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1996-03-04
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Document 0729
DOCN M9640729
TI A serological survey of bovine syncytial virus in Ontario: associations
with bovine leukemia and immunodeficiency-like viruses, production
records, and management practices.
DT 9604
AU Jacobs RM; Pollari FL; McNab WB; Jefferson B; Department of Pathology,
University of Guelph, Ontario.
SO Can J Vet Res. 1995 Oct;59(4):271-8. Unique Identifier : AIDSLINE
MED/96127198
AB Of the 920 cows tested, 56.7% showed antiretroviral serological
reactivity. Prevalence rates (95% confidence interval) of antiretroviral
antibodies among individual dairy cows in Ontario were: BIV 5.5%
(4.0-7.0), BLV 25.7% (22.9-28.6), and BSV 39.6% (36.4-42.8). The
following percentages of cows showed serological reactivity against the
specified retroviruses: BIV 2.3%, BLV 14.0%, BSV 27.5%, BIV and BSV
1.3%, BIV and BLV 0.9%, BLV and BSV 9.9%, BIV and BLV and BSV 0.9%.
These rates of sero-positivity are similar to those found in other
countries. Serological test results were not adjusted for sensitivity
and specificity. The prevalence rates of antibodies to the three
retroviruses (BIV, BLV, and BSV) were significantly different, but no
associations were observed between specific retroviral serological test
results among individual cows. The prevalence rates of BIV and BSV
seropositivity were constant across Ontario, whereas, there was a
significant trend for the prevalence rate of BLV seropositivity to
decrease going from southwestern to eastern Ontario; cows in eastern
Ontario had approximately half the prevalence rate of those in
southwestern Ontario. Cows that were seropositive for BSV were
significantly older than BSV seronegative cows. There was no association
between culling rate and BSV serology. Significant negative associations
were found with winter or summer housing of calves separate from adults
and summer outdoor exercise for dry cows. The use of calf hutches in the
summer had a significant positive association with BSV seropositivity.
Regression analyses were done to assess the association of retroviral
(BIV, BLV, and BSV) seropositivity on calving interval, milk somatic
cell count, and milk production. Serological test results for BIV, BLV,
and BSV were entered into all models and all models were adjusted for
intra-cluster (intraherd) correlation. Herd size and age were found to
be important confounding variables. BIV seropositivity was not
associated with any changes in production using this approach, however
when considered in isolation BIV seropositivity remained associated with
decreased milk production. BLV seropositivity was significantly
associated with longer calving intervals and higher somatic cell counts
in older cows. As well, in older cows, BSV seropositivity was
significantly associated with higher milk production.
DE Age Factors Animal Antibodies, Viral/*BLOOD Birth Intervals Cattle
Cattle Diseases/*EPIDEMIOLOGY/IMMUNOLOGY/VIROLOGY Female Housing,
Animal Immunodeficiency Virus, Bovine/*IMMUNOLOGY Leukemia Virus,
Bovine/*IMMUNOLOGY Milk/METABOLISM Ontario/EPIDEMIOLOGY Prevalence
Retroviridae Infections/EPIDEMIOLOGY/IMMUNOLOGY/*VETERINARY/ VIROLOGY
Spumavirus/*IMMUNOLOGY Support, Non-U.S. Gov't JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).