Creatine Monohydrate and Guanidinoacetic Acid Supplementation Affects the Growth Performance, Meat Quality, and Creatine Metabolism of Finishing Pigs

Molecular Mechanism of ε-Polylysine Treatment of Animal-Derived Foods: Glycine Amidinotransferase Activity Implicates Upregulation of l-Arginine and Creatine

ε-Polylysine is a novel food preservative approved by the U.S. Food and Drug Administration (FDA), yet the mechanism of its effect on animal-derived foods remains unclear. Assessment of the effect of preservatives on goat meat products is necessary. Herein, metabolite accumulation and protein expression of ε-polylysine (0.025%, w/w) spiked with goat meat were investigated by nontarget metabolomics and proteomics combined with ultrahigh performance liquid chromatography quadrupole-Orbitrap high-resolution-mass spectrometry (UHPLC-Q-Orbitrap HRMS) in a simulated in vitro digestion model. The amino side chain of ε-polylysine increased the activity of glycine aminotransferase due to its nucleophilic nature, inducing a significant upregulation of l-arginine (0.43-0.72 mg kg-1) and creatine (3.98-6.89 mg kg-1), with an improvement in muscle quality of goat meat. Downregulation of enzyme phenylalanine hydroxylase expression led to upregulation of l-phenylalanine (2.26-3.25 mg kg-1) and l-tyrosine (0.98-1.29 mg kg-1). Collectively, this study first revealed the biochemical mechanism of ε-polylysine in goat meat products, which makes available new prospects for more accurate use of ε-polylysine in animal-derived foods.

Guanidinoacetic Acid Attenuates Adipogenesis through Regulation of miR-133a in Sheep

Guanidinoacetic acid (GAA) is an amino acid derivative, previously described in the skeletal muscle of vertebrates, that serves as an important regulator of cellular bioenergetics and has been widely used as a feed additive. Nevertheless, the effect of GAA on adipose tissue growth remains unclear. Here, we hypothesized that dietary GAA negatively affected adipose tissue development in lambs. Lambs were individually fed diets with (0.09%) or without GAA for 70 d ad libitum, and the subcutaneous adipose tissues were sampled for analysis. The results showed that dietary GAA supplementation decreased the girth rib (GR) value (p < 0.01) of lamb carcasses. Both real-time PCR and Western blot analysis suggested that dietary GAA inhibited the expression of adipogenic markers, including peroxisome proliferator-activated receptor γ (PPARγ, p < 0.05), CCAAT/enhancer-binding protein α (C/EBPα, p < 0.01) and sterol-regulatory-element-binding protein 1c (SREBP1C, p < 0.01) in subcutaneous adipose tissue. In vitro, GAA inhibited sheep stromal vascular fraction (SVF) cell proliferation, which was associated with downregulation of proliferating cell nuclear antigen (PCNA, p < 0.05), cyclin-dependent kinase 4 (CDK 4, p < 0.05) and cyclin D1 (p < 0.01). GAA suppressed adipogenesis of SVF cells. Furthermore, miRNA sequencing revealed that GAA affected the miRNA expression profile, and real-time PCR analysis confirmed that miR-133a expression in both subcutaneous adipose tissue and SVF cell was downregulated by GAA. Meanwhile, miR-133a promoted adipogenic differentiation of SVF cells by targeting Sirt1. miR-133a mimics alleviated the inhibitory effect of GAA on SVF cells' adipogenic differentiation. In summary, GAA attenuated adipogenesis of sheep SVF cells, which might occur through miR-133a-modulated Sirt1 expression.

Guanidine Acetic Acid Alters Tissue Bound Amino Acid Profiles and Oxidative Status in Finishing Pigs

This study aims to investigate the effects of guanidine acetic acid (GAA) on carcass traits, plasma biochemical parameters, tissue antioxidant capacity, and tissue-bound amino acid contents in finishing pigs. Seventy-two 140-day-old (body weight 86.59 ± 1.16 kg) crossbred pigs (Duroc × Landrace × Large White) were randomly assigned into four treatments with six replicate pens and three pigs per pen, which were fed the basal diets supplemented with 0, 0.05%, 0.10%, or 0.15% GAA, respectively. The plasma glucose concentration decreased, and creatine kinase activity and levels of GAA and creatine increased with the dietary GAA concentration. GAA linearly improved creatine content in the longissimus thoracis muscle (LM) and heart. The activities of superoxide dismutase, total antioxidant capacity, and glutathione peroxidase increased linearly in tissue or/and plasma, while the contents of malondialdehyde and protein carbonyl decreased linearly. GAA improved the contents of multiple-bound amino acids (such as proline or isoleucine) in the myocardium and LM. In conclusion, GAA enhanced the plasma biochemical parameters, oxidative status, and bound amino acid profiles of the heart and LM in finishing pigs.

Transcriptome, proteome and metabolome analysis provide insights on fat deposition and meat quality in pig

Intramuscular fat (IMF) content, which is an important determinant of meat quality characteristics such as tenderness, juiciness and flavor, has long been a research hotspot. Chinese local pig breeds are famous for their excellent meat quality which is mainly reflected in the high IMF content, strong hydraulic system and et al. However, there are few analysis of meat quality by omics methods. In our study, we identified 12 different fatty acids, 6 different amino acids, 1,262 differentially expression genes (DEGs), 140 differentially abundant proteins (DAPs) and 169 differentially accumulated metabolites (DAMs) (p < 0.05) with metabolome, transcriptome, and proteome. It has been found that DEGs, DAPs and DAMs were enriched in the Wnt signaling pathway, PI3K-Akt signaling pathway, Rap1 signaling pathway, and Ras signaling pathway which were related to meat quality. Moreover, our Weighted genes co-expression network construction (WGCNA) showed RapGEF1 was the key gene related to IMF content and the RT-qPCR analysis was used to perform validation of the significant genes. In summary, our study provided both fundamental data and new insights to further uncover the secret of pig IMF content.

Effects of dietary adenosine and adenosine 5′-monophosphate supplementation on carcass characteristics, meat quality, and lipid metabolism in adipose tissues of finishing pigs

This study investigated the effects of adenosine (ADO) and adenosine 5'-monophosphate (AMP) supplementation on the growth performance, carcass characteristics, meat quality, and lipid metabolism in adipose tissues of finishing pigs. The pigs were allocated to three treatment groups: the control diet, 0.2%ADO diet, or 0.2%AMP diet. Compared with CON group (CON), both ADO and AMP groups increased in carcass straight length (P < 0.05) and decreased in drip loss (P < 0.05), while AMP group tended to increase in redness value (P = 0.05) and decreased in free amino acid content in longissimus thoracis (LT) muscle (P < 0.05). Additionally, ADO or AMP supplementation increased the ADO or AMP content in serum, adipose tissue, and LT muscle (P < 0.05), as well as the protein level of adenosine 2A receptor (A2a) in adipose tissue (P < 0.05). Moreover, both ADO and AMP groups showed an increase in the expression of lipolysis genes (ATGL and HSL) in adipose tissue (P < 0.05). Overall, AMP supplementation could improve meat quality, and ADO and AMP supplementation regulate the lipid metabolism of finishing pigs.

Dietary Guanidine Acetic Acid Addition Improved Carcass Quality with Less Back-Fat Thickness and Remarkably Increased Meat Protein Deposition in Rapid-Growing Lambs Fed Different Forage Types

The aim of this study was to investigate whether guanidine acetic acid (GAA) yields a response in rapid-growing lambs depending on forage type. In this study, seventy-two small-tailed Han lambs (initial body weights = 12 ± 1.6 kg) were used in a 120-d feeding experiment after a 7-d adaptation period. A 2 × 3 factorial experimental feeding design was applied to the lambs, which were fed a total mixed ration with two forage types (OH: oaten hay; OHWS: oaten hay plus wheat silage) and three forms of additional GAA (GAA: 0 g/kg; UGAA: Uncoated GAA, 1 g/kg; CGAA: Coated GAA, 1 g/kg). The OH diet had a greater dry matter intake, average daily gain, and hot carcass weight than the OHWS diet. The GAA supplementation increased the final body weight, hot carcass weight, dressing percentage, and ribeye area in the longissimus lumborum. Meanwhile, it decreased backfat thickness and serum triglycerides. Dietary GAA decreased the acidity of the meat and elevated the water-holding capacity in mutton. In addition, the crude protein content in mutton increased with GAA addition. Dietary GAA (UGAA or CGAA) might be an effective additive in lamb fed by different forage types, as it has potential to improve growth performance and meat quality.

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.

Effect of guanidine acetic acid on meat quality, muscle amino acids, and fatty acids in Tibetan pigs

This study investigated the effects of guanidine acetic acid (GAA) supplementation on growth performance, carcass traits, and meat quality in Tibetan pigs. A total of 18 male Tibetan pigs (21.35 ± 0.99 kg) were randomly assigned to the control (basal diet) and GAA (basal diet + 800 mg/kg GAA) groups for 125 days. Growth performance, carcass traits, and meat quality in pigs, and the chemical composition of Longissimus thoracis (LT) were not altered by GAA. In LT, compared to the control group, dietary GAA increased the superoxide dismutase activity, transcripts of stearoyl CoA desaturase (SCD) and fatty acid synthase (FAS), and contents of glutamate, glutamine, C24:0, C20:3n-6, C20:4n-6, and polyunsaturated fatty acids (P < 0.05), but it decreased the malondialdehyde content (P < 0.001). In back fat, dietary GAA reduced the transcript of peroxisome proliferator-activated receptor γ (PPARγ) and the contents of C10:0, C12:0, C14:0, and C16:0 (P < 0.05), whereas it increased the contents of C22:0, C20:1, C22:1, C24:1, C20:2, C20:3n-3, and C22:2 (P < 0.05). These findings will provide a basis for high-quality Tibetan pork production.

Guanidine acetic acid exhibited greater growth performance in younger (13–30 kg) than in older (30–50 kg) lambs under high-concentrate feedlotting pattern

Guanidine acetic acid (GAA) is increasingly considered as a nutritional growth promoter in monogastric animals. Whether or not such response would exist in rapid-growing lambs is unclear yet. The objective of this study was to investigate whether dietary supplementation with uncoated GAA (UGAA) and coated GAA (CGAA) could alter growth performance, nutrient digestion, serum metabolites, and antioxidant capacity in lambs. Seventy-two small-tailed Han lambs initially weighed 12 ± 1.6 kg were randomly allocated into six groups in a 2 × 3 factorial experimental design including two forage-type rations [Oaten hay (OH) vs. its combination with wheat silage (OHWS)] and three GAA treatment per ration: no GAA, 1 g UGAA, and 1 g CGAA per kg dry matter. The whole experiment was completed in two consecutive growing stages (stage 1, 13–30 kg; stage 2, 30–50 kg). Under high-concentrate feeding pattern (Stage 1, 25: 75; Stage 2, 20: 80), UGAA or CGAA supplementation in young lambs presented greater dry matter intake (DMI) in stage 1 and average daily gain (ADG) in the whole experimental period; lambs in OH group had higher ADG and DMI than that in OHWS group in stage 1 and whole experimental period, but this phenomenon was not observed in stage 2. Both UCGA and CGAA addition increased dietary DM, organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) digestion in both stages. In blood metabolism, UCGA and CGAA addition resulted in a greater total protein (TP) and insulin-like growth factor 1(IGF-1) levels, as well as antioxidant capacity; at the same time, UCGA and CGAA addition increased GAA metabolism-creatine kinase and decreased guanidinoacetate N-methyltransferase (GAMT) and L-Arginine glycine amidine transferase catalyzes (AGAT) activity. In a brief, the results obtained in the present study suggested that GAA (UGAA and CGAA; 1 g/kg DM) could be applied to improve growth performance in younger (13–30 kg) instead of older (30–50 kg) lambs in high-concentrate feedlotting practice.

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.

Effects of Rumen-Protected Creatine Pyruvate on Meat Quality, Hepatic Gluconeogenesis, and Muscle Energy Metabolism of Long-Distance Transported Beef Cattle

Pre-slaughter long-distance transport resulted in a rapid depletion of muscle glycogen and led to a higher rate of dark, firm and dry (DFD) meat. Therefore, enhancing muscle glycogen reserves is critical for beef cattle prior to transportation. Creatine pyruvate (CrPyr) can provide simultaneous pyruvate and creatine and both are proven to promote the glycogen reserves. This study aimed to investigate the effects of transport treatment and dietary supplementation of rumen-protected (RP)-CrPyr on the meat quality, muscle energy metabolism, and hepatic gluconeogenesis of beef cattle. Twenty 18 month-old male Simmental crossbred cattle (659 ± 16 kg) were allotted 4 treatments based on a 2 × 2 factorial arrangement with two RP-CrPyr levels (140 g/d or 0 g/d) and two transport treatments (12 h or 5 min): ST_CrPyr0, ST_CrPyr140, LT_CrPyr0 and LT_CrPyr140. Three cattle per group were slaughtered after 30 days of feeding. The interaction of transport and RP-CrPyr had a significant effect on the muscle pH45 min, redness, glycogen content, GP, and AMP level (P &lt; 0.05). Compared with short-distance transport, long-distance transport increased the muscle pH45 min value, redness, yellowness, drip loss, creatine level (P &lt; 0.05), decreased muscle glycogen content, glycolytic potential (GP), and liver glucose amount (P &lt; 0.05). Supplementation of RP-CrPyr decreased the activities of creatine kinase and lactate dehydrogenase in serum, muscle pH24 h value, redness, yellowness, lactate content, AMP level, and AMP/ATP (P &lt; 0.05), increased the muscle glycogen content, GP, hexokinase activity, ATP and ADP levels, and ATP/ADP, liver pyruvate and glucose contents, activity of pyruvate carboxylase in the liver of cattle than those in the nonsupplemented treatments (P &lt; 0.05). These results indicated that dietary RP-CrPyr supplementation might be favorable to improve meat quality and regulatory capacity of energy metabolism of beef cattle suffering long-distance transport followed with recovery treatment by increasing muscle glycogen storage, energy supply, and hepatic gluconeogenesis.

Guanidine acetic acid supplementation altered plasma and tissue free amino acid profiles in finishing pigs

Background

As a nutritive feed additive, guanidine acetic acid (GAA) participates in the metabolism of energy and proteins. This study aimed to investigate the effects of GAA on growth performance, organ index, plasma and tissue free amino acid profiles, and related metabolites in finishing pigs. A total of 72 crossbred pigs (body weight 86.59 ± 1.16 kg) were randomly assigned to 1 of 4 dietary treatments (GAA0, GAA500, GAA1000, and GAA1500). They were fed the basal diets supplemented with 0, 500, 1000, or 1500 mg/kg GAA for 42 days, respectively. The growth performance and organ weight were evaluated, and the contents of crude protein, free amino acids, and metabolites in plasma and tissues were determined. Spearman correlation between plasma and tissue free amino acids and related metabolites was also analyzed.

Results

Growth performance in pigs was not altered by GAA (P > 0.05). The absolute and relative weight of kidneys increased (quadratic, P < 0.05). As dietary GAA concentration was increased, the contents of plasma glycine, serine, leucine, ornithine, and ratio of ornithine/arginine decreased (linear or quadratic, P < 0.05), but the contents of plasma isoleucine and taurine and the ratios of alanine/branched-chain amino acids and proline/ornithine increased quadratically (P < 0.05). The hepatic γ-amino-n-butyric acid content increased linearly and quadratically (P < 0.001), while the carnosine content decreased (quadratic, P = 0.004). The contents of renal arginine, proline, cystine, glutamate, and total amino acids (TAA) decreased quadratically (P < 0.05), but the contents of glycine (quadratic, P = 0.015) and γ-amino-n-butyric acid (linear, P = 0.008) increased. The pancreatic tryptophan content (quadratic, P = 0.024) increased, while the contents of pancreatic proline (linear, P = 0.005) and hydroxyproline (quadratic, P = 0.032) decreased in response to GAA supplementation. The contents of cardiac essential amino acids (EAA), nonessential amino acids (NEAA), and TAA in GAA1000 were higher than those in GAA1500 (P < 0.05). Supplementing with GAA linearly increased the contents of methionine, threonine, valine, isoleucine, leucine, phenylalanine, tryptophan, lysine, histidine, arginine, serine, alanine, glutamine, asparagine, tyrosine, proline, taurine, cystathionine, α-aminoadipic acid, β-aminoisobutyric acid, EAA, NEAA, and TAA in the spleen (P < 0.05). A strong Spearman correlation existed between plasma and tissue free amino acids and related metabolites.

Conclusion

GAA supplementation did not altered pig growth performance, but it altered plasma and tissue free amino acid profiles and the contents of related metabolites in pigs in a tissue-dependent manner.

Relationship between indirect genetic effects for growth, environmental enrichment, coping style and sex with the serum metabolome profile of pigs

Including Indirect Genetic Effects (IGE) in breeding programs to reduce aggression in group housed animals has been proposed. However, the effect of selection for IGE for growth on animal metabolism and physiology is unknown. The purpose of this study was twofold: (1) To investigate the effects of this new breeding method along with two housing (barren and straw), coping style (high and low resisters) and sex (female and castrated males) options on the metabolome profile of pigs. (2) To identify and map biological processes associated with a regrouping test at 9 weeks of age. We used Nuclear Magnetic Resonance to quantify 49 serum metabolites at week 8, 9 and 22. Also, we quantified 3 catecholamines (tyramine, epinephrine, phenylethylamine) and serotonin and three water soluble vitamins (B2, B5 and B7). Overall, no significant differences were observed between negative and positive IGE animals. The magnitude of change (delta) of many metabolites as a response to the regrouping test was significantly affected by IGE, especially that of the amino acids (P < 0.05), being greater in positive IGE pigs. The regrouping test was associated with alteration in glycine, serine and threonine metabolism. In conclusion positive and negative IGE animals respond differently to the regrouping test.

Regulative Mechanism of Guanidinoacetic Acid on Skeletal Muscle Development and Its Application Prospects in Animal Husbandry: A Review

Guanidinoacetic acid is the direct precursor of creatine and its phosphorylated derivative phosphocreatine in the body. It is a safe nutritional supplement that can be used to promote muscle growth and development. Improving the growth performance of livestock and poultry and meat quality is the eternal goal of the animal husbandry, and it is also the common demand of today's society and consumers. A large number of experimental studies have shown that guanidinoacetic acid could improve the growth performance of animals, promote muscle development and improve the health of animals. However, the mechanism of how it affects muscle development needs to be further elucidated. This article discusses the physical and chemical properties of guanidinoacetic acid and its synthesis pathway, explores its mechanism of how it promotes muscle development and growth, and also classifies and summarizes the impact of its application in animal husbandry, providing a scientific basis for this application. In addition, this article also proposes future directions for the development of this substance.

Effects of guanidinoacetic acid and complex antioxidant supplementation on growth performance, meat quality, and antioxidant function of broiler chickens

BACKGROUND

This study was conducted to evaluate the effects of adding guanidinoacetic acid (GAA), or complex antioxidant (CA), or their combination, in diets on the growth performance, carcass traits, meat quality, and antioxidant capacity of broilers. A total of 192 25-day-old broilers were assigned to a 2 × 2 factorial design including two dietary supplements at two different levels, in which the main effects were the addition of GAA (0 or 600 mg kg^-1 ) and CA (0 or 150 mg kg^-1 ). This trial lasted for 18 days.

RESULTS

Compared with the control group, the GAA group, CA group, and GAA + CA group, decreased feed conversion ratio by 7.02%, 6.58%, and 11.40%, respectively. Guanidinoacetic supplementation increased eviscerated yield, pH_24h (P < 0.05). Complex antioxidant supplementation increased the a* values (P < 0.05). The combination of GAA and CA did not affect the carcass traits and meat quality. Guanidinoacetic acid alone and CA alone and combined with GAA and CA decreased the reactive oxygen species (ROS) level and malonaldehyde (MDA) content (P < 0.05), and the GAA + CA group had the lowest ROS level and MDA content of broilers.

CONCLUSION

Dietary supplementation of GAA, CA or their combination had beneficial effects on growth performance and breast antioxidant capacity, and the combination of GAA and CA could exert a synergistic effect in improving antioxidant capacity. © 2020 Society of Chemical Industry.

Mass spectrometry-based metabolomics to reveal chicken meat improvements by medium-chain monoglycerides supplementation: Taste, fresh meat quality, and composition

This study was conducted to reveal the differences of chicken fresh meat quality, composition and taste induced by medium-chain monoglycerides (MG) supplementation. Results demonstrated that both chicken broth and meat taste were improved by MG supplementation. The up-regulated l-carnosine, sarcosine, uridine and nicotinamide in the chicken broth of the MG group contributed to the umami and meaty taste. Dietary MG increased the total superoxide dismutase activity and amino acid content in the muscle of chicken breast and reduced the malondialdehyde content and drip loss. Moreover, meat metabolome revealed that creatine, betaine, l-anserine, inosine 5'-monophosphate, hypoxanthine, inosine and phospholipid, as well as amino acid and purine metabolism pathway connected to the improvements of meat quality, composition and taste of broilers by MG addition. In conclusion, these findings provide convincing evidence regarding the improvements of fresh meat quality, composition and taste of broilers by MG supplementation.

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 ± 2.94 kg) 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 450 mg/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.

Effects of guanidinoacetic acid supplementation on growth performance, nutrient digestion, rumen fermentation and blood metabolites in Angus bulls

Guanidinoacetic acid (GAA) can improve the growth performance of bulls. This study investigated the influences of GAA addition on growth, nutrient digestion, ruminal fermentation and serum metabolites in bulls. Forty-eight Angus bulls were randomly allocated to experimental treatments, that is, control, low-GAA (LGAA), medium-GAA (MGAA) and high-GAA (HGAA), with GAA supplementation at 0, 0.3, 0.6 and 0.9 g/kg DM, respectively. Bulls were fed a basal diet containing 500 g/kg DM concentrate and 500 g/kg DM roughage. The experimental period was 104 days, with 14 days for adaptation and 90 days for data collection. Bulls in the MGAA and HGAA groups had higher DM intake and average daily gain than bulls in the LGAA and control groups. The feed conversion ratio was lowest in MGAA and highest in the control. Bulls receiving 0.9 g/kg DM GAA addition had higher digestibility of DM, organic matter, NDF and ADF than bulls in other groups. The digestibility of CP was higher for HGAA than for LGAA and control. The ruminal pH was lower for MGAA, and the total volatile fatty acid concentration was greater for MGAA and HGAA than for the control. The acetate proportion and acetate-to-propionate ratio were lower for MGAA than for LGAA and control. The propionate proportion was higher for MGAA than for control. Bulls receiving GAA addition showed decreased ruminal ammonia N. Bulls in MGAA and HGAA had higher cellobiase, pectinase and protease activities and Butyrivibrio fibrisolvens, Prevotella ruminicola and Ruminobacter amylophilus populations than bulls in LGAA and control. However, the total protozoan population was lower for MGAA and HGAA than for LGAA and control. The total bacterial and Ruminococcus flavefaciens populations increased with GAA addition. The blood level of creatine was higher for HGAA, and the activity of l-arginine glycine amidine transferase was lower for MGAA and HGAA, than for control. The blood activity of guanidine acetate N-methyltransferase and the level of folate decreased in the GAA addition groups. The results indicated that dietary addition of 0.6 or 0.9 g/kg DM GAA improved growth performance, nutrient digestion and ruminal fermentation in bulls.

From broiler breeder hen feed to the egg and embryo: The molecular effects of guanidinoacetate supplementation on creatine transport and synthesis

Supplementation of broiler breeder hens with beneficial additives bears great potential for affecting nutrient deposition into the fertile egg. Guanidinoacetate (GAA) is the endogenous precursor of creatine that is used as a feed additive for improving cellular energy metabolism in animal nutrition. In the present study, we have investigated whether GAA supplementation in broiler breeder feed affects creatine deposition into the hatching egg and molecular mechanisms of creatine transport and synthesis within hens and their progeny. For this, broiler breeder hens of 47 wk of age were supplemented with 0.15% GAA for 15 wk, and samples from their tissues, hatching eggs and progeny were compared with those of control, nonsupplemented hens. A significant increase in creatine content was found within the yolk and albumen of hatching eggs obtained from the GAA group, compared with the control group. The GAA group exhibited a significant increased creatine transporter gene expression compared with the control group in their small intestines and oviduct. In GAA group progeny, a significant decrease in creatine transporter expression at embryonic day 19 and day of hatch was found, compared with control group progeny. At the day of hatch, creatine synthesis genes (arginine glycine amidinotransferase and guanidinoacetate N-methyltransferase) exhibited significant decrease in expression in the GAA group progeny compared with control group progeny. These results indicate that GAA supplementation in broiler breeder feed increases its absorbance and deposition into hatching eggs, subsequently affecting GAA and creatine absorbance and synthesis within broiler progeny.

Dietary guanidinoacetic acid improves the growth performance and skeletal muscle development of finishing pigs through changing myogenic gene expression and myofibre characteristics

This study aimed to evaluate the effects of dietary guanidine acetic acid (GAA) supplementation on growth performance, carcass traits and the expression of muscle growth-related genes in finishing pigs. A total of 128 (81.03 ± 1.09 kg body weight) crossbred pigs (Duroc × Landrace ×Yorkshire) were blocked by body weight and allotted to 16 pens (eight pigs per pen), and pens were randomly assigned within blocks to one of five dietary treatments, with a basal diet (control group) or a basal diet supplemented with 0.03%, 0.06% and 0.09% GAA respectively. During the 60-day trial, GAA increased the average dairy gain (ADG) and average daily feed intake (ADFI) (p < .05). The back fat thickness of pigs fed 0.06% GAA was lower than other groups (p < .05). Pigs fed 0.06% GAA had improved lean meat percentage, loin muscle area, shear force and cross-sectional area of muscle fibre in comparison with control group (p < .05). The drop loss and the muscle fibre density in pigs fed 0.06% GAA were lower than control (p < .05). In addition, dietary GAA enhanced the expression of myosin heavy chain gene (MYH4), myogenic determination (Myod) and myogenic factor 5 (Myf5) in longissimus dorsi and carnitine palmitoyltransferase-1(CPT-1) in liver (p < .05). Meanwhile, GAA decreased the expression of Myostatin in longissimus dorsi and fatty acid synthase (FAS) in liver (p < .05). In conclusion, our results showed that appropriate dietary GAA supplementation (0.06%) promotes skeletal muscle development through changing myogenic gene expression and myofibre characteristics.

1H NMR-based metabolomics study of breast meat from Pekin and Linwu duck of different ages and relation to meat quality

This study investigated the effects of breed and age on meat quality, and metabolite profiles of duck breast meat, and the relationship between changes in metabolite profiles and the meat quality. The meat quality and ¹H nuclear magnetic resonance (NMR)-based metabolomics of breast meat from Pekin and Linwu ducks at 2 different ages (42 and 72d) was analyzed. The results showed that age exerted a greater effect on the observed meat quality traits of breast meat than breed, and its interaction (breed × age) effect on pH values and yellowness (b*) of duck breast meat was significant. Total of 32 metabolites were detected in breast meat of Pekin and Linwu duck. The difference of metabolite profiles in breast meat between Pekin and Linwu duck at 72 d was greater than that at 42 d, while the effects of age on metabolites of duck meat from both breeds were similar. Anserine, aspartate, and carnosine were the most relevant metabolites of duck breast meat quality, and nicotinamide in duck breast meat was negatively correlated with cooking loss. These results provide an overall perspective for bridging the gap between the breed and age on duck meat quality and metabolome, and improve the understanding of the relationship between metabolites and duck meat quality.

Dietary supplementation of guanidinoacetic acid improves growth, biochemical parameters, antioxidant capacity and cytokine responses in Nile tilapia (Oreochromis niloticus)

A total of 180 unsexed Nile Tilapia fish (initial weight, 21 g) fed isonitrogenous (32%), isocaloric (3000 kcal/kg) diets containing different levels of guanidinoacetic acid (GAA) at levels of (GAA1, 0.06%, GAA2, 0.12%, GAA3, 0.18%); for 60 days. Results showed higher final body weight (FBW) and body weight gain (BWG) in groups supplemented with different levels of GAA. Specific growth rate (SGR) was the highest in groups supplemented with 0.12% and 0.18% GAA. Lipid % of whole-body composition was higher in all groups excluding GAA3 group. Serum creatine kinase (CK) activity, cholesterol, and creatinine levels showed a marked significant (P < 0.05) increase in all GAA supplemented groups compared to the control one. Triglycerides level demonstrated a higher elevation (P < 0.05) in both GAA2 and GAA3 supplemented groups. No significant observed in total protein, albumin, globulin, and A/G ratio. Lipid peroxidation marker (malondialdehyde/MDA) is markedly decreased along with a significant increase of superoxide dismutase (SOD), reduced glutathione (GSH), and nitric oxide (NO) levels in both GAA2 and GAA3 compared to other groups. Similarly, interleukin 1β (IL-1β) and tumor necrosis factor (TNF-α) gene expression levels were downregulated along with upregulation of transforming growth factor β1 (TGF-β1) at higher GAA levels, particularly at 0.18%. Our findings give important insights for the growth promoting, antioxidant and immunomodulatory effects of GAA supplemented diet particularly at level of 0.18%.