RADIOIMMUNOLOGISCHE LH-BESTIMMUNG IM BLUTSERUM VOM RIND UNTER BESONDERER BERÜCKSICHTIGUNG DES BRUNSTZYKLUS

Abstract

For radioimmunoassay of LH in bovine blood the preparation LER-LH-791-l as antigen for radioiodination and the double antibody technique using filtration for separation was applied. LH-determinations were carried out in about 700 serum samples from 5 cows and 1 heifer during a total of 13 oestrous cycles. Basic levels normally ranged between 0.4 and 2.7 ng LH/ml serum. Distinct peaks, which were represented by values between 3 and 62 ng/ml, appeared no longer than 6 hours. Commonly, one peak could be demonstrated around day 8 or 9 of the cycle, another 15 – 22 hours prior to ovulation; the latter is sometimes accompanied by movements of the LH level, performing also peaks a day before and/or after this more distinct preovulatoric peak. In some cases an extra peak occurred 3 – 6 days before ovulation. The finding of LH release twice (or more times) during the bovine cycle is in agreement with preliminary results obtained by earlier studies with the OAAD-test