NUTRITIONAL MODULATION OF SOMATOTROPIC AXIS CYTOKINE RELATIONSHIPS INCATTLE - A BRIEF REVIEW

The objective of this review is to summarize data on the interrelation ships that exist between nutrition, the endocrine system and their mod ulation of plasma tumor necrosis factor-alpha responses to endotoxin i n cattle. During stress, intake of nutrients often is compromised and a percentage of available nutrients are diverted away from growth proc esses to stabilize other physiological processes of a higher survival priority. Management practices that minimize the magnitude and duratio n of disease stress will aid in speeding the return to homeostatic equ ilibrium. However, the shift away from growth during stress is almost inevitable as a mechanism to survive. Some degree of control and manag ement of the metabolic cost of disease stress involves understanding t he integration of nutritional, endocrine and immune signals by cells a nd working with the natural homeostatic processes. Endocrine hormones and immune system cytokine signals participate in redirecting nutrient use during disease stress. In an intricate interplay, hormones and cy tokines regulate, modify and modulate each other's production and tiss ue interactions to alter metabolic priorities. Levels of dietary prote in and energy intake affect patterns of hormones and cytokines in the blood after endotoxin challenge and further modulate the biological ac tions of many of these regulatory effecters. In vivo, administration o f growth hormone to young calves has significant effects to decrease t he many specific physiological responses to endotoxemia. Many aspects of nutrition can attenuate or facilitate this effect. Copyright (C) 19 97 Elsevier Science Inc.