Neonatal levels of plasma thyroxine in male and female calves fed acolostrum or immunoglobulin diet or fasted for the first 28 hours oflife

Abstract

The effect of diet on changes in plasma thyroxine levels was studied in 83 newborn Friesian X Holstein calves. Fifty-four received four copious meals of first-milking colostrum at 4, 10, 16 and 22 neonatal hours. At the same time, 24 animals received four meals of a solution of colostrum immunoglobulins containing little energy, and 5 calves were kept fasted. The last two treatments resulted in lower plasma thyroxine levels than those in colostrum-fed calves. At the same time, plasma thyroxine level was higher in females than in males during the first neonatal week.