7 Research-Supported Alternatives to Antibiotics in Feed: Application Guidelines for Organic Acid Feed Additives

As the global animal farming industry continuously promotes the reduced use of antimicrobial drugs, feed enterprises and farming groups are seeking more stable and sustainable alternatives to antibiotics in feed.

Currently common alternatives to antibiotics in feed include:Organic acid feed additives, probiotics, prebiotics, synbiotics, plant-derived feed additives, feed enzymes, antimicrobial peptides, and bacteriophages

Among them, organic acid feed additives can cover feed raw material preservation, finished feed hygiene, acidity management, and animal digestive environment simultaneously, so they are usually suitable as an important basis for comprehensive antibiotic reduction programs. However, it must be clarified that no feed additive can completely replace therapeutic antibiotics under all conditions, and animal diseases should still be diagnosed and treated regularly by veterinarians.

Why does the feed industry need to seek alternatives to antibiotics?

Since January 1, 2006, the EU has prohibited the use of antibiotics as growth promoters; the Ministry of Agriculture and Rural Affairs of China's Announcement No. 194 stipulates that from July 1, 2020, feed production enterprises shall stop producing commercial feeds containing growth-promoting drug feed additives; the US FDA has also canceled the use of medically important antibacterial drugs for productive purposes such as growth promotion, and requires that relevant feed medications be used under veterinary supervision.

These policies do not mean that food animals cannot use antibacterial drugs in any circumstances, but rather require breeding enterprises to reduce unnecessary use, mainly use antibacterial drugs for disease treatment, control, and necessary prevention, and strengthen veterinary supervision and antibacterial drug management.

Therefore, "replacing antibiotics" is not simply finding a product to replace antibiotics, but rather reducing animals' dependence on antibacterial drugs through various measures such as feed nutrition, raw material quality, intestinal management, biosecurity, environmental control, and disease prevention.

7 common feed antibiotic replacement solutions

Large research reviews and Meta-analyses show that non-antibiotic feed additives such as probiotics, prebiotics, organic acids, plant-derived additives, enzyme preparations, and antimicrobial peptides have the potential to reduce the use of antibiotics, but the effects are not completely consistent under different animals, products, dosages, and production conditions.

1. Organic Acid Feed Additives

What are organic acid feed additives?

Organic acid feed additives are functional feed additive products mainly composed of formic acid, propionic acid, lactic acid, citric acid, butyric acid and their salts or compound formulations, which are used in feed ingredients, compound feeds, animal drinking water, or breeding sites.

Common products include:

• Formic acid and formates;
• Propionic acid and propionates;
• Lactic acid;
• Citric acid;
• Butyric acid and butyrates;
• Compound organic acids;
• Coated organic acids;
• Liquid acidulants.

“Organic acid” is a chemical classification concept and is not equivalent to "organically certified feed".

How do organic acid feed additives work?

Regulate feed and digestive environment

Organic acids can reduce the pH of feed, drinking water, or specific parts of the digestive tract according to their own characteristics, creating different environmental conditions for the digestion process and microbial management.

Support microbial risk management

Some undissociated organic acids can pass through the cell membranes of certain microorganisms and dissociate inside the cells, affecting the acid-base balance and metabolic processes of microorganisms.

The ability of organic acids to act on different microorganisms is affected by factors such as the type of acid, pKa, lipophilicity, concentration used, environmental pH, and contact time.

Improve feed storage conditions

Propionic acid and propionates are usually used for mildew prevention and preservation of grains, feed ingredients, and finished feeds; formic acid and its compound products are often used for feed acidification, raw material hygiene, and liquid feeding management.

Support nutrient digestion

A reasonable acidification program may affect protein digestion, mineral utilization, digestive enzyme environment, and gut microbiota. However, meta-analysis shows that the average effect of organic acids may be lower than that of traditional antibiotic growth promoters, and there are obvious differences under different test conditions.

Therefore, organic acid feed additives should be designed according to animal species, age, feed formula, and application goals, rather than simply increasing the addition amount.

Why are organic acids suitable as the basis for comprehensive antibiotic reduction programs?

Compared with some additives that only act in the animal body, organic acid feed additives can act on multiple links simultaneously:

1. Feed ingredient storage;
2. Finished feed preservation;
3. Feed production and transportation processes;
4. Drinking water and liquid feeding systems;
5. Animal gastrointestinal digestion environment;
6. On-farm hygiene management.

This means that organic acids can not only be used as animal nutrition products but also become part of feed quality management and breeding risk control systems.

However, research shows that when there is a high microbial challenge, the sole use of organic acids may not achieve all the effects of traditional antibiotic growth promoters, so they are more suitable for combination with probiotics, enzyme preparations, plant-derived additives, biosecurity, and precision nutrition measures.

2. Probiotics

Probiotics are generally live microorganisms that can exert beneficial effects on the host under appropriate conditions of use. Common strains in animal feed involve lactic acid bacteria, bacilli, yeasts, etc.

Probiotics may function in the following ways:

• Competing with harmful microorganisms for nutrients and adhesion sites;
• Producing lactic acid, bacteriocins, or other metabolites;
• Supporting the intestinal barrier;
• Regulating local immune responses;
• Improving the digestion and utilization of some nutrients.

The effects of probiotics are highly strain-specific, and the product value cannot be judged solely based on the strain name. When purchasing, attention should also be paid to the number of viable bacteria, strain number, acid and bile salt tolerance, granulation stability, and the number of viable bacteria at the end of the shelf life.

3. Prebiotics and Synbiotics

Prebiotics are substrates that can be utilized by specific gut microorganisms and bring potential health benefits to the host. Common directions include mannan oligosaccharides, fructooligosaccharides, xylooligosaccharides, and other functional carbohydrates.

Prebiotics are usually used for:

• Providing fermentation substrates for beneficial bacteria;
• Regulating the structure of the gut microbiota;
• Adsorbing or interfering with some harmful microorganisms;
• Supporting the intestinal barrier and immune function.

The combination of prebiotics and probiotics is usually called synbiotics. However, the combined product does not necessarily automatically produce a synergistic effect, and it is still necessary to verify whether the strain, substrate, and target animal are matched.

4. Plant-derived feed additives

Plant-derived feed additives are also known as plant extracts or phytatins, and may contain essential oils, polyphenols, saponins, tannins, and other plant active ingredients.

Common raw materials include:

• Oregano;
• Thyme;
• Cinnamon;
• Garlic;
• Rosemary;
• Citrus plants;
• Peppers and other spices.

Plant-derived feed additives may involve multiple directions such as feeding, digestive juice secretion, antioxidant status, and microbial environment. A 2024 research review believes that plant-derived additives have become an important direction for antibiotic replacement in animal production, but their effects will be affected by plant source, extraction method, active substance content, and formula combination.

5. Feed enzyme preparations

Feed enzymes are not traditional antibacterial products. Their main value is to improve the release and utilization efficiency of feed nutrients.

Common enzyme preparations include:

• Phytase;
• Xylanase;
• β-glucanase;
• Protease;
• Amylase;
• Cellulase.

By reducing the entry of undigested nutrients into the hindgut, enzyme preparations may indirectly reduce the substrates available to harmful microorganisms and help improve fecal quality and feed conversion efficiency.

Selection of enzyme preparations needs to be combined with raw material structure. For example, different enzyme combinations are required for wheat-based, corn-soybean meal-based, or high-fiber by-product-based diets.

6. Antimicrobial Peptides

Antimicrobial peptides are active substances composed of amino acids that can interact with the cell structures of some microorganisms.

Compared with broad-spectrum antibiotics, some antimicrobial peptides have potential characteristics such as fast action and relatively low residue risk. In the comprehensive evaluation of antibiotic alternatives for pigs, antimicrobial peptides have shown certain application potential in the weaned piglet stage.

Its commercial application still needs to focus on:

• Raw material cost;
• Gastrointestinal stability;
• Processing tolerance;
• Effective release location;
• Safety evaluation;
• Registration requirements in different countries and regions.

7. Bacteriophages

Bacteriophages are a class of viruses that can infect specific bacteria. Due to their host specificity, bacteriophages can develop precise control solutions for Salmonella, Escherichia coli, or other target bacteria.

The advantage of bacteriophages is that they are relatively precise in acting on target bacteria and may have less impact on non-target microbial communities. But this specificity is also a limitation: when the bacterial strains in the farm change, the original bacteriophage combination may not cover the new target strains.

Bacteriophages also face problems such as production stability, feed processing tolerance, storage, administration methods, and regulatory approval. Therefore, they are currently more suitable as supplementary measures for specific pathogen risks.

Which feed antibiotic alternative is the most effective?

No feed antibiotic alternative can maintain the best effect in all animals, all diets, and all breeding environments.

The actual selection should be determined according to the main issues:

Relevant research and industry practices both show that a single substitute is difficult to undertake all functions such as growth promotion, disease prevention and treatment at the same time. A more realistic approach is to establish a comprehensive integrated solution.

How to choose organic acid feed additives?

1. Clarify the application goal

First determine the main use of the product:

• Feed mildew prevention;
• Raw material preservation;
• Feed acidification;
• Drinking water management;
• Piglet intestinal health;
• Poultry production;
• Liquid feeding;
• Long-distance transportation and high-temperature and high-humidity environment.

Different application goals require selecting different acid species and product forms.

2. Check the effective acid content

When purchasing, do not only compare the price per ton of the product, but should check:

• Content of formic acid, propionic acid, lactic acid, etc.;
• Total organic acid content;
• Ratio of free acid to acid salt;
• Proportion of moisture and carrier;
• Coating or sustained-release technology;
• Recommended addition amount;
• Effective acid cost per ton of feed.

3. Selection according to animal stage

Weaning piglets, fattening pigs, broilers, laying hens, aquatic animals and ruminants have different digestive physiology, so exactly the same organic acid formula should not be adopted.

4. Evaluation of feed buffering capacity

Rations with high protein, high minerals or a higher proportion of specific ingredients may have higher buffering capacity, and the actual acidification effect needs to be evaluated in combination with the ration structure.

5. Pay attention to palatability and safety

Concentrated organic acids may be irritating and corrosive. Need to evaluate:

• Animal feed intake;
• Product odor;
• Tank material;
• Conveying pumps and pipelines;
• Spraying equipment;
• Operator protection;
• SDS and labeling requirements.

6. Verification through production data

It is recommended to first carry out small-scale control tests, and then evaluate according to the following indicators:

• Feed mold and bacteria indicators;
• Feed shelf life;
• Feed intake;
• Daily gain;
• Feed-conversion ratio or feed-egg ratio;
• Diarrhea rate;
• Mortality rate;
• Comprehensive cost of feed per ton.

Comprehensive application ideas of organic acids from Jiayijia Group

Jiayijia Group can divide feed antibiotic replacement solutions into five interrelated application dimensions around organic acid technology:

Feed raw materials

Formulate raw material preservation and acidification plans according to the moisture, storage time, and microbial risks of corn, wheat, soybean meal, by-products, and high-moisture raw materials.

Feed quality

Select formic acid, propionic acid and their salts or composite products around mildew prevention, preservation, transportation stability of finished feed, and hygiene management in the production process.

Intestinal health

Design combinations of organic acids, acid salts, coated acids, and other functional additives according to the physiological stages of pigs, poultry, aquatic products, and ruminants.

Digestion and nutrition

Combine organic acids with enzyme preparations, probiotics, plant-derived products, and precise formulas to improve the feed utilization environment, instead of using a single acidification product in isolation.

Breeding site

Combine drinking water, liquid feeding, storage tanks, conveying pipelines, environmental hygiene and biosafety to form a continuous management plan from feed production to the breeding site.

This multi-dimensional plan does not simply claim "complete replacement of antibiotics", but supports breeding enterprises to gradually reduce their dependence on non-essential antibacterial drugs by reducing risks in feed and breeding links.

Common problems

Can organic acid feed additives completely replace antibiotics?

Cannot be simply completely replaced.

Organic acid feed additives can be used for feed preservation, acidification, microbial management and digestive environment support, but cannot replace veterinarians' diagnosis and treatment of bacterial diseases.

What are the differences between formic acid and propionic acid?

Formic acid usually focuses more on feed acidification, raw material hygiene and liquid feeding; propionic acid usually focuses more on mildew prevention and fresh-keeping of grains and finished feed.

Compound organic acid products can combine different acid species according to application goals.

Can organic acids and probiotics be used simultaneously?

Joint use can be evaluated.

Organic acids mainly change the feed and digestive environment, while probiotics play a role through live microorganisms. When using, it is necessary to evaluate whether acidity will affect the activity of probiotics and reasonably arrange the addition position and use method.

Is a higher addition amount better?

No.

A too low addition amount may be difficult to achieve the goal, while a too high addition amount may affect palatability, increase corrosion risk and use cost. It should be determined according to product concentration, feed moisture, animal stage and actual goal.

How to choose between liquid organic acids and solid organic acids?

Liquid products are suitable for spraying, raw material treatment, drinking water and liquid feeding; solid products are usually more convenient for transportation, storage and direct addition to compound feed.

The final choice needs to combine factory equipment, application scenarios and logistics conditions.