Relationship between parameters of the glucose tolerance test (GTT) in young sires and their estimated breeding value (EBV)

A high milk performance connected with sound health regarding metabolism an d sufficient fertility in dairy cows depends on a well balanced distributio n of energy in the body. The terms "type of turnover" and "type of depositi on" embody two extremes of food energy preferably for milk production or fo r body composition. Insulin plays an outstanding role based on its central position in energetic metabolism. The function of insulin may be recorded b y means of the intravenous glucose tolerance test (GTT). The reaction of in sulin and glucose was investigated after infusion of 1 g grucose/kg(0.75) b ecause of the probable genetic determination of the reactive ability. The c oefficients of heritability range from h(2) = 0.07 +/- 0.07 to h(2) = 0.20 +/- 0.12. Investigating 52 sires the correlation coefficients amount to r = -0.5 for parameters of GTT and estimated breeding values (EBV) which is a closer relation than between pedigree breeding value (PBV) and GTT.