Comparison of blood plasma growth hormone levels in young dairy and beef cattle

Abstract

The characteristics of the growth hormone (GH) secretion pattern in the peripheral blood plasma of young dairy and beef cattle were described. Ten Black and White (BW) and nine Piemontese cattle of both sexes, aged 11 months, were tested. The blood was sampled through catheters at 15-min intervals over a period of 4 h. The GH concentration was determined by double antibody radioimmunoassay. Pulse characteristics of GH were calculated using the PULSAR program. The results obtained confirmed the pulsatile nature of GH release in the analyzed breeds. Moreover, significant differences (P<0.01) of mean GH values between BW and Piemontese heifers (17.8 vs 2.8 ng/mL) and of smooth mean (9.5 vs 1.3 ng/mL), as well as the peak amplitude between BW and Piemontese bulls (20.8 and 6.7 ng/ml, respectively) were found. A high GH concentration appears to be characteristic of young dairy cattle when compared with beef cattle, and to reflect a genetic potential for high milk production.