemia virus-infected and normal cows

Peripheral blood lymphocytes (PBL) from normal and bovine leukemia virus (BLV)-infected cattle were prepared by density gradient technique and incubated with and without phytohaemagglutinin (PHA) and pokeweed mitogen (PWM). RNA synthesis was determined at different periods of incubation by 3H-uridine incorporation. PBL from BLV-infected cows with persistent lymphocytosis (PL) showed the highest spontaneous RNA synthesis. PBL from BLV-infected cows with normal lymphocyte counts synthesized more RNA than cells from normal animals. Decreased mitogen responses were observed in PBL from infected cows with PL in comparison to normal and BLV-infected cattle without PL. PHA and PWM did not show significant differences in their degree of stimulation of RNA synthesis.     

Leukoencephalomalacia in a horse induced by fumonisin B1 isolated from Fusarium moniliforme

Each of two horses was dosed by stomach tube with culture material on maize of Fusarium moniliforme MRC 826. One horse developed severe hepatosis and mild oedema of the brain after 6 doses of 2.5 g of culture material/kg body mass/day in 7 days. The second horse, in a similar experiment but at a dosage rate of 1.25 g/kg/day, developed mild hepatosis and moderate oedema of the brain. In both animals the brain oedema was particularly noticeable in the medulla oblongata. The mycotoxin fumonisin B1 was extracted and purified from the culture material of F. moniliforme MRC, 826 which contained approximately 1 g/kg of this compound. A horse was injected intravenously 7 times from Day 0-Day 9 with 0.125 mg of fumonisin B1/kg body mass/day. Clinical signs of neurotoxicosis, which appeared on Day 8, included nervousness followed by apathy, a wide-based stance, trembling, ataxia, reluctance to move, paresis of the lower lip and tongue, and an inability to eat or drink. Euthanasia was performed on the horse on Day 10 while the animal was in a tetanic convulsion. The principal lesions were severe oedema of the brain and early, bilaterally symmetrical, focal necrosis in the medulla oblongata. This report provides experimental evidence that fumonisin B1, produced by F. moniliforme, causes equine leukoencephalomalacia.     

Bovine viral diarrhoea virus infections in piglets born to sows vaccinated against swine fever with contaminated vaccine

On eight farms a congenital pestivirus infection in piglets was detected which could be traced to vaccination of the dams against swine fever (SF). Viruses isolated from the piglets were not recognised by monoclonal antibodies (MCAs) against swine fever virus (SFV) and were shown to be bovine viral diarrhoea virus (BVDV) or Border disease virus. The expected 'Chinese' strain of SFV could not be demonstrated in the batch of vaccine that had been used on these farms. Instead, a contaminating pestivirus was recovered which was not recognised by the MCAs against SFV. The contaminant had an unexpectedly high virulence for lambs and induced antibodies against BVDV in lambs and pigs. It could, therefore, be characterised as BVDV or Border disease virus.     

Neodymium:yttrium, aluminum, and garnet laser energy delivered transsclerally to the ciliary body of dogs

Using a hand-held optical fiber, a surgical neodymium:yttrium, aluminum, and garnet laser was used transsclerally on the left ciliary body of 25 dogs. Dogs were assigned to groups and were given low (100 J) and high (238 J) energy levels. In 12 dogs given 100-J energy, the intraocular pressure decreased a mean value of 6 mm of Hg below that in the untreated right eye. However, intraocular pressure returned to the pretreatment value 1 week after treatment. Intraocular lesions were not found by histologic examination 28 days later. In the second group of 13 dogs treated with 238-J energy, 6 were euthanatized 7 days after treatment and 7 were euthanatized 28 days after treatment. A mean decrease in intraocular pressure of 10 mm of Hg in the treated left eye, relative to the untreated right eye, persisted throughout the evaluation period. In eyes examined histologically 7 days after treatment, ciliary hemorrhage and necrosis were prominent. Other histologic changes were minimal and consisted principally of iris stromal hemorrhage. Of 7 dogs examined for 28 days after treatment, 6 remained sighted; in 1 dog, extensive intraocular hemorrhage occurred, eventually resulting in phthisis bulbi. Ciliary atrophy and fibrosis were the important histologic lesions observed 28 days after treatment. Laser energy delivered transsclerally by this optical system effectively induced ciliary necrosis and may be an effective treatment for canine glaucoma.