Efficacy of Phytogenic Feed Additive on Performance, Production and Health Status of Monogastric Animals – A Review

The growing concerns of consumers on the use of antibiotic as a growth promoter in livestock feed have fueled the interest in alternative products. In the recent years a group of natural products known as phytogenics has been a focus of several studies. Phytogenics are a heterogeneous group of feed additives originating from plants and consist of herbs, spices, fruit, and other plant parts. These feed additives are reported to have a wide range of activities including antimicrobial, anthelminthic, antioxidant, growth enhancer, and immune modulator. Besides these properties they are also reported to stimulate feed intake and endogenous secretion and enhance production. They include many different bio-active ingredients such as alkaloids, bitters, flavonoids, glycosides, mucilage, saponins, tannins phenolics, polyphenols, terpenoids, polypeptide, thymol, cineole, linalool, anethole, allicin, capsaicin, allylisothiocyanate, and piperine. These feed additives have been tested in the form of extracts, cold pressed oils, essential oils in a number of animals but the results are variable. Therefore, their application as feed additive has been limited, largely owing to their inconsistent efficacy and lack of full understanding of the modes of action. The future of these feed additives depend on the characteristics of herbs, the knowledge on their major and minor constituents, the in-depth knowledge on their mode of action and their value based on the safety to animal and their products. The aim of this review is to summarize on the current knowledge on the use of phytogenic as a feed additive in monogastric animals.