Colostrum effects on the gastrointestinal tract, and on nutritional, endocrine and metabolic parameters in neonatal calves

Newborn calves are characterised by marked cardio-respiratory, metabolic and endocrine changes which continue during ensuing weeks and months. Thus, although the somatotrophic axis is basically functioning in neonatal calves, it is not yet mature. The speed of the adaptations of the various traits differs widely. The ability to digest colostrum and milk requires specific structures and functions of the gastrointestinal tract. Colostrum composition exhibits major changes after the onset of lactation. Colostrum intake is important for passive immunity, but also for the provision of carbohydrates, lipids, proteins, minerals and vitamins. In addition, colostrum contains hormones, growth factors, cytokines, enzymes, polyamines and nucleotides, which in the neonatal calf can exert biological effects. Thus, insulin-like growth factor I, which in colostrum is present in high amounts, may enhance gastrointestinal tract development and function of neonatal calves. Colostrum should be ingested as soon as possible after birth for efficient and sufficient absorption not only of immunoglobulins, but apparently also of (essential and non-essential) fatty acids and fat-soluble vitamins (b-carotene, retinol and a-tocopherol). The pattern of essential amino acids and the glutamine /glutamate ratio in blood plasma also greatly depend on whether and when colostrum is fed. In addition, there are considerable effects on hormones (especially on concentrations of insulin, glucagon, insulin-like growth factor-I, including its binding proteins, and cortisol) that are dependent on time and amount of colostrum fed.  2000 Elsevier Science B.V. All rights reserved.