title: The acute effect of oestrogen injection on plasma LH in freemartin heifers.
abstract: The acute effects on plasma LH concentrations of an injection of oestradiol-17beta were studied in 7 non-cyclic heifers and 19 freemartins. One freemartin showed a normal LH surge due to the positive feedback effect of oestrogen on the hypothalamus. Of the other 18 freemartins, 4 showed positive increases in plasma LH and 6 were unclassified. There was no correlation between the degree of chimaerism and responsiveness to oestrogen. The results also showed that injected oestradiol suppressed the spontaneous fluctuations of plasma LH.
mesh_terms: D000818:Animals; D002417:Cattle; D004958:Estradiol / Q000008:administration & dosage* / Q000097:blood; D005260:Female; D005611:Freemartinism / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood*; D013997:Time Factors
chemical_list: D004958:Estradiol; D007986:Luteinizing Hormone