| Popis: |
Publisher Summary The chapter presents a discussion on the potential benefits and risks of metabolic modifiers in animal nutrition. Somatotropin enhances the growth of animals through effects on maintenance, intake, digestibility and the efficiency of nutrient utilization, and affects these processes through direct and indirect (via IGF-1) actions. Optimal use of somatotropin requires more knowledge of nutrient requirements and details of its mechanisms of action. Ghrelin and leptin are important components of the integrated pathway regulating physiological energy balance with potential to enhance animal production. Chromium picolinate supplements may enhance growth and body composition in pigs and in poultry, but in cattle, may only be beneficial during periods of stress, as in calves following transport to the feedlot. The chapter focuses on the recent developments in knowledge concerning metabolic modifiers. The chapter presents a discussion on feed additives, implants and pharmaceuticals, endogenous factors that may modulate how feed additives, pharmaceuticals or nutrients influence biological responsiveness. Some of these factors may have an environmental or genetic basis. Some of the substances considered are endogenous compounds involved in modulation of aspects of growth or cell biology in response to variations in hormone activity or nutrition. Although many of the compounds that fall into the category of metabolic modifiers show merit for improvement of growth, productivity or body composition of livestock, there are also substantial concerns regarding the health and safety aspects of using some of these products in food-producing animals. Activation of α-adrenergic receptors can have important physiological and metabolic effects, especially concerning heat and energy conservation. |
