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Feed Additives

Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use

Published: December 30, 2011
By: CASPAR WENK - Institute of Animal Sciences, Switzerland (Courtesy of Alltech Inc.)
The various ways in which human food is produced are vigorously discussed and questioned in modern societies. We expect food from plants, farm animals and microorganisms to be of good quality, healthy and inexpensive.

Furthermore the food industry and politicians are increasingly concerned about environmental matters and keeping energy inputs low. In addition, arguments for food produced as naturally as possible are increasingly heard from organic farming organizations and consumer organizations.

The use of new technologies such as genetic engineering in food and animal feed production is being questioned. Even synthetic amino acids, vitamins or other feed additives produced by modern technologies are banned in certain (organic) production systems. In general, all of us expect our food to be as natural as possible and free of any toxic or undesired substances.

In highly developed countries we do not always feel the impact of the steady growth of world population. In 25 years there will be almost 9 billion inhabitants (FAOSTAT, 1998) on earth who expect to get enough food to meet their nutritional needs. The goal to produce sufficient food for everyone can only be achieved if world food production increases by about 2% per year. It is expected that world animal production will follow this trend. According to FAOSTAT (1998) world production will grow about 2.0% for pigs and poultry in the next 20 years. For beef production a slight reduction of 0.4% is expected, mainly in developed countries.

World food production must also accomplish this growth without increasing the environmental waste load. This precondition demands the efficient and responsible use of all available resources, of traditional and modern technologies and also of feed additives. There is no doubt that worldwide agricultural productivity must increase. However, consumers in highly developed countries, who spend only a minor percentage of income on food (in Switzerland less than 10%), make increasingly pointed demands about quality and have idealistic images of food that focus attention on issues other than yield.

Antibiotic feed additives have been banned in animal nutrition in Sweden since 1986. The ban is being discussed throughout Europe due to increased occurrence of pathogens resistant to therapeutic antibiotics used in both animals and humans. The increase has been viewed to be related to use of antibiotic feed additives as growth promoters in farm animals. Despite the report of the SCAN (1996) showing no evidence that use of avoparcin has led to increased resistance to vancomycin (an antibiotic used in human medicine), avoparcin was banned in the European Union (EU) in April of 1997.

After an intensive debate, Switzerland banned all antimicrobial feed additives as performance promoters in 1999. A report of the Swiss Office of Health (1999) stated later that the ban was politically based and that animal feed supplements contributed only marginally to the actual resistance situation. Coccidiostats are still permitted in poultry diets. Recently the EU has banned tylosin phosphate, virginiamycin, zinc bacitracin and spiramycin. A further law banned the use of olaquindox and carbadox as feed additives for 1999.

With the restricted use or outright ban of dietary antimicrobial agents, new ways of improving and protecting the health status of farm animals must be explored. Furthermore, useful additives should ensure optimum animal performance and increase nutrient availability. This goal can be attained by good housing or climate conditions as well as by the best possible combination of the so-called pronutrients (Rosen, 1996) available including pro- or prebiotics, organic acids, dietary fiber, highly available nutrients, herbs, spices or botanicals. Rosen defined the pronutrients as ‘microfeedingstuffs used orally in a relatively small amount to improve the intrinsic value of the nutrient mix in an animal diet’.


Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 1

Figure 1.Pronutrients instead of antibiotics.

The effect of a pronutrient on the performance of a farm animal can vary over a wide range. Many reasons for this variation can be considered.

Generally, pronutrients are more effective in animals with low performance and (or) unfavorable health status, those kept under adverse environmental and management conditions and animals receiving diets with low nutritive value.

Beside feed enzymes, probiotics (lactobacilli, yeast culture, etc.), prebiotics (oligosaccharides) and organic acids, the herbs and botanicals can be used as feed additives. In recent years the modern western world has been learning what many Asians (eg. Keys, 1976) and native Americans (eg. Bye and Linares, 1999) have known for centuries, namely that plant extracts and spices can play a significant role in health and nutrition.


What are herbs, spices or botanicals?

Definitions for herbs, spices and botanicals derived from Webster’s Encyclopedic Cambridge Dictionary of the English Language (1989) are as follows:
Herb:A flowering plant whose stem above ground does not
become woody and persistent. A plant valued for its medical properties, flavor, scent, or the like.
Spice:Any of a class of pungent or aromatic substances of
vegetable origin, as pepper, cinnamon, cloves, and the like, used as seasoning, preservatives, etc.
Botanical:A drug made from part of a plant, as from roots, leaves, bark, etc.
Essential oils:Any of a class of volatile oils obtained from plants possessing the odor and other characteristic properties of the plant, used chiefly in the manufacture of perfumes, flavors and pharmaceuticals (extracts after hydro-distillation).
Plants have evolved a wide range of low molecular weight secondary metabolites. Generally these compounds enable the plant to interact with the environment and may act in defense against physiological and environmental stress as well as predators or pathogens. Some plant metabolites are toxic to animals, however several have been reported to provide beneficial effects in food products and also in mammalian metabolism. The latter are primarily in herbs and spices and are specifically enriched and eventually standardized in botanicals.

Modes of action of herbs, spices and botanicals

Herbs and botanicals benefit farm animals by increasing feed intake, improving immune response and by their antibacterial, coccidiostatic, anthelmintic, anti-viral, anti-inflammatory or, particularly, antioxidant properties. Most of these active secondary plant metabolites belong to the flavonoid and glucosinolate classes of isoprene derivatives; and many of these compounds have been suggested to have antibiotic or antioxidant effects in vivo and in food. Reviews of physiologically active secondary plant metabolites (e.g. Rhodes, 1996 or Hirasa and Takemasa, 1998) and their principle antioxidant characteristics (e.g. Halliwell et al., 1995) have been presented by several authors.

Herbs are active initially in animal feeds as flavors, and can therefore influence eating patterns, secretion of digestive fluids and total feed intake. The primary site of activity is the digestive tract. Herbs or the phytochemicals can selectively influence the intestinal microflora by either antimicrobial activity or by favorably promoting eubiosis of the microflora resulting in better nutrient utilization and absorption, or stimulation of the immune system. Finally, herbs can contribute to nutrient requirements, stimulate the endocrine system and affect intermediate nutrient metabolism.

The diverse activities of herbs and other feed additives can have considerable importance during the growth phase of animals. In the very young animal nutrient digestion and metabolism are not yet fully functional. Furthermore, the immune system and a stable digestive tract microflora (eubiosis) must be established, for which regular feed intake is of prime importance. After this critical period, digestive processes can be optimized and adapted to the available feedstuffs. In these later stages of growth, factors related to product quality (both feed quality and meat, milk or egg quality) play a major role.


Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 2

Figure 2. Modes of action of feed additives in growing animals.



Often the desired activity of herbs or spices is not constant. Conflicting results may derive from the natural variability in composition of plant secondary metabolites. Plant composition is affected by variety, many soil and climatic factors and stage of maturity at harvest. In addition, method of conservation and length of storage, the extraction method used and potentially synergistic or antagonistic effects including anti-nutritional factors or microbial contamination are factors which may substantially affect the results of in vivo experiments.

For example, rosemary and sage from different geographical locations and types of processing (dried herbs vs. essential oil (Svoboda and Deans, 1992)) or from different suppliers (Wenk et al., 1998) had significant differences in antioxidant capacity. Furthermore, several plant metabolites have strong flavors, which may alter feed sensory characteristics and therefore affect feed intake. Additionally, antibacterial properties (probably concentration-dependent) and effects on feed intake and nutrient digestion should be expected and taken into consideration when conducting in vivo experiments with phytochemicals in farm animals.


INFLUENCE OF HERBS ON FEED INTAKE

After the ban on antibiotic use in practical pig production, herbs are increasingly used as feed additives to promote growth and general health. A product from the rhizomes of Sanguinaria canadensis is frequently used in Europe. Other herb mixtures such as Porcin Herba (Bourne, personal communication) lead to increased feed intake as well as better growth performance in piglets and grow/finish pigs.

We have studied the influence of dietary supplementation of five single herbs and two mixtures on feed intake and growth performance of weanling pigs (Table 1). All additives were added at 0.5% of the diet; and performance was compared with an unsupplemented basal diet. The basal diet consisted of barley, wheat, oats, corn, soybean meal, potato protein, fish meal, fat, amino acids and a mineral/vitamin premix. The analyzed nutrient content of the basal and experimental diets was almost identical (Gebert et al., 1999a).


Table 1.Herbal supplements used in growth experiments with piglets.

Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 3



There were no animal losses during the four week experimental period. Added at 0.5% of the diet, only one of the herbs tested (Phyto starter 004) led to an increase in daily feed intake (Table 2). A distinct reduction in feed intake was observed in response to rhubarb and Tibet bitter root inclusion. The increase in feed intake did not correspond to higher growth rate, but the reduced feed intake was clearly reflected in lower daily body weight gain, especially for piglets given diets containing rhubarb or Tibet bitter root. It was concluded that the herbs tested did not generally increase feed intake and growth performance, but some herbs reduced growth performance.


Table 2. Effect of different herbs and two herbal mixtures on performance of piglets weeks 1-4 post-weaning.

Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 4
Gebert et al., 1999b.
abMeans in a column differ, P<0.05




In addition to the growth parameters, fecal consistency and organic matter digestibility were evaluated. Fecal consistency scores were unaffected by treatment with the exception of lower scores and dry matter content for pigs given diets containing rhubarb (Table 3). Although the variation in organic matter digestibility was extremely low, no significant differences between treatments were noted. There was a trend toward increased digestibility in the diet containing Magnoliavine fruit and a similar trend toward reduced digestibility in the diet containing Herba epimedii.


Table 3.Effect of different herb supplements on organic matter digestibility, fecal dry matter content and fecal score of piglets.

Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 5
11 = normal; 2 = wet; 3 = diarrhea
abMeans in a column differ, P<0.05



The reduced intake and higher fecal water content when pigs were given rhubarb can be explained by chemical constituents of this herb. In addition to the presence of oxalic acid, anthrachino-glycans in rhubarb can have specific effects on the digestion processes. According to Engelshowe (1975), anthrachino-glycans can be used to prevent constipation and chronic diarrhea as well as other digestive disorders. Furthermore, there are some indications that rhubarb reduces cholesterol and has antioxidant effects in humans (Goel et al., 1997).

In this experiment, the herbs were added at 0.5% of the experimental diets. Therefore, it was of interest to evaluate whether there was a doseresponse effect of rhubarb on performance. This was evaluated by adding rhubarb to the starter diet of piglets at 0.1, 0.25 or 0.5% and to the broiler diet at 0.25 or 0.5%. In these experiments, a further treatment was included with an antimicrobial supplement as a positive control. Piglet growth was evaluated over a four week period.

Feed intake and growth performance significantly increased with carbadox supplementation compared to the unsupplemented control (Table 4). In all treatments with rhubarb, feed intake and performance were reduced. Daily weight gain of pigs given 0.5% rhubarb was half that of pigs fed the control diet. Addition of 0.1% rhubarb slightly reduced growth rate, however feed intake was markedly lower than controls. As in the previous trial, rhubarb reduced fecal dry matter content. In further experiments with rhubarb from another origin, addition of 0.1% increased feed intake and growth rate; however 0.25 and 0.5% led to a significant decrease (Gebert et al., 1999b).


Table 4. Growth experiments with rhubarb in piglets.

Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 6
Gebert et al., 1999b.
abMeans in a row differ, P<0.05.



In an experiment with growing chickens, rhubarb supplements were compared with zinc bacitracin as antimicrobial agents. The feeding experiment began following a week adaptation period post-hatch and continued throughout the 39 day growth period. Seven birds from the negative control treatment had to be excluded from the experiment while only two birds were lost in each of the other treatments. Deaths or removals from treatment were due to heart failure, ascites and leg weakness (mainly caused by fast growth). Zinc bacitracin increased feed intake and growth rate slightly (Table 5). In contrast to the piglet experiments, 0.25% rhubarb increased feed intake and growth rate by about 8%. There was no detrimental effect on excreta dry matter content and no effect on water intake. However, supplementation of 0.5% rhubarb reduced feed intake and performance, an observation which corresponds well with the piglet experiments. Obviously, the birds were less influenced by the rhubarb than the pigs.


Table 5. Growth experiments with rhubarb in broilers.

Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 7
Messikommer, 1999; personal communication.
abMeans in a row differ, P<0.05.




ANTIMICROBIAL AND COCCIDIOSTATIC ACTIVITIES OF HERBS AND BOTANICALS

The antimicrobial activity of herbs and botanicals has been studied in many different in vitro assays (Huang, 1999; Baratta et al., 1998; Deans and Richie, 1987). In Table 6 some examples for Chinese herbs are presented. Some of the herbs tested had a wide spectrum of antimicrobial activity against Gram-positive and Gram-negative bacteria. Others were mainly active against Gram-positive species (Spring et al., 1998, personal communication).

Results of in vitro tests as shown in Table 6 indicate that herbs can have specific antimicrobial activities. Transforming such results into the digestive tract of an animal is not easy. Herbs or botanicals added to a diet must compete with the major nutrients as well as with other possible secondary plant constituents present in the feed. Furthermore the microbial population of the digestive tract varies with factors such as pH, transit time, nutrient density, absorption rate, etc.

An interesting approach was made by Gàbor and Boros (personal communication), in which an oil extract of several plants (clove, thyme, peppermint and citrus) was tested under practical farm conditions in comparison with a diet containing a standard coccidiostat. Birds given the oil extract performed similarly to the flocks given diets containing coccidiostat (Table 7). Allen et al. (1998) also found that certain plant products have coccidiostatic activity and can be used as feed additives.


Table 6.Antimicrobial activity of Chinese herbs in comparison to garlic.

Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 8
Recent tests with Chinese herbs (Spring, Wang and Ding, 1998 personal communication ).



Table 7.Comparison of an oil extract of clove, thyme, peppermint and lemon and a standard coccidiostat in diets for broilers.

Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 9



HERBS AND BOTANICALS AS ANTIOXIDANTS


The antioxidant status of an animal depends on several different factors (Wenk et al., 2000). The animal itself represents a homeostatic balance regulated by the available enzymes. Nutrients with different potentials for oxidation are ingested in feed, with the polyunsaturated fatty acids (PUFA) representing the highest risk for oxidation. In addition, feedstuffs may contain substances like iron, copper or phytases that can catalyze nutrient oxidation. Finally, antioxidants like tocopherols, carotenoids, flavonoids, etc. protect compounds prone to oxidation.


Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 10

Figure 3.Activity of antioxidants in monogastric animals.



Activity of various antioxidants varies with the type of antioxidant, polarity, solubility and site of activity (Figure 3). Some antioxidants protect nutrients in feed during storage. Others are primarily active in the digestive tract where they may also aid absorption of the nutrients they protect. Antioxidants are responsible for many functions in intermediary metabolism including protection of intact membranes. In farm animals dietary antioxidants can ultimately influence shelf life of animal products.

The antioxidant activity of herbs can be measured by methods such as the Rancimat test (Metrohm, Herisau, CH). Herbs or botanicals are added to an oil that is heated and ventilated by an air stream for accelerated oxidation. The results are expressed as an antioxidant factor which corresponds to the induction time of oxidation relative to the untreated oil. Thus high values indicate high oxidative stability.

The antioxidant capacity of several Chinese herbs or their ethanol extracts was measured in comparison to rosemary using the Rancimat test with soybean oil as the carrier. Rosemary is well-known as a potent antioxidant, especially in countries around the Mediterranean Sea. Soybean oil itself contains high amounts of tocopherols and therefore has natural capacity for protection against oxidation. In comparison to rosemary, only Radix et Rhizoma Rhei showed similar effects on AF (Figure 4). The ethanol extracts of Herba epimedii, Magnoliavine fruit, Radix puerariae and Ramulus taxilii also had some antioxidant activity.

The Rancimat test used as described selects only for lipid soluble antioxidants; however it is of interest to know whether other water soluble constituents also have antioxidant activity. Therefore, in a further study the Rancimat test was compared with the microsome peroxidation assay in which thiobarbituric acid reactive substances were measured after starting oxidation of rat liver microsomes using FeCl2/H2O2. In the microsome peroxidation test, primarily water soluble antioxidants are detected. The values given in Figure 5 are relative to the control with low values indicating Figure 4. Antioxidative capacity of different herbs and commercial mixtures measured with the Rancimat system (AF = antioxidative factor) (Scheeder et al., 1999). delayed oxidation. Oleic acid was used instead of soybean oil in the Rancimat test.


Figure 4. Antioxidative capacity of different herbs and commercial mixtures measured with the Rancimat system (AF = antioxidative factor) (Scheeder et al., 1999).



In the Rancimat test Cortex eucommiae and Magnoliavine fruit were the most effective antioxidants, but other Chinese herbs showed significant activity. Cortex eucommiae did not react at all. Other herbs like Herba epimedii or Radix et Rhizoma rhei had excellent antioxidant activity in the water soluble fraction. These data indicate that in vitro tests will not be able to characterize the antioxidant actives of a herb properly.

Deans et al. (1993) studied the antioxidant activity of essential oils from different herbs in detail. Some of the results are shown in Table 8. The essential oils extracted by hydro-distillation from rosemary, thyme etc. had distinct antioxidant activity in this test. On the other hand, essential oils from estragon or sage had pro-oxidative activity. Some other herbs showed no activity against oxidation. In experiments with mice Deans et al. (1993) demonstrated that essential oils from thyme were able to protect highly polyunsaturated fatty acids (C20:4 and C22:6) and prevent rapid aging. From these experiments, it can be concluded that the antioxidant activity of thyme also had a significant role for animal metabolism.

The effects of phytochemical antioxidants on lipid oxidation in meat and meat products is of major concern. Plant oils used as feed ingredients in monogastric nutrition may readily alter fatty acid composition of all body lipid fractions by generally increasing the amount of PUFA and therefore consequently decreased firmness of salami produced (Scheeder et al., 1998). On the other hand, oxidative stability was higher in the lard of oliveoil supplemented pigs than expected from the degree of unsaturation compared to lard of pigs fed diets without fat, or supplemented with soybean oil or pork fat (Gläser et al., 1999; Figure 6).


Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 11

Figure 6.Relationship between oxidative stability of lard from pigs fed different fat supplements and the fat score (a measure of double bonds) showing the elevated oxidative stability of lard from olive oil supplemented pigs (Gläser et al., 1999).



The effects of herbs or herb extracts used as dietary supplements were examined in two other studies. Greber (1997) fed dried sage to pigs and reported a significant decrease of TBARS (thiobarbituric acid resistant substances) in the lard with increasing concentration of sage from 0.6% to 1.2% of the diet. In contrast, the Rancimat test showed no significant effect. Lopez-Bote et al. (1998) also reported that they did not find an antioxidant effect in pork when oleoresins of rosemary and sage were fed. However, feeding the same oleoresins (500 mg/kg) to broilers led to improved oxidative stability in red (leg) and white (breast) meat (measured as TBARS) as well as a lower amount of cholesterol oxidation products. The oleoresins were not as effective as "-tocopherol acetate (200 mg/kg), but it may be concluded that at least part of the ingested antioxidant compounds were retained in the muscle and that they were still active in the meat.

However, investigations on effects of dietary secondary plant metabolites on muscle and adipose tissues of farm animals are still rare. In addition, knowledge about effects of secondary plant metabolites in feed and in the gut, their bioavailability with respect to absorption and metabolism, and the extent to which they might be retained in animal tissues is not readily available.

Lopez-Bote et al. (1998) used extracts of rosemary and thyme in their experiments. It was therefore of interest to know whether entire herbs were also able to react as antioxidants in diets for chickens. In experiments of Ding et al. (1999) the antioxidative effects of rhubarb, Herba epimedii and Magnoliavine fruit were evaluated. The herb supplements were added to a standard diet based on corn, soybean meal and fish meal in amounts of 0.25 and 0.5% fed for an eight week period. Mortality was unaffected by treatment (Table 9). Daily body weight gain in the treatments with rhubarb were slightly higher, and in the treatments with Magnoliavine fruit slightly lower, compared to the control diet containing avilamycin as antimicrobial agent (200 ppm). The improved body weight gain was associated with improved feed conversion.


Table 9.Daily body weight gain and feed conversion of broilers given diets containing antioxidant Chinese herbs.

Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 12
Ding et al., 1999.



Antioxidant activity of the herbs was measured as superoxide dismutase activity (SOD) and as malondialdehyde (MDA) in liver, in blood serum and in abdominal fat issues. With an increased antioxidant status in the three different tissues (high SOD values) a reduced amount of oxidative products is expected (lower MDA values). The results in Table 10 confirm this relationship for all herbs. Moreover, improved stability of the tissues against oxidation was observed. Thus it can be concluded that in addition to extracts, the entire herb added in amounts of 0.25 and 0.5% will have a positive effect. This means that these herbs were able to increase shelf life, reduce off flavors and therefore improve quality of the products.


Conclusions: the need for alternative strategies


Beneficial effects on health status, performance, and nutrient and energy utilization are the main reasons for the wide use of antibiotic feed additives. The trend toward more ‘natural’ animal production systems has led to an increasingly critical attitude on the part of consumers about in-feed antimicrobial agents. Therefore, agriculture is looking for ‘friendly’ supplements with better acceptance by the consumer. Whether herbs, spices or botanicals (eg. essential oils) are appropriate must be considered in each practical application.


Table 10. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) content of liver, serum and abdominal lipids (means ±sd).

Herbs, spices and botanicals: ‘Old fashioned’ or the new feed additives for tomorrow’s feed formulations? Concepts for their successful use - Image 13



The banning of antibiotics in Europe and in other countries in the near future has brought about discussion of alternative strategies. They are of primary interest in veal production and in young pigs, in addition to poultry. Such strategies must be based primarily on optimal management and housing conditions. The main aspects of environmental management are:
- temperature (microclimate of the calves and piglets)

- fresh air, no draughts

- space allowance and appropriate floor surface

- straw bedding, if possible

- low humidity and minimal dust

- good rotation system
Nutrition must primarily focus on supplying animals with all essential nutrients and energy in adequate amounts. Adequate feed trough space is necessary where large groups of animals are fed. Overeating by heavier animals should be avoided in order to prevent digestive disorders.

With the following measures the risks of digestion problems, especially in the young pig, can be minimized:
-Low acid binding capacity

- reduced mineral content (< 6 g Ca and < 5 g P per kg feed)

- reduced protein content (essential amino acids according to requirement)

- organic acids (mainly fumaric and lactic acid)

Enzymes, prebiotics and dietary fiber sources
- mainly phytases and carbohydrases

- fructose and mannose oligosaccharides

- pectins or other soluble dietary fibers

Liquid feeding systems with the possibility of fermentation before feeding
- herbs, botanicals, spices or essential oils

- probiotics (lactobacilli)

- avoidance of anti-nutritional factors
In the concept of production of healthy farm animals without using antibiotics, herbs can be relevant in many different ways. There is evidence that they can regulate feed intake and stimulate digestive secretions. An optimized digestion capacity and a reduced risk of digestive disorders are the consequence. Several phytochemicals like essential oils or dietary fiber can contribute to a balanced microflora, an optimal precondition for an effective protection against pathogenic microorganisms and an intact immune system. In addition, herbs and botanicals contain many different antioxidants with a high potential for the protection of nutrients against oxidation in the digestive tract, in intermediary metabolism as well as in meat, milk and eggs.


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