Bovine spongiform encephalopathy: detection of fibrils in the central nervous system is not affected by autolysis

The effect of autolysis on the electron microscopic detection of the characteristic abnormal fibrils, originally called 'scrapie-associated fibrils', was investigated in four different areas of the central nervous system (CNS) from 10 clinically suspect BSE cattle after post mortem delay and compared with the histopathological diagnosis. The tissues for fibril detection were subjected to controlled incubations to simulate autolysis. Fibril detection in all areas sampled from nine animals in which BSE was confirmed by histopathology was not affected by combined post mortem delays and specific controlled treatments. Detection of fibrils from the cervical spinal cord was no less sensitive than from brain areas. Fibrils were not detected in the one suspect case in which histopathology did not reveal lesions of BSE. The study confirms that fibril detection is of diagnostic value in BSE when post mortem autolysis renders CNS material unsuitable for histopathology.     

Neuropathological findings in cats with clinically suspect but histologically unconfirmed feline spongiform encephalopathy

Central nervous system (CNS) tissues from 192 cats with neurological signs were examined histologically, and tissues from 173 of them were later examined immunohistochemically as part of a survey to determine the prevalence of feline spongiform encephalopathy (FSE). One of the cats was from Norway and the others were from Great Britain. The most commonly recorded clinical signs were ataxia, behavioural changes and epilepsy, but none of the cats had histopathological evidence of FSE. The most common organic CNS lesions were non-suppurative encephalomyelitis in 28 per cent, neoplasia in 15 per cent and a heterogeneous group of degenerative encephalopathies in 9 per cent of the cats. A range of minor histological lesions of uncertain significance was also observed. No histological lesions were observed in the tissues of 63 (33 per cent) of the cats. Disease-specific prion protein (PrP(Sc)) was observed in only one of the 173 cats examined by immunohistochemistry.     

Economic analysis of feeding pasteurized nonsaleable milk versus conventional milk replacer to dairy calves

OBJECTIVE: To determine growth, morbidity, and mortality rates in dairy calves fed pasteurized nonsaleable milk versus commercial milk replacer and compare economics of feeding pasteurized nonsaleable milk versus commercial milk replacer in dairy calves. DESIGN: Clinical trial. ANIMALS: 438 dairy calves. PROCEDURE: Calves were assigned at 1 to 2 days of age to be fed pasteurized nonsaleable milk or a commercial milk replacer until weaned. Body weight was measured at the time of study enrollment and at the time of weaning, and any medical treatments administered and deaths that occurred prior to weaning were recorded. A partial budget model was developed to examine the economics of feeding pasteurized nonsaleable milk versus commercial milk replacer. RESULTS: Calves fed conventional milk replacer had significantly lower rates of gain (-0.12 kg/d [-0.26 lb/d]), lower weaning weights (-5.6 kg [-12.3 lb]), higher risk for treatment during the summer and winter months (odds ratio [OR], 3.99), and higher risk of death during the winter months (OR, 29.81) than did calves fed pasteurized nonsaleable milk. The estimated savings of feeding pasteurized nonsaleable milk, compared with milk replacer, was dollars 0.69/calf per day. The estimated number of calves needed to economically justify the nonsaleable milk pasteurization system was 23 calves/d. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that dairy calves fed pasteurized nonsaleable milk have a higher growth rate and lower morbidity and mortality rates than do calves fed conventional milk replacer. Feeding pasteurized nonsaleable milk could be an economically viable strategy for dairy calf producers.     

Herd-level factors associated with isolation of Salmonella in a multi-state study of conventional and organic dairy farms II. Salmonella shedding in calves

The objective of this study was to evaluate associations between herd-level factors and the isolation of Salmonella in calves from dairy farms in Minnesota, Wisconsin, Michigan and New York. Study farms were 129 conventional and organic farms enrolled without regard to previous history of Salmonella infection. Herds were sampled at 2-month intervals over a 1-year period. Salmonella was isolated in fecal samples from 176 (3.8%) of 4673 preweaned calves with 40 (31.0%) of 129 farms having at least one positive calf sample over the course of the study. Multivariable logistic regression using the generalized estimating equations approach was used to evaluate risk factors for Salmonella shedding after adjustment for effects of herd size, season, state of origin and the multiple sampling occasions per herd. Factors retained in the final model that were associated with an increased odds for Salmonella shedding were lack of routine feeding of milk replacer containing antimicrobials to preweaned calves (OR = 2.8, 95% CI: 1.4, 5.8), use of maternity housing as a hospital area for sick cows more than once a month (OR = 2.1, 95% CI: 1.1, 4.0), and cow prevalence level by visit, categorized into the following four-levels: ≥20% (OR = 11.6, 95% CI: 5.7, 23.7), 10–19.9% (OR = 4.7, 95% CI: 2.0, 11.5), 0.1–9.9% (OR = 3.6, 95% CI: 1.5, 8.7) and 0% (reference level). Herd size was not associated with Salmonella shedding in the final multivariable model.     

The immunoprophylaxis of of rotavirus infections in lambs.

The effect of colostrum or serum feeding on subsequent rotavirus infections was investigated in neonatal gnotobiotic lambs. Immunity after feeding colostrum did not depend on absorption of passively acquired antibody into the circulation. Protection against clinical disease depended on the volume of colostrum ingested. The protection afforded by feeding serum was specific, since serum free of rotavirus antibody failed to confer protection. Immune serum fed at a rate of 2.5 ml per kg twice daily protected against rotavirus infection. Also, it was shown by intraperitoneal inoculation of immune serum that protection could occur in the absence of ingested antibody, presumably by transfer of antibody into the gut. The implications of these findings for immunoprophylaxis of rotavirus diarrhoea in lambs and calves are discussed.     

A comparison of red and white light and high and low dietary protein regimes for growing pullets

Medium‐weight hybrid pullets were used to test the effects of (a) providing red instead of white light from 3 to 18 weeks of age and (b) feeding a diet containing 15\ per cent crude protein from 6 to 12 weeks followed by one containing 12 \ per cent crude protein to 18 weeks of age instead of feeding the first‐mentioned diet from 8 to 18 weeks of age.

Results showed that these alternative rearing practices had only a small influence on performance. On balance, any immediate advantages resulting from the use of red light and/or low‐protein food were outweighed by disadvantages which arose in the subsequent laying period.     

Chronic vascular catheterisation of the koala and the rabbit

SUMMARY: Vascular access ports were surgically placed, first in rabbits maintained under laboratory conditions, and then in koalas maintained in a wildlife park. The ports remained patent for 9 months in rabbits and for up to 13 months in the koalas and were removed successfully. They allowed collection of blood samples without assistance or disturbance in koalas, and without stress as reflected by plasma cortisol concentration. The use of retention rings on the cannula tubing is recommended.     

Development of a combined clostridial and Pasteurella haemolytica vaccine for sheep

The efficacy of a multicomponent clostridial vaccine containing Pasteurella haemolytica antigens was tested in specific pathogen free or conventionally reared lambs exposed to experimental infection with P haemolytica serotypes A1, A2 or A6. In four experiments assessment was based upon the findings of clinical, pathological and bacteriological examinations. Three experiments carried out in conventionally reared lambs demonstrated protection against challenge infection with P haemolytica serotypes A1, A2 and A6 in vaccinated lambs. However, the inconsistency of the disease induced in these experiments emphasised the need to perform definitive studies in specific pathogen free conditions. The final experiment was carried out with specific pathogen free lambs and confirmed the efficacy of the multicomponent clostridial vaccine containing P haemolytica antigen in protecting against the effects of infection with P haemolytica serotype A6. In addition, this experiment indicated that the inclusion of several components in a vaccine did not affect the efficacy of an individual antigenic component.