A heterologous radioimmunoassay for avian prolactin: application to the measurement of prolactin in the turkey.

A specific heterologous double-antibody radioimmunoassay has been developed to measure turkey prolactin (PRL) using a guinea pig anti-hPRL antiserum and 125I-labelled ovine PRL [125I]oPRL. Turkey pituitary prolactin and serum give parallel dose-response curves and no cross-reaction is seen with turkey growth hormone, LH or FSH, or mammalian LH, FSH, TSH, GH or placental lactogens. The RIA is accurate and precise and is sufficiently sensitive to measure PRL in all physiological situations investigated in the turkey. The RIA will measure PRL in several avian species including the chicken, duck, goose, pheasant, pheasant X chicken F1 hybrid, pigeon, quail and rock. Plasma PRL concentrations in laying and broody turkey hens were not significantly different (46.5 +/- 2.5 vs. 39.7 +/- 3.8 ng/ml) but both were significantly higher (P less than 0.001) than in non-laying turkey hens (4.6 +/- 0.7 ng/ml). Oestradiol injection into laying hens did not alter PRL levels while the same injection in non-laying hens caused a significant three-fold increase in plasma PRL levels.