Pregnancy Detection via the Early Conception Factor Assay
by Darrel J. Kesler, Teresa L. Steckler, Raymond N. Summers, and Theodore F. Lock
TAKE HOME MESSAGES
- Both the ECF and progesterone assays were 100 percent accurate in
diagnosing open cows (cows open ÷ cows diagnosed open) although eight of the
cows diagnosed pregnant via ECF, and two cows diagnosed pregnant via
progesterone were open. Both
pregnant cows were diagnosed pregnant with both assays.
- Although both assays were 100 percent repeatable, three of the
four non-inseminated cows were diagnosed pregnant by the ECF assay. Therefore, these authors can not recommend the early conception factor
assay; however, further research is warranted.
A new method of pregnancy detection has been advertised. This method involves the assay of serum samples collected 12 to 48 hours
after insemination. The
manufacturer (Concepto Diagnostics of Knoxville, TN) reports that it “is a
unique immunoassay to identify the open cow within 12-48 hours of breeding. The test is conducted only on serum samples using the monoclonal-polyclonal
antibody ‘dip stick’ methodology with gold as the indicator. This is not an absolute diagnosis of open cows. There are approximately 4 percent false positive results in serum samples
collected 12-24 hours” after insemination. Because the manufacturer does not identify the compound being assayed and
because no early conception factor has been reported in the scientific
literature, the authors purchased kits and evaluated the assay on a group of
cows synchronized with the “OvSync” procedure.
MATERIALS AND METHODS
Early conception factor kits were purchased from Concepto
Diagnostics (Knoxville, TN) and used for three evaluations. The early conception factor assay utilizes test cassettes, droppers, and
wash solution. Test cassettes are
removed from a foil pouch and labeled. One
drop of serum is added to the well in the cassette followed by four drops of
wash solution. Results are read 0.5 to 2 hours later by observing for the
presence of one (nonpregnant) or two (pregnant) bands. Materials for 25 assays and were purchased for $128 ($5.12 per assay).
Evaluation 1. A
group of sixteen mature lactating cows were bled 30 hours and 21 days after
insemination (day +1). Before
insemination, cows were administered GnRH (day -9), PGF2"
(day -2), and GnRH (day 0) for synchronization (the “Ovsync” procedure). Serum samples were assayed for early conception factor (+30
hour blood samples; ECF) and progesterone (day +21 blood samples; P4). Pregnancy was confirmed by transrectal ultrasonography 29 days
Evaluation 2. Four
samples from evaluation 1 were randomly selected and assayed via the ECF assay a
second time on another day.
Evaluation 3. Four
samples from cows not inseminated were selected from another study and assayed
via the ECF assay.
RESULTS AND DISCUSSION
Because it was difficult to ascertain the presence of the
second band (the band indicating pregnancy) on the test cassettes, six
individuals were asked to read the cassettes for pregnancy. Individuals read the cassettes without knowledge of the decision of the
others. Four of the six individuals
agreed in all cases.
In evaluation 1, two of the cows were diagnosed pregnant
and 14 open by ultrasound. Both
assays (ECF and progesterone) were 100 percent accurate in diagnosing open cows
(cows open ÷ cows diagnosed open), although eight of the cows diagnosed
pregnant via ECF and two cows diagnosed pregnant via progesterone were open
(Table 1). This may suggest high
embryonic loss. Both pregnant cows
were diagnosed pregnant with both assays. In
evaluation 2, both assays were repeatable (Table 1). In evaluation 3, three of the four non-inseminated cows were diagnosed
pregnant (Table 1).
The ECF assay correctly identified open cows and pregnant
cows although eight of the cows diagnosed pregnant were open. The eight open cows diagnosed pregnant may have had early embryonic loss. The assay was 100 percent consistent (evaluation 2). However, three of the non-inseminated cows were diagnosed
pregnant (evaluation 3). Therefore,
the assay is not measuring a substance produced by the embryo. However, because the assay correctly identified open cows and pregnant
cows in evaluation 1 although eight of the cows diagnosed pregnant were open,
the ECF assay may be assaying some factor associated with favorable
establishment of pregnancy.
Progesterone was determined on day 21 as a control assay. Although progesterone has never been demonstrated to be 100 percent
accurate because of embryonic loss, it was more reliable than the early
conception factor assay. Therefore, these authors can not recommend the early
conception factor assay, but the progesterone assay may be a useful management
(Table can be viewed in the
Table 1. Results of the
early conception factor (ECF) and progesterone (P4) assays.