Serum LH concentrations in cyclic buffalo (Bubalus bubalis).

Circulating LH levels of 14 Murrah buffaloes were determined by a double-antibody radioimmunoassay using an homologous bovine system. At the onset of oestrus, the mean peak circulating LH level was 20.80 +/- 3.43 (s.e.m.) ng/ml in the hotter months (June-August) and 21.24 +/- 0.98 ng/ml during the cooler months (October-December), values remaining high for about 4 h. Basal levels throughout the rest of the cycle averaged 1-2 ng/ml. Conception occurred in 7 of the animals showing LH peaks (2/8 in June-August, 5/6 in October-December).