Phytobiotics: an Alternative to Antibiotic Growth Promoters

The use of antibiotic growth promoters (AGPs) in animal production began half a century ago, when Stokstad and Jukes added residues of chlortetracycline production to chicken feed. They were added with the objective to serve as a source of vitamin B12, but they caused a growth stimulation that was far too large to be explained only as a vitamin effect.

The almost obvious cause lays in the antibiotic activity of the residues. This observation was quickly extended to other antibiotics and to other animal species, leading to widespread adoption of AGP inclusion in feeds. Antibiotics have been used for treatment and prevention of diseases, improvement of feed efficiency in conventional livestock and poultry industries. The first use of antibiotics in these industries was a way to meet the increasing demand of food as antibiotics given to pigs  were estimated to save as much as 20% of feed per pound because of the weight gain. Similar results have been reported in poultry industries also. Immense and extensive use of antibiotics has created a strong selective pressure, which resulted in the survival and spread of resistant bacteria providing best example of survival for the fittest or natural selection theory of Darwin. Quick concerns have been arisen about the development of resistant pathogens associated with human and animal diseases, as well as increase in the resistance gene pool in bacteria, but all these risks were outweighed by the benefits of reduced cost to the industry.

At present we are confronting a major issue of antibiotic resistance in both human and animals resulting into severe health issues. A lot of debates are going on all over the world and recently European Union and Canada has banned the use of antibiotics in the animal feed industries. In China certain antibiotics have been banned and others are under observation. In United States, also discussions are going on about the uses of antibiotics and it is expected have big measures in the nearest future. In Mexico still animal feed industries are using extensively the antibiotics, ignoring the health issues and focusing on the commercials benefits of the respective companies. But it’s not too far when the strong legal measures will be implemented in Mexico also. From personal point of view, it’s a demand of the time, to take care of the health interests of consumers and prepare ourselves to look for other alternatives of the antibiotics as growth promoters.

These alternatives might have similar effects in food producing animals. Studies to find the alternatives have resulted into probiotics, prebiotics, symbiotics, enzymes, organic acids and phytobiotics. Despite of initial and then often justified distrust of these alternatives by nutritionists and veterinarians, they are becoming rightly accepted after the debates going on all over the globe about the use of the antibiotics and related health concerns. The change in European Union feed additive legislation has also contributed to create enough space for these alternatives.

Among the mentioned alternatives, phytobiotics have drawn a lot of attentions because of being natural, non toxic and residue free. Phytobiotics are defined as plant-derived products added to the feed in order to improve performance of agricultural livestock.

With respect to biological origin, formulation, chemical description and purity, phytobiotics comprise a very wide range of substances and four subgroups may be classified:

1) Herbs -product from flowering, non-woody and non-persistent plants
2) Botanicals -entire or processed parts of a plant, e.g., root, leaves, bark
3) Essential oils- hydro distilled extracts of volatile plant compounds and
4) Oleoresins- extracts based on non-aqueous solvents

Positive effects of the phytobiotics on the growth performance and animal health have been attributed to their antimicrobial activity and immune enhancement and immune modulation properties. In diseased chicken (infected with avian mycoplasma or Eimeria tenella) it has been demonstrated that plant and their extracts could improve the growth performance, reduce the coliforms and improve both cellular and humoral immune responses of chickens.

A common feature of phytobiotics is that they are a very complex mixture of bioactive components as a result exerts multiple functions in the animal body. Different studies have reported growth enhancement through the use of phytobiotics probably by synergetic effects among complex active molecules existing in the phytobiotics. However, the exact growth enhancement mechanisms of the phytobiotics in chicken are not very well understood and further investigations are required to better understand the mechanism at molecular level.

Among Phytobiotics, essentials oils have drawn a lot of attention as an effective alternative to the antibiotic growth promoter and have been applied into chicken feed in Europe, USA and many Asian countries. In Mexico, till date negligible research has been conducted to see the effect of essential oils in animal feed.

However the results are still controversial as some research report no essential oil effects on the performance of the bird and some demonstrate similar to or even better than an antibiotic treatment. It´s very important to mention that while comparing the effects of essential oils on chicken performance one should always keep in mind that the quality as well as the quantity of the oil determines the response. Additionally, efficacy of essential oils in feeds is affected by intrinsic and extrinsic factors such as nutritional status of animals, infection, diet composition and environment. Till now research has been conducted with the essentials oils of Ginger, Cinnamon, Capsicum, Garlic, Thyme and Oregano among others, in different parts of the world. The results are really interesting and show positive effects on the performance of the birds. As mentioned above environment plays an important role in determining the effect of the essential oils, it is highly recommendable to conduct in field study in Mexico before launching the products in the market.

Conclusions 

Because of the increasing concerns about the use of antibiotics as growth promoters in poultry industries, the animal feed industry is in search of other alternatives with good cost benefits. The phytobiotics, especially the essential oils are opening new opportunities and possibilities as a replacement of antibiotics. But the cost is an issue which is restricting the animal feed industries to accept these products as the cost of antibiotics is cheaper than other alternatives. But if we give close look to the authorization to new antibiotics by Food and Drug Administration (FDA), in year 2008-2009 only one antibiotic was approved. FDA is also releasing new guidelines for the use of antibiotics. All these strong measures will definitely help to answer the cost issue and force the consumers to accept alternative like Phytobiotics as essentials oils.

REFERENCES.

1. Cromwell, G.L. (2002) Why and how antibiotics are used in swine production. Anim. Biotechnol. 13, 7–27
2. Guo, F.C., et al. (2004c) Effects of mushroom and herb polysaccharides on cellular and humoral immune responses of Eimeria tenella-infected chickens. Poultry Science 83: 1124-1132