“…As a consequence, the maturation of the postnatal somatotropic axis is delayed and leptin status is reduced in calves with insufficient colostrum supply (Hammon and Blum, 1997;Sauter et al, 2003;Blum et al, 2005). In the present study, we observed reduced plasma concentrations of IGF-I, leptin, T 3 , and T 4 as well as reduced plasma insulin, but elevated plasma cortisol concentrations, as was shown in other experiments (Hammon and Blum, 1998;Rauprich et al, 2000;Steinhoff-Wagner et al, 2011a), indicating an impaired energy status in calves fed no colostrum but a milk replacer with comparable energy content (Brockman and Laarveld, 1986;Hammon et al, 2012Hammon et al, , 2013. Greater plasma concentrations of leptin may point to larger fat depots in colostrum-fed calves (Reidy and Weber, 2000;Ingvartsen and Boisclair, 2001;Blum et al, 2005) and greater IGF-I plasma concentrations accentuate stimulation of anabolic processes in calves after feeding colostrum (Hammon and Blum, 1997;Sauter et al, 2003;Hammon et al, 2012).…”