The plasma levels of triiodothyronine, thyroxine and cortisol in newborn calves

Abstract

The aim 'of this investigation was to determine the concentrations of triiodothyronine (T3), thyroxine (T4) and cortisol in blood plasma from calves during the first 32 h of postnatal life, as well as at 7 days old. The experiment involved two groups of calves. The first group was offered the standard amount of colostrum while the second group received half the recommended amount. The results obtained showed that the calves were born with high plasma concentrations of 73, 74 and cortisol up to four times greater than values found at 7 days old. In the calves given the full ration of colostrum there was a gradual increase of mean 73 concentration to levels which plateaued from 8 to 28 h after birth, while the level of T4 increased slightly but significantly up to 18 h. Sharp highly significant increases in 73 and 74 concentrations were observed during the first 4 h of postnatal life in the group of calves given half the usual amount of colostrum to levels which persisted up to 20 h. Except at 4 and 20 h there were no significant differences between the groups. At 7 days old the levels of plasma 73 and 74 in both groups of calves were within the limits found for adult animals. The plasma concentrations of cortisol decreased during the first 18 h afterbirth in both groups of calves and then increased somewhat. At 32 h the mean concentration was higher in group two than in group one. At 7 days old cortisol concentrations were up to four times lower than the level immediately after birth. It was concluded that a decrease in the amount of colostrum consumed had only minor effects on the plasma concentrations of the examined hormones in neonatal calves

Serum concentration of thyroxine and triiodothyronine in newborn calves from cows supplemented with barium selenate

“…The decrease in the concentration of hormones as time elapses from birth is consistent with that reported for ruminants by other authors (Awadeh et al, 1998;Takahashi et al, 2001;Stojić et al, 2002;Guyot et al, 2011;Rose et al, 2012). In this sense, the highest initial concentration of T3 in the newborn is related to the synthesis of thermogenin, a protein necessary for the production of heat in brown adipose tissue (Carstens, 1994).…”

“…Although it was not possible to find studies conducted under similar conditions, other authors report values of thyroid hormones in the newborn by applying different experimental models that differ from those indicated in this study (Davicco et al, 1982;Stojić et al, 2002;Kirovski et al, 2008). These differences can be attributed not only to factors inherent to the methodologies used for the determination of the hormones but also to the potential influence of the environment on the animals subjected to experimentation.…”

Thermoregulatory Responses and Performance of Dairy Calves Fed Different Amounts of Colostrum

“…Cold stimulus after birth has been shown to increase T3 and T4 concentrations [ 26 ]. Stojić et al [ 37 ] reported that different amounts of colostrum consumed by newborn calves had a minor effect on plasma concentrations of T3, T4, and cortisol. Cortisol stimulated by cold stress enhances the maturation of the thyroid axis leading to increased thyroid hormone levels and conversion of T4 to T3 in the BAT [ 16 ].…”