great lakes dairy sheep symposium - the Department of Animal ...

ACCURACY OF THE PORTASCC® MILK TEST FOR THE DETECTION OF
SOMATIC CELLS IN SHEEP MILK
Introduction
Yves M. Berger
Spooner Agricultural Research Station
University of Wisconsin- Madison, Spooner, Wisconsin, USA
Cheesemakers are more and more concerned about high somatic cell count in milk because
of lower cheese yield and possible cheese flavor alteration. Many of them are including financial
premiums or penalties for milk with low or high somatic cell count. It is therefore important to
be able to identify, quickly and accurately, animals that consistently have high somatic cell
counts (indicators of chronic mastitis). Up to now the CMT (California Mastitis Test) was the
only animal side test available, but was often found to be inaccurate or insensitive. Recently,
Portacheck (www.portacheck.com), a division of Portascience Inc., developed a quick,
affordable on-farm somatic cell test for sub-clinical mastitis screening. This test could be an
excellent management tool for dairy herds. No trial, however, has been performed to control the
accuracy of the test on sheep milk. During the course of the 2006 milking season, the Spooner
Research Station tested the product for a possible application as part of its management routine.
Description of the Product
PortaSCC® consists of a strip (2.75 inch long, 5/8 inch wide, and 1/8 inch thick). At one end,
there is a small circular cut out forming a well. A drop of the milk to be tested is poured in the
well through a calibrated pipette included in the kit. Three drops of an activator solution are
poured in the same well. Both, milk and solution are quickly absorbed by the material of the
strip. The test strip is allowed to dry for 45 minutes during which chemical reactions occur.
Reading of the strip can be done either by examination of the color changes in the well which
gives a range of somatic cell counts ( 2
million cells) or through a small hand held electronic reader for more accurate information. The
test is easy to perform and does not require any special equipment
Description of Tests Performed
A total of 242 sheep milk samples were tested with the PortaSCC® according to
manufacturer information at four different stages of the lactation. Ewes were chosen at random at
each test.
- 54 early lactation ewes on 2/21/06
- 52 early-mid lactation ewes on 3/21/6
- 18 ewes on 4/17/06 and 7 ewes on 4/20/06
- 30 in mid lactation ewes on 5/30/06
- 41 late lactation ewes on 8/22/06, repeated twice (2 different strips)
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