Factors Affecting Plasma Glucose, Insulin and Cortisol Levels and the Reliability of their Repeated Measurements in Cattle

Abstract

Factors affecting plasma glucose, insulin and cortisol levels were surveyed and the reliability of their repeated measurements was examined, using twenty nine progeny (steers and heifers) of two different bulls of the Japanese Black Cattle. Blood samples were taken at 10:00 a.m. in three consecutive days within one month before the end of performance testing. Plasma glucose, insulin and cortisol levels were determined and the reliability for these traits was calcu-lated using the variance components. From the results of analysis of variance, the effect of sire was significant for plasma glucose and insulin levels and the effect of progeny within sire was significant for all traits. The reliabilities of the mean of three repeated measurements for plasma glucose, insulin and cortisol were 0.801, 0.435 and 0.612, respectively. From the results of this study, it is suggested that an inherent value exist in these plasma levels and the inherent level seems to be confirmed by the mean of three repeated measurements, under the presented sampling procedure.