Growing concern about AGPs in animal nutrition around the world has created efforts to use different alternative growth-promoting agents in swine nutrition. Among potential candidates, phytogenics represent a new and exciting group of feed additives, originating principally from herbs, spices or other plants. An improvement in feed conversion ratio has been observed in recent trials conducted at different universities and research institutes in the United States and Europe. It is, however, not only their flavoring properties, but also a number of biological activities, which make phytogenics an encouraging approach in animal nutrition. Significant improvements in feed conversion have been obtained in comparison to antibiotic growth promoters.

Phytogenics affect feed conversion

Optimizing feed conversion ratio is crucial for efficiency in swine production. A trial was recently carried out at Kansas State University to evaluate the efficacy of phytogenics in comparison to AGPs in post-weaning piglets (Sulabo et al., 2007). In the trial, 192 piglets (22 days of age) were assigned to four treatment groups: Group 1 was fed a negative control diet without growth-promoters. Both groups 2 and 3 received the negative control diet supplemented with phytogenics (shown in Figures 1 and 2 as Phytogenics A and B). Group 4 was offered a positive control diet containing AGPs (140 g/t neomycin sulfate and 140 g/t oxytetracycline HCl). Growth performance was significantly improved over the negative control group when phytogenics or AGPs were added to the feed. In terms of average daily gains, the pigs fed phytogenics were intermediate between the negative control and the AGPs (Figure 1). Feed conversion, however, was best in the groups receiving phytogenics (Figure 2). The phytogenic feed additive under investigation, Biomin P.E.P., contained a defined blend of essential oils from anise, citrus and oregano, as well as plant extracts. Trials conducted in Denmark and South Africa showed similar results with improved daily gain and feed conversion ratios.

Substitute for AGPs

Phytogenic feed additives are usually available in the form of dried and ground material, extracts or essential oils. They contain a large number of biological activities, therefore having the potential to beneficially affect gut health and performance. However, phytogenic feed additives usually vary greatly in their chemical composition. Hence, there are large differences in efficacy between phytogenic products in the market.


Since they do not pose any risk regarding antibiotic resistance or residues in animal products such as meat, eggs or milk, phytogenics are expected to gain high consumer's acceptance and are generally regarded as safe alternatives to AGPs. Particular attention, however, has to be paid on the composition of formulations which are available in the market.[FM]