I. Application Background
Calcium 2-hydroxy-4-(methylthio)butyrate (HMTBa-Ca) is the calcium salt form of a methionine hydroxy analogue (chemical name: Calcium bis(2-hydroxy-4-(methylthio)butyrate)). It does not directly provide a nitrogen-containing amino structure but supplies the methionine carbon skeleton in the form of a hydroxy analogue. It is metabolically converted within the body to generate biologically active L-methionine, which participates in protein synthesis and various metabolic processes.
Methionine is one of the most common limiting amino acids in livestock and poultry feed, particularly prone to deficiency in corn-soybean meal-based diets. To meet animal nutritional requirements for methionine, DL-methionine has traditionally been supplemented in feed. However, methionine hydroxy analogues and their calcium salts are gradually gaining attention as novel methionine sources. Compared to DL-methionine, HMTBa-Ca offers better thermal stability and processing adaptability, making it more conducive to nutrient preservation during feed pelleting and high-temperature processing.
The European Food Safety Authority (EFSA) conducted a systematic assessment of the safety and efficacy of HMTBa and its calcium salt, confirming its safety as a feed additive for all animal species. It does not leave residues in animal tissues or products and poses no significant environmental risks, providing regulatory support for its application in animal nutrition.
II. Application Effects
Numerous studies have shown that HMTBa-Ca, as a methionine source, can improve animal growth performance and nutrient utilization efficiency. In pigs, poultry, and aquatic animals, supplementation with HMTBa-Ca can increase average daily gain, feed conversion ratio, and nitrogen utilization while reducing nitrogen excretion. This is particularly beneficial for low-protein or precision-formulated amino acid diets.
In poultry, HMTBa-Ca supplementation not only helps enhance production performance but also improves antioxidant capacity, immune function, and intestinal health. In laying hens, its appropriate application helps maintain laying performance and improve egg quality. In aquatic animals, as the proportion of plant-based protein ingredients increases, methionine deficiency becomes more prominent. Research indicates that HMTBa-Ca can serve as an effective supplementary source, improving growth rate and body protein deposition.
As a methionine precursor, HMTBa-Ca can promote the utilization of essential amino acids and protein synthesis within the body and improve body composition by regulating related metabolic pathways. Although its overall biological efficacy is generally lower than that of DL-methionine, it still demonstrates high nutritional value in various animals. In practical application, appropriate supplementation levels can be rationally designed using conversion factors.
III. Mechanism of Action
The mechanism of action of HMTBa-Ca primarily lies in its role as a methionine precursor participating in internal metabolism. HMTBa-Ca is converted into L-methionine in the digestive tract through enzymatic reactions and microbial metabolism. It subsequently participates in protein synthesis, one-carbon metabolism, and the regulation of antioxidant systems (such as glutathione synthesis), playing a crucial role in maintaining amino acid balance and improving nutrient utilization efficiency.
Compared to DL-methionine, the absorption and metabolic pathways of HMTBa-Ca differ slightly. Its hydroxy analogue structure confers a degree of increased stability, particularly exhibiting certain rumen bypass characteristics in ruminants, which helps increase the supply of methionine available to the small intestine.
IV. Main Target Animal Species
1. Pigs (Weaned Piglets, Growing-Finishing Pigs)
In pig nutrition, methionine is one of the limiting amino acids. Studies have shown that supplementing HMTBa-Ca in low-protein or amino acid-balanced diets can effectively improve nitrogen utilization, promote protein deposition, and reduce nitrogen excretion. Compared to traditional DL-methionine, HMTBa-Ca can meet methionine requirements while improving amino acid utilization efficiency. It is particularly suitable for nutritional regulation during the weaning stress phase and in pigs with high lean meat rates.
2. Poultry (Broilers, Laying Hens, Breeders)
In poultry diets, HMTBa-Ca is widely used to replace or partially replace DL-methionine. Research indicates that its supplementation can significantly improve the average daily gain and feed conversion ratio of broilers and positively impact antioxidant capacity, immune parameters, and intestinal health. In laying hens, appropriate supplementation of HMTBa-Ca helps maintain laying performance, improve egg quality, and participate in regulating protein and sulfur amino acid metabolism, which is especially important for high-producing layers.
3. Aquatic Animals (Fish, Crustaceans)
In aquatic feed, due to the increasing proportion of plant-based protein ingredients, methionine deficiency has become more pronounced. Multiple studies indicate that HMTBa-Ca can serve as an effective methionine source in fish (e.g., seabass, trout) diets, significantly improving growth rate, feed utilization, and body protein deposition. Its stability and adaptability in aquatic environments give it good application potential in formulated aquatic feeds.
4. Ruminants (Dairy Cows, Beef Cattle, Sheep)
Unlike non-ruminants, methionine in ruminant diets is often primarily limited by degradation by rumen microorganisms, making efficient methionine supplementation forms particularly important. Research shows that methionine hydroxy analogues (including their calcium salt form) possess certain resistance to degradation in the rumen, allowing partial escape from rumen microbial fermentation and conversion to utilizable methionine in the small intestine, thereby increasing the supply of metabolizable protein.
V. Conclusion and Outlook
In summary, HMTBa-Ca, as a novel methionine supplement source, demonstrates promising application potential in animal nutrition. Future research should further focus on the mechanisms for improving its biological efficacy, determining precise supplementation levels for different animal species and growth stages, and exploring its synergistic effects with other nutritional additives. This will promote its functional and efficient application in modern feed systems.
Post time: Feb-03-2026
