THE EFFECT OF DIETARY-PROTEIN ON REPRODUCTION IN THE MARE - IV - SERUM PROGESTAGEN, FSH, LH AND MELATONIN CONCENTRATIONS DURING THE ANOVULATORY, TRANSITIONAL AND OVULATORY PERIODS IN THE NONPREGNANT MARE

The effect of total protein intake and protein quality on the serum co ncentrations of certain reproductive hormones during the anovulatory, transitional and ovulatory periods were studied in 36 Angle-Arab mares . High-quality protein stimulated FSH and LH production during the lat e transitional period. Serum progestagen and melatonin concentrations were unaffected by the quality of protein nutrition during the anovula tory period. Mares receiving high-quality protein exhibited a 10-14-da y cyclical pattern of FSH release approximately 4-6 weeks earlier than the mares fed the lower-quality protein diet, and also ovulated 3-4 w eeks earlier than the mares on the lower-quality protein diet. Progest erone concentrations during the Ist oestrous cycle after the anovulato ry period were unaffected by protein quality in the diet.