Probiotics and phytogenics for poultry: Myth or reality?

Removal and restriction of subtherapeutic antibiotics from poultry diets in many parts of the world has amplified interest in improving intestinal health and nutrient utilization. Some probiotic (direct-fed microbials) and plant-derived (phytogenic) feed additives are gaining market presence. Defined probiotic cultures have the potential to succeed, in large part because of in vitro screening and selection. However, regulatory approval delays, particularly in Europe, have stymied the commercial application of some microorganisms in poultry diets. Phytogenic feed additives have demonstrated ranges of antimicrobial activities in vitro and are building a track record of improvements in bird performance. Hesitation by nutritionists to incorporate these feed additives are due in part to 1) unfamiliarity, 2) the overselling of plausible effects by industry, 3) product inconsistency, 4) a lack of documented physiological and microbiological effects in vivo, and, in the case of probiotics, 5) a lack of documentation of persistence.