Determination of steroid hormones in goats' milk and plasma as an aid to pregnancy diagnosis using an ELISA

Department of Veterinary Clinical Science, University of Liverpool Veterinary Field Station, Leahurst, Neston, South Wirral.

Commercial ELISA kits for the determination of steroid hormones in milk and blood of domestic animals have been used by veterinary surgeons in practice as a method of pregnancy diagnosis in cattle, horses and pigs. In goats, the complex metabolism of steroid hormones in the mammary gland has made the test unsatisfactory. In five non-pregnant Saanen does, milk and blood samples were taken daily through a complete oestrous cycle, and the concentrations of progesterone measured by ELISA. A wide variation in the pattern of progesterone concentration was recorded. In seven non-pregnant and early pregnant does (less than 35 days) the mean concentration of oestrogens in milk was 0.5 ng/ml. Pregnancy in 88 does was subsequently predicted, based upon a concentration of oestrone sulphate in milk over 0.5 mg/ml, and was approximately 80 per cent accurate for determination of both pregnancy and non-pregnancy when compared with actual kidding data. Reasons are given for these errors.