Use of feed additives for improving poultry production

Dr. Ravindra Jadhav¹, M.V.Sc., Ph.D and Dr. M.Manobhavan², M.V.Sc., Ph.D

1. Nutritionist, Premium Chick Feeds Pvt. Ltd, Alibag (Maharashtra) 402108

2.Assistant Professor, Department of Animal Nutrition, Madras Veterinary College, TANUVAS, Chennai-600007

Introduction:

Feed additives are products used in animal nutrition for purposes of improving the quality of feed and the quality of food from animal origin, or to improve the animals’ performance and health, e.g. providing enhanced digestibility of the feed materials. In general, the term “feed additive” refers to a non-nutritive product that affects utilisation of the feed or productive performance of the animal which may economise the cost of animal origin foods. 

Many feed additives are gaining importance because of increased raw material cost, need for used of alternative raw materials, low market prices of poultry meat and eggs, and government regulations as well as consumer awareness about environmental and human health attributes of food (carbon footprint, antimicrobial resistance, sustainability).

As per European Food Safety Authority, feed additives include:

• Technological additives – e.g. preservatives, antioxidants, emulsifiers, acidity. regulators, silage additives.
• Sensory additives – e.g. flavours, colourants.
• Nutritional additives – e.g. vitamins, amino acids, trace elements.
• Zootechnical additives – e.g. digestibility enhancers.
• Coccidiostats and histomonostats.

As mentioned above additives may be nutritive or non-nutritive, in this article we are discussing about non-nutritive types.

1. Enzymes: These are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products.

Following are different enzymes used in poultry feed.

1. Phytase: This is most widely used enzyme in poultry feed, which makes available phytate bound phosphorous to the birds. Phytate is anti-nutritional factor in plant derived feed which binds minerals and increase amino acid loss through increased intestinal mucus secretion. It economizes feed formulation as well as by improving bound phosphorous utilization it reduces phosphorous excretion in faeces reducing the environmental pollution. Apart from phosphorous it also improves the utilization of amino acids and other minerals improving the birds weight gain and feed efficiency.
2. NSPases: This is group of enzymes that acts on Non starch polysaccharides (NSP).  They act in following ways to benefit the bird i) Attenuation of the antinutritive effect (reduced digesta viscosity) ii) reduction of the non-digested portion of the substrate 3) improvement of the growth performance of the chicken by increasing energy availability. In addition, it increases production of short chain fatty acids like butyrate which are important for gut health. Examples of NSPases are xylanase, β mannanase, β Glucanase.

Some enzymes like α galactosidases which act on oligosaccharides (present in beans) are also gaining importance.

• Protease: Act on proteins and makes it highly digestible by breaking peptide bonds. Depending on the functional amino acid at active side, proteases are classified as- serine (mostly bacterial- bacillus), cysteine (plant derived-papain), aspartate and metalloproteases.

Use of Protease is also not uncommon now a days, because of use of alternative protein sources (poorly digestible) on account of increased prices of Soya DOC. Also, it reduces nitrogen excretion through faeces reducing litter quality issues N and pollution. It also reduces amount of undigested protein entering large intestine which otherwise will be used by harmful bacteria for growth (protein fermenters).

• Other enzymes such as lipase, amylase cellulase are also available for poultry feed. Recently enzymes are also used for mycotoxins biotransformation to non-harmful metabolites

• Emulsifiers: Emulsifiers improve fat utilization and digestion in poultry. They work by breaking down and dispersing large fat molecules into smaller droplets, making them more available for absorption. Also, they help in micelle formation in which hydrophobic fat is arranged in hydrophilic structure to help its transportation across intestinal epithelium. Bile is natural emulsifier produced in liver. In poultry, bile secretion and lipase activity are not sufficient in early age, so making it one of promising additive.

Examples of emulsifier include soy-lecithin, lysophatidylcholine or lysolecithin, bile salt, glycerol polyethylene glycol ricinoleate, and sodium stearoyl-2-lactylate (SSL) etc. Some emulsifiers also increase pellet mill output saving the power consumption.

• Antibiotics growth promoters: These are substances which are produced by living organisms (mould, bacteria) and which in small concentration have bacteriostatic or bactericidal properties.  They were originally developed for medical and veterinary purposes to control specific pathogenic organisms.

Their use in feed is now restricted as due to continuous use antibiotic resistant microbes have evolved which are difficult to control and causing health issues in humans too. AGPs still in use are avilamycin, virginiamycin, flavomycin. AGPs should be changed after every 2-3 months to avoid resistance.

Halquinone (non-antibiotic compound) can also be used to control gut pathogens growth, it also modulates gut peristalsis, slower down feed passage rate, improving feed digestibility.

• Anticoccidial medicines: Serious economic and health impacts of coccidiosis are well known. Various ionophore and chemical compounds are used to prevent coccidiosis.  Lasalocid, Monensin, Narasin, Salinomycin, Nicarbazine (in combination with Naracin/Maduramycin), Decoquinate, Clopidol are working well.

However, it should be changed frequently (within two months for ionophores, one month for chemical) to avoid the resistance.

• Probiotics (Direct fed microbials) :  Probiotics are live microbes that supplement the gastrointestinal flora and help to maintain a healthy digestive system, thereby promoting the growth performance and overall health of poultry (Jha et al 2020).

How they act?

1. Having a direct antagonistic effect against specific group of undesirable or harmful organism through production of antibacterial compounds, competition for the nutrient and or attachment site.
2. Some microbes release enzymes which help in digestion
3. Stimulation of immunity

Examples – Bacillus (bacteria), Saccharomyces (yeast).

Probiotics is important additive in without AGP feed, to maintain gut health.

• Prebiotics: Prebiotics are known as non-digestible carbohydrates that selectively stimulate the growth of beneficial bacteria, thus improving the overall health of the host. Once prebiotics are introduced to the host, 2 major modes of action can potentially occur. Initially, the corresponding prebiotic reaches the intestine of the chicken without being digested in the upper part of the gastrointestinal tract but are selectively utilized by certain bacteria considered beneficial to the host. Secondly, other gut activities occur due to the presence of the prebiotic, including generation of short-chain fatty acids and lactic acid as microbial fermentation products, a decreased rate of pathogen colonization, and potential bird health benefits (Ricke et al 2020). In addition they can bind mycotoxins and stimulate immune system.

The commonly used prebiotics are MOS (Mannan oligosaccharides), FOS (Fructan oligosaccharides.

• Postbiotics: It is a “preparation of inanimate microorganisms and/or their components that confers a health benefit on the host”. Other related terms have also been used, including ‘paraprobiotics’, ‘parapsychobiotics’, ‘ghost probiotics’, ‘metabiotics’, ‘tyndallized probiotics’ and ‘bacterial lysates (Salminen et al., 2021). Postbiotics are stable during industrial processing and storage. Postbiotics boost poultry growth, feed efficiency, intestinal pathogen reduction, and health, making them acceptable drivers of sustainable poultry production (Saeed et al., 2023).

• Stimbiotics: These are a relatively new class of non-digestible feed additives that promote dietary fibre utilisation by the commensal microbiota through a smooth transition process (González-Ortiz et al., 2019). In contrast to prebiotics, stimbiotics are added at such low doses, effective as low as 50 g/t (Morgan et al., 2023), that they contribute little to the production of SCFAs through direct fermentation but instead are thought to signal fibre-digesting bacterial species to become more active and increase the fermentation of fibre already present in the diet (Ribeiro et al., 2018). For example, xylo-oligosaccharides (XOS) act as stimbiotics by selectively stimulating the growth and activity of beneficial bacteria commonly found in the gut such as Lactobacillus spp. and Bifidobacterium spp. 

9. Antioxidants:  Antioxidants are compounds that scavenge free oxygen radicals preventing oxidative rancidity.  Rancidity once develops, may cause destruction of vitamins A, D and E and several of the B complex vitamins.  Breakdown products of rancidity may react with lysine and thus affects the protein value of the ration.  

Examples- Ethoxyquin, BHT (butylated hydroxyl toluene), BHA (butylated hydroxyl anisole).

Ethoxyquin is carcinogenic, therefore its maximum level in animal feed is restricted to 150 ppm (FDA).

1. Organic acids: Chemically, organic acids are weak acids and only partially dissociate. They are considered safe and have been used for preservation of food for centuries. Nowadays, organic acids have been reported for antibacterial, immune potentiating, and growth promoters in broilers. Propionic acid, formic acid, citric acid, and acetic acid are promising alternatives to antibiotics. Their inclusion in the broiler feed has been shown to enhance the feed intake, growth, and feed efficiency (Khan et al 2022).

1. Toxin binders/incativators and mold inhibitors: Mycotoxin binders are nutritionally inert substances added to animal feed to tightly bind and immobilize mycotoxins in the gastrointestinal tract of animals, thus reducing their bioavailability. This process is known as adsorption, and it constitutes the most well-known approach to detoxification of mycotoxins. Now a days mycotoxin bio transformer enzyme solutions are available which are more effective than adsorbents and are not affecting micronutrient availability. Propionic acid is well known mold inhibitor.

But this can’t provide 100% protection and farmer should be very cautious about the raw material quality.

1. Phyto-Chemicals: Several Phytochemicals or plant secondary metabolites are used in animal industry. Secondary metabolites are compounds naturally produced by plants, that are not involved in the primary growth and development of plants. However, they help plants in several processes like reproduction and protection from pests and pathogens. Most of them like essential oils, flavonoids, tannins have antibacterial, anti-inflammatory activity. Saponins are anti-protozoal and ammonia binder.

1. Pigments: Pigments are used in birds for the improvement of the final product according to consumer preferences, without altering the normal metabolism of animals. Birds can store pigments in yolk, fat deposits, skin and in their legs. It has been proven that color is associated with palatability amongst consumers. Therefore, alterations in color can be associated with better taste, or may cause rejection.

Please remember that not all products which give color to feed (curcumin extracts), are able to deposit in the body as a pigment.

Examples- red pigments: citranaxanthin, capsanthin; yellow pigments: Apo-ester, zeaxanthin.

1. Flavours: Flavors are a series of diverse compounds that aim to increase feed intake in sensitive animals, especially young ones. Despite the low number of taste buds in chickens, they also appear to benefit from using flavoring agents in their diet. While using unconventional bitter raw materials in feed sweet flavouring agents (molasses like flavour) may help to avoid drop in feed consumption.

1. Pellet binders: Pellet binders are products that are used to hold the various feed components together in order that they will maintain pellet integrity during subsequent operations after they are extruded from the pellet die. Poor pellet quality (>5% fines) affects broiler performance significantly. Two major types of binder are lignosulfonate and colloidal clays.

1. Deworming compounds: Birds grown in non-cage environment are exposed to parasitic worms. Such challenges may be prevented or minimized with the use of antihelminthic agents such as piperazine, but in laying birds yolk discoloration is observed when piperazine is supplemented.

1. Odour and fly control: Intensive poultry production system results in range of air pollutants, some of which can cause complaints from neighbors because of odor. Ammonia is problematic to both birds and humans. Saponin containing products can reduce ammonia release from manure.

For fly control cyromazine, which is metabolite of insect growth regulator is commonly used at 1-2 ppm in feed. It does not accumulate in birds fat depots, resistance is slowly developed and there’s little effect on birds performance even at 1000 ppm.

Conclusion:

As mentioned above there are several feed additives with different purpose are available in market, it optimizes nutrient utilization reducing the feed cost and some additives like probiotics, organic acids, phytochemicals, enzymes are helpful in without antibiotic poultry production and are environment friendly, however, one should go with which is suitable for his business.

Before using any such product don’t trust blindly, consider following things

1. Returns on investment.
2. Production and R&D facility with manufacturer
3. Certificate of analysis from the competent laboratory
4. Any trial reports available?
5. Conduct your own trials with small feed quantity before using in all feed
6. Consult your Animal Nutritionist for efficient bird’s performance and profitability