THE ISOLATION OF LENTOGENIC STRAINS OF NEWCASTLE DISEASE VIRUS IN AUSTRALIA

SUMMARY Twelve isolations of Newcastle disease virus were made from 77 clinical samples from chickens with conjunctivitis, respiratory disease, proventriculitis and bursal atrophy. Nine of the Isolations were made from chickens with conjunctivitis. The viruses were identified as Newcastle disease virus by inhibition of their haemagglutinins with specific antiserum to Newcastle disease virus. The viruses failed to kill chicken embryos after inoculation into the allantoic cavity and they were judged to be lentogenic strains. There was no evidence that the Newcastle disease viruses were responsible for any of the clinical conditions from which they were isolated. The presence of other agents in 10 of the samples was indicated by reduced production of haemagglutinin in allantoic fluids of infected embryos, by deaths of infected embryos, by the production of cytopathic changes in avian cell cultures and by electron microscopy. Three isolations of infectious bronchitis virus, 2 of avian adenovirus and one of avian reovirus were made. Other samples were suspected of containing infectious bronchitis virus and mycoplasmas, but these were not isolated. The Newcastle disease viruses failed to produce plaques in chicken embryo fibroblast cell cultures and they were separated from the contaminating agents by haemagglutination and elution followed by passage at terminal dilution in chick embryos. No Newcastle disease virus was isolated from 60 caecal tonsils and 60 lung samples from 9-week-old broiler chickens. Eight lung samples yielded mycoplasmas that caused haemadsorption in chicken cell cultures. The mycoplasmas were probably Mycoplasma gallisepticum.     

Attitudes and practices of Queensland dairy farmers to the control of the cattle tick, Boophilus microplus

Objective To determine practices for the control of cattle ticks on dairy farms in Queensland, the attitudes of farmers to tick infestations and to identify opportunities for and barriers against the introduction of non-chemical methods of tick control.
Design A survey of 199 dairy farmers from tick-infested parts of Queensland was undertaken by 20 dairy advisers and stock inspectors from October 1996 to June 1997. The sample was a proportional, random selection of dairy farms from four regions. A personal interview was conducted with each farmer and answers to 134 questions were obtained.
Results and conclusions Most farmers were not concerned by cattle ticks on their own farms, although they believed that ticks are important to the dairy industry. They were most concerned about the development of chemical resistance by cattle ticks. Inadequate facilities and lack of motivation appeared to be the factors most limiting to improving the methods of control. Most farmers claimed to have only small numbers of ticks at worst. Although a control program recom mended by the Queensland Dairyfarmers' Organisation was well regarded by farmers, few had adopted it. Many farmers saw no need to implement a strategic control program.     

A successful attempt to raise goat kids free of infection with caprine arthritis encephalitis virus in an endemically infected goat herd

Goat kids from a herd endemically infected with caprine arthritis encephalitis (CAE) virus were raised according to 3 methods. One group of ten goat kids was removed from infected does at birth before suckling or licking by the doe could occur (snatch birth technique). Kids were fed on goat colostrum, which had been heated to 57 degrees C for ten minutes and then held in a thermos flask for one hour. Subsequently the kids were fed reconstituted spray dried cows' milk powder. They were raised apart from infected goats with separation maintained by a wire fence. Contact occurred across-the-fence. Passively acquired serum antibody to CAE virus was detected in some kids at two to three months of age. Nine of the ten goats were negative for serum antibody to CAE virus when tested at 5-6, 9 and 12 months of age. One goat was positive at three and nine months of age but was negative when tested at 12 months of age. A second group of four kids was removed at birth and fed heat-treated goat colostrum, followed by milk from CAE virus-infected does. All four kids became infected with CAE virus; they developed serum antibody to CAE virus between 5-6 and 9 months of age. A third group of two kids was not removed from their infected dams. Both kids were infected at 5-6 and 9 months of age.     

Cell surface markers on canine lymphocytes.

Reference values for T and B lymphocytes were determined on lymphocytes from canine thymus, spleen, lymph node, bone marrow, and peripheral blood by use of erythrocyte (E) and erythrocyte-antibody-complement (EAC) rosette assays, plus a direct fluorescent technique for assay of surface immunoglobulins. Numbers of T lymphocytes, indicated by E rosette formation with human erythrocytes, ranged from a low of 1% in the thymus to 13% in the peripheral blood, whereas B-lymphocyte numbers ranged from 3% (thymus) to 41% (bone marrow) and from 6% (thymus) to 36% (bone marrow), as indicated by EAC rosette formation or presence of surface immunoglobulins respectively. Stimulation of peripheral blood lymphocytes with either phytohemagglutinin or concanavalin A increased the total number of E-rosetting cells two to threefold, whereas the number of EAC-rosetting cells decreased by half. Further, the percentage of cells bearing Fc receptors increased after phytohemagglutinin stimulation. These results indicate the E rosette technique can be used to identify and to monitor a population of canine T lymphocytes.     

Embryo Production in Superovulated Goats Treated with Insulin Before or After Mating or By Continuous Propylene Glycol Supplementation

Seventeen adult and cyclic Moxoto goats were synchronized using 60 mg MPA vaginal sponge for 11 days and 50 μg cloprostenol, 48 h before sponge removal, and superovulated with 120 mg pFSH i.m. in decreasing doses at 12 h intervals for three consecutive days. In seven goats, 0.2 IU/kg BW/day of long acting insulin was subcutaneously injected at same time as pFSH, and in the other five goats, the same dose of insulin was injected for three consecutive days starting 24 h after mating. Finally, five goats were supplemented with an oral dose of 80 ml/goat/day of propylene glycol continuously during the experiment. The animals were flushed at 7 days after mating and the embryos were classified based on International Embryo Transfer Society criteria. Blood samples were collected every 3 days for insulin assay. Administration of insulin raised the insulin levels of the goats (p < 0.05), whereas in the group treated with propylene glycol, insulin rate was different only between FSH treatment and after mating (p < 0.05). Similar rates of recovery for total (80.05 ± 9.78%) or transferable structures (61.03 ± 15.13%) were obtained. Treatment was not influenced (p > 0.05) by responsiveness to superovulation, which averaged 64%. By contrast, insulin treatments were shown to increase the number of embryos considered excellent with respect to goats supplemented with propylene glycol (p < 0.05). When insulin was given before mating, a strong relationship (r = 0. 90) (p < 0.05) between number of transferable embryo and ovulations was observed in the animals. In conclusion, superovulated goats treated with low doses of exogenous insulin resulted in an enhancement in embryo quality, which was related to changes in circulating insulin concentrations.