Taurine Deficiency Research Articles

Synergistic Enhancement of 5-Fluorouracil Chemotherapeutic Efficacy by Taurine in Colon Cancer Rat Model.

Colorectal cancer (CRC) is one of the top 10 most common cancers worldwide and caused approximately 10 million deaths in 2022. CRC mortality has increased by 10% since 2020 and 52.000 deaths will occur in 2024, highlighting the limitations of current treatments due to ineffectiveness, toxicity, or non-adherence. The widely used chemotherapeutic agent, 5-fluorouracil (5-FU), is associated with several adverse effects, including renal, cardiac, and hepatic toxicity; mucositis; and resistance. Taurine (TAU), an essential β-amino acid with potent antioxidant, antimutagenic, and anti-inflammatory properties, has demonstrated protective effects against tissue toxicity from chemotherapeutic agents like doxorubicin and cisplatin. Taurine deficiency is linked to aging and cancers such as breast and colon cancer. This study hypothesized that TAU may mitigate the adverse effects of 5-fluorouracil (5-FU). Carcinogenesis was chemically induced in rats using 1,2-dimethylhydrazine (DMH). Following five months of cancer progression, taurine (100 mg/kg) was administered orally for 8 days, and colon tissues were analyzed. The results showed 80% of adenocarcinoma (AC) in DMH-induced control animals. Notably, the efficacy of 5-FU showed 70% AC and TAU 50% while, in the 5-FU + TAU group, no adenocarcinoma was observed. No differences were observed in the inflammatory infiltrate or the expression of genes such as K-ras, p53, and Ki-67 among the cancer-induced groups whereas APC/β-catenin expression was increased in the 5FU + TAU-treated group. The mitotic index and dysplasia were increased in the induced 5-FU group and when associated with TAU, the levels returned to normal. These data suggest that 5-FU exhibits a synergic anticancer effect when combined with taurine.

The association between taurine concentrations and dog characteristics, clinical variables, and diet in English cocker spaniels: The Canine taURinE (CURE) project.

Occurrence of low blood taurine concentrations (B-TauC) and predisposing factors to taurine deficiency in English Cocker Spaniels (ECS) are incompletely understood. Investigate the occurrence of low B-TauC in a Swedish population of ECS and evaluate the association between B-TauC and dog characteristics, clinical variables, and diet composition. One-hundred eighty privately owned ECS. Dogs were prospectively recruited and underwent physical examination, blood analyses, and echocardiographic and ophthalmic examinations. Dogs with clinical signs of congestive heart failure (CHF) also underwent thoracic radiography. Taurine concentrations were analyzed in plasma (EDTA and heparin) and whole blood. Diets consumed by the dogs at the time of the examination were analyzed for dietary taurine- (D-TauC), cysteine- (D-CysC), and methionine concentrations (D-MetC). Fifty-three of 180 dogs (29%) had low B-TauC, of which 13 (25%) dogs had clinical and radiographic signs of CHF, increased echocardiographic left ventricular (LV) dimensions and volumes, and impaired LV systolic function. Five (9%) dogs with low B-TauC had retinal abnormalities. Dietary MetC, dietary animal protein source (red/white meat), and age were associated with B-TauC in the final multivariable regression model (P < .001, R2 adj = .39). Low B-TauC suggests that taurine deficiency may play a role in the development of myocardial failure and CHF in ECS. Low D-MetC and diets with red meat as the animal protein source were associated with low B-TauC. Dogs with B-TauC below the normal reference range were older than dogs with normal concentrations.

Reduced Taurine Serum Levels in Inflammatory Bowel Disease.

Taurine is a semi-essential micronutrient that acts as an anti-inflammatory molecule. The oral administration of taurine to colitic mice attenuates ongoing mucosal inflammation. This study aimed to determine whether inflammatory bowel diseases (IBDs) are marked by changes in the circulating levels of taurine. We measured the serum concentrations of taurine in 92 IBD patients [46 with ulcerative colitis (UC) and 46 with Crohn's disease (CD)] and 33 healthy controls with a commercial ELISA kit. The taurine levels were significantly decreased in both patients with UC and patients with CD compared to the controls, while there was no difference between CD and UC. Taurine levels declined with age in healthy controls but not in IBDs. IBD patients younger than 50 years had levels of taurine reduced compared to their age-matched controls. In the IBD group, taurine levels were not influenced by the body mass index of the patients and the consumption of taurine-rich nutrients, while they were significantly reduced in UC patients with clinically active disease compared to those in clinical remission. These findings indicate that IBDs are marked by serum taurine deficiency, which would seem to reflect the activity of the disease, at least in UC.

Cancer SLC6A6-mediated taurine uptake transactivates immune checkpoint genes and induces exhaustion in CD8+ T cells

Taurine is used to bolster immunity, but its effects on antitumor immunity are unclear. Here, we report that cancer-related taurine consumption causes Tcell exhaustion and tumor progression. The taurine transporter SLC6A6 is correlated with aggressiveness and poor outcomes in multiple cancers. SLC6A6-mediated taurine uptake promotes the malignant behaviors of tumor cells but also increases the survival and effector function of CD8+ Tcells. Tumor cells outcompete CD8+ Tcells for taurine by overexpressing SLC6A6, which induces Tcell death and malfunction, thereby fueling tumor progression. Mechanistically, taurine deficiency in CD8+ Tcells increases ER stress, promoting ATF4 transcription in a PERK-JAK1-STAT3 signaling-dependent manner. Increased ATF4 transactivates multiple immune checkpoint genes and induces Tcell exhaustion. In gastric cancer, we identify a chemotherapy-induced SP1-SLC6A6 regulatory axis. Our findings suggest that tumoral-SLC6A6-mediated taurine deficiency promotes immune evasion and that taurine supplementation reinvigorates exhausted CD8+ Tcells and increases the efficacy of cancer therapies.

Taurine Deficiency Is a Hallmark of Injured Kidney Allografts.

Taurine is one of the most abundant amino acids in humans. Low taurine levels are associated with cellular senescence, mitochondrial dysfunction, DNA damage, and inflammation in mouse, all of which can be reversed by supplementation. It is unknown whether taurine metabolism is associated with kidney allograft function and survival. We performed urine metabolomic profiling of kidney transplant recipients in the early and late phases after transplantation combined with transcriptomic analysis of human kidney allografts. Single-nucleus RNA sequencing data sets of mouse kidneys after ischemia-reperfusion injury were analyzed. We analyzed the association of urinary taurine levels and taurine metabolism genes with kidney function, histology, and graft survival. Urine taurine concentrations were significantly lower in kidney transplant recipients who experienced delayed graft function. In a mouse model of ischemia-reperfusion injury, the taurine biosynthesis gene, CSAD , but not the taurine transporter SLC6A6 , was repressed. In the late stage of transplantation, low level of taurine in urine was associated with impaired kidney function and chronic structural changes. Urine taurine level in the lowest tertile was predictive of graft loss. Expression of the taurine transporter SLC6A6 in the upper median, but not CSAD , was associated with chronic kidney injury and was predictive of graft loss. Low urine taurine level is a marker of injury in the kidney allograft, is associated with poor kidney function, is associated with chronic histological changes, and is predictive of graft survival. The differential expression of CSAD and SLC6A6 , depending on the time after transplantation and marks of injury, highlights different mechanisms affecting taurine metabolism.

Taurine: a supplement for extending life-span and health

The world population is aging. In our recent study, we identified that levels of an amino acid called taurine decline during aging. When we used taurine supplementation to reverse this decline, it improved healthspan in worms, mice and monkeys, and lifespan in worms and mice. Thus, taurine deficiency could be a driver of aging and taurine supplementation a potential anti-aging intervention.

Study of correlations between serum taurine, thyroid hormones and echocardiographic parameters of systolic function in clinically healthy Golden retrievers fed with commercial diet.

Taurine deficiency predisposes to the development of nutritional dilated cardiomyopathy and is widespread in dogs fed with non-traditional diets. However, Golden retrievers show lower plasma taurine concentration and an impaired systolic function compared to breeds of the same size and morphotype. For these reasons, it can be difficult to classify a subject from a cardiological point of view, with the risk of considering as pathological characteristics that can be completely normal in this breed. This is a cross-sectional multicenter study. The aims were 1) to identify breed-specific range of serum taurine concentration, 2) to describe a correlation between serum taurine concentration and echocardiographic parameters of systolic function in clinically healthy Golden retrievers fed with traditional diet, 3) to identify a correlation between thyroid hormones, serum taurine concentration and echocardiographic indices. Sixty clinically healthy Golden retrievers (33% males, 67% females) were included. Fifty-three dogs were fed with traditional diets and their range of serum taurine concentration was 398.2 (31.8-430) nmol/ml. Serum taurine concentration was found to be negatively correlated to systolic internal diameter of the left ventricle and systolic and diastolic left ventricular indices and volumes obtained with different methods, whereas was positively correlated to the left ventricle ejection and shortening fractions but difference was not statistically significative. A weak but significant correlation between serum taurine and T4 was demonstrated. Serum taurine median values in dogs with normal systolic function were higher than in dogs with impaired systolic function. A cut-off of serum taurine concentration of 140.6 nmol/ml had a moderate sensitivity and specificity in the identification of an impaired left ventricular systolic function (AUC 0.6, Se 78%, Sp 44%). This study showed that the median serum taurine concentration was significantly lower in dogs with impaired systolic function. Therefore, echocardiographic monitoring is recommended in all dogs with serum taurine concentration lower than 140.6 nmol/ml.

Long‐Lasting Stabilization and Improvement of Dry Age‐Related Macular Degeneration by a High Oral Taurine Dose

Purpose: To examine the therapeutic potential of the amino acid taurine in the non‐ neovascular or ∙dry” form of Age‐Related Macular Degeneration (AMD), one of the main causes of vision loss in the elderly, which still lacks effective treatments. Taurine is the most abundant amino acid in the retina and exerts trophic and neuroprotective actions in cellular and animal models. Likewise, a recent Science paper indicates that taurine deficiency is a driver of aging and that taurine supplementation may be an effective treatment for age‐related diseases. Case Description: A dry AMD patient (F.A., male, 62‐yr old) presented a Snellen best corrected visual acuity of 0.15 on the Right Eye (RE) and 0.2 on the Left Eye (LE) in June 2013, together with central retina atrophy and reduction of central macular thickness to 144 µm (RE) and 159 µn (LE) (OCT analysis; Topcon 3D OCT1000). Oral taurine intake (600 mg t.i.d.) arrested macular degeneration over a 5.5‐yr period and moderately improved visual acuity and macular thickness after doubling the dose from 1.8 g/day to 3.6 g/day in December 2018. This improvement remained stable until last control visit in January 2023. Conclusion: Taurine may have disease‐modifying properties in dry AMD at the dose used. The present observations add to existing literature to foster proof‐of‐concept clinical trials using a high oral dose of taurine for the treatment of AMD.

Taurine deficiency as a driver of aging

Taurine deficiency as a driver of aging

Taurine: a promising nutraceutic in the prevention of retinal degeneration.

Taurine is considered a non-essential amino acid because it is synthesized by most mammals. However, dietary intake of taurine may be necessary to achieve the physiological levels required for the development, maintenance, and function of certain tissues. Taurine may be especially important for the retina. The concentration of taurine in the retina is higher than that in any other tissue in the body and taurine deficiency causes retinal oxidative stress, apoptosis, and degeneration of photoreceptors and retinal ganglion cells. Low plasma taurine levels may also underlie retinal degeneration in humans and therefore, taurine administration could exert retinal neuroprotective effects. Taurine has antioxidant, anti-apoptotic, immunomodulatory, and calcium homeostasis-regulatory properties. This review summarizes the role of taurine in retinal health and disease, where it appears that taurine may be a promising nutraceutical.

Taurine deficiency as a driver of aging.

Aging is associated with changes in circulating levels of various molecules, some of which remain undefined. We find that concentrations of circulating taurine decline with aging in mice, monkeys, and humans. A reversal of this decline through taurine supplementation increased the health span (the period of healthy living) and life span in mice and health span in monkeys. Mechanistically, taurine reduced cellular senescence, protected against telomerase deficiency, suppressed mitochondrial dysfunction, decreased DNA damage, and attenuated inflammaging. In humans, lower taurine concentrations correlated with several age-related diseases and taurine concentrations increased after acute endurance exercise. Thus, taurine deficiency may be a driver of aging because its reversal increases health span in worms, rodents, and primates and life span in worms and rodents. Clinical trials in humans seem warranted to test whether taurine deficiency might drive aging in humans.

Taurine depletion impairs cardiac function and affects tolerance to hypoxia and high temperatures in brook char (Salvelinus fontinalis).

Physiological and environmental stressors can cause osmotic stress in fish hearts, leading to a reduction in intracellular taurine concentration. Taurine is a β-amino acid known to regulate cardiac function in other animal models but its role in fish has not been well characterized. We generated a model of cardiac taurine deficiency (TD) by feeding brook char (Salvelinus fontinalis) a diet enriched in β-alanine, which inhibits cardiomyocyte taurine uptake. Cardiac taurine levels were reduced by 21% and stress-induced changes in normal taurine handling were observed in TD brook char. Responses to exhaustive exercise and acute thermal and hypoxia tolerance were then assessed using a combination of in vivo, in vitro and biochemical approaches. Critical thermal maximum was higher in TD brook char despite significant reductions in maximum heart rate. In vivo, TD brook char exhibited a lower resting heart rate, blunted hypoxic bradycardia and a severe reduction in time to loss of equilibrium under hypoxia. In vitro function was similar between control and TD hearts under oxygenated conditions, but stroke volume and cardiac output were severely compromised in TD hearts under severe hypoxia. Aspects of mitochondrial structure and function were also impacted in TD permeabilized cardiomyocytes, but overall effects were modest. High levels of intracellular taurine are required to achieve maximum cardiac function in brook char and cardiac taurine efflux may be necessary to support heart function under stress. Taurine appears to play a vital, previously unrecognized role in supporting cardiovascular function and stress tolerance in fish.

Muscle Pathology in Dystrophic Rats and Zebrafish Is Unresponsive to Taurine Treatment, Compared to the mdx Mouse Model for Duchenne Muscular Dystrophy.

Inflammation and oxidative stress are strongly implicated in the pathology of Duchenne muscular dystrophy (DMD), and the sulphur-containing amino acid taurine ameliorates both and decreases dystropathology in the mdx mouse model for DMD. We therefore further tested taurine as a therapy using dystrophic DMDmdx rats and dmd zebrafish models for DMD that have a more severe dystropathology. However, taurine treatment had little effect on the indices of dystropathology in both these models. While we and others have previously observed a deficiency in taurine in mdx mice, in the current study we show that the rat and zebrafish models had increased taurine content compared with wild-type, and taurine treatment did not increase muscle taurine levels. We therefore hypothesised that endogenous levels of taurine are a key determinate in potential taurine treatment efficacy. Because of this, we felt it important to measure taurine levels in DMD patient plasma samples and showed that in non-ambulant patients (but not in younger patients) there was a deficiency of taurine. These data suggest that taurine homeostasis varies greatly between species and may be influenced by age and disease progression. The potential for taurine to be an effective therapy may depend on such variables.

Impact of blood tube additives and timing of sampling on blood taurine concentrations in clinically healthy dogs

IntroductionDilated cardiomyopathy can be associated with taurine deficiency in dogs. Blood taurine concentrations can be analyzed in whole blood (WB) and plasma. The study objectives were to investigate agreement between taurine concentrations measured in WB, heparin plasma, and EDTA plasma, determine intraindividual variation in healthy dogs, and evaluate if time from feeding to sampling impacts concentrations. AnimalsTen English Cocker spaniels and 10 dogs of various breeds. Materials and methodsDogs were fasted 12 h prior to initial blood sampling, and the blood was collected at five occasions over eight h. Food was offered immediately after first and one h after fourth sampling time point. ResultsAgreement between taurine concentrations in EDTA plasma and heparinized plasma was good (mean difference 4.5 nmol/mL, 95% confidence interval (CI) 36.8–45.8 nmol/mL). Whole blood concentrations were systematically higher than EDTA and heparin plasma concentrations (mean difference 132.7 nmol/mL, 95% CI 23.6–241.8 nmol/mL, and 127.6 nmol/mL, 95% CI 28.6–226.6 nmol/mL, respectively, all P < 0.001). Intraindividual daily variations in taurine concentration were seen in all additives, with largest variations in plasma (P < 0.001). Taurine concentration in heparinized plasma was higher at first and fifth sampling time points compared to the fourth (P = 0.014). DiscussionAgreement was found between taurine concentrations measured in different additives, with expected higher concentration in WB than plasma. Taurine concentrations measured in heparinized plasma varied with sampling time point. Intraindividual daily variations were observed in all additives, but mainly in plasma samples. ConclusionTaurine concentrations in dogs with suspected deficiency should be interpreted with caution.

Taurine, a non-proteinous essential amino acid for human body systems: an overview

PurposeTaurine (2-aminoethane sulfonic acid; C2H7NO3S) is a nonprotein sulfur-containing β-amino acid present in nearly all mammalian tissues and the most ubiquitous free endogenous biomolecule in human cells. Taurine is commonly known as a conditionally essential amino acid because taurine is one of the few amino acids that are not incorporated in protein synthesis. The purpose of this study is to review the existing articles related to taurine and to give an account how useful is taurine to the different body systems. In this thorough overview, taurine is covered in terms of its essentiality, sources, advantages for neonates and the elderly, the effects of taurine deficiency, and the safety and toxicity of taurine supplements.Design/methodology/approachThis is a narrative review into the subject matter. Published articles were searched on different portals like PubMed, EMBASE, Scopus, Google Scholar, PubChem etc. The authors also evaluated the availability of taurine in commercially available energy drinks.FindingsThis comprehensive review, presents the potential clinical benefits and functional properties of taurine as a conditionally essential amino acid. Energy drinks containing taurine (and their concentration) are also reported in this review.Originality/valueThis is the first data that the authors are aware of that shows taurine content in a variety of energy drinks on the market.

Effects of fishmeal replacement by Clostridium autoethanogenum protein on the growth, digestibility, serum free amino acid and gene expression related to protein metabolism of obscure pufferfish (Takifugu obscurus)

A 63-day feeding trial was conducted to evaluate the effect of Clostridium autoethanogenum protein (CAP) on the growth, digestibility, postprandial free amino acid concentrations in serum, and gene expression related to protein metabolism in obscure pufferfish (Takifugu obscurus). The basal diet with 420 g/kg of fishmeal was used as the control diet (CAP0), and then 20 % (CAP20), 40 % (CAP40) and 80 % (CAP80) dietary fishmeal were replaced by CAP. Compared with diet CAP0, the growth and feed utilization was not affected in fish fed diet CAP20, but was significantly reduced in fish fed diets CAP40 and CAP80 (P < 0.05). The apparent digestibility coefficients (ADCs) of dry matter and protein in the CAP80 group were significantly lower (P < 0.05) than those of the other three groups, and the ADC of lipid was significantly decreased (P < 0.05) in the CAP40 and CAP80 groups. Fish fed diets CAP40 and CAP80 had lower taurine content in muscle compared to those fed diets CAP0 and CAP20 (P < 0.05). Higher free essential amino acid concentrations in serum were observed in fish fed diet CAP80 compared to the other diets at 2 h after refeeding (P < 0.05). Fish fed diets CAP40 and CAP80 showed lower hardness and gumminess in muscle than those fed the other diets (P < 0.05). The expression of peptide transporter1 (PepT1) in intestine and target of rapamycin (TOR) in muscle were significantly up-regulated in the CAP40 groups compared to the control (CAP0) (P < 0.05). However, relative expressions of 4F2 heavy chain (4F2hC), L-type amino acid transporter 2 (y+LAT2) and T-type amino acid transporter1(TAT1) in intestine were not significantly affected by graded levels of CAP (P > 0.05). The inclusion of CAP did not significantly affect the expression of ribosomal protein S6 kinase 1 (S6K1), eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) and 4E-BP2 (P > 0.05) in muscle and liver. In summary, in a basal diet containing 420 g/kg fishmeal, 20 % fishmeal in diets could be successfully substituted by CAP, while high-level CAP decreased the growth, feed utilization and digestibility in juvenile obscure pufferfish. The main reasons for the inhibition of growth performance were probably that excessive CAP caused dietary taurine deficiency and the imbalance of amino acid absorption.

Functional ingredient taurine: adequate and clinically effective doses

Taurine is a sulfur-containing amino acid. Taurine is necessary for the conjugation of bile acids, has antioxidant, anti-inflammatory properties, acts as an anti-apoptotic factor; cell membrane stabilizer; regulator of Ca2+ signaling, fluid homeostasis in cells, retinal photoreceptor activity; contributes to osmoregulation and conduction in the nervous and muscular systems; a neurodevelopmental stimulant; and an inhibitory neurotransmitter in the central nervous system. Taurine is not only synthesized from cysteine and methionine, but also comes from food. Taurine intake is 40–400 mg/day. The main food sources are animal products: shellfish, fish, meat. Taurine is part of breast milk and adapted milk formulas for the nutrition of young children. Under stress and some diseases, the endogenous synthesis of taurine is reduced. The risk groups for taurine deficiency include people who follow a vegetarian diet and observe religious fasts. There are a number of products in which taurine is added: specialized food products (SF) and food supplements (FS) contain 60–1200 mg of taurine per serving, energy drinks – 300–400 mg per 100 ml. The clinical effects of taurine in diabetes mellitus, heart failure are manifested when it is included in diet therapy in doses of 1.5–3 g for 2–16 weeks. Even the maximum doses allowed for use as part of SFP and dietary supplements are significantly less than the doses that ensure the achievement of a clinical effect, which does not guarantee the expected result when using SF.

Plasma and Whole Blood Taurine Concentrations in Dogs May Not Be Sensitive Indicators of Taurine Deficiency When Dietary Sulfur Amino Acid Content Is Reduced

BackgroundTaurine status is impacted by dietary supply of methionine and cysteine (SAA) and possibly intestinal microbial activity, where plasma and whole blood taurine concentrations are currently used to evaluate taurine status.ObjectiveWe determined effects of dietary SAA restriction on rate and extent of taurine depletion of blood and skeletal muscle in dogs of two body sizes, and whether oral antibiotic administration affected the taurine depletion and fecal bile acid excretion of the dogs.MethodsAdult, male, Beagles (n = 6; 10.1–13.1 kg) and larger mixed-breed dogs (n = 6; 28.5–41.1 kg) were given four dry-expanded diets, whereby each successive diet contained lower protein and/or SAA concentration. After receiving the final diet for 44 weeks, all dogs were orally administered a mixture of ampicillin, neomycin sulfate, and metronidazole for 12 weeks. Taurine concentrations were determined every 2–4 weeks in venous blood and voided urine and every 4 to 16 weeks in biopsied semimembranosus muscle. Fecal bile acid excretion before and after antibiotics administration were quantified.ResultsWhen given for 36 weeks the lowest SAA diet, 3.4% methionine and 2.9% cystine, taurine concentrations in whole blood were not different between groups, while taurine in plasma declined (P < 0.05) in large but not in small dogs, and taurine in biopsied muscle decreased (P < 0.05) by 50% in large and by 37% in small dogs. Concentrations of taurine in muscle were lower (P < 0.01) and fecal bile acids greater (P = 0.001) in large than small dogs. Antibiotic administration restored plasma and muscle taurine to initial concentrations and halved fecal bile acid excretion by dogs of both groups.ConclusionsBlood taurine concentration may not be a sensitive indictor of taurine depletion caused by low intake of bioavailable SAA in dogs, especially in large dogs. Taurine status and dietary SAA requirements of dogs may substantively depend on taurine loss mediated by intestinal microbiota.

The optimal dietary taurine supplementation in zero fish meal diet of juvenile snakehead fish (Channa striata)

The most common alternative protein sources are plant-based proteins such as soybean meal but one of the limitations is taurine deficiency that can be especially detrimental for carnivorous fish. This study was to determine the important roles of dietary taurine on the growth performance, feed utilization and body composition of juvenile snakehead fish with an initial weight of 4.66–4.71 g/fish. Five test diets were investigated, using various taurine supplementation levels and both isonitrogenous and isoenergetic formulas: 1)control (fish meal inclusion); 2)zero fish meal diet (ZF) without taurine supplementation (T0); 3) ZF with taurine supplementation at 0.5% (T0.5); 4) ZF with taurine supplementation at 1.0% (T1.0); 5) ZF with taurine supplementation at 1.5% (T1.5). Fish were fed with five different dietary taurine levels for 60 days. Weight gain (WG), average daily gain (ADG) and specific growth rate (SGR) were higher in the control group of fish, followed by the T0.5 and T1.0 group but the lowest level was observed in fish fed the T0 and T1.5 (p < 0.05). The statistical results of Survival rate (SR), feed conversion ratio (FCR) and protein efficiency ratio (PER) were not significantly different (p > 0.05) among all experimental groups, whereas fish fed diet T0.5 and T1.0 had good trend in FCR and PER value similar to the control group. Dietary taurine might not affect on whole-body composition in juvenile snakehead fish (p > 0.0). Taurine accumulation in fish whole body and the liver both showed the increasing trends varying supplementation levels in each experimental diet. In the current study, taurine supplementation had no observable effects on the histological structures of liver and distal intestines of snakehead fish. This phenomenon indicated that the taurine supplementation at 0.5% in the plant protein-based diet (ZF) cloud be improved the growth performance and feed utilization of juvenile snakehead fish. Leading to, this is a positive sign of a possibility to reduce feed cost by completely taking fish meal out of a future commercial aquafeed for better aquaculture business sustainability.

Blood Taurine Dynamics in Captive Lions: Relationship with Feed and Bile Acid Composition.

Taurine is an essential nutrient for felines including lions. Various severe symptoms induced by taurine deficiency have been reported for domestic and captive felines. Particularly for captive lions in zoos, little information related to taurine requirements is available. Therefore, this study evaluated the relationship between blood taurine concentration and taurine content in prey feed given at zoos, as well as the composition, types, and conjugation properties of bile acids (BAs) in blood collected repeatedly from four lions housed at three zoos. Blood taurine concentrations in four lions were within the normal range, although individual differences and variations were found. Taurine was abundant in feed supplied at the zoos. A positive correlation between blood taurine concentration and feed amount was observed in lions housed at the same zoo. Approximately 70-80% of the total BA pool was cholic acid, with 50-70% being taurine-conjugated. Individual differences and variations were found. No correlation was found between blood taurine concentration and the compositions of BAs in the blood. Results showed that supply of taurine was sufficient for all lions fed the prey feed. Future studies must be conducted to clarify influences on individual differences, as well as individual variations in blood taurine concentration and blood BA composition.