A note on the variability of hormone concentrations in twice-weekly blood samples taken from heifer calves during the first 110 days of life

Publisher Website
Google Scholar
Abstract
To assess the variability of hormone values obtained from calves at an early age, plasma concentrations of prolactin, growth hormone, insulin and thyroxine were measured in blood samples taken twice-weekly from seven heifers maintained under commercial conditions during their first 110 days of life. With the possible exception of thyroxine, there was considerable variation in the concentration of each hormone in each animal throughout the period of sampling, thus indicating that twice-weekly sampling was inadequate for investigating differences in hormonal concentrations between cattle of different production potential. Although there were trends in the pattern of plasma hormone concentrations as the calves progressed from the pre-ruminant to ruminant states, few of the changes during the pre-weaning, weaning and post-weaning periods were consistent between animals.