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Non-Nutrient Feed Additives in Poultry: Classification, Uses and Examples
Non-nutrient feed additives are substances incorporated into poultry diets to support bird health, feed quality, digestive efficiency, and production performance without serving as direct sources of essential nutrients. They include a diverse range of compounds, such as antimicrobials, coccidiostats, enzymes, antioxidants, pellet binders, pigments, and probiotics.
This group of feed additives does not have any direct nutritional role but is added to the feed to reduce mortality and morbidity caused by various diseases and stress factors; to improve feed efficiency through better digestion, absorption, and utilization of nutrients; to enhance the color, flavor, consistency, and quality of feed; and to improve the shelf life of the feed by reducing caking, mold growth, mustiness, oxidation, and other physical, chemical, and microbiological degradation.
Classification, Uses, and Examples
Non-nutrient feed additives are classified as follows based on their nature and functions:
- Antibiotic Feed Supplements: Used to control subclinical bacterial infections and thereby improve performance. Examples include tetracyclines, tiamulin, lincomycin, tylosin, erythromycin, colistin, doxycycline, bacitracin, flavomycin, virginiamycin, etc. It is advisable to use antibiotics that are not used in the treatment of human and animal diseases. The introduction of probiotics containing beneficial microorganisms has now limited the use of antibiotics in feed.
- Non-Antibiotic Antimicrobial Feed Supplements: Help control bacterial infections and promote performance. Examples include furazolidone and chlorhydroxyquinoline.
- Antimycotic Agents: Prevent mold growth and toxin production. Examples include gentian violet, copper sulfate, propionic acid, calcium propionate, and sodium benzoate.
- Coccidiostats: Prevent outbreaks of coccidiosis. Examples include dinitro-ortho-toluamide, salinomycin, robenidine, nicarbazine, monensin, and maduramycin.
- Antiparasitic Additives: Help control various parasitic infestations. Examples include dichlorophan, niclosamide, and praziquantel.
- Antioxidants: Prevent oxidative rancidity of fats and oils. Examples include BHT, BHA, and ethoxyquin.
- Enzymes: Help improve the digestion of feed. Examples include protease, lipase, cellulase, amylase, phytase, and pectinase.
- Hormones: Promote growth rate, feed efficiency, and egg production. Examples include caseated iodine, melengestrol acetate, ethylestranol, and stanazol.
- Arsenicals: Promote growth rate, feed efficiency, and carcass finish. An example is 3-nitro-4-hydroxyphenyl arsanilic acid.
- Adsorbents: Absorb or bind toxins and prevent their absorption from the intestine. Examples include zeolites and activated charcoal.
- Pellet Binders: Used to facilitate feed pelleting and the preparation of crumbled feed for broilers. Examples include bentonite, sodium alginate, carboxymethyl cellulose, gelatin, lignosulfonate, carrageenan, and guar gum.
- Deodorizing Agents: Reduce ammonia production in the litter. An example is yucca extract.
- Flavoring Agents: Improve feed flavor and thereby increase feed intake, growth rate, and production. Examples include essential oils, fish oils, etc.
- Pigments: Impart an attractive color to the feed as well as to products such as egg yolk and skin. Examples include canthaxanthin, lutein, zeaxanthin, etc.
- Herbal Preparations: Support liver function, improve appetite, and increase disease and toxin resistance in birds. Examples include herbal extracts.
- Performance Boosters: Improve the overall performance of birds through various mechanisms. Examples include nitrovin, avoparcin, etc.
- Immunostimulants: Stimulate antibody production, cell-mediated immunity, and general resistance to disease. Examples include tetrahydrophenylimidazole, immogen, levamisole, etc.
- Other Miscellaneous Feed Additives: Perform specific functions in the body or feed and thereby improve performance. Examples include electrolytes, egg-up, egg toner, etc.
Probiotics or Direct-Fed Microbials (DFM)
A probiotic is a live microbial feed supplement that beneficially affects the host animal by improving its intestinal microbial balance, resulting in better performance in terms of growth or feed efficiency. Probiotic preparations are made from bacteria, yeast, and fungi.
Common probiotic preparations used in various combinations include:
- Bacteria: Strains of Lactobacillus, Leuconostoc, Bifidobacterium, Pediococcus, and Streptococcus
- Fungi: Strains of Aspergillus
- Yeast: Strains of Saccharomyces
Probiotics act by suppressing viable counts of pathogenic bacteria such as Escherichia coli, producing antibacterial compounds, and competing for nutrients and adhesion sites in the intestinal epithelium. In general, probiotics increase growth rate in broilers, egg production in layers, and reproductive performance in breeders. However, the effects of probiotics are more noticeable in stressed birds than in healthy ones.
