Dietary Guanidinoacetic Acid Research Articles

Dietary guanidinoacetic acid supplementation improves water holding capacity and lowers free amino acid concentration of fresh meat in finishing pigs fed with various dietary protein levels.

The current study was carried out to detect the effect of dietary guanidinoacetic acid (GAA) supplementation on carcass characteristics and meat quality in finishing pigs fed different dietary crude protein (CP) levels. Sixty-four barrows with an initial body weight of 73.05 ± 2.34 kg were randomly allocated into 1 of 4 dietary treatments in a 2 (100% vs. 125% NRC CP level) × 2 (0 vs. 300 mg/kg GAA) factorial arrangement (n = 7). The feeding trial lasted for 49 d. GAA supplementation significantly reduced drip loss (P = 0.01), free water distribution (T23 peak area ratio) (P = 0.05) and the concentrations of free alanine, threonine, methionine and isoleucine (P < 0.05); but increased total glycine content (P = 0.03) in the longissimus dorsi muscle of finishing pigs regardless of the dietary CP levels. Furthermore, primary myogenic cell differentiation system was employed to investigate the influence of inclusion of GAA on free amino acid concentrations in myotubes (n = 4) and validate the finding in the animal feeding trial. We found that GAA inclusion in culture medium also decreased intracellular concentrations of free alanine, threonine, methionine, isoleucine, valine and proline in differentiated primary myogenic cells in vitro (P < 0.05). Meanwhile, relative to diets with 100% NRC CP level, the intake of diets with 125% NRC CP level improved sarcoplasmic protein solubility, increased the contents of carnosine and total free amino acids as well as flavor amino acids in the longissimus dorsi muscle and decreased backfat thickness at the 6–7th ribs in pigs (P < 0.05). In addition, we observed that the impact of dietary GAA supplementation on the last rib fat thickness, shear force, and free lysine content in the longissimus dorsi muscle was dependent on dietary CP levels (P < 0.05). Collectively, dietary GAA supplementation can reduce drip loss, decrease the concentrations of free amino acids and flavor amino acids of fresh meat independent of dietary CP levels.

Skeletal muscle mass, meat quality and antioxidant status in growing lambs supplemented with guanidinoacetic acid

Guanidinoacetic acid (GAA) exists naturally as a precursor of creatine, which possesses several biological functions. In the present study, the effects of dietary GAA supplementation on skeletal muscle mass and meat quality of lambs were investigated. The GAA supplementation increased final body weight, promoted muscle mass and changed the distribution of myofiber size. Meanwhile, elevated ultimate pH and water holding capacity (WHC) of resulting meat were observed in GAA fed lambs. Moreover, the total antioxidative capacity was elevated. Dietary GAA accelerated myofibril protein synthesis through regulation with IGF-1/Akt/mTOR signaling pathway and minimized protein breakdown via regulating abundances of myostatin and phosphorylated FoxO1. In vitro, GAA treatment inhibited sheep primary myoblasts proliferation, and enhanced its myogenic potential. Collectively, these results suggested that GAA might be a feed additive for use by the lamb meat industry as it has potential to improve growth performance, antioxidant status and WHC of resulting meat.

Influence of dietary supplemental guanidinoacetic acid on performance, haematological parameters, carcass characteristics and enzyme activities in male broilers with cold-induced ascites

ABSTRACT This study aimed to evaluate the effects of dietary guanidinoacetic acid (GAA) on performance, enzyme activity and biochemical variables of broilers with cold-induced ascites. A total of 640 day-old male broiler chicks (Cobb 500) were randomly assigned to four treatments (with 8 replicates of 20 birds) including a control and diets supplemented with 0.6, 1.2 and 1.8 g of GAA per kg of feed. On day 14, the temperature was reduced to 17°C during the daytime and 14°C at night. Dietary inclusion of 0.6 g/kg GAA decreased BWG in compared to those fed other levels in the grower period (P < 0.05). The ratio of right to total ventricle, mortality and relative weights of liver were lower in birds fed the diet with 1.2 g/kg GAA compared to bids fed other levels (P < 0.05). The plasma activity of creatine kinase (CK) increased in the birds fed with 1.2 and 1.8 g/kg GAA compared to chicks fed the control diet. It can be concluded that dietary supplemental 1.2 g/kg GAA would be a beneficial way to decrease the mortality rate of broiler reared under cold stress conditions. In addition, the blood levels of HDL-C increased in broilers fed the 1.2 g/kg GAA diet.

Guanidinoacetic Acid as a Nutritional Adjuvant to Multiple Sclerosis Therapy.

Tackling impaired bioenergetics in multiple sclerosis (MS) has been recently recognized as an innovative approach with therapeutic potential. Guanidinoacetic acid (GAA) is an experimental nutrient that plays a significant role in high-energy phosphate metabolism. The preliminary trials suggest beneficial effects of supplemental GAA in MS, with GAA augments biomarkers of brain energy metabolism and improves patient-reported features of the disease. GAA can also impact other metabolic footprints of MS, including demyelination, oxidative stress, and GABA-glutamate imbalance. In this mini-review article, we summarize studies evaluating GAA effectiveness in MS, explore mechanisms of GAA action, and discuss the challenges of using dietary GAA as an element of MS therapy.

Supplementation of guanidinoacetic acid and rumen-protected methionine increased growth performance and meat quality of Tan lambs.

ObjectiveTan lambs (n = 36, 3 mo old, 19.1±0.53 kg) were used to assess effects of dietary guanidinoacetic acid (GAA) and rumen-protected methionine (RPM) on growth performance, carcass traits, meat quality, and serum parameters.MethodsLambs were randomly assigned to three treatment groups, with 6 pens per group and 2 lambs per pen. Dietary treatments were: basal diet alone (I); basal diet supplemented with 0.08% GAA+0.06% RPM (II); and basal diet supplemented with 0.08% GAA+0.08% RPM (III). Diets were provided three times a day for 90 d. Intake per pen was recorded daily and individual lamb body weight (BW) was measured monthly. Carcass traits were measured after slaughter and meat quality at the end of the experiment, blood samples were taken on a subgroup of lambs for analysis of indicators mostly related to protein metabolism.ResultsFinal BW and average daily gain for the first and second month, and for the entire experiment were greater in Treatment II compared to Treatment I (p<0.05), whereas feed to gain ratio was lower (p<0.05). Treatment II had the optimal dressing percentage and net meat weight proportion, as well as crude protein and intramuscular fat concentrations in muscles. Treatment II improved meat quality, as indicated by the greater water holding capacity, pH after 45 min and 48 h, and lower shear force and cooking loss. Dietary supplementation of GAA and RPM also increased the meat color a* and b* values at 24 h. Finally, Treatment II increased total protein, and serum concentrations of albumin and creatinine, but decreased serum urea nitrogen concentrations, indicating improved protein efficiency.ConclusionIn this study, 0.08% GAA+0.06% RPM supplementation improved growth performance and meat quality of Tan lambs.

Effects of dietary guanidinoacetic acid on growth performance, guanidinoacetic acid absorption and creatine metabolism of lambs.

Guanidinoacetic acid (GAA) is the only precursor for the creatine synthesis of vertebrates. Creatine (Cr) and phosphocreatine (PCr) are able to provide energy for the rapid growth and development of the muscle tissue. This study evaluated the effects of dietary different levels GAA on growth performance, GAA absorption and creatine metabolism of lambs. Twenty-four 3-month-old healthy Kazakh male lambs (body weight = 27.35± 0.58 kg) were randomly divided into four groups with 6 lambs in each group. The lambs were fed with the basal diets supplemented with 0 (0 mg/kg group), 500 (500 mg/kg group), 1000 (1000 mg/kg group) and 1500 mg (1500 mg/kg group) GAA per kg diet (DM basis), respectively. The results showed that, as the GAA content of the diet increased, there was a quadratic change in DMI, with the lowest in the 500 mg/kg group and the highest in the 0 mg/kg group. The CK enzyme activity and ATP content in quadriceps muscle increased linearly with increasing levels of diary GAA in the diet. PCr levels and ADP levels in the longest dorsal muscle increased linearly with increasing levels of GAA in the diet. The relative expression of SLC6A6 and SLC6A8 mRNA in the jejunum and ileum mucosa showed a quadratic change as the dietary GAA level increased, with the lowest relative expression in both the 1500 mg/kg group. With the increase of dietary GAA level, both Cr concentration in hepatic vein plasma and the portal plasma GAA concentration shows a quadratic change, with the highest concentration in the 500 mg/kg group and the lowest concentration in the 0 mg/kg group. Therefore, dietary supplementation with 500~1000 mg/kg DM GAA is recommended for lambs.

Safety of Dietary Guanidinoacetic Acid: A Villain of a Good Guy?

Guanidinoacetic acid (GAA) is a natural amino acid derivative that is well-recognized for its central role in the biosynthesis of creatine, an essential compound involved in cellular energy metabolism. GAA (also known as glycocyamine or betacyamine) has been investigated as an energy-boosting dietary supplement in humans for more than 70 years. GAA is suggested to effectively increase low levels of tissue creatine and improve clinical features of cardiometabolic and neurological diseases, with GAA often outcompeting traditional bioenergetics agents in maintaining ATP status during stress. This perhaps happens due to a favorable delivery of GAA through specific membrane transporters (such as SLC6A6 and SLC6A13), previously dismissed as un-targetable carriers by other therapeutics, including creatine. The promising effects of dietary GAA might be countered by side-effects and possible toxicity. Animal studies reported neurotoxic and pro-oxidant effects of GAA accumulation, with exogenous GAA also appearing to increase methylation demand and circulating homocysteine, implying a possible metabolic burden of GAA intervention. This mini-review summarizes GAA toxicity evidence in human nutrition and outlines functional GAA safety through benefit-risk assessment and multi-criteria decision analysis.

Creatine nitrate supplementation strengthens energy status and delays glycolysis of broiler muscle via inhibition of LKB1/AMPK pathway

This study aimed to evaluate the effects of dietary creatine nitrate (CrN) on growth performance, meat quality, energy status, glycolysis, and related gene expression of liver kinase B1/AMP-activated protein kinase (LKB1/AMPK) pathway in Pectoralis major (PM) muscle of broilers. A total of 240 male Arbor Acres broilers (28-day-old) were randomly allocated to one of 5 dietary treatments: the basal diet (control group), and the basal diets supplemented with 600 mg/kg guanidinoacetic acid (GAA), 300, 600, or 900 mg/kg CrN (identified as GAA600, CrN300, CrN600, or CrN900, respectively). We found that dietary GAA and CrN supplementation for 14 d from d 28 to 42 did not affect broiler growth performance, carcass traits, and textural characteristics of breast muscle. GAA600, CrN600, and CrN900 treatments increased pH24h and decreased drip loss of PM muscle compared with the control (P < 0.05). The PM muscles of CrN600 and CrN900 groups showed higher glycogen concentration and lower lactic acid concentration accompanied by lower activities of phosphofructokinase (PFK), pyruvate kinase (PK), and lactate dehydrogenase (LDH) (P < 0.05). Simultaneously, GAA600 and all CrN treatments increased concentration of muscle creatine, phosphocreatine (PCr) and ATP, and decreased AMP concentration and AMP/ATP ratio (P < 0.05). Meanwhile, the concentrations of muscle creatine, PCr, and ATP were increased linearly, while muscle AMP concentration and AMP/ATP ratio were decreased linearly and quadratic as the dose of CrN increased (P < 0.05). GAA600, CrN600, and CrN900 treatments upregulated mRNA expression of CreaT in PM muscle, and CrN600 and CrN900 treatments downregulated GAMT expression in liver and PM muscle compared with the control or GAA600 groups (P < 0.05). The mRNA expression of muscle LKB1, AMPKα1, and AMPKα2 was downregulated linearly in response to the increasing CrN level (P < 0.05). Overall, CrN showed better efficacy on strengthening muscle energy status and improve meat quality than GAA at the some dose. These results indicate that CrN may be a potential replacement for GAA as a new creatine supplement.

Performance, Carcass Yield, Muscle Amino Acid Profile, and Levels of Brain Neurotransmitters in Aged Laying Hens Fed Diets Supplemented with Guanidinoacetic Acid.

Simple SummaryIn commercial laying hens, aging is associated with a lower egg production rate and the marketing of spent hen carcasses shows some difficulty, probably due to the expected low meat yield. Using these hens as whole carcasses or to produce meat products for large-scale consumption could provide economic benefits to the poultry markets in developing countries. Thus, the aim of this study was to investigate the effect of dietary supplementation with guanidinoacetic acid (GA) on the carcass yield and muscle amino acid profile of aged laying hens. Dietary GA supplements were shown to improve the carcass yield and the levels of essential amino acids in the breast and thigh muscles of laying hens.Guanidinoacetic acid (GA) is a natural precursor of creatine in the body and is usually used to improve the feed conversion and cellular energy metabolism of broiler chickens. The objective was to elucidate the effect of dietary supplementation of GA on carcass yield, muscle amino acid profile, and concentrations of brain neurotransmitters in laying hens. In total, 128 72-week-old ISA Brown laying hens were assigned to four equal groups (32 birds, eight replicates per group). The control group (T1) was fed a basal diet with no supplements, while the other experimental groups were fed a basal diet supplemented with 0.5 (T2), 1.0 (T3), and 1.5 (T4) g GA kg−1 diet. The T3 and T4 groups showed higher hen-day egg production and carcass yield compared to the control group (p = 0.016 and 0.039, respectively). The serum creatine level increased linearly with the increased level of dietary GA (p = 0.007). Among the essential amino acids of breast muscle, a GA-supplemented diet linearly increased the levels of leucine, isoleucine, phenylalanine, methionine, and threonine in the breast (p = 0.003, 0.047, 0.001, 0.001, and 0.015, respectively) and thigh (p = 0.026, 0.001, 0.020, 0.009, and 0.028, respectively) muscles. GA supplementation linearly reduced the level of brain serotonin compared to the control group (p = 0.010). Furthermore, supplementation of GA in the diet of laying hens linearly increased the level of brain dopamine (p = 0.011), but reduced the level of brain Gamma-aminobutyric acid (p = 0.027). Meanwhile, the concentration of brain nitric oxide did not differ between the experimental groups (p = 0.080). In conclusion, the dietary supplementation of GA may improve the carcass yield and levels of essential amino acids in the breast muscles, as well as the brain neurotransmitters in aged laying hens.

Effects of low eggshell temperatures during incubation, in ovo feeding of L-arginine, and post-hatch dietary guanidinoacetic acid on hatching traits, performance, and physiological responses of broilers reared at low ambient temperature

This study aimed to investigate the effect of eggshell temperature (ET) manipulations during incubation, in ovo feeding (IOF) of arginine, and post-hatch dietary supplementation with guanidinoacetic acid (GAA) on hatching traits and subsequent growth and physiological performance of hatched broiler chicks reared under subnormal temperature. In experiment 1, from d 8 of incubation onward, a total of 2,160 hatching eggs were randomly arranged in a 2 × 3 factorial design, in which the eggs were exposed to 2 ET (37.8°C or periodically low ET), and 3 IOF treatments (noninjected, diluent-injected, and 1% arginine solution-injected). In experiment 2, a total of 576 one-day-old male broiler chicks from 2 temperature conditions and 2 IOF treatment groups (noninjected and Arg-injected) were reared for 42 d with or without GAA supplementation in a 2 × 2 × 2 factorial design. Each treatment had 6 replicates with 12 birds each. A subnormal ambient temperature (17°C) was applied from 15 d onward to induce ascites. Results from experiment 1 showed a 2-way interaction between ET and IOF for embryonic mortality rate during 19 to 21 d of incubation and residual yolk weight at hatch (P < 0.05). A periodically low ET significantly increased yolk free body mass, first-grade chicks, and relative heart weight than an ET of 37.8°C. In the second experiment, overall average daily gain (ADG) was increased, but feed conversion ratio (FCR), ascites mortality, and serum thyroid hormones and corticosterone were reduced in the low ET group (P < 0.05). There were also IOF × GAA interactions for ADG and FCR (P < 0.05). IOF of arginine or dietary GAA increased serum nitric oxide concentration and jejunal villus height, but decreased ascites mortality (P < 0.05). In conclusion, a periodically low ET accompanied by IOF of arginine during incubation and posthatch dietary supplementation with GAA could be a useful strategy for improving the chick quality at hatch and subsequent improvements in post-hatch performance and ascites indices in cold-stressed broilers.

Effect of dietary guanidinoacetic acid or nucleotides supplementation on growth performances, carcass traits, meat quality and occurrence of myopathies in broilers

This study was conducted to evaluate the effects of diets supplemented with nucleotides and guanidinoacetic acid (GAA) on broiler chickens growth performance, blood metabolites, leukocyte differential count, mitotic activity of satellite cells, carcass yield, meat quality, chemical analysis of breast muscle, incidence of breast myopathies, and skin lesions from 0 to 42d. A total of 600 one-day-old male broiler chickens were randomly distributed among three treatments with eight replicates and 25 broiler chickens per pen. Treatments consisted of a control diet (CD), the CD + one g/kg of nucleotides (fed from 0 to 28 d, afterwards broilers were fed CD) and the CD + 0.6 g/kg of GAA (fed from 0 to 42 d). On 10 d, broiler chickens fed with GAA had an improved feed conversion ratio (FCR) (P < 0.05), increased BWG (P < 0.05), and plasmatic concentration of creatine kinase (P < 0.05) when compared to broiler chickens fed the CD. On 28 d, breast meat of broiler chickens fed with GAA showed a reduction in fat content, compared to the nucleotides. Broiler chickens fed with GAA had a reduction in dermatosis and incidence of moderate and average scores of wooden breast (WB) scoring, besides the proportions of severe and average scores of white stripping (WS) scoring at 42 d, compared to broiler chickens fed diets supplemented with nucleotides. In conclusion, supplementation of nucleotides increases the incidence of breast myopathies, without affecting other variables and GAA supplementation improves broiler chickens growth performance compared to control group from 0 to 10 d and reduced the severity of myopathies and the occurrence of dermatosis at 42 d.

Effects of Dietary Guanidinoacetic Acid on the Feed Efficiency, Blood Measures, and Meat Quality of Jinjiang Bulls.

An experiment was conducted to determine the effects of supplementing the diet of Jinjiang bulls with guanidinoacetic acid (GAA) on their feed efficiency [feed efficiency were evaluated with feedlot average daily gain (ADG), average daily feed intake (ADFI), and feed-to-gain ratio (F:G)], blood measures, and meat quality. Forty-five Jinjiang bulls (24 ± 3 months old and 350.15 ± 30.39 kg by weight) were randomly distributed among five experimental groups (each n = 9) and each group was randomly fed with one of five diets (concentrate: roughage ratio of 60:40): (1) control; (2) 0.05% GAA; (3) 0.1% GAA; (4) 0.2% GAA; and (5) 0.4% GAA, respectively. After a 52-days feeding trial, five bulls from the control group and five bulls from the optimal GAA supplementing group were randomly selected and slaughtered for collection of the longissimus thoracis (LT) and semitendinosus (SM) muscles to determine meat quality. The results showed that dietary GAA improved the ADG, decreased the value of F:G, and affected blood measures and antioxidant variables. Supplementing 0.2% GAA into the diet was optimal for feeding efficiency and most of the measured blood measures. Supplementing 0.2% GAA into the diet increased the a* (redness) values, and b* (yellowness) values, and the amount of creatine kinase (CK), muscle glycogen, creatinine (CRE), and laminin (LN) in LT muscles. However, it decreased the drip loss, L* (lightness) value, and lactate dehydrogenase (LDH) content of LT muscles. Drip loss and shear force decreased in SM muscles, as did the amount of type IV collagen (CV–IV). In conclusion, supplementing 0.2% GAA into the diet could enhance feed efficiency to improve beef growth and meat quality.

Effects of dietary supplementation of guanidinoacetic acid on physiological response of broiler chicken exposed to repeated lactic acid injection

Increased blood lactic acid is likely to be involved in the incidence of sudden death syndrome (SDS) in broiler chicken. Guanidinoacetic acid (GAA) with direct or indirect influence on the cardiovascular system may provide, to some degree, protection against lactic acidemia in birds. A total number of 144 male broiler chicks (Ross 308) were used in a complete randomised block design to investigate the effects of dietary supplementation of GAA at 0.6, 1.2, 1.8, 2.4 and 3 g/kg on the physiological response of broiler chicks to an acute lactic acidosis in an 8-days experiment. Birds receiving 1.8 and 3 g/kg GAA exhibited lesser mortality percentage compared with the control birds and those received dietary GAA at 0.6 and 1.2 g/kg (p < .03). Dietary inclusion of 1.2 g/kg GAA to broiler chicks increased serum concentration of uric acid compared to the control birds and those received 2.4 g/kg (p < .02). The mean serum concentration of creatinine was greater in the birds receiving different GAA levels compared with the control birds (p < .0001). The serum concentration of nitric oxide decreased in the birds receiving 1.2 g/kg GAA by 21.05 and 15.57% compared with the control birds and those received 1.8 g/kg of GAA, respectively (p < .04). A lesser frequency for liver colour score 5 was observed in the birds fed on the diet with 0.6 g/k GAA (p < .0001). It was concluded that dietary administration of GAA deteriorates the adaptive physiological responses to an acute lactic acidosis in broiler chicken possibly through liver and kidney dysfunction. HIGHLIGHTS Dietary guanidinoacetic acid decreased mortality but showed an adverse effect on growth performance in chickens exposed to acute lactic acidosis. The adverse effects of guanidinoacetic acid may happen through liver and kidney dysfunction. No firm evidence was found to suggest a significant effect of extra nutritional guanidinoacetic acid on the incidence of sudden death syndrome in chicken.

Effects of guanidinoacetic acid supplementation on zootechnical performance and some biometric indices in broilers challenged with T3-Hormone

The objective was to elucidate the effects of dietary guanidinoacetic acid (GAA) supplementation on broiler performance, serum enzymes, oxidative biomarkers, mitochondrial activities, carcase traits, gross lesion of cardiac muscle and liver histopathology in broilers challenged with T3-hormone. A total-of-192 one-day-old mixed sexed broilers were randomly assigned in a two factorial design, including two dietary treatments; control diet supplemented with or without T3-hormone (1.5 ppm) and GAA diet (0.06%) supplemented with or without T3-hormone (1.5 ppm). Each group was subdivided into eight replicates. Results showed interactions between GAAxT3-hormone. GAA diet significantly mitigated the negative effect of T3-hormone on serum total creatine kinase (CK), cardiac muscle (CK-MB), liver malondialdehyde (MDA) and superoxide dismutase (SOD), mitochondrial activities of cardiac muscle and liver histopathological lesion. In conclusion, GAA at a rate of 0.06% may have the potential to mitigate the negative effect of dietary T3-hormone but could not reduce the ascites mortality at such inclusion rate. HIGHLIGHTS GAA protected heart muscle. GAA mitigated the oxidative radicals in T3-hormone challenged birds. GAA modulated the mitochondrial activities in T3-hormone challenged birds.

Effect of guanidinoacetic acid and betaine supplementation in soybean meal-based diets on growth performance, muscle energy metabolism and methionine utilization in the bullfrog Lithobates catesbeianus

This study was carried out to evaluate the impacts and interactions of guanidinoacetic acid (GAA) and betaine (BT) supplementation of soybean-meal-based diets on the growth, meat quality, and methionine utilization in the bullfrog Lithobates catesbeianus. A basal diet was supplemented with 0 or 4 g/kg of BT and/or 0, 0.4, or 4 g/kg GAA to formulate six experimental diets, designated Control (BT/GAA: 0/0), B0G0.4 (0/0.4), B0G4 (0/4), B4G0 (4/0), B4G0.4 (4/0.4) and B4G4 (4/4). Each diet was fed to three individual bullfrogs (initially weighing 51.70 ± 0.33 g) for 8 weeks. As a result, bullfrogs fed diets with GAA showed greater weight gain than the control group (P < 0.05). The addition of GAA or BT to the diets increased whole-body protein deposition and the hind leg index (P < 0.05). Diets supplemented with GAA led to reduced muscle glycolysis, which increased the muscle pH value 24 h after euthanasia (P < 0.05). However, a combination of BT and GAA had an insignificant effect on the expression of betaine homocysteine methyltransferase mRNA compared with the diets supplemented with GAA-only (P > 0.05). The findings of this study suggest that dietary GAA supplementation improves bullfrog growth performance and muscle energy metabolism after slaughter, but GAA combined BT supplementation does not improve methionine utilization for bullfrog.

Dietary guanidinoacetic acid response on digestibility, growth performance, feed utilization and carcass quality in Nile Tilapia ( Oreochromis niloticus )

Creatine plays a vital part in the energy metabolism and physiological roles. It is exclusively found in ingredients of animal origin, so using all-plant protein-based diets increases the risk of creatine deficiency. The objectives of this current study were to determine the optimal level of dietary guanidinoacetic acid (GAA) with regard to the nutrient digestibility, growth performance, feed utilization and carcass quality of Nile tilapia (Oreochromis niloticus). The fish (27.33 ± 0.70 g) were fed with five different isonitrogenous and isoenergetic diets for 60 days: T1 was the positive control diet (HF; 6% fish meal inclusion); T2 was the negative control formulated to contain no GAA (NC, free fish meal); and T3, T4 and T5 were NC supplemented with 0.06%, 0.12% and 0.18% of GAA respectively. At the end of the experiment, it was found that growth performance and feed utilization were not significantly different (p > .05) among the groups. However, fish from the T3 and T4 groups had slightly better weight gain and growth rate, as well as improved digestibility of protein, methionine, lysine and histidine (p < .05). Fish fed the dietary GAA at 0.06 or 0.12% had clearly larger width increment than the other groups. This is important as consumers prefer large dorsal muscles. This result from this study showed no adverse effect on haematological parameters, serum biochemistry parameters, fillet texture quality and histopathological change in the liver of Nile tilapia. Therefore, these results indicate that GAA supplementation at 0.06%–0.12% in Nile tilapia diet can potentially improve fish growth and feed utilization without setback on health.

Effect of dietary sulphur amino acid levels and guanidinoacetic acid supplementation on performance, carcase yield and energetic molecular metabolites in broiler chickens fed wheat-soy diets

The aim of the present study was to evaluate the effects of dietary total sulphur amino acids (TSAA) levels and guanidinoacetic acid (GAA) supplementation on performance, carcase yield and energetic molecular metabolites in heart and breast muscle of broiler chickens fed wheat-soy diet. A total of 450, male one-day-old Ross-308 broiler chicks were assigned in a 3 × 3 factorial arrangement of nine treatments, five replicates and 10 birds each. Dietary treatments included three graded levels of supplementary TSAA (+0.4 g/kg per level) resulting in a deficient, adequate and plus level of recommended by strain, with three levels of GAA (0, 0.6 and 1.2 g/kg) and were fed for 35 days. Dietary TSAA levels only enhanced performance during the starter period (p < .05). At adequate TSAA level, weight gain (WG) and feed conversion ratio (FCR) in the grower phase were positively affected by supplementing GAA at 1.2 g/kg (p < .05). The FCR during the overall experimental period was significantly lower when feeding GAA at 0.6 and 1.2 g/kg compared to non-supplemented (p < .05). Heart and breast muscle ATP/AMP ratio and breast muscle ADP and PCr concentration and PCr/CrN ratio in the birds fed 1.2 g/kg GAA diet were significantly higher than non-supplemented (p < .05). It is concluded, effects of dietary GAA supplementation were influenced by dietary TSAA level, this indicates to need for proper dietary sulphur amino acid formulation by GAA supplementation. Dietary GAA supplementation could improve broiler chicken’s growth performance via regulating some aspects of energy metabolism. HIGHLIGHTS Guanidinoacetic acid plays a critical role in energy homeostasis. The effect of dietary Guanidinoacetic acid supplementation may influenced by the dietary sulphur amino acids.

Guanidinoacetic acid as a novel food for skeletal muscle health

Abstract Guanidinoacetic acid (GAA) is a direct endogenic precursor of creatine. GAA is also a re-discovered nutraceutical that has been put forward as an energy-facilitating compound by many animal and a few human studies. Recent trials indicated that dietary GAA might have yet another role in muscle growth promotion, acting as an anticatabolic and/or anabolic compound. This opinion paper summarizes the latest findings for advancing (or impeding) dietary GAA in skeletal muscle medicine, discussing open questions that need to be answered before the translation of supplemental GAA use from bench to bedside.

Dietary guanidinoacetic acid supplementation improved carcass characteristics, meat quality and muscle fibre traits in growing-finishing gilts.

This study was designed to evaluate the effects of guanidinoacetic acid (GAA) on growth performance, carcass characteristics, meat and muscle fibre traits of growing-finishing gilts. 300 female PIC pigs were randomly divided (30.10±2.94kg) into 2 treatments with 6 replicates of 25 each for a 100-day trial. Two dietary treatments were comprised of a control diet and a control diet fortified with 450mg/kg GAA. Growth performance was evaluated for each phase. Carcass characteristics and meat quality were determined at last phase. Gilts had free access to feed and water during the experiment. The result indicated that GAA did not affect growth performance (p>0.05). GAA not only increased longissimus dorsi (LM) muscle weight but also decreased its shear force, b*value and drip loss (p<0.05). Mandibular fat index was decreased by GAA (p<0.05). GAA upregulated myosin heavy chain (MyHC) I mRNA expression with lower myofibre cross-sectional area and fibre diameter in LM muscle (p<.05). In conclusion, GAA can improve carcass characteristics and meat quality by changing muscle fibre characteristics and reducing mandibular fat index in finishing gilts.

Short-term GAA loading: Responders versus nonresponders analysis.

Dietary guanidinoacetic acid (GAA) has been suggested to be advantageous for favorable changes in tissue bioenergetics in terms of responder versus nonresponder performance, yet no studies so far explored the proportion of two distinct populations following short‐term GAA intervention. A secondary analysis of previously completed guanidinoacetic acid (GAA) trials has been carried out in aim to classify individuals into responders and nonresponders using cut‐off criteria for an increase in intramuscular creatine. A total of 30 individuals (mean age = 34.5 years, women 66.7%) who were supplemented with up to 3 g/day of GAA for at least 28 days with total muscle creatine evaluated using 1.5 T magnetic resonance spectroscopy studies were included in this examination. Pre–post measures included total creatine content (creatine plus phosphocreatine) determined from the quadriceps muscle, with participants were classified by arbitrary cut‐off points in three categories, including responders (>10% increase in total creatine content at follow‐up), quasi‐responders (5%–10% increase), and nonresponders (<5% increase in total intramuscular creatine at postadministration). An average change in total creatine content after GAA supplementation was 22.9%, with 13.3% participants were categorized as nonresponders, 6.6% as quasi‐responders, and 80.0% as responders (p < .001). A fairly high prevalence of individuals sensitive to dietary GAA advances this innovative agent as a rather effective tool to improve muscle creatine levels for at least 10% or more during 28‐day loading.