Use of commercially available ELISAs to help determine estrous status in female swine

Gary C. Althouse, DVM, PhD, Dipl. ACT; James E. Hixon, MS, PhD

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Objective: To determine the accuracy of two commercially available ELISAs in discriminating between high and low serum progesterone (P4) concentrations in female swine.

Methods: Serum was randomly harvested from 65 crossbred females of various ages and parities. Progesterone concentrations were categorized as "high" (> 2.5 ng per mL) or "low" (<= 2.5 ng per mL) using the Progestassay(TM) (Synbiotics Corp., San Diego, California) ELISA assay. Similarly, P4 concentrations were categorized as "high" (> 5.0 ng per mL) or "low" (<= 5 ng per mL) using the Target (BioMetallics, Princeton, New Jersey) ELISA assay. The specificity and sensitivity for each ELISA were determined by comparing the results of both test kits to radioimmunoassay (RIA) methods.

Results: Serum P4 concentrations using RIA were either <= 0.42 ng per mL, or ranged from 3.35-17.87 ng per mL. Both ELISA test kits produce a blue color that is inversely related to serum P4 concentration. Both test kits allowed a clear distinction between high and low concentrations of P4 in swine serum. The Progestassay was 100% specific and 95.1% sensitive for differentiating low versus high P4 concentrations. The Target test kit was 100% specific and 86.9% sensitive. For the serum samples included in the present study, the lowest concentration, as measured by RIA, that tested as "high" by the Progestassay was 3.35 ng per mL, and the lowest RIA concentration that tested as "high" by the Target assay was 5.57 ng per mL. Statistically, no differences were found between the RIA and Progestassay (P=.25) but differences between the RIA and Target were significant (P=.007). Differences between the Progestassay and Target approached significance (P=.06).

Implications: Both the Progestassay and Target ELISA test kits work well at semi-quantitative measurement of serum P4 concentrations in swine. Both kits are simple to run and take only 15-25 minutes to perform on the farm. The ability to run these tests sow-side should make them a practical aid when investigating herd reproductive problems.

Keywords: serum, progesterone, ELISA, reproduction

RIS citationCite as: Althouse GC, Hixon JE. Use of commercially available ELISAs to help determine estrous status in female swine. J Swine Health Prod 1999;7(2):65-68.

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