Phytogenics: More than sensory additives

Bioactive molecules derived from nature already have a long history in human medicine. Although these molecules (also referred to as botanicals, herbs or phytogenics) have a history of medicinal (and human food) use, there is little or no history in animal feed applications. In recent years, the ban of in-feed antibiotics, which was implemented in Europe in January 2006, has driven research activities regarding the potential of plant extracts and essential oils as alternatives to antibiotic growth promoters. The potential benefits such as increased feed intake, stimulation of digestion and improved feed efficiency among others have therefore raised the interest among animal nutritionists. However, it is not only in recent years that ideas of phytogenics in animal feed have been present. In 1984 the first steps of developing phytogenic feed additives were made by Austrian company Delacon. Twenty five years later and backed up by many research papers and trials, phytogenics (plant extracts) are approaching a point where they are a standard ingredient in modern livestock diets. The immense data on this topic gathered over the last years were shared at the two day symposium in Greece, organised by Delacon.

Mode of action
Prof Dr Wilhelm Windisch from the University of Natural Resources and Applied Life Sciences in Vienna, Austria gave a clear summary of the current alternatives for antibiotic growth promoters (AGPs). According to Windisch, essential oils from the labiatae plant family (e.g. thyme and oregano) are widely known to exert antimicrobial effects in vitro and several in vivo studies suggest that their overall impact on gut functions is similar to that of AGPs. “However, we still don’t know exactly if the antimicrobial activity of phytogenics is the real mode of action. Enhanced intestinal mucus production through bitter and/or hot substances is discussed as an alternative mode of action reducing the intestinal pathogen pressure in the animal. Regarding consumer safety Windisch said that it should be considered that many phytogenic principles are highly absorbable (e.g. essential oils). However, elimination of absorbed phytogenic substances seems to be quite efficient and therefore edible residues do not seem to pose a major concern to consumer safety. At the same time, Lucas Cypriano from Eurotec in Brazil explained that phytogenics can have a synergetic effect with antibiotic growth promoters. “A phytogenic product is often used with an AGP when it is still allowed (US, Asia), and we see a synergetic effect in combining the two”, Cypriano explained. However, it still remains unclear why this interaction occurs. He said that Brazilian poultry farmers don’t always use a combination treatment of an AGP and a phytogenic product, but pig farms in the South American country often use a combination of a plant extract and an in-feed antibiotic. Prof Dr. Ortwin Simon from the Free University Berlin in Germany also addressed some facts about the mode of action of phytogenics. “Most of these products are known and used because of their sensory properties, but essential oils have more beneficial effects such as increased excretion of digestive juices, antioxidant effects and anthelmintic effects. In trials that we did with a phytogenic product (Biostrong 510) in broilers we saw an increased pre-caecal nutrient digestibility and an improved feed to gain ratio”, Simon explained.

Application in pig diets
Ken Purser from Value-Added Science & Technologies (VAST) in the US gave the audience a little insight in the use of Fresta F in pig diets. In the US, the product is primarily used in weaning diets and diets for lactating sows. Purser explained a large trial that was done to put the phytogenic product Fresta F to the test. It was shown that pigs with the phytogenic product gained 5.9% faster and 2.6% more efficient than the control pigs. It reduced the number of small pigs at 63 days with 39%. Jorge Marin, head nutritionist from Land O’Lakes in the US explained the use of a combination of a phytogenic (Fresta F) with a hydrating gel for pigs. “Water intake is very important and a reduced water intake leads to less feed intake and reduced performance” explained Marin. By providing a combination of a phytogenic product in combination with a gel, you get both the health stimulation effect of the plant extract and the hydrating effect of the gel. Marin explained that this type of product can be beneficial for light, heavy, sick, shipped and vaccinated pigs. Trials that were presented in the presentation showed that the product increased ADG and feed intake, improved gut health, reduced the pig weight variation and days to market.

US prepares itself
Dari Brown from Land O’Lakes in the US highlighted the current trends in the North American swine industry. These include: the economic crisis, increased use of DDGS, increased use of synthetic amino acids, rising concerns regarding the use of AGPs, animal welfare and handling concerns and increased litter sizes among others. “The last six months we heard a lot about the future ban on AGPs in the US and we notice that the pressure on the sector in increasing. Many feed companies and research institutes are increasing their efforts to test alternative products such as phytogenics, so when the ban is implemented we are ready to serve the market” Brown explained.

Application in poultry diets
Neivaldo Burin from a large poultry integrator in Brazil (C. VALE Cooperativa Agroindustrial) gave an excellent overview of the Brazilian poultry industry. Brazil is the current number 1 poultry exporter in the world, shipping an annual 3,645 million tonnes (2008). Burin explained that the Brazilian chicken industry from the 1980s has revealed itself as being one of the most dynamic activities of the Brazilian economy. The strong presence of Brazilian poultry is due to the fact that the country has many raw materials on hand (soy, maize and wheat). The climate is excellent for having 2 (sometimes 3) harvests per year. In addition, the industry is based on an integrated system, which can reduce the overall cost price of the end product. However, there are also some weak points in the chicken industry in Brazil. According to Burin, the country struggles with a deficient infrastructure system, scarce credit, very high interest rates, and very high tax burden and customs barriers. “Our challenge is to overcome these hurdles, so we can still increase our production in a sustainable way without sacrificing the Amazon for raw materials. Dr Jan Dirk van der Klis from Schothorst Feed Research in the Netherlands talked about several challenges the European poultry market is facing or will be facing in the near future. He mentioned the EU welfare directive for broilers (to come into effect in 2010) and the EU welfare directive for layers (to come into effect in 2012). These new rules make maximum stocking density and NH3output important criteria. “Animal nutritionists have therefore an important role in optimising poultry diets and improving the competitiveness of European poultry production despite these regulations,” said van der Klis.

Effect on immune system
Prof. Dr. Jürgen Zentek from the Free University in Berlin, Germany gave an overview of the immune system in monogastric animals and the role nutrition can have to boost it. He addressed that the gastro intestinal tract of the animal is the biggest immune organ and the barrier to the “outer world”. It has the purpose to uptake nutrients but also refuse pathogens from this outer world. “We can steer this to a certain extent by the choice of ingredients in the animal diets” according to Zentek. He specifically mentioned that the weaning period in pigs is a very stressful event, and in turn gives a drop in immune responses. Nutritionists should be aware of this, and add specific immune boosting additives at this stage of the production cycle. Examples of these additives are plant extracts and beta-glucans. Stefanie Gärtner from the same University in Berlin presented her Ph.D.-work on the effect of Fresta F on the adhesion of pathogenic E. colito porcine intestinal cells and on immunological parameters in piglets. The results from her in vitro trials indicate an interference of the phytogenic feed additive with the adhesion of E. coli IPEC-J2 cells, she explained. The feeding trial showed some differences in the immunological traits between the trial and control group. “However, further studies should be done to explain the consequence for animal health” according to Gärtner.

Phytogenics and the environment
Prof. Dr. Gerhard Flachowsky highlighted that there is still a lot of work to do before an accurate calculation of the so called “Carbon footprints” can be used for regulations or restrictions. He also pointed out that there is also a lot of “sun” in the rumen as undegradeable roughage can be transformed into high quality nutrients, and that this should never be forgotten even if there is the “shadow” of methane which is making a big portion of green house gas emissions caused by them. However emissions from livestock are already under legislative regulation. Carlos Piñeiro from PigCHAMP Pro-Europe in Spain pointed out some of the remedies to minimise the ammonia output from livestock production.
Livestock produces 37% of the total global methane output, 65% of the total global N oxide and 64% of the total global ammonia output. “As a livestock industry we therefore have to take our responsibility to find solutions to bring these numbers down”, said Piñeiro. Ammonia not only is a big threat to the environment it can also cause harm to the animals itself. Pigs may experience respiratory problems when they are in contact with ammonia in the barn. The epithelium of the lungs will be irritated, which may lead to production losses. As possible solutions Piñeiro considered the reduction of crude protein in the diet – reducing 1 point crude protein can lead to an ammonia reduction of 60%, the implementation of phase feeding – shifting to a two phase feeding which can reduce the ammonia output with 10%, the use of specific feed additives such as phytogenics to improve the utilisation of the raw protein and to reduce the urease activity (urease speeds up the formation of ammonia).

Conclusion
From the amount of research work presented at the symposium we can certainly state that the interest (and the need) to use phytogenic feed additives is growing. The need to increase digestion, improve feed conversion, boost immunity and improve overall health through natural solutions is becoming more important in countries where in feed antibiotics are phased out or will be banned in the near future. However, more research is still needed to learn the exact mode of action of some known plant extracts, find new substances and increase our knowledge about the right application for different animal species.

Source: FeedMix vol 17 nr 6, 2010