Title page for ETD etd-04142009-040817
|Type of Document
||Grove, Tina Moler
||Effects of using an enzyme-linked immunosorbent assay to monitor the control of Staphylococcus aureus mastitis in dairy herds
||Master of Science
|Jones, Gerald M.
|Barnes, Michael A.
|Bishop, J. Russell
|Vinson, William E.
- Enzyme-linked immunosorbent assay
|Date of Defense
Bovine mastitis is the most important economic disease to the dairy
industry with losses estimated at 2 billion dollars per year in the United
States. Staphylococcus aureus (.§.. aureus) is the primary cause of
contagious mastitis. Conventional culture methods (National Mastitis
Council) were used as a basis for comparing the ability of the enzyme linked
immunosorbent assay. ProStaph I™, to identify s. aureus. The test
had an accuracy of 96%, with a sensitivity of 90% and a specificity of
97%. Results indicated that rinsing teat-cup liners with a 25 ppm
iodophor or 100 ppm chlorine solution reduced the presence of S. aureus on
the liners by 97%. ProStaph I was used to rapidly screen DHIA preserved
milk samples in 10 Virginia cooperator herds. Herds were classified as
high (>10% infected) or low prevalence (<10% infected). There were six
high prevalence herds after the first test. Average prevalence of cows
scoring Ab +2 and +3 was 11.9% ± 7.9. Over the seven month study,
prevalence of positive cows declined significantly (P<.OI), but somatic
cell count remained relatively unchanged (P>.lO). Four herds continued to
have >10% of the animals infected. Incidence of new infection averaged
3.6% ± 2.8 from the first to the last test. Chronic cows averaged 6.9% ±
4.8 over the seven month study. Analysis of variance showed significant
(P<.Ol) effects of herd on ProStaph I score J milk yield, and see.
Elevated ProStaph I scores were highly correlated (P <.01) with increases
in lactation number. ProStaph I changed quadratically (P<.Ol) with
increasing SCC. Somatic cell count increased (P<.OI) as ProStaph I score
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