l.mengying@cnhu.com zhanglei@cnhu.com z.honghe@cnhu.com s.xiaowei@cnhu.com
1Researchers, Zhejiang NHU Company Ltd., Animal Nutrition Application Service Center
Global warming has led to a sustained increase in ambient temperature, which has become a critical abiotic stress factor limiting modern intensive poultry production. Poultry are characterized by high metabolic rates, dense feather coverage, and the absence of sweat glands, which results in limited thermoregulatory capacity. Under prolonged or acute high‑temperature conditions, poultry are susceptible to heat stress, which disrupts homeostasis and induces a series of physiological disorders, including exacerbated oxidative stress, immune dysfunction, intestinal barrier damage, and abnormal apoptosis. Ultimately, heat stress leads to substantial production losses in poultry. For broilers, chronic heat stress may reduce daily weight gain by 9.8%–51% and feed intake by 9.2%–30%, worsen the feed conversion ratio by 0.17, elevate mortality risk by 3.74-fold, and markedly decrease breast meat yield[1-2]. In laying hens, heat stress lowers egg production rate by 11%–36.4%, egg weight by 3.41%, and eggshell thickness by 5%–8%, with mortality rising significantly[3-4]. These losses cause severe economic losses to the poultry industry.Therefore, the development of safe, efficient, and scalable nutritional strategies to alleviate heat stress in poultry has become a research priority in the fields of animal nutrition and production.
Taurine (2-aminoethanesulfonic acid) is a sulfur-containing conditionally essential amino acid that acts as a downstream metabolite of methionine and cysteine metabolism.It is widely distributed in different tissues and organs of animals.As an important functional amino acid, taurineexhibits its physiological roles mainly in the following four aspects.Taurine exerts multiple protective effects on heat-stressed poultry. It can effectively enhance the antioxidant capacity of the body, scavenge excessive reactive oxygen metabolites induced by high temperature, reduce lipid peroxidation damage, and maintain the normal morphological structure of cells[5-6]. Meanwhile, taurine improves the immune status of poultry, alleviates excessive inflammatory responses caused by heat stress, and prevents immunosuppression induced by continuous high temperature stimulation[7]. In addition, taurine stabilizes the cell membrane structure, maintains intracellular osmotic pressure balance, mitigates high temperature-induced cell damage and abnormal cell death, and protects the integrity of tissues and organs[8-9]. Furthermore, dietary taurine supplementation can promote protein deposition, alleviate muscle atrophy, enhance nutrient digestion and utilization, regulate lipid metabolism, and effectively stabilize the growth performance and reproductive capacity of poultry under a high-temperature environment[5,8].
2. Application of Taurine in Alleviating Heat Stress
2.1 Taurine supplementation
Under heat stress conditions, taurine can be administered either as a feed additive or via drinking water. The optimal supplemental dose is influenced by poultry species, growth stage, stress type (acute/chronic), and ambient temperature and humidity, and thus requires tailored application protocols.
In broiler production, under chronic heat stress (constant high ambient temperature of 32–34 °C), dietary supplementation is the preferred route. Supplementation with 5 g/kg (0.5%) taurine significantly increases average daily feed intake and daily gain, reduces the feed-to-gainratio, alleviates breast muscle wasting, improves breast meat pH, reduces drip loss and lightness (L*) value, enhances meat quality, and decreases hepatic lipid deposition[8]. Under acute heat stress or when feed intake is markedly reduced, taurine should be administered preferentially via drinking water at a dose of 5–8 g/L. This route provides rapid absorption and uniform distribution, quickly alleviating the outbreak of oxidative stress and cellular damage induced by high-temperature[10-11].
In laying hen production, under sustained summer heat stress, dietary supplementation with 3 g/kg taurine stabilizes the laying rate, increases egg weight, improves eggshell strength and thickness, reduces the rate of cracked and deformed eggs, alleviates fatty liver hemorrhagic syndrome, and reduces mortality. For high-producing and aged laying hens during heat stress, the dose can be increased to 5 g/kg to compensate for insufficient endogenous taurine synthesis under high-yielding conditions and to enhance antioxidant and stress resistance capacities [12].
Regarding the supplementation timing, supplementation initiated 7–10 days before the onset of the hot season can effectively increase the body’s antioxidant reserves, providing a preventive effect. Continuous supplementation throughout the heat stress period maximizes the mitigation of production losses. Taurine is stable, non-toxic, and residue-free in animals, demonstrating excellent applicability for production.
2.2 Combined application of taurine with other functional additives
A single additive often cannot cover the multidimensional damage caused by heat stress. The combined use of taurine with other anti-stress, antioxidant, or gut-protective functional additives can produce synergistic effects through complementary targets and overlapping physiological functions. This approach is particularly suitable for intense stress scenarios such as extreme heat, high humidity, and high stocking density, representing an important direction for nutritional management of heat stress in poultry.
Taurine combined with betaine: Both are effective osmolytes that synergistically stabilize cellular osmotic pressure and reduce cell dehydration caused by heat stress. They are highly complementary in antioxidant capacity, intestinal barrier protection, and alleviation of lipid metabolism disorders. Taurine primarily scavenges ROS and protects mitochondrial structure, while betaine provides methyl groups and maintains intestinal morphological integrity. A recommended combination is 5 g/kg taurine and 0.5 g/kg betaine, which is suitable for long-term heat stress management in broilers and laying hens in hot and humid regions[13].
Taurine combined with probiotics and prebiotics: This combination synergistically maintains intestinal health. Taurine protects the integrity of the intestinal mucosal barrier and reduces intestinal leakage, while probiotics modulate the gut microbiota and enhance nutrient absorption[16]. Probiotics (e.g., Lactobacillus) can effectively alleviate heat stress by improving gut microbiota and enhancing intestinal barrier function, thereby improving growth performance and immune function in poultry[17]. Their combined use with taurine mitigates heat stress‑induced intestinal morphological damage and dysbiosis.
When combining additives, the principles of effect superposition and cost control should be followed, prioritizing combinations with different mechanisms of action. Supplementation levels can be appropriately increased under extreme heat and severe stress conditions.
2.3 Practical application considerations
For dietary supplementation, thorough mixing is essential to avoid local concentration differences that could affect efficacy. For administration via drinking water, the solution should be prepared fresh daily and used immediately, good water quality should be ensured, and mixing with strong oxidizing agents is not recommended. The supplemental dose should be appropriately increased as ambient temperature rises and gradually reduced when temperatures fall. Combining taurine supplementation with management measures such as ventilation, cooling, and reduced stocking density can maximize its anti-heat-stress effects. The effective dose range in current research is relatively broad. In practical application, the dose should be adjusted according to cost-effectiveness analysis and specific stress intensity.
3. Conclusion and Prospects
Heat stress poses a serious threat to poultry health and production performance. Dietary taurine supplementation is a safe and effective nutritional strategy to alleviate the detrimental effects of heat stress. Taurine exerts its protective roles by enhancing antioxidant capacity, regulating immune function, maintaining cellular integrity, and improving product quality. Future research should focus on determining the optimal supplementation levels for distinct poultry species and growth stages, exploring synergistic effects with other functional additives, and elucidating the underlying molecular mechanisms.
With the intensification of global warming, further studies on the application of taurine will provide vital theoretical support for the sustainable development of the poultry industry.
References
[12]Передерій,ДБ,Вудмаска, et al. Впливтауринунабіохімічніпоказникикровікурейуразітепловогостресу[J]. Physiological Journal/fiziologichnyi Zhurnal, 2025, 71(1).
[14]Erika,Rodríguez-Martínez,Concepción, et al. ANTIOXIDANT EFFECTS OF TAURINE, VITAMIN C, AND VITAMIN E ON OXIDATIVE DAMAGE IN HIPPOCAMPUS CAUSED BY THE ADMINISTRATION OF 3-NITROPROPIONIC ACID IN RATS[J]. Int J Neurosci, 2004, 114(9): 1133-1145.