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Six ruminally cannulated Holstein steers (256 ± 14 kg) were used in a 6 × 6 Latin square design to assess effects of guanidinoacetic acid (GAA) supplementation on N retention and methionine (Met) methyl group flux in growing cattle fed corn-based diets. Factorial treatments were two levels of Met (0 or 5 g/d) and three levels of GAA (0, 7.5, or 15 g/d) delivered by continuous abomasal infusion. Periods were 10 d in length and included 6 d of treatment adaptation, 3 d for total fecal and urine collections, and 1 d for blood sampling and flux measurements. Urinary N linearly increased (P < 0.01) with GAA supplementation and decreased (P < 0.05) with Met supplementation. Fecal N excretion was unaffected (P ≥ 0.42) by treatment. Retained N was not affected by GAA supplementation, but it was increased (P < 0.01) by Met supplementation. Use of methionine for transmethylation reactions, as well remethylation of homocysteine, was not affected by GAA supplementation when Met was not supplemented, but tended to be linearly increased by GAA supplementation when Met was supplemented (GAA-linear × Met interaction; P = 0.07), with the increases matching the amount of GAA provided. This response suggests that methylation reactions for compounds other than GAA were reduced by GAA supplementation when Met supply was deficient. Plasma concentrations and urinary excretion of creatine increased linearly (P = 0.03 and P = 0.06, respectively) when GAA was supplemented. There was a linear increase (P < 0.01) in urinary GAA excretion with GAA supplementation. Neither plasma concentration nor urinary excretion of creatinine was affected (P ≥ 0.17) by treatment. No treatment differences (P ≥ 0.13) were observed for plasma haptoglobin concentrations. Plasma urea-N linearly increased (P < 0.05) with GAA supplementation. Concentrations of Met and taurine increased (P < 0.05) when Met was supplemented. Plasma arginine was greatest at the intermediate level of supplemental GAA (quadratic, P < 0.05). The increase in N retention when Met was supplemented demonstrates Met was limiting in the corn-based diet. Supplementation of GAA alone or with Met as a methyl donor did not increase N retention in growing steers, perhaps because creatine production was favored over protein deposition as a use for Met.

Simple SummaryThis study evaluated the effects of dietary guanidinoacetic acid (GAA) supplementation on growth and metabolism in yaks by randomly assigning twenty-four male animals to a control group (basal diet) and two treatment groups (0.055% or 0.11% GAA) for a 90-day feeding trial. The results showed a positive trend in growth performance, with the higher GAA supplementation level leading to a more noticeable improvement in average daily gain. Serum biochemical indices were generally unaffected, though a tendency of reduced glutathione peroxidase activity was observed. Non-targeted metabolomics in plasma identified multiple differentially abundant metabolites across groups. Enrichment analysis highlighted significant alterations in metabolic pathways related to tryptophan, glycerophospholipid, and arginine metabolism. Notably, metabolites such as N(omega)-Hydroxyarginine, 5-hydroxytryptophan, and serotonin were specifically affected. In conclusion, dietary GAA supplementation, particularly at 0.11%, has the potential to enhance growth in yaks, which may be attributed to its role in modulating amino acid metabolism, especially arginine and tryptophan pathways. These findings provide a metabolic perspective for the application of GAA as a feed additive in yak production.This study aimed to investigate the effects of dietary guanidinoacetic acid (GAA) supplementation on yak physiology by evaluating growth performance, serum biochemical indices and plasm metabolomic profiles to elucidate the underlying regulatory mechanisms. Twenty-four male yaks (4–5 years; 249.38 ± 11.69 kg BW) were randomly allocated to three dietary treatments (n = 8): CON (basal diet), GAA1 (basal diet + 0.055% GAA), and GAA2 (basal diet + 0.11% GAA), with 55:45 of concentrate:roughage (DM basis). After a 10-day adaptation period, the feeding trial lasted 90 days. Body weights were measured on days 0 and 90 for growth performance evaluation, with blood samples collected on the final day for separation into serum and plasma to assess serum metabolic and antioxidant parameters and for plasma metabolomic profiling. The result showed that growth performance parameters displayed a positive trend, with average daily gain (ADG) showing marginal improvement (p = 0.072). Serum biochemical analysis revealed that dietary supplementation of GAA had no effect on serum biochemical parameters while tendency decreased GSH-Px activity (p = 0.087). Non-targeted metabolomics identified 39–121 differentially abundant metabolites in plasma across treatment groups. Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis of these metabolites revealed pathways such as tryptophan metabolism, glycerophospholipid metabolism, and arginine metabolism. Among the differentially abundant metabolites, N(omega)-Hydroxyarginine and tryptophan metabolites such as 5-hydroxytryptophan and serotonin were specifically highlighted. In conclusion, dietary supplementation of GAA in yaks has been confirmed to improve ADG, with a 0.11% supplementation level being more effective, and this may be associated with GAA enhancing amino acid metabolism, particularly arginine and tryptophan metabolism.

The purpose of this study was to determine the effects of dietary supplementation of arginine (ARG) or guanidinoacetic acid (GAA), with or without phenylalanine (PHE), on the ascites susceptibility in the cold-stressed broilers fed canola meal (CM)-based diet. A total of 450 one-day-old male broiler chicks were randomly allocated to 30 floor pens with 6 replications for each of the 5 treatments. The dietary treatments were as follows: CM-based diet (control), CM-based diet+2.57g/kg ARG, CM-based diet+1.8g/kg GAA, CM-based diet+2.57g/kg ARG+1.5g/kg PHE and CM-based diet+1.8g/kg GAA+1.5g/kg PHE. The groups experienced cold stress induction starting at 32°C on day one, with gradual reductions to 15°C on days 21. The temperature was then held at 15°C for the remainder of the experiment. The supplements ARG+PHE and GAA+PHE resulted in improved feed conversion ratios (FCR) when compared to the control group. In comparison with the control group, supplementation of ARG and ARG+PHE decreased the ascites mortality by increasing the plasma nitric oxide level (NO), blood O2 partial pressure, blood O2 saturation (SO2), and decreasing the blood CO2 partial pressure (PCO2) and right ventricle to total ventricle (RV:TV) ratio. Supplementation of GAA and GAA+PHE also declined ascites mortality by reducing blood PCO2 while increasing blood SO2 and plasma NO levels. Although plasma corticosterone level and RV:TV ratio were similar between the GAA and control groups, adding GAA+PHE significantly reduced both compared to the control group. In summary, supplementing cold-stressed broiler chicken diets with 2.57g/kg ARG may alleviate hypertension. Additionally, 1.8g/kg GAA proves to be an effective substitute for dietary ARG in low-ARG diets, alleviating adverse effects from cold stress. Proper PHE formulation, at 1.5g/kg in this study, is crucial when using ARG and GAA supplements.

Two separate comparative feeding trials were conducted to evaluate if supplemental dietary guanidinoacetic acid (GDA), either singly or in combination with creatine, could enhance growth performance of red drum. The basal diet for both trials was formulated with practical ingredients but was not supplemented with creatine or GDA. For the experimental diets, creatine (0 or 20 g/kg) and GDA (0, 5 or 10 g/kg) were added to the basal diet in a 2 × 3 factorial arrangement for trial 1. Another 2 × 3 experimental design was adopted in trial 2 to further evaluate creatine (0 or 20 g/kg) and GDA (0, 10 or 20 g/kg) supplementation. Each diet was fed to juvenile red drum in either quadruplicate (trial 1) or triplicate (trial 2) aquaria twice daily for a total of 8 weeks. After each feeding trial, fish were sampled for body condition indices and whole‐body composition analysis, as well as determination of plasma, liver and muscle creatine concentrations. In trial 1, dietary creatine supplementation alone significantly (p < .05) improved weight gain and feed efficiency of red drum. An interaction between creatine and GDA was seen in whole‐body protein and lipid in the two trials. In trial 1, the highest levels of whole‐body protein and lipid were observed in fish fed 10 g GDA/kg, and in trial 2, supplementation of the diet with 10 g GDA/kg increased muscle protein and muscle lipid although there was a trending decline in fish fed the 20 g/kg GDA‐supplemented diet. In both trials of the present study, dietary GDA significantly (p < .05) enhanced liver creatine content. Dietary creatine also significantly (p < .05) enhanced plasma and muscle creatine content of red drum. Based on the results of this study, creatine was effective in enhancing weight gain and feed efficiency of red drum as seen in previous studies; however, GDA was not effective in influencing growth performance but limited synthesis of creatine from dietary GDA was apparent.

Recent research has demonstrated that feeding rumen protected methionine (MET) products increases circulating methionine while feeding guanidinoacetic acid (GAA) may result in a methyl deficiency. Therefore, we hypothesized that maternal MET or GAA supplementation from 63 days before breeding until d 63 of gestation would increase fetal hepatic methyl donors or result in a fetal hepatic methyl donor deficiency, respectively. Eighty MARC II heifers (n = 20 per treatment; initial BW = 344 ± 8 kg; day -63) were weighed and assigned to one of four breeding groups and four treatments stratified by age and starting weight. Heifers were fed a total mixed ration to gain 0.68 kg/d and received 100 g of one of four treatments top dressed: control supplement of ground corn (CON), MET (10 g/d) in a ground corn carrier, GAA (40 g/d) in a ground corn carrier, or MET + GAA (10 g/d MET + 40 g/d GAA) in a ground corn carrier. At breeding (d 0), all heifers were bred to a single sire using male sexed semen. At d 63 of gestation, 35 heifers (CON n = 10, MET n = 8, GAA n = 7, MET + GAA, n = 10) confirmed pregnant with bull calves were humanely slaughtered and fetal liver tissues were collected and sent to Metabolon Inc. for global metabolomics analysis. Data were analyzed as a 2 x 2 factorial with 2 levels of GAA and 2 levels of MET with breeding group included in the model. For this abstract, only metabolites from the methionine cycle and adjacent pathways will be reported and only metabolites with significant P-values will be discussed (P ≤ 0.05). There were no main effects or interactions for the abundance of methionine, GAA, creatine, SAM, SAH or homocysteine. Glycine was decreased and sarcosine increased in fetuses from MET supplemented dams. Serine was affected by a MET x GAA interaction being decreased in livers of CON, MET, and MET + GAA fetuses compared with GAA. Cystathione, S-methylcysteine, s-methylcysteine sulfoxide, and hypotaurine were greater in fetuses of MET supplemented heifers and pyridoxal phosphate was reduced in fetal liver of MET supplemented heifers. The abundance of urea was greater in GAA supplemented fetuses. These results indicate that fetuses from dams fed methionine may be able to maintain balance in methionine supply by shunting methionine through adjacent pathways including the transsulfuration pathway. We also interpret these data to imply that excess methionine is not utilized by the fetus and is metabolized to products that can be excreted. Lastly, GAA did not alter the fetal methyl supply. USDA is an equal opportunity provider and employer. Funded by (USDA-NIFA-AFRI # 2022-67015-36196).

Effects of dietary supplementation of meat-type quail breeders with guanidinoacetic acid on their reproductive parameters and progeny performance

SUMMARY Nowadays, broiler chicken is considered an important source of high-quality protein in the human diet; hence, poultry production makes an essential component of world food security. The increase in poultry products demand warrants optimum production efficiency along with heat stress, disease management problems and antibiotic resistance. Guanidinoacetic acid (GAA), a creatine precursor, has been of interest for its potential to improve growth efficiency, meat quality and general health in birds. In this review, effects of GAA supplementation on growth performance, carcass traits and meat quality, antioxidant activity, immune function and intestinal health in broiler chickens were summarised. Previous works have shown that GAA supplementation had positive effects on feed efficiency, daily gain and muscle yield especially at heat stress environment. A supplemental dose of GAA of 0.6–1.2 g/kg in broiler diets has been noted to be sufficiently effective as a growth promoting agent and improve meat quality, due to the promotion on the activity of antioxidant enzymes and immune responses. In addition, GAA supplementation may also modulate genes in intestinal mucosal morphology and gut health. While the results are promising, the variability in outcomes between studies (for instance, dosage of GAA incorporated into feed supplementation duration, environment, etc.), indicates that additional research is needed for optimal use of GAA in a given poultry production system. The GAA supplementation is suggested to be a cost-effective and sustainable approach to poultry production delivering productivity and bolstering welfare.

BackgroundThe influence of circadian rhythms and menstrual cycle phases on athletic performance and psychological responses is critical for optimizing training and competition strategies for female athletes. This study aimed to investigate the effects of time of day and menstrual cycle phases on the physical performance and psychological responses of elite female Tunisian volleyball players.MethodsThirteen elite female volleyball players were assessed during three different phases of their menstrual cycle (menstrual, follicular, and luteal) and at two different times of day (morning and evening). Physical performance was evaluated using the Modified Agility Test (MAT), Reactive Agility Test (RAT), and Repeated Sprint Ability (RSA) Test. Psychological responses were measured using the Profile of Mood States (POMS), Hooper’s Questionnaire, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Vis-Morgen Questionnaire, and Spiegel Questionnaire.ResultsSignificant effects of menstrual cycle, time of day, and competition on physical performance, cognitive function, mood, and sleep parameters were found. Physical performance, including the Countermovement Jump (CMJ), the Modified Agility T-test (MAT) and the Reactive Agility test (RAT), was higher in the afternoon than in the morning across all menstrual phases (CMJ: p < 0.001, η² = 0.836; MAT: p < 0.001, η² = 0.777; RAT: p < 0.001, η² = 0.859). After the competition, performance decreased significantly, especially in the follicular and luteal phases. As measured by the Stroop test, cognitive function showed significant diurnal effects (p < 0.001, η² = 0.910), with pre-competition performance being better in the afternoon. Mood disturbances (POMS) increased after the competition, especially in the morning and during the luteal phase (p < 0.001, η² = 0.961). Sleep parameters were significantly influenced by time and menstrual cycle, with higher fatigue (Hooper score: p < 0.001, η² = 0.754) and poorer sleep quality (PSQI: p < 0.001, η² = 0.627) in the morning, especially after the competition.ConclusionOur results suggest that aligning high-intensity training and competitions with afternoon circadian peaks may enhance physical and cognitive performance in elite female athletes. Recovery strategies and workload adjustments should account for menstrual phases, particularly reducing morning demands during the luteal phase to mitigate fatigue and mood disruptions. Integrating circadian timing with menstrual cycle monitoring offers a practical, evidence-based approach to optimize athlete readiness and resilience.

ABSTRACT1. Guanidinoacetic acid (GAA) is the single endogenous precursor of creatine, which plays a critical role in energy homeostasis of cells. Since GAA is endogenously converted to creatine by methylation, it was hypothesised that the effects of dietary GAA supplementation might determine the methionine (Met) availability in corn-soybean based diets.2. A total of 540, one-day-old male Ross 308 broilers were allocated to nine dietary treatments with six replicates (10 birds each) in a 3 × 3 factorial arrangement with three graded levels of supplementary Met (+0.4 g/kg per level), whilst cystine was equal across groups, resulting in a low, medium and high level of total sulphur amino acids, and with three levels of GAA (0, 0.6 and 1.2 g/kg). Birds were fed for 42 days.3. Increasing levels of supplemental Met enhanced performance indices in all rearing periods, although there was no effect on feed conversion ratio in the grower or feed intake in the finisher periods. Final body weight was 8.8% and 14.6% higher in the birds fed medium and high Met diets, respectively, compared to the low Met level. Relative breast weight and protein content in muscle on d 25 linearly increased with higher levels of Met. At low and high Met levels, growth in the finisher phase was negatively affected by supplementing GAA at 1.2 g/kg. It was suggested that disturbances in methylation homeostasis and/or changes in Arg metabolism might explain these findings. At the end of the grower phase, muscle creatine content was higher when feeding GAA at 0.6 and 1.2 g/kg (4464 and 4472, respectively, vs. 4054 mg/kg fresh muscle in the control group).4. The effects of dietary GAA supplementation were influenced by the dietary Met level only in the finisher period, which indicates the need for proper sulphur amino acid formulation in diets when feeding GAA.

The different substances in biomass can regulate the metabolism and reproduction of broilers. Guanidino-acetic acid (GAA) is a natural feed additive that showed a potential application in dietary for broilers, while its amount is scarce in biomass. The objective of the present study was to investigate the effects of dietary supplemented with GAA on muscle glycolysis of broilers subjected to pre-slaughter transportation. A total of 160 Qiandongnan Xiaoxiang chickens were randomly assigned into three treatments, including a basal control diet without GAA supplementation (80 birds) or supplemented with 600 mg/kg (40 birds) or 1,200 mg/kg (40 birds) GAA for 14 days. At the end of the experiment, the control group was equally divided into two groups, thus resulting in four groups. All birds in the four groups aforementioned were separately treated according to the following protocols: (1) no transport of birds of the control group fed with the basal diet; (2) a 3-h transport of birds of the control group fed with the basal diet; (3) a 3-h transport of birds fed with diets supplemented with 600 mg/kg GAA; and (4) a 3-h transport of birds fed with diets supplemented with 1,200 mg/kg GAA. The results demonstrated that 3-h pre-slaughter transport stress increased corticosterone contents and lowered glucose contents in plasma (P < 0.05), decreased pH24h (P < 0.05), and resulted in inferior meat quality evidenced by elevating the drip loss, cooking loss, and L∗ value (P < 0.05). Meanwhile, 3-h pre-slaughter transport stress decreased the contents of Cr and ATP in muscle (P < 0.05) and elevated the ratio of AMP:ATP and the glycolytic potential of muscle (P < 0.05). Moreover, 3-h pre-slaughter transport resulted in a significant elevation of mRNA expressions of LKB1 and AMPKα2 (P < 0.05), as well as the increase in protein abundances of LKB1 phosphorylation and AMPKα phosphorylation (P < 0.05). However, 1,200 mg/kg GAA supplementation alleviated negative parameters in plasma, improved meat quality, and ameliorated postmortem glycolysis and energy metabolism through regulating the creatine–phosphocreatine cycle and key factors of AMPK signaling. In conclusion, dietary supplementation with 1,200 mg/kg GAA contributed to improving meat quality via ameliorating muscle energy expenditure and delaying anaerobic glycolysis of broilers subjected to the 3-h pre-slaughter transport.

There is limited research on female football players, especially related to their physical and cognitive performance under different climactic conditions. We analyzed the impact of a hot environmental temperature on physical performance and anticipation in elite female football players during a fatigue-inducing intermittent protocol. Elite female players (n = 21) performed the countermovement jump (CMJ) and responded to filmed sequences of offensive play under two distinct environmental temperatures (i.e., mild environment temperature- 20°C and 30% rh versus hot environment temperature- 38°C and 80% rh), interspersed by 1-week interval. Linear mixed models were used. CMJ performance declined following the intermittent protocol on both temperature conditions (p < 0.05). Moreover, there were significant main effects for protocol on CMJ speed (m/s) (p = 0.001; ηp 2 = 0.12), CMJ power (p = 0.002; ηp 2 = 0.11), and CMJ Heightmax (p = 0.002; ηp 2 = 0.12). After performing the intermittent protocol, exposure to a hot temperature caused a greater decline in anticipation accuracy (mild temperature = 64.41% vs. hot temperature = 53.44%; p < 0.001). Our study shows impaired performance in elite female football players following an intermittent protocol under hot compared with mild environmental conditions. We report decreased performance in both CMJ and anticipation performance under hotter conditions. The results reveal that exposure to hot temperatures had a negative effect on the accuracy of their anticipatory behaviors. We consider the implication of the work for research and training interventions.

The growth, haemato-biochemical indices, and antioxidant status of broiler chickens fed varying levels of Guanidino Acetic Acid (GAA) were evaluated over the course of an eight-week feeding trial. In low ME (2700Kcal/kg) basal diets, the Guanidino Acetic Acid was supplemented at 0, 0.6, and 1.2g/kg, designated as diets I, II, and III, respectively. The average final weight of chickens fed diet III was the highest at the end of the feeding trial. The best feed conversion ratio was observed in birds fed diet III. The packed cell volume and haemoglobin were highest in birds fed diet I. Significantly higher Cholesterol and Albumin were recorded in diets III and II, respectively. All the antioxidant parameters were significant except Catalase. The glutathione peroxidase increased with increased Guanidino acetic Acid supplementation while Catalase reduced with increased GAA supplementation. According to the findings of this study, Guanidino Acetic Acid improved the health of broilers while having no negative effects on their health. It is therefore concluded that supplementation of Guanidino Acetic Acid at 1.2g/kg with low metabolizable energy promoted superior growth effect of the chickens and also reduce cost of production.

ABSTRACT: The objective with the present study was to evaluate the effect of guanidinoacetic acid (GAA) on the growth performance of nursery piglets as well as a possible molecular mechanism of action on lean mass gain. Seventy-two pigs, weaned at 21 d, weighing 6.80 ± 1.2 kg were distributed in a completely randomized design into one of three dietary treatments (control, control + 1.2 g/kg GAA or control + 2.4 g/kg GAA) and 8 replicates per treatment. The control diet was an animal protein-free diet based on corn and soybean meal. Body weight, average daily weight gain, average daily feed intake and feed efficiency were evaluated at 35, 49, and 56 days. At the end of the experiment, one animal per pen was slaughtered and samples of the vastus lateralis muscle were collected for RT-qPCR and protein abundance analysis. Overall (from 21 to 56 d), GAA supplementation improved feed efficiency (P &lt; 0.03). Skeletal muscle of pigs fed with GAA diet had greater mRNA expression of Akt (P &lt; 0.04) and RPS6KB2 (P&lt;0.01). In conclusion, supplementation with 2.4 g/kg GAA to nursery piglets improves feed efficiency and activates molecular mechanisms important to lean mass gain.

Studies on females' decisive physical components to physical match-play performance are sparse and only emphasize endurance tests. Thus, the influence of maximal strength and power on physical performance during match-play is currently unknown. The aim of this study was to assess the association between one repetition maximum (1RM) half squat strength, 5-, 10-, and 15-m sprint times, countermovement jump (CMJ) height, and physical high-intensity match-play performance in high-level female football players. Thirty-seven female high-level football players completed 1-2 football matches with physical performance measured by local positioning tracking. Correlations were assessed between physical match-play performance variables (total distance covered, running distance, high-intensity running distance, sprinting distance as well as acceleration and deceleration counts, and peak speed) and laboratory tests (half squat 1RM, 15-m sprint, and CMJ). We found no correlation between 1RM and physical match-play performance. Further, 10-m- and 15-m sprint time (r=-0.56, r=-0.56, p<0.001) and CMJ jump height (r=0.50, p<0.01) strongly correlated with peak match speed. Further, there was a moderate correlation between 15-m sprint time and ACC (r=-0.43, p<0.05). 5-m sprint time did not correlate with physical match-play performance. Laboratory-based sprint and jump performance, but not maximal half squat strength, showed moderate to large correlations with high-intensity physical match-play performance measures in high-level female football players.

Objectives; Guanidinoacetic acid (GAA) is a natural precursor of creatine, yet the potential use of GAA as a nutritional additive for restoring creatine availability in humans has been limited by unclear efficacy and safety after exogenous GAA administration. The present study evaluated the effects of orally administered GAA on serum and urinary GAA, creatine and creatinine concentration, and on the occurrence of adverse events in healthy humans. Methods and Results; Twenty-four healthy volunteers were randomized in a double-blind design to receive either GAA (2.4 grams daily) or placebo (PLA) by oral administration for 6 weeks. Clinical trial registration: www.clinicaltrials.gov, identification number NCT01133899. Serum creatine and creatinine increased significantly from before to after administration in GAA-supplemented participants (P < 0.05). The proportion of participants who reported minor side effects was 58.3% in the GAA group and 45.5% in the placebo group (P = 0.68). A few participants experienced serum creatine levels above 70 µmol/L. Conclusion; Exogenous GAA is metabolized to creatine, resulting in a significant increase of fasting serum creatine after intervention. GAA had an acceptable side-effects profile with a low incidence of biochemical abnormalities.