Relationship between serum iron and insulin-like growth factor-I concentrations in 10-day-old calves

Abstract

Newborn calves are often deficient in iron and progressive reduction in blood iron concentration occurs over the first weeks of life. Some reports indicate the importance of interactions among iron and components of the insulin-like growth factor system. The aim of the study was to determine if there is a relationship between serum iron and insulin-like growth factor-I concentrations in neonatal calves. Blood samples were collected from 16 female Holstein-Friesian calves on day 10 of age. Erythrogram determination and measurements of serum iron, total protein, albumin, total iron binding capacity and serum insulin-like growth factor-I concentrations were performed. Haematological values were measured using an automatic analyzer, biochemical properties were determined spectrophotometrically, insulin-like growth factor-I concentration was measured by radioimmunoassay. Calves were divided into 2 groups according to iron concentrations; the first group of iron-deficient calves (n = 8, Fe < 10 μmol/l) and the second group of calves with optimal iron concentration (n = 8, Fe > 18 μmol/l). Blood indicators in all calves from the first group followed a pattern typically observed in anaemic calves. Insulin-like growth factor-I concentrations were significantly (P < 0.01) lower in the first group compared to the second group. However, insulin-like growth factor-I very strongly correlated with iron in calves from the second group compared to iron-deficient calves (r = 0.624; P < 0.01 and r = 0.478; P > 0.05, respectively). Based on our results, iron seems to have an important relationship to secretion of insulin-like growth factor-I in 10-day-old calves. This is the first report about such relationship in this age group of animals.