|Company Name||Use of phytogenic products as feed additives for poultry|
|Contact Person||Dr. AJAZ A. GANIE|
Karnal, Haryana, India.
|Zip / Postal Code||132001|
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USE OF PHYTOGENIC PRODUCTS AS FEED ADDITIVES FOR POULTRY
Ajaz A. Ganie and I.A.Mir Dairy Cattle Nutrition Division,
National Dairy Research Institute, Karnal (Haryana) -132001, India
Since ancient times, medicinal plants have been used to treat humans and livestock. The preparations made from plants were either from raw materials (leaves, roots or branches) or processed (cooked or boiled). Most likely, natural medicine has been evaluated in two directions; the first is based on observing animalsí self-medication, whereas the second is associated with human folk medicine. Nowadays the industrialised medicaments may also be plant derivatives. Phytogenic feed additives are plant-derived products used in animal feeding to improve the performance of agricultural livestock. This class of feed additives has recently gained increasing interest, especially for use in swine and poultry, as can be derived from a significant increase in the number of scientific publications since 2000. In this context, phytogenic feed additives are discussed possibly to add to the set of nonantibiotic growth promoters, such as organic acids and probiotics, which are already well established in animal nutrition. Phytogenics, however, are a relatively new class of feed additives and our knowledge is still rather limited regarding their modes of action and aspects of their application. Further complications arise because phytogenic feed additives may vary widely with respect to botanical origin, processing, and composition. Most studies investigate blends of various active compounds and report the effects on production performance rather than the physiological impacts. In this context, the following provides an overview of recent knowledge on the use of phytogenic feed additives in piglet and poultry diets, possible modes of action, and safety implications. Phytogenic compounds as feed additives in poultry diets has been claimed to have antioxidative and antimicrobial actions, beneficial effects on palatability and gut functions, and growth-promoting efficacy.
Antioxidative properties are well described for herbs and spices. Among a variety of plants bearing antioxidative constituents, the volatile oils from the Labiatae family (mint plants) have been attracting the greatest interest, especially products from rosemary. Their antioxidative activity arises from phenolic terpenes, such as rosmarinic acid and rosmarol. Other Labiatae species with significant antioxidative properties are thyme and oregano, which contain large amounts of the monoterpenes thymol and carvacrol. Plant species from the families of Zingiberaceae (e.g., ginger and curcuma) and Umbelliferae (e.g., anise and coriander), as well as plants rich in flavonoids (e.g., green tea) and anthocyans (e.g., many fruits), are also described as exerting antioxidative properties. Furthermore, pepper (Piper nigrum), red pepper (Capsicum annuum L.), and chili (Capsicum frutescene) contain antioxidative components. In many of these plants, parts of the active substances are highly odorous or may taste hot or pungent, which may restrict their use for animal feeding purposes. The antioxidant property of many phytogenic compounds may be assumed to contribute to protection of feed lipids from oxidative damage, such as the antioxidants usually added to diets (e.g., α-tocopheryl acetate or butylated hydroxytoluene). Although this aspect has not been explicitly investigated for piglet and poultry feeds, there is a wide practice of successfully using essential oils, especially those from the Labiatae plant family, as natural antioxidants in human food as well as in the feed of companion animals.
The principal potential of feed additives from the Labiatae plant family containing herbal phenolic compounds to improve the oxidative stability of animal-derived products has been demonstrated for poultry meat, pork, rabbit meat, and eggs. Oxidative stability was also shown to be improved with other herbal products. Nevertheless, it remains unclear whether these phytogenic antioxidants are able to replace the antioxidants usually added to the feeds (e.g., α-tocopherols) to a quantitatively relevant extent under conditions of common feeding practice.
DIETARY PALATABILITY AND GUT FUNCTIONS
Phytogenic feed additives are often claimed to improve the flavor and palatability of feed, thus enhancing production performance. However, the number of studies having tested the specific effect of phytogenic products on palatability by applying a choice-feeding design is quite limited. They show dose-related depressions of palatability in pigs fed essential oils from fennel and caraway, as well as from the herbs thyme and oregano. On the other hand, there are numerous reports on improved feed intake through phytogenic feed additives in swine. However, an increase in feed intake in swine is a common result of the use of growth-promoting feed additives, such as antibiotics, organic acids, and probiotics, and, in the first instance, it may be considered to reflect the higher consumption capacity of animals grown larger compared with untreated controls. Therefore, the assumption that herbs, spices, and their extracts improve the palatability of feed does not seem to be justified in general. A wide range of spices, herbs, and their extracts are known from medicine to exert beneficial actions within the digestive tract, such as laxative and spasmolytic effects, as well as prevention from flatulence. Furthermore, stimulation of digestive secretions (e.g., saliva), bile, and mucus, and enhanced enzyme activity are proposed to be a core mode of nutritional action). Phytogenic feed additives were also reported to stimulate intestinal secretion of mucus in broilers, an effect that was assumed to impair adhesion of pathogens and thus to contribute to stabilizing the microbial eubiosis in the gut of the animals.
Herbs and spices are well known to exert antimicrobial actions in vitro against important pathogens, including fungi. The active substances are largely the same as mentioned previously for antioxidative properties, with phenolic compounds being the principal active components). Again, the plant family of Labiatae has received the greatest interest, with thyme, oregano, and sage as the most popular representatives. The antimicrobial mode of action is considered to arise mainly from the potential of the hydrophobic essential oils to intrude into the bacterial cell membrane, disintegrate membrane structures, and cause ion leakage. High antibacterial activities are also reported from a variety of nonphenolic substances, for example, limonene and compounds from Sanguinaria Canadensis. Another implication of the antimicrobial action of phytogenic feed additives may in be improving the microbial hygiene of carcasses. Indeed, there are isolated reports on the beneficial effects of essential oils from oregano on the microbial load of total viable bacteria, as well as of specific pathogens (e.g., Salmonella) on broiler carcasses.
The primary mode of action of growth-promoting feed additives arises from stabilizing feed hygiene (e.g., through organic acids), and even more from beneficially affecting the ecosystem of gastrointestinal microbiota through controlling potential pathogens. This applies especially to critical phases of an animalís production cycle characterized by high susceptibility to digestive disorders, such as the weaning phase of piglets or early in the life of poultry. Because of a more stabilized intestinal health, animals are less exposed to microbial toxins and other undesired microbial metabolites, such as ammonia and biogenic amines. Consequently, growth-promoting feed additives relieve the host animals from immune defense stress during critical situations and increase the intestinal availability of essential nutrients for absorption, thereby helping animals to grow better within the framework of their genetic potential. Recent studies with swine and poultry indicated stabilizing effects of phytogenic feed additives on the ecosystem of gastrointestinal microbiota. Relief from microbial activity and related by-products is of high relevance, especially in the small intestine, because production of VFA counteracts stabilization of the intestinal pH required for optimum activity of digestive enzymes. In addition, intestinal formation of biogenic amines by microbiota is undesirable not only because of toxicity, but also because of the fact that biogenic amines are produced mainly by decarboxylation of limiting essential AA (e.g., cadaverine from Lys, scatol from Trp). Consequently, relief from microbial fermentation in the small intestine may improve the supply status of limiting essential nutrients.
In conclusion, phytogenic feed additives are claimed to exert antioxidative, antimicrobial, and growth-promoting effects in livestock, actions that are partially associated with enhanced feed consumption, supposedly because of improved palatability of the diet.
|Last Updated: 2011-08-29 23:11:24|
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