Herbs and spices and a host of other plant derivatives used in animal feeding as feed additives are referred to as
phytogenic feed additives. This class of feed additives is increasingly gaining popularity in livestock production.
A number of studies have demonstrated antioxidative and antimicrobial efficacy in vitro. Methane reducing
effects of some herbs and spices in ruminants have also been reported. Studies show that some of these plant
materials improved the palatability of feed. There are suggestions that they may specifically enhance activities of
digestive enzymes and nutrient absorption. Experimental comparisons of these phytogenic additives with
antibiotics and organic acids have suggested similar effects on the gut. This include reduced bacterial colony
counts, fewer fermentation products, greater nutrient digestion and probably reflecting an overall improved gut
equilibrium. In addition, some of the herbs and spices or their derivatives have been reported to promote
intestinal mucus production. This effect may explain improved production performance after including these
phytogenic feed additives. In general, available literature suggests that phytogenic feed additives such as herbs
and spices may add to the set of non-antibiotic growth promoters for use in livestock like organic acids and
probiotics. However, a systematic approach toward the efficacy and safety of phytogenic materials used as feed
ingredients or additives is needed. There should also be studies to show the possible interaction of these plant
materials with other feed ingredients in vivo. There is also the need to study herbs and spices which are
indigenous to the tropics for their utilization in livestock production.