Serum levels of insulin like growth factor-I and total protein in newborn calves offered different amounts of colostrum

The aim of this investigation was to determine the concentrations of insulin like growth factor-I (IGF-I) and total protein in blood serum from calves consuming different amounts of colostrum 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. At birth serum concentration of IGF-I was in the range from 5 to 13 nmoI/L. Compared to the initial level there was a marked decrease of mean IGF-I concentration in both groups of calves at 2 h after the first intake of colostrum. Thereafter, the level gradually increased until 20 h of age, more markedly in the group which received the full ration of colostrum. The highest mean IGF-I concentrations were recorded at 20 h in both groups (11.81 nmol/L for group one and 8.96 nmol/L for group two), and were significantly higher than values recorded 2h after the first intake of colostrum. Two hours after the third intake of colostrum, serum concentration of IGF-I dropped in both groups, compared with the value recorded at 20 h. During the time period from 4 h to 32 h afterbirth, the calves that received the standard amount of colostrum had a significantly higher mean concentration of serum IGF-I than the calves which received an insufficient amount. Calves were born with serum concentrations of total proteins, which were lower than those found for adult animals. Serum protein concentrations in the calves that consumed normal amounts of colostrum increased more rapidly than in the calves that received insufficient amounts of colostrum. Presumably, total protein concentrations increased as a consequence of colostral immunoglobulin absorption. Thus our results indicate that the amounts of colostrum received during the first 32 h of postnatal life had strong effects on the serum concentrations of IGF-I and total proteins. The differences in IGF-I concentrations between the two groups of calves may have been a consequence of greater colostral IGF-I absorption and/or the result of greater absorption of other colostral components, which stimulate endogenous synthesis of this bioactive substance in the tissues of neonatal calves.