Increasing either energy or protein intakes resulted in higher rates of gain, wool growth, N retention, fat synthesis and higher plasma concentrations of insulin but lower concentrations of GH. Plasma concentrations of Val, Leu, Met, Tyr, Phe and Lys were higher in sheep fed high protein diets, whilst Val, Leu, Phe, Trp and ornithine increased with increasing levels of intake. Responses to glucose tolerance test were mildly affected by treatment, and sites of DM digestion were similar in all sheep.
When the same diets were fed to 800 ewes (Smith, 1985), increasing protein and energy intakes were associated with increased ovulation. The strongest relationship between ovulation rates measured in ewes and parameters measured in wethers was with plasma concentrations of branched chain amino acids (Val, Leu, Ile).
Keywords: NZSAPAB; Protein; energy; metabolism; digestion; amino acids; ovulation rate