Role of Antioxidants in Feed

Role of Antioxidants in FeedAntioxidants play a major role in animal health, production and performance. This is due to the detrimental effects of radicals and toxic products of their metabolism on various metabolic processes. It is a well known fact that oxidative stress is involved in many degenerative disorders. The oxidative free radicals are therefore considered as pathobiochemicals mechanism for initiating or progression of various diseases. The prooxidant-antioxidant balance can be regulated by optimal nutrient uptake or providing herbal antibiotics. Thus, the essential step in maintaining the balance between the oxidative damage and antioxidative defence in the animal body would be to boost the antioxidant capacity by optimising the dietary intake of antioxidants.

Vitamin C is a water-soluble antioxidant. It is an important anti-stress agent. However, it can be easily oxidized. Sources of vitamin C are citrus fruits and vegetables. Vitamin C is required in collagen biosynthesis and protein metabolism.

Vitamin E is the found in the biological membranes and lipid droplets. Vitamin E is absorbed in the small intestine with various efficacious depending on the diet composition, level of supplementation, age, sex and other individual characteristics of animals. It is the main chain-breaking antioxidant in biological systems.

Carotenoid is a natural pigment, responsible for yellow, orange and sometimes red pigmentation’s in plants, insects, birds and marine animals. They possess antioxidant activity. They have some health promoting properties, including immune system modulation. They are found in some plant-derived feed ingredients.

Manganese has an essential part of a range of enzymes taking part in antioxidant protection, bone growth and egg shell formation carbohydrate and lipid metabolism including processing of cholesterol.

Zinc is the second most abundant trace element trace element in mammals and they take part in antioxidant defence as an integral part of SOD, hormone secretion, keratin generation and epithelial tissue integrity immune function.

Iron has a vital role in antioxidant defence as an essential component of catalase, energy and protein metabolism, hence respiratory carrier, electron transport, oxidation-reduction reaction.

Poultry Gut Microbiome

Poultry Gut MicrobiomeThe microbiome of the gastrointestinal (GI) tract of poultry is very diverse yet relatively stable in a dynamic state. The poultry (e.g. duck, chicken and turkey) GI tract consists of cloaca, colon, cecum, small intestines (duodenum, jejunum and ileum), gizzard, proventriculus, crop and esophagus. The GI tract of the poultry is much shorter than that of mammalian animals. But it contains highest bacterial abundance and diversity. The bacteria found in the intestine mostly include Escherichia coli, Lactobacillus, Bacteroids, Eubacterium, Peptostreptococcus, Propionibacterium as predominant organisms. Other group of micro organisms such as anaerobic, gram-negative cocci, facultative anaerobic cocci and streptococci are also found in the GI tract. In this article we briefly discuss the factors affecting the poultry gut micro biome and its importance for poultry nutrition.

Microbiome and Host

Many intestinal bacteria hydrolyze carbohydrates to simple sugars which are further fermented to short chain fatty acids (SCFA) (viz., butyrate, propionate and acetate) by other intestinal bacteria. The SCFA are utilized as a source of energy and carbon. Gut bacteria also contribute to host nitrogen metabolism. These bacteria metabolize uric acid to NH3, which is utilized by the host to synthesize a few amino acids such as glutamine. Gut micro biome of poultry may also serve as a source of vitamin to its host. Mucins secreted by goblet cells of the gut are important source of carbon, nitrogen and energy for some commensal and pathogenic bacteria. Gut micro biome also has impact on intestinal morphology of poultry. One such effect is evident when birds raised on a conventional diet show shorter intestinal villi and shallow crypts with low load of bacteria. However, dietary supplementation of probiotic organisms increases villus height: crypt depth ratio in ileum of broilers.

Microbiome and Immunity

The first line of defense mechanism in the inner surface of avian gut is the gel-like mucus layer formed from mucin glycoprotein produced by the goblet cells. The mucus layer prevents the intestinal pathogens from penetrating into intestinal epithelium. The disruption of the mucus layer is probably due to the severe necrosis of the intestinal mucosa which results in vast shedding of goblet cells. Production of beta-defensin is another important strategy present on the intestinal epithelial surface. Βeta-defensin are produced by avian macrophage, heterophils and epithelial cells that kills various intestinal pathogens by disrupting cell membrane permeability. In birds, the cell mediated immunity (T and B cells) can be found in dispersed areas (lamina propria and epithelium) and in more organized lymphoid tissues (Payer’s patches and bursa of fabricius).

Microbiome and Diet

Diet has great potential to modulate the host digestion and nutrient absorption. Wheat, barley or rye-based diets have more impact on the gut micro biome. These diets contain high levels of water-soluble, indigestible, non-starch polysaccharide that favor necrotic enteritis. Excessive non-starch polysaccharide leads to rise in digesta viscosity, decreased digesta passage rate and a decline in nutrient digestibility. Another potential diet ingredient, soyabean is used as a source of protein to promote the growth lactobacilli population and reduce the number of coliforms in cecum of poultry. Some of the gut micro organisms are also influenced by dietary fat source. Dietary enzymes such as xylanase and beta-glucanase, increase intestinal lactic acid bacteria

(LAB) and decrease the population of adverse and pathogenic bacteria such as E. coli. Dietary supplementation with xylanase and beta-glucanase protects against necrotic enteritis as the enzyme breakdown the non starch polysaccharide in the diet and reduce the digesta viscosity. Plant derived trans-cinnamaldehyde and eugenol are effective in reducing S. enteritis colonization in 20-d old broiler chickens. Others such as blend of essential oils, containing thymol, carvacrol, eugenol, curcumin and piperin reduce the colonization and proliferation of such pathogens. Antibiotic growth promoter (AGP) is another feed additive used to improve feed efficiency, increase animal growth and maintain animal health. The inclusion of AGP in poultry diet reduces the incidence of disease and promotes better performance of the birds by inhibiting the growth of enteric pathogens. However, due to rising antibiotic resistance among the pathogens, the use of AGP has been prohibited. The proliferation of the bacteria present in the gut can be increased by the ingestion of prebiotics. Prebiotics are polysaccharides such as galatosaccharide (GOS) and fructosaccharide (FOS). GOS favors the growth of Bifidobacteria in the GI tract of broiler chicken.

Competition for nutrient and attachment site

The GI tract of newly hatched chick is sterile, but is immediately colonized by surrounding organisms. Over the period of time, normal colonization and succession of gut micro biome takes place in healthy adult poultry’s intestine. The GI tract serves as an ideal habitat for micro organisms however, due to limited space and resources; there is competition among organisms for nutrient resources. Some bacteria produce bacteriostatic or bactericidal substances to kill its competitors. The LAB ferment carbohydrates to organic acids and inhibits the growth of certain pathogens such as E. coli and Salmonella by reducing the pH of the gut. Certain bacteria such as Enterococcus sp., Pediococcus sps., Bacillus subtilis also produce antimicrobial agent called bacteriocins to selectively inhibit the growth of other bacteria. However, pathogens are adapted to new environment very fast mediated by a process such as conjugation, transformation and transduction. Providing probiotics (live microbial feed supplement) benefits the host through the following mechanisms: (1) inhibiting the growth of pathogenic bacteria from colonizing and proliferating in the gut through competition for nutrient and attachment site (2) production of bacteriostatic and bactericidal substances against pathogens (3) enhancing gut barrier function and (4) enhancing host immunity.

Poultry litter microorganisms influence gut microbiome

Chickens are in constant contact with the micro organisms from the surrounding environment. The poultry litter usually harbors a complex microbial community. Reuse of poultry litter commonly practiced by poultry farmers to reduce produce cost, influences chicken guts micro biome. The reused litter may also harbor disease-causing micro organisms from the previous flock and thus serves as a source of pathogens to the subsequent flock.

Conclusion

The gut represents an essential microbial ecosystem that lives in symbiosis with the host. The development of GI micro biome plays a crucial role in the nutrition, health and growth of the chicken. Thus further research on the intestinal micro biome of the poultry can potentially provide us more knowledge to improve management of poultry diseases, antibiotic resistance and better control of colonization and spread of human pathogens.

Anti Antibiotics – The Way Ahead

Anti Antibiotics – The Way AheadFor years together Livestock has been an in separable part of humanity. The cheapest and most readily available source of protein.  The methods of rearing livestock have evolved in leaps; this is clearly evident in case of the poultry industry. The word broiler is now taken as Cobb or Ross and to keep up with the protein deficit of the world new strains are being introduced to cultivate meat faster and in an efficient way.

In this process several mechanisms have been devised to improve the bird, the environment or the final product. This introduces us to fields of Breeder genetics, Nutrigenomics, Housing, Management, Bio-security, Carcass traits, Packaging, Logistics and shelf life, all of which try to improve the profitability and the product quality.

The market is full of different feed additives working on the aspects latter to genetic improvement in breeders. For years antibiotics and specifically antibacterial have been used on a large scale to kick up revenues and cover up management flaws. Pumping in these drugs at these rates has resulted in the pathogenic bacteria being destroyed but also leads to the whole gastrointestinal micro floral balance instability. The era of misuse of antibiotics began. There are several views, as the use of antibiotics in livestock being good or bad. There are several reasons not to use antibiotics in livestock, the primary not being the antibiotic resistance but yes an important reason. Thus, apart from the common facts that using antibiotics may cause parallel resistance affecting human treatment regimes, it is also important for us to understand the foot print that antibiotics leave on the animal world.

The Livestock production arena is an amalgamation of bacterial opportunistic propagation driven entities. The race is already on between the eradication of these bacteria versus survival responses of these highly adaptive microbes. This is especially when we throw a cocktail of antibiotics on them. Every time zapping a bug with a new bullet does end the life of the bug, but also helps the bug to evolve a better armor, one that is non penetrable by the same bullet.  But why are we focusing on the bullet and not on the gun? Something that the bug may not even see, something that the bug is never exposed to!! The ideal route for restricting the excessive use of antibiotics is thus to improve the management practices on the farm which include impeccable bio-security. As this is not possible in all circumstances the use of anti-infective and growth promoters will always be used as a preventive and a treatment regime for under performing birds. However, we can always use a better trigger mechanism, there is middle way out. Why not use the natural responses of the bird itself fight the average management practices.

To improve the bird’s immunity and to overcome microbial challenges one should focus on certain specialised feed additives. The feed additive market carries an endless list of antibiotic re-placers which can be summarised in the categories of Acidifiers, Probiotics, Prebiotics and Phytobiotics. However, every trigger is only sensitive to a specific environment, a specific bacteria or a narrow mechanism of action. Acidifier resistance is well documented in recent literature, this with pH as low as 2.5 not proving effective against common taboo bacteria as salmonella. Probiotics work mainly in the finisher stages and farms still have to rely on antibiotics to curb the early chick mortality. Moreover, the probiotics work at variable dose with variable outcomes, some proving unsuitable to certain environments and ineffective in certain strains of poultry.  Prebiotics could have been an effective way to tackle the problem only if the cost and dosage would comply. Also there are various supportive nutrients fuelling the pathogenic bacteria in the gut which easily overcome prebiotics.  What the industry needs is something broad spectrum and natural. An effective Phytobiotic, and yes they work, but nobody wants to rely on a trigger that differs in sensitivity every time you are in a gunfight. What we really need is an effective and reliable Phytogenic antibiotic replacer which uses only standardised herbal Phytoconstituents as ingredients.