Swine Diet Acidification

Swine Diet Acidification

In-feed antibiotics have historically played a central role in swine nutrition, primarily to prevent disease and to promote growth.¹ However, prolonged use of these antibiotics presents regulatory and health challenges to the pigs. Beyond the economic costs, continuous administration of antibiotics significantly contributes to the rise of antimicrobial resistance (AMR), a global issue for the livestock and poultry industry. Additionally, they can induce intestinal dysbiosis, disrupting the balance of gut microbiota which is essential for maintaining pig health.²

Emerging technologies are reducing the need for antibiotics while maintaining animal health and performance. Strategies like diet acidification, novel probiotics, and precision nutrition have shown promise in this regard.

Notably, diet acidification has emerged as an effective method to reduce antibiotic dependence. By incorporating acidifiers into swine diets, producers can enhance feed digestion, improve nutrient absorption, and create an inhospitable environment for pathogenic bacteria.³

Acidifiers in Animal Nutrition

Definition and Types of Acids

Acidifiers are feed additives used to lower gastric and intestinal pH, enhancing the activity of digestive enzymes and inhibiting the growth of harmful microorganisms. This strategy aims to improve the overall performance of animals.⁴ Acidifiers can be classified into two main categories: organic and inorganic acids.

1. Organic Acids: These compounds offer dual benefits by enhancing digestion and exhibiting antimicrobial properties. With proper application methods, they are especially effective in targeting specific areas of the gastrointestinal tract, promoting better nutrient absorption and overall gut health.⁵ Examples: formic, propionic, benzoic, lactic, and citric acids.
2. Inorganic Acids: Primarily utilized for their rapid and effective reduction of dietary pH.⁶ Example: phosphoric acid.

Understanding pKa

While the pH of an acid determines whether it is a weak or strong acid, the pKa value of an acid is crucial for determining its effectiveness. It represents the pH at which the acid is 50% dissociated (H⁺ ion separated). Acids with a pKa close to the target environment’s pH are more effective in releasing hydrogen ions, thereby lowering the pH more efficiently.⁷

Table 1. Acid, pKa, Corrosiveness and Odor⁸

Mode of Action

1. On Digestion: Acidifiers lower stomach pH, activating and also optimizing conditions for enzymatic activity, especially pepsin, which is essential for protein digestion. This leads to better nutrient absorption and growth performance. Various organic acids have been shown to improve protein and energy digestibility, decrease pathogenic bacterial populations, and act as antimicrobial agents, making their mode of action multifaceted.⁹
2. On Bactericidal and Bacteriostatic Effects: Acidifiers can either kill bacteria (bactericidal effect) or inhibit their growth (bacteriostatic effect). By reducing pH in the gastrointestinal tract, they create an environment hostile to pathogens like Escherichia coli and Salmonella, thereby decreasing the possibility of infections originating from the gut and the need for antibiotics.^9,10

Benefits of Acid Blends and Coating Technologies

Using blends of different acids, such as combinations of organic acids or mixtures of organic and inorganic acids, can maximize the acidification effects in animal diets.^11,12,13

1. Acid Blends: Combining various acids can produce synergistic effects, enhancing the overall efficacy of acidifiers. This approach allows for a more sustained release of the acids throughout the gastrointestinal tract, improving pH management and microbial control.¹⁴
2. Coating Technology: Some acidifiers are coated to ensure slower and more targeted release throughout the digestive system. Coating protects the acids from early degradation in the stomach, ensuring their availability in the intestines. This targeted delivery method enhances the health and performance of pigs while reducing the required dosage. Coating technologies like matrix coating or encapsulation have been developed to address the limitations of uncoated organic acids, which are rapidly absorbed and metabolized in the upper gut, limiting their effectiveness in the lower gut where the proliferation of pathogenic bacteria happens frequently.^15,16,17,18

Diet Acidification

ABC-4 Concept

ABC-4, or Acid Binding Capacity at pH 4, measures the amount of acid needed to lower the pH of feed ingredients to 4. The ABC-4 value is determined by titrating feed ingredients with HCl (Hydrochloric acid), which measures their acid-binding capacity. This value is expressed in milliequivalents of HCl per kilogram of feed sample, indicating the amount of acid the feed can neutralize. In short, the lower the ABC-4 value of a feed ingredient the easier it is for piglets to digest feed, particularly the proteins.

The concept of ABC involves maintaining the stomach’s pH at its intended range of 2-3 by incorporating low acid-binding ingredients.¹⁹ This is crucial in formulating diets, especially for weaned piglets who haven’t reached the optimum level of gastric acid production, leading to higher stomach pH. Maintaining an acidic stomach environment is essential for optimal digestion and pathogen control, as increased gastric pH allows opportunistic pathogens to survive and compromise the digestive tract. Additionally, increased gastric pH may allow undigested nutrients, particularly proteins, to enter the intestine causing proliferation of pathogenic bacteria²⁰

Young pigs have a limited ability to produce HCl in the stomach. HCl production is low at birth but increases with advancing age. The greater the acid production in the stomach, the lower the gastric pH. Administering acids can improve digestion for pigs and reduce harmful pathogen loads. The pH in the stomach is a major factor which regulates the infiltration of viable bacteria to the small intestine. Every acid dissociates at its own rate. Inorganic acids dissociate quickly, causing a rapid drop in the pH of a solution, whereas organic acids dissociate more slowly in comparison.²¹

Strategies to Reach ABC-4 Targets

FORMYL^™ from Kemin is a formic acid-based additive designed to effectively lower the ABC-4 value. It contains a blend of encapsulated calcium formate and citric acid, ensuring optimal delivery and efficacy. The encapsulated form facilitates targeted delivery and enhanced acidification, which supports both protein digestion and gut health.

KEM-GEST^™ from Kemin is an acidifier with a very low ABC-4 value which can help significantly neutralize high-buffering ingredients in swine feed. This helps maintain an optimal gastric pH and supports digestive health. The product is a blend of both organic and inorganic acids, providing an economical solution for feed acidification in swine diets. KEM-GEST^™ specifically aids in the gastric acidification of nursery pigs, which is crucial for enhancing gut barrier function and overall intestinal health. Additionally, it promotes the activity of gastric enzymes post-weaning, leading to improved digestion.

The impact of KEM-GEST^™ on nursery pigs is twofold: first, it delivers phosphoric acid directly to the pig’s stomach, stimulating the production of hydrochloric acid (HCl), which is often deficient during the weaning period. This process improves the digestive capacity of piglets. Second, organic acids—namely fumaric, citric, and lactic acids—are transported to the hindgut, providing further benefits that enhance the digestive health of piglets.⁵

Benefits of Diet Acidification on Pig Performance

Improved Growth Performance

Supplementing pig diets with acidifiers has been shown to improve growth performance, particularly in weaned piglets.^22,23 A study showed that including 5 g/kg of benzoic acid in young pigs’ diets significantly improved their growth metrics (P < 0.05). After 14 days, pigs in the benzoic acid group showed a 6.6% higher final body weight, a 20.7% greater average daily gain, and a 15.0% increase in average daily feed intake. These results highlight the positive impact of diet acidification on growth and feed efficiency.

Also, studies have demonstrated that incorporating organic acids can enhance the apparent ileal digestibility of proteins and amino acids and improve mineral absorption in fattening pigs.^24,25 These benefits not only contribute to improved overall performance but also reduce nitrogen and phosphorus excretion, thus minimizing environmental pollution. Additionally, a study found that supplementing diets with fumaric acid, along with reducing mineral content to decrease ABC-4 levels, significantly enhanced nursery pig performance. This effect was most notable during the first two weeks post-weaning, particularly when diarrhea was present.²⁶

Conclusion

Diet acidification is an effective strategy for improving pig health, enhancing performance, and reducing antibiotic use. By carefully managing acid levels in both feed and water, producers can promote better digestion, nutrient absorption, and a healthier gut environment in an economical way. This approach supports microbial control, improves feed conversion efficiency, and reduces the need for antibiotics by fostering a favorable gut environment. To maximize benefits, acidifiers should be tailored to different growth stages, with regular monitoring to ensure optimal conditions. Integrating this approach into broader health management practices can enhance productivity and support more sustainable swine production.

References

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