Vaccination and challenge studies with psittacine beak and feather disease virus

SUMMARY: Psittacine beak and feather disease virus (PBFDV) was administered to adult galahs ( Eolophusroselcapillus ) by mouth or by intramuscular injection. Concentration of PBFDV antibodies in serum and excretion of PBFDV were monitored by haemagglutlnation inhibition (HI) and haemagglutination (HA) respectively. After oral administration, 17 of 18 galahs remained clinically normal and a small rise in antibody titre was detected in 3 of 18 birds. After intramuscular administration, antibody was detected in all birds. PBFDV was not detected in the feather dander of birds in either group. One bird developed diarrhoea and high faecal HA titres within 4 days of oral administration and then died. Adult and nestling cockatoos were vaccinated with an experimental inactivated double-oil emulsion vaccine. PBFDV antibody responses are comparable to those induced by a primary-oil emulsion vaccination regimen using Freund's adjuvants. Both vaccines protected nestlings. Three sibling wild-caught sulphur-crested cockatoos were vaccinated but died of PBFD before experimental challenge despite antibody responses in all birds. Unvaccinated control chicks developed acute PBFD within 4 weeks of challenge, probably from PBFDV-induced hepatitis since high concentrations of PBFDV were detected in their livers.     

Laboratory diagnosis of psittacine beak and feather disease by haemagglutination and haemagglutination inhibition

SUMMARY Simple and sensitive haemagglutination and haemagglutination Inhibition assays were developed for psittacine beak and feather disease (PBFD) virus and serum antibody, respectively. The assays were used in the examination of samples from 73 birds clinically affected with PBFD. High antigen titres (log₂ 9 to log₂ 12) were detected In feathers, faeces and cloacal contents of PBFD-affected birds. Antigen was not detected In either faecal or feather samples from 20 normal galahs (Eolophus roselcapillus) and 9 normal sulphur crested cockatoos (Cacatua galerita). After kaolin treatment and haemadsorption of serum, haemagglutination inhibition (HI) antibody titres could not be detected in serum from 42 PBFD-affected birds, whereas serum HI titres from 64 normal psittacine birds ranged from less than log₂ 1 to log₂ 8. Serum and yolk HI antibody responses of 6 PBFD virus-inoculated layer hens were measured. Pre-inoculation chicken sera contained high concentrations of non-specific haemagglutination inhibitors (not detected in chloroform-extracted yolk), which were removed by kaolin treatment and haemadsorption.     

Phosphorus supplements and fluorosis in cattle—a northern Australian experience

SUMMARY Chronic fluoride toxicosis caused lameness, dental lesions and illthrift in an extensive beef cattle herd in northern Australia. Up to 15% of the herd was lame and the disease forced the culling of large numbers of cows. The source of fluoride was fertiliser-grade monoammonium and diammonlum phosphate fed as part of a mineral supplement. Large quantities of mineral supplement were provided to the cattle because lameness was attributed to phosphorus deficiency, which is endemic in the area. Most lameness developed in the late dry season in the post-lactation phase. Severe lameness was caused by fractured pedal bones.     

Epidemiological and clinical investigations into big liver and spleen disease of broiler breeder hens

SUMMARY The epidemiological and clinical features of big liver and spleen disease (BLS) in flocks on two broiler breeder farms were investigated by serology and gross pathology. The most common necropsy findings on farm 1 were splenomegaly and hepatomegaly, with kidney enlargement in some birds. In one flock (farm 1), a decline in egg production began at 40 weeks of age and lasted for 9 weeks. Seroconversion to BLS antigen was first detected at 45 weeks (3.1% of birds) and increased to 72% at 50 weeks, which coincided with clinical recovery in the flock. Antigen was detected before antibody at 44 weeks and persisted at low incidence (<15%). Farm egg production statistics and serology indicated that the disease affected all flocks on the farm. In three of eight flocks, seroconversion was detected in birds before peak production. The birds in the remaining sheds did not seroconvert or become sick until after peak production. On the second farm, sampling began within a flock already experiencing BLS. Clinical signs and pathology were similar to those seen in flocks on farm 1. However, the lesions that were seen in the pancreas in 15% of birds have not been reported previously. BLS antibody was detected in 78%, and circulating antigen in 14%, of sick birds.     

Reproductive and Metabolic Responses of Early‐lactating Dairy Cows Fed Different Dietary Protein Sources

Optimal reproduction is very closely tied with optimal nutrition, and early‐lactation diets in cows are critical to successful reproduction and monitoring is important. To evaluate the effects of different dietary protein sources on metabolic parameters and reproductive activity, a total of 36 Italian Friesian early‐lactating dairy cows were assigned for 16 weeks to three dietary treatments as follow: the control diet contained soya bean meal (SBM) as the main protein source, whereas the experimental diets contained faba bean (FB) or pea seeds (PS) as alternative protein sources. Diets were formulated to be isocaloric and isonitrogenous. Cow blood samples were collected, and plasma were analysed for metabolites, biological enzymes, β‐hydroxybutyrate (BHBA) and non‐esterified fatty acids (NEFA). Feeding alternative protein sources had no effects on most metabolic blood profile, except for blood cholesterol, triglycerides and urea. Results from reproductive parameters indicated that cows fed FB diet had a lower insemination index, but a shorter calving to conception period and an improved conception rate and artificial insemination outcome, when compared to cows fed SBM or PS diets. It can be concluded that replacing conventional dietary SBM with alternative protein sources, especially FB, resulted in improved reproductive performances and metabolic parameters in early‐lactating dairy cows.     

Methods of detection of Chlamydia psittaci in domesticated and wild birds

OBJECTIVE: To study the occurrence of Chlamydia psittaci in domesticated and wild birds and compare the sensitivity of molecular detection with cell culture isolation. DESIGN: Study of cell culture isolation and PCR detection of C psittaci in avian samples. PROCEDURE: Samples were obtained from 485 birds. Domesticated birds were selected at random from pet shops, private aviaries and zoos, while wild birds were captured locally, sampled, and immediately released. Swabs were collected from choanal slit, conjunctiva and cloaca of each bird and pooled. Samples were divided into equal portions for use in PCR dot-blot and cell culture detection. PCR and dot-blot detection was based on the ompB gene. RESULTS: Prevalence of infection varied markedly between flocks of captive birds. It was highest where there were frequent changes in the flock members or where there were many birds confined in small areas. C psittaci was not detected in wild birds or water birds. The sensitivity of cell culture compared to PCR dot-blot detection was 68%. All samples positive by cell culture were also positive by PCR. CONCLUSIONS: PCR-dot blot detection of C psittaci in birds appears to be more sensitive than cell culture isolation in this study. C psittaci infection of birds may occur in clinically normal captive birds.