Illini DairyNet Papers
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- 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 post-insemination.
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 tool.
(Table can be viewed in the PDF file)
Table 1. Results of the early conception factor (ECF) and progesterone (P4) assays.