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

The characteristics of the growth hormone (GH) secretion pattern in the per ipheral blood plasma of young dairy and beef cattle were described. Ten Bla ck 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 o ver a period of 4 h. The GH concentration was determined by double antibody radioimmunoassay. Pulse characteristics of GH were calculated using the PU LSAR program. The results obtained confirmed the pulsatile nature of GH rel ease 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 a nd Piemontese bulls (20.8 and 6.7 ng/ml, respectively) were found. A high G H concentration appears to be characteristic of young dairy cattle when com pared with beef cattle, and to reflect a genetic potential for high milk pr oduction.