Performance promoters in animal nutrition. I. Quantitative factorial analysis of effectiveness

The nutritional efficacy of antibacterial feed additives in improving animal performance and reducing production costs has been studied extensively for over thirty years. Responses vary greatly with time and place and quantitative estimates thereof are required, with appropriate confidence limits for different circumstances, to assist efficient practical application of such performance promoters in animal production. Modern computers have facilitated multi-factorial analysis of dose-response relationships and the elucidation of the influence of diverse other determinants, such as level of animal performance and duration of supplementation. The objectives, underlying principles, methodology and future prospects of comprehensive assessments, in the format of algebraic models, are reviewed and are illustrated by examples drawn from the use of copper, tylosin and bacitracin in the nutrition of pigs, broilers and laying hens.