As mentioned earlier, nutritional diarrhea in piglets originates from impaired gastric digestion, and the effective activation of pepsin is highly dependent on an appropriately low pH Environment. By adding a functionally defined digestive acid, the gastric contents can be effectively reduced. pH , enhancing protein digestibility and initially regulating microbial balance. However, scientifically assessing the dietary acid–base buffering capacity and selecting appropriate types of digestive acids and their supplemental levels still require systematic data support. Buffering power, as a key evaluation index, provides both theoretical justification and practical guidance for the precise application of acids. The following section will focus on elaborating the buffering power database ( NIC2025 ) the progress of its development, the acidifying characteristics of different raw materials, and strategies for their application in weaner feed formulations, thereby advancing the industry toward a new, precision‑driven, efficient, data‑centric phase of acidified nutrition.

( 1 ) Composition and Types of Feed Ingredients

There are significant differences in the inherent acid-binding capacity among different categories of raw materials; mineral raw materials generally exhibit higher acid-binding capacities, such as stone powder and calcium carbonate, because they are rich in basic cations that can react with acids, such as Ca²⁺ 、 Mg²⁺ and anionic groups such as CO₃²⁻ 、 PO₄³⁻ , followed by animal-derived ingredients, while plant-based ingredients are relatively lower.

( 2 ) Types and levels of added digestive acids

Different digestive acids, due to their physicochemical properties (molecular weight, molecular structure, dissociation constant Ka/pKa ) and biological characteristics (antimicrobial spectrum, metabolic pathways) differ, its reduction pH There are differences in efficacy compared to acid-binding capacity. Generally, Ka The larger the value (or pKa The lower the value, the stronger the acid; at the same concentration, its solution's pH The lower the value, the more it means that it H⁺ The stronger and faster the release capacity, the more effective it is at neutralizing alkaline substances in feed, thereby significantly reducing the feed’s buffering capacity. In addition, the level of acidifier added directly affects its efficacy; generally, within a certain range, increasing the amount of acidifier leads to a more pronounced decrease in the feed’s buffering capacity.

( 3 ) Protein Sources and Levels

Proteins themselves contain substances that can bind to H⁺ Since they contain combined alkaline groups, feed with higher protein content generally exhibits higher potential acid-binding capacity. As mentioned earlier, there is a positive correlation between the protein content and acid-binding capacity of conventional soybean meal; however, fermented soybean meal and extruded soybeans, whose protein structures are improved through processing, have significantly lower acid-binding capacities than conventional soybean meal. The typical ranking of acid-binding capacities among various animal-derived protein ingredients is: plasma protein powder > fish meal > High-Protein Whey Powder > Low-protein whey powder. Plasma protein powder has a high acid-binding capacity due to its unique protein composition and mineral content.

( 4 ) Selection of mineral sources such as calcium

As the most abundant mineral element in animals, the choice of calcium source significantly affects feed acid-binding capacity. Under identical levels of acidifiers and feed formulations, different calcium sources exert varying effects on feed acid-binding capacity; calcium carbonate (limestone powder), as the most commonly used calcium source, exhibits the highest acid-binding capacity and, when added to feed, markedly increases the overall pH Acid-binding capacity and buffering capacity. Completely or partially replacing limestone powder in the feed formulation with organic calcium sources such as calcium formate, calcium lactate, or calcium citrate is an effective and practical approach to reducing the feed’s acid-binding capacity. Moreover, these organic calcium salts can serve as important synergists to acidifiers, working together to enhance their acidifying effect.

( 5 ) Effect of zinc oxide

Zinc oxide is commonly added to weaned piglet diets due to its significant efficacy in preventing diarrhea (reducing incidence, shortening disease duration, alleviating symptoms, and improving survival rates) and maintaining intestinal health (enhancing barrier function, inhibiting pathogen adhesion and biofilm formation, and reducing endotoxin translocation). However, zinc oxide exhibits very high acid-binding capacity, NIC The acid-binding capacity of a zinc oxide sample was measured ( ABC-4 ) Gundam 2428.51meq/kg This means that adding zinc oxide to feed sharply increases the feed’s total acidity, which is a critical and often overlooked limiting factor when using high-zinc regimes and an important consideration when seeking alternatives.

Feed acid-binding capacity is a complex property influenced by multiple interacting factors. When designing and optimizing feeds—especially for young animals—formulators must comprehensively consider the combined effects of ingredient selection (minerals, types and processing methods of protein sources, calcium sources) and functional additives (types and levels of acids, trade-offs associated with high zinc levels) on acid-binding capacity. This allows for precise control of feed acidity, thereby more effectively promoting gastric digestion and absorption, facilitating further intestinal digestion, inhibiting pathogenic bacteria, and supporting gut health. However, feed ingredients are diverse and vary in nutritional quality and processing methods. Consequently, it is particularly important to investigate the acid-binding capacity of feed ingredients across different regions and systematically establish a database of typical values for common feed ingredients.

The acid strength database is maintained by NIC A foundational database has been established to comprehensively collect acid information and investigate feed acidifying capacity, providing a scientific basis for feed formulation design. The database has now been systematically constructed, from 2021 Since the database was established, NIC Over a thousand sample types have been tested, primarily including energy and protein ingredients, fermentation-derived ingredients, mineral chelates, amino acids, vitamin ingredients, single‑acid ingredients, and carrier ingredients, with ongoing continuous improvements and additions. The following lists the buffering capacity of common feed ingredients. NIC(2025) The essence of the edition.

( 1 ) Energy and protein feed ingredients

( 2 ) Fermented feed ingredients

( 3 ) Mineral element chelates, amino acids, and vitamin feed ingredients

Thus, it is evident that mineral feed ingredients exhibit very high acid-binding capacity, particularly zinc oxide and limestone. Among energy–protein feeds, animal-derived ingredients such as fish meal also possess a relatively high acid-binding capacity. After fermentation, the acid-binding capacity of feed ingredients decreases significantly. Therefore, when addressing diarrhea in weaned piglets, greater consideration should be given to incorporating fermented feed ingredients into creep feed formulations, substituting organic calcium sources for limestone, and reducing or eliminating the use of zinc oxide.

( 4 ) Feed company starter feed acid capacity database ( 2024 )

( 5 ) National Feed Company Nursery Feed Acid Strength Database ( 2024 )

( 6 ) National Feed Company Weaner Feed Acid Capacity Database ( 2024 )

Thus, it can be seen that the acid-binding capacity of creep feed at most feed companies nationwide is ( ABC-4 ) in 20-35meq/kg Around this range, which is relatively wide, reflects the varying practices of different enterprises regarding the early post-weaning period for piglets (typically 21-28 age in days) differentiated strategies for extreme stress conditions. Meanwhile, the buffering capacity of nursery feed and weaner pig feed is 20-30meq/kg Around this range has become the industry‑wide accepted optimization window, as it continues to provide essential gastrointestinal support while avoiding palatability or other potential issues that might arise from excessive acidification. Therefore, when formulating diets for weaned piglets at this stage, target buffer capacity values can be based on the aforementioned industry consensus range and fine‑tuned according to specific conditions. During the creep feed phase, it is recommended to maintain buffer capacity at 20-30meq/kg , for high-risk groups experiencing significant weaning stress, it may be advisable to approach 20-25 meq/kg . During the nursery or weaner piglet phase, it is recommended to keep the acid-binding capacity stably controlled at 20-30meq/kg Within the range, 25meq/kg Around this point represents a relatively ideal balance, but further exploration is needed to confirm it.

Summary

 

One of the core nutritional causes of the high incidence of diarrhea in weaned piglets is a sudden drop in gastric acid secretion and immature digestive function, leading to an acidic environment in the stomach... pH Elevated levels inhibit the complete digestion of proteins and conditionally promote the excessive proliferation of intestinal pathogens. Therefore, Under antibiotic-free conditions, maintaining gastrointestinal health in nursery piglets hinges first and foremost on preserving normal gastric function. 。 Adding digestive acid can effectively reduce the gastric environment pH It significantly enhances the activity of digestive enzymes such as pepsin, improves protein digestion, and reduces damage to the mucosa of the mid-to-distal small intestine and colon caused by the putrefaction of undigested proteins. At the same time, the acidic environment it creates directly inhibits the proliferation of pathogenic bacteria, decreases the likelihood of harmful microorganisms surviving gastric passage, promotes the growth of probiotics like lactobacilli, restores intestinal microecological balance, and further lowers the risk of diarrhea.

 

Acid Innovation Center ( NIC ) A systematic database of acidification potential covering various raw materials and commercial feedstuffs has been established. ， With over a thousand sample types analyzed, it provides core support for precise formulation design and is regularly published annually to the piglet feed nutrition industry. Leveraging this continuously refined database—combined with digestibility data for nutrients such as protein, calcium, and phosphorus, as well as considerations of piglets’ physiological stages and health status—the system optimizes raw material selection and precisely matches the type and dosage of acidifiers. NIC Will be subject to 2024 Piglet Digestive Acid Selection Model Published in [Year] APP 1.0 Perform continuous updates , providing feed for the creep-feeding and nursery phase of piglets ” ideal ” Based on the principles of acid digestion, we are building a more dynamic and personalized “precision acid application” system. NIC It is believed that adding digestive acids based on an ideal acidification profile will lay the foundation for enhancing gastric function and reducing nutritional diarrhea caused by excessive protein malabsorption, while, together with intestinal acidification that inhibits pathogenic microorganisms, it will strengthen microbial balance in the distal small intestine and colon. Therefore, To better achieve feed-based antibiotic replacement and reduce antibiotic use in livestock farming, “acidic water, acidic environment, acidic feed” is an important approach; by modulating the piglet’s “stomach” - “Overall gut health,” using “digestive acids” + The principle of “precision acidification” with antibacterial acids aims to minimize nutritional and bacterial diarrhea, thereby enhancing both the economic and ecological benefits of aquaculture.

 

For related articles, please see: « The Feed Acidifying Power Database (NIC2025) has been updated! A further advancement in the digestive system for precise acid use! (Part 1) >, 《 Not fearing that floating clouds may obscure one’s vision, NIC Leading the innovation of acidulant formulations into the digital age 》, 《 Wakō Forum | Researcher Hu Youjun: A Reassessment of the Preventive and Control Effects and Mechanisms of Acidic Preparations in Piglet Diarrhea (Part I) 》

Written by: Wen Wei

Kuai Yunyi

Zhao Xiaonan

He Qiantai

Review: Hu Youjun