“…During the first week of life major changes in blood levels of hormones that are in part associated with nutrition typically occur, such as shown for PRL, adrenocorticotrophic hormone (ACTH), GH, IGFs (and their binding proteins 1–3), insulin, glucagon, leptin, thyroxine (T 4 ), T 3 and cortisol (Ronge and Blum, 1988; Ohta and Sasaki, 1989; Grütter and Blum, 1991a,b; Baumrucker and Blum, 1994; Baumrucker et al., 1994b; Kinsbergen et al., 1994; Skaar et al., 1994; Hadorn et al., 1997; Hadorn and Blum, 1997; Egli and Blum, 1998; Hammon and Blum, 1997a,b,1998a,b,1999; Hammon et al., 2000; Kühne et al., 2000; Rauprich et al., 2000a,b; Bittrich et al., 2002; Nussbaum et al., 2002; Schiessler et al., 2002; Sauter et al., 2003; Zanker et al., 2000a,b,2001a,b; Sparks et al., 2003; Blum et al., 2005). Insulin and IGF‐1 are barely absorbed in the intestine in neonatal calves, even when administered in pharmacological amounts (Baumrucker and Blum, 1994; Grütter and Blum, 1991a; Hammon and Blum, 1997b; Vacher et al., 1995), as in neonatal pigs.…”