A competitive enzyme immunoassay for the determination of ovine growth hormone (oGH) was developed. The assay is based on (anti-rabbit IgG) goat IgG-coated microtitreplates, anti-oGH from rabbits, biotinyl-oGH and streptavidin-horseradish peroxidase. The assay is done directly with 40 ml of plasma and the calibration graph (90% relative binding at 0.38 ± 0.02 ng ml -1 and 50% relative binding at 3.80 ± 0.18 ng ml -1 ) is prepared in plasma without measurable endogenous oGH. Recovery in different plasma samples with added oGH amounted to 96.78 - 100.03 %, and all variabilities were < 10.44. The assay shows no significant binding of oFSH, oLH, oTSH and oPRL. The assay detects high and low plasma oGH levels within the physiological variation as well as changes in plasma oGH after stimulation with growth hormone releasing factor. Hence, it offers a reliable alternative radioimmunoassay. However, a reference method providing evidence of the identity of exogenous oGH will be required for proving illegal treatment with oGH and for forensic purposes.

A competitive enzyme immunoassay for the determination of ovine growth hormone (oGH) was developed. The assay is based on (anti-rabbit IgG) goat IgG-coated microtitreplates, anti-oGH from rabbits, biotinyl-oGH and streptavidin-horseradish peroxidase. The assay is done directly with 40 ml of plasma and the calibration graph (90% relative binding at 0.38 ± 0.02 ng ml -1 and 50% relative binding at 3.80 ± 0.18 ng ml -1 ) is prepared in plasma without measurable endogenous oGH. Recovery in different plasma samples with added oGH amounted to 96.78 - 100.03 %, and all variabilities were < 10.44. The assay shows no significant binding of oFSH, oLH, oTSH and oPRL. The assay detects high and low plasma oGH levels within the physiological variation as well as changes in plasma oGH after stimulation with growth hormone releasing factor. Hence, it offers a reliable alternative radioimmunoassay. However, a reference method providing evidence of the identity of exogenous oGH will be required for proving illegal treatment with oGH and for forensic purposes.