02296naa a2200253 a 450000100080000000500110000800800410001910000160006024500560007626000090013252016880014165000110182965000120184065000190185265000100187165300120188165300130189365300140190665300140192065300150193465300130194970000150196277300650197717887062017-03-13       1999    bl ---       0--  u    #d1 aBLUM, J. W.  aEndocrine and metabolic aspects in milk-fed calves.  c1999  aIn neonatal calves besides adaptations in organ function there are marked metabolic and endocrine changes. The growth hormone (GH)-insulin-like growth factor (IGF) acis is basically functioning, but needs maturation. Various metabolic and endocrine traits do not exhibit marked ontogenetic changes after the first week of life, but others remain different from the adult stage. Thus, plasma oxytocin or an axytocin-like substance and nitrate concentrations are elevated for months. The ability to digest colostrum (C) and milk involves great alterations in structure and function of the gastrointestinal (GI) tract. C intake is important for passive immunity, provision of nutrients, minerals and vitamins, and contains biuologically active substances. IGF-I, present in C in high amounts, appears to enhance GI tract development and function. For suffucuent absorption not only of immunoglobulins, but also of fatty acids and fat-soluble vitamins, C should be ingested immediately after birth. Tne amino acid pattern and the glutamine/glutamate ratio depends greatly on whether C is fed or not. Effects on insulin, IGF-I, and OGF binding proteins depend on time-point and amounts of C fed. After the colostral period calves are almost exclusively fed milk and milk substitutes or weaned. Low iron inatke, required for the production of pale meat, besides anemia causes metabolic and endocrine adaptations, such as enhanced insulin-dependent glucose utilization and appears to reduce IGF-I responses to GH. Metabolic and encocrine changes, such as insulin resistance and distrubed glucose metabolism, can be observed in part in association with high feeding intensity in veal calves.  acalves  aBezerro  aEndocrinologia  aLeite  aControl  aControle  aEndocrine  aMetabolic  aMetabolico  aMilk-fed1 aHAMMON, H.  tDomestic Animal Endocrinologygv.17, n.2/3, p.219-230, 1999.