Plasma hormonal and electrolyte alterations in cycling buffaloes (Bubalus bubalis) during hot summer months.

Plasma levels of progesterone, prolactin, luteinizing hormone, and electrolytes were monitored by radioimmunoassay in ten cycling buffaloes maintained at Punjab Agricultural University, Ludhiana during the hot summer months of June-July. The plasma progesterone concentration ranged from 0.28 +/- 0.04 to 3.09 +/- 0.03 ng/ml at various stages of the oestrous cycle. Prolactin values ranged from 319 +/- 23 to 371 +/- 25 ng/ml and LH levels from 0.95 +/- 0.05 to 1.35 +/- 0.08 ng/ml. Concentrations differed significantly (P less than or equal to 0.05) at various stages of the cycle. Levels of electrolytes, viz. Ca++, Na+ and K+, were well within the normal range. The high levels of prolactin, progesterone and LH during the hot summer were assessed in relation to poor reproductive efficiency in buffaloes.