Co-dependence of genotype and dietary protein intake to affect expression on amino acid/peptide transporters in porcine skeletal muscle

Different effects of dietary β-hydroxy-β-methylbutyrate on composition of fatty acid and free amino acid, and fatty metabolism in the different muscles of broilers

In the study, 336 broiler chickens were selected to explore dietary effects of different β-hydroxy-β-methylbutyrate (HMB) levels (0 (control), 0.05, 0.10, and 0.15%) on the compositions of fatty acids and free amino acids, and lipid metabolism in the different muscles of broilers. In the breast muscle, dietary HMB supplementation hardly affected the free amino acid composition (P > 0.05). Compared to the control group, dietary 0.10 and 0.15% HMB supplementation decreased the content of C18:1n9c and thus the monounsaturated fatty acid (MUFA), and dietary 0.15% HMB supplementation increased the sum of saturated fatty acids (SFA) (P < 0.05). Moreover, compared to the control group, dietary 0.05 and 0.10% HMB increased the mRNA expression of proliferator activated receptor-γ and the activity of fatty acid synthase (FAS), and dietary 0.10% HMB increased the acetyl-CoA carboxylase activity (P < 0.05). In the leg muscle, dietary 0.10 and 0.15% HMB increased the MUFA content and decreased the polyunsaturated fatty acid (PUFA) content, the PUFA to SFA ratio, the mRNA expression of sterol regulatory element binding proteins-1c, and the activities of acyl-CoA oxidase 1 and acetyl-CoA synthetase (P < 0.05). Moreover, dietary 0.10% HMB decreased the activities of hydroxy-3-methylglutaryl-CoA synthase 1 and FAS in comparison to the control group (P < 0.05). Dietary 0.05% HMB decreased the contents of essential amino acids and nonessential amino acids (NEAA), and dietary 0.15% HMB decreased the NEAA content (P < 0.05). In summary, dietary 0.10% HMB supplementation had superior efficiency on lipogenesis in the breast muscle of broilers. However, dietary HMB supplementation, especially at the level of 0.05 and 0.15%, decreased meat nutritional values and the lipogenesis in leg muscles.

Mulberry leaf extract reduces abdominal fat deposition via adenosine-activated protein kinase/sterol regulatory element binding protein-1c/acetyl-CoA carboxylase signaling pathway in female Arbor Acre broilers

This experiment was carried out to investigate the mechanism of action of mulberry leaf extract (MLE) in reducing abdominal fat accumulation in female broilers. A total of 192 one-day-old female Arbor Acres (AA) broilers were divided into 4 diet groups, with each group consisting of 8 replicates with 6 birds per replicate. The diets contained a basal diet and 3 test diets with supplementation of 400, 800, or 1,200 MLE mg/kg, respectively. The trial had 2 phases that lasted from 1 to 21 d and from 22 to 56 d, respectively. The growth performance, abdominal fat deposition, fatty acid composition, serum biochemistry and mRNA expression of genes related to fat metabolism in liver were determined. The results showed that, 1) dietary supplementation with MLE had no significant impact on broilers final body weight, average daily gain (ADG), or feed to gain ration (F/G) (P > 0.05), but linearly reduced abdominal fat accumulation in both experimental phases (P < 0.05); 2) the total contents of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), such as palmitoleic acid, oleic acid, and eicosadienoic acid, were increased quadratically as a result of dietary supplements of 400, 800, and 1,200 mg/kg MLE (P < 0.01), while the total contents of saturated fatty acids (SFA), such as teracosanoic acid were decreased (P < 0.01); 3) the addition of 800 or 1,200 MLE mg/kg to the diet linearly reduced total cholesterol (TC) in the serum and liver (P < 0.05). Adenosine-activated protein kinase (AMPK) mRNA expression in the liver was quadratically increased by the addition of 800 or 1,200 MLE mg/kg to the diet (P < 0.05), and the mRNA expression of sterol regulatory element binding protein-1c (SREBP-1c), acetyl-CoA carboxylase (ACC), and acetyl-CoA carboxylate), fatty acid synthase (FAS) were linearly decreased (P < 0.05). In conclusion, MLE can be employed as a viable fat loss feed supplement in fast-growing broiler diets since it reduces abdominal fat deposition in female AA broilers via the AMPK/SREBP-1c/ACC signaling pathway. MLE can also be utilized to modify the fatty acid profile in female broilers (AA) at varied inclusion levels.

Maternal pyrimidine nucleoside supplementation regulates fatty acid, amino acid and glucose metabolism of offspring

Pyrimidine nucleosides (PN) are abundant in mammalian milk and mainly involved in glycogen deposition and lipid metabolism. To investigate the effects of maternal supplementation with pyrimidine nucleoside on glucose, fatty acids (FAs), and amino acids (AAs) metabolism in neonatal piglets. Forty pregnant sows were randomly assigned into the control (CON) group (fed a basal diet, n = 20) or the PN group (fed a basal diet supplemented with PN at 150 g/t, n = 20). Litter size, born alive and birth litter weight were recorded. The serum and placenta of sows, and jejunum and liver of neonatal piglets were sampled. The results indicated that supplementing sow diets with PN decreased birth mortality and increased the birth weight of piglets (P < 0.05). In addition, neonates from sows supplemented with PN had higher glucose levels in serum and liver compared with the CON group (P < 0.05). Moreover, maternal PN supplementation regulated the ratio of saturated FAs and polyunsaturated FAs, and AAs content in serum and liver of piglets (P < 0.05). Furthermore, an up-regulation of mRNA expression of genes related to glucose and AA transport were observed in the neonatal jejunum from the PN group (P < 0.05). Additionally, hepatic protein expressions of phosphorylated hormone-sensitive lipase (P-HSL), HSL, sterol regulatory element-binding transcription factor 1c (SREBP-1c), and phosphorylated protein kinase B (P-AKT) was higher in the piglets from the PN group than the CON group (P < 0.05). Together, maternal PN supplementation may regulate nutrient metabolism of neonatal piglets by modulating the gene expression of glucose and AA transporters in placenta and jejunum, and the gene and protein expression of key enzymes related to lipid metabolism in liver of neonatal piglets, which may improve the reproductive performance of sows.

Improvement of hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) by enzyme-digested poultry by-product: Growth performance, amino acid and peptide transport capacity, and intestinal morphology

Background

At present, fish meal (FM) resources are in short supply, and competition for food between humans and animals is becoming increasingly critical. Finding non-grain protein sources that can replace FM is the key to solving the rapid development of aquaculture.

Methods

Seven trial diets were prepared with 0 g/kg (EP0), 30 g/kg (EP3), 60 g/kg (EP6), 90 g/kg (EP9), 120 g/kg (EP12), 150 g/kg (EP15), and 180 g/kg (EP18) of enzyme-digested poultry by-product meal (EPBM) by replacing of FM. A total of 630 hybrid groupers (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) were equally portioned into 21 tanks. At 8:00 and 16:00 each day, groupers were fed until they were full for a cumulative period of 8 weeks.

Results

The results showed that 30 g/kg of EPBM significantly increased the rates of weight gain and special growth (P < 0.05). Significantly higher activities of serum glutamic pyruvic transaminase, glutamic oxaloacetic transaminase, catalase, and superoxide dismutase were observed in the EP3 group (P < 0.05). The categories and numbers of the top 10 dominant bacteria in the phylum and genus levels were not significantly influenced by feed (P > 0.05). In the proximal intestine and distal intestine, there were significantly higher expressions of SNAT3, LAAT1, CAT2, and CAT1 in the EP3 group compared with the EP0 group (P < 0.05). In the EP3 group, the expressions of PepT1, LAAT1, B0, +AT, and CAT2 were significantly increased in MI than those in all other groups (except the EP0 group, P < 0.05).

Conclusion

When FM was replaced by 30 g/kg of EPBM, growth performance, antioxidant capacity, and the ability to transport amino acids and peptides of hybrid grouper were significantly improved.

Nuclear Magnetic Resonance-Based Metabolomic Analysis Reveals Physiological Stage, Breed, and Diet Effects on the Intramuscular Metabolism of Amino Acids and Related Nutrients in Pigs

Skeletal muscle is a complex tissue that exhibits considerable plasticity in response to nutrients, animal, or its growth stage, but the underlying mechanisms are largely unknown. This study was conducted to evaluate the effects of physiological stage, breed, and diet on the metabolome of the skeletal muscle of pigs. Ninety-six barrows, including 48 purebred Bama mini-pigs, representing the fat type, and 48 Landrace pigs, representing the lean type, were randomly assigned to either a low- or adequate-protein diet (n = 24 per group). The experimental period commenced at 5 weeks of age and extended to the finishing period. Psoas major muscles (PMMs) were collected at the nursery, growing, and finishing stages; and the contents of amino acids (AAs), fatty acids (FAs), and metabolites were analyzed using a nuclear magnetic resonance-based approach. Results showed that most AAs and monounsaturated FAs (MUFAs; including C16:1 and C18:1) contents were increased (p < 0.05) gradually, while those of polyunsaturated FAs (including C18:2, C20:4n−6, C20:5n−3, and C22:6n−3) were decreased (p < 0.05) in the PMM with increasing age. Compared with Landrace pigs, Bama mini-pigs had higher (p < 0.05) contents of flavor-related AAs (including methionine, phenylalanine, tyrosine, leucine, and serine) in the nursery and growing stages and higher (p < 0.05) percentages of saturated FAs and MUFAs throughout the trial. Dietary protein levels affected the muscular profiles of AAs and FAs in an age-dependent manner. In addition, the adequate-protein diet increased (p < 0.05) the muscular contents of α-ketoglutarate in the two breeds. These findings indicate that the dynamic profiles of AAs, FAs, and metabolites in pig muscle tissues are regulated by breed, diet, and physiological stage.

Maternal yeast-based nucleotide supplementation decreased stillbirth by regulating nutrient metabolism

BACKGROUND

As an enzymatic product of yeast, yeast-based nucleotide (YN) is rich in nucleotides. To test the effects of maternal dietary supplementation with YN during late pregnancy on placental nutrient transport and nutrient metabolism in neonatal piglets, 64 pregnant sows (day 85 ± 3) were assigned into two groups: (i) control (CON) and (ii) treatment (YN; 4 g kg^-1 ). Blood, placenta and liver samples of neonates during delivery were collected.

RESULTS

The results showed that maternal YN supplementation decreased stillbirth rate and intra-uterine growth restriction rate (P < 0.05). In addition, maternal YN supplementation increased total serum protein, albumin and total cholesterol (P < 0.05). Furthermore, in neonatal piglets in the YN group, both serum amino acidand nucleotide profiles were affected, as well as liver amino acid, and fatty acid profiles were regulated (P < 0.05). Moreover, maternal YN supplementation increased liver mRNA expression of SLC28A3, SLC29A1, SLC29A2, PC, PCK1, FBP1, SREBP1c, HSL and CYP7a1 of neonatal piglets (P < 0.05). Meanwhile, there was a decrease in placental gene expression of EAAT2, EAAT3, LAT1 and PAT1, as well as lower protein expression of peroxisome proliferator-activated receptor (PPAR)γ, AKT, phosphorylated-AKT, phosphorylated-mammalian target of rapamycin (mTOR) and Raptor, in the YN group (P < 0.05).

CONCLUSION

Taken together, these results indicate that maternal YN supplementation regulates placental nutrient transport by regulating the mTOR complex 1-PPAR pathway, and affects the liver metabolism of nucleotides, amino acids and fatty acids in neonatal piglets, thereby improving the reproductive performance of sow to a certain extent. © 2020 Society of Chemical Industry.

Alterations of the Muscular Fatty Acid Composition and Serum Metabolome in Bama Xiang Mini-Pigs Exposed to Dietary Beta-Hydroxy Beta-Methyl Butyrate

Simple Summary

Pork is the most consumed meat source for humans, and the utilization of nutritional approaches to produce pork with an appropriate content of intramuscular fat (IMF) and a balanced ratio of different kinds of fatty acid is an important objective pursuit of swine production. We speculated that dietary supplementation of beta-hydroxy beta-methyl butyrate (HMB) may provide benefits in lipid metabolism of skeletal muscle. In this study, we try to investigate the effects of dietary HMB supplementation on muscular lipid metabolism in Bama Xiang mini-pigs. We found that HMB supplementation could decrease the IMF content and increase n3 polyunsaturated fatty acids as well as regulate the related metabolites (N-Methyl-l-glutamate and nummularine A) in the serum of Bama Xiang mini-pigs, thus improving their meat quality.

Abstract

This study aimed to investigate the effects of dietary beta-hydroxy beta-methyl butyrate (HMB) supplementation on muscular lipid metabolism in Bama Xiang mini-pigs. Thirty-two piglets (8.58 ± 0.40 kg, barrow) were selected and fed a basal diet supplemented either with 0 (control), 0.13%, 0.64%, or 1.28% HMB for 60 days. Throughout the experiments, they had free access to clean drinking water and diets. Data of this study were analyzed by one-way ANOVA using the SAS 8.2 software package, followed by a Tukey’s studentized range test to explore treatment effects. The results showed that compared to the control, 0.13% HMB decreased the intramuscular fat (IMF) content and increased polyunsaturated fatty acids (PUFAs) in Longissimus thoracis muscle (LTM), and increased the n3 PUFAs in soleus muscles (SM, p < 0.05). Moreover, HMB supplementation led to alterations in the mRNA expression of genes related to lipid metabolism. Serum metabolome profiling showed that in both LTM and SM of Bama Xiang mini-pigs, N-Methyl-l-glutamate was positively correlated with SFA and nummularine A was negatively correlated with C18:3n3 PUFA (p < 0.05). Therefore, N-Methyl-l-glutamate and nummularine A might be potential biomarkers of the HMB-supplemented group. These results suggested that dietary HMB supplementation could decrease the IMF content and increase n3 PUFAs as well as regulate the related metabolites (N-Methyl-l-glutamate and nummularine A) in the serum of pigs.

Dietary supplementation with betaine or glycine improves the carcass trait, meat quality and lipid metabolism of finishing mini-pigs

The objective of the study is to evaluate and compare the effects of betaine or glycine on carcass trait, meat quality and lipid metabolism of finishing Huan Jiang mini-pigs. Betaine called trimethylglycine is a methyl derivative of glycine, but few researches were conducted to compare the impact of dietary betaine and glycine on pigs. One hundred and forty-four Huan Jiang mini-pigs (body weight = 10.55 ± 0.15 kg; 70 d) were randomly divided to 3 treatment groups (basal diet, glycine or betaine). Results indicated that dietary betaine increased the average daily gain (ADG) and final weight (P < 0.05). Dietary glycine or betaine markedly reduced average backfat thickness (P < 0.05) and heightened lean percentage (P < 0.01) compared to the control group. Moreover, in comparison with the control group, betaine significantly improved the redness (a∗) and tenderness (shear force) of the longissimus dorsi (LD) muscle (P < 0.05), whereas glycine only raised the value of a∗ of the LD muscle (P < 0.05). These results showed that diet supplemented with 0.25% betaine and equimolar amounts of glycine could regulate cascass trait and meat quality of finishing Huan Jiang mini-pigs, and the effect of betaine was superior to that of glycine.

Mulberry leaf powder regulates antioxidative capacity and lipid metabolism in finishing pigs

This study evaluated the potential of mulberry leaf powder as an unconventional feed material for finishing pigs by assessing the growth performance, antioxidative properties, fatty acid profile, and lipid metabolism in 180 Xiangcun black pigs. Pigs with an initial body weight (BW) of 71.64 ± 1.46 kg were randomly assigned to 5 treatment groups, including the control diet and 4 experimental diets. The corn, soybean meal, and wheat bran in the control diet were partly replaced by 3%, 6%, 9%, or 12% mulberry leaf powder in experimental diets. There were 6 replicates (pens) of 6 pigs per replicate in each treatment. Blood and muscle samples were collected after the 50-day feed experiment. Compared with the control group, the 3%, 6%, and 9% mulberry diets had no adverse effect (P > 0.05) on the growth performance of pigs. The serum glutathione peroxidase activity and glutathione concentration increased linearly (P < 0.05) with the increase in dietary mulberry inclusion. There was no significant difference in the relative expression levels of antioxidant-related genes in muscle tissue between the control and mulberry groups. Inclusion of dietary mulberry powder increased (P < 0.05) the content of polyunsaturated fatty acids, especially in the longissimus dorsi (LD) muscle, up-regulated (P < 0.05) the relative mRNA expression level of uncoupling protein-3 in muscle tissue, but down-regulated (P < 0.05) the relative mRNA expression levels of hormone-sensitive lipase, acetyl CoA carboxylase α, lipoprotein lipase, and peroxisome proliferator-activated receptor γ in LD in a linear pattern. The nuclear respiratory factor 2 expression level in the LD muscle of pigs fed the 9% mulberry diet was higher (P < 0.01) than that in the other mulberry groups and control group. The inclusion of less than 12% dietary mulberry did not detrimentally affect the growth performance of Xiangcun black pigs, but enhanced the serum antioxidant property, increased the polyunsaturated fatty acid content, and inhibited lipid oxidation by regulating gene expression levels of lipid metabolism and mitochondrial uncoupling protein in muscle tissue. Mulberry leaves can be utilized as a forage crop in the diet of finishing pigs.

A selectively suppressing amino acid transporter: Sodium-coupled neutral amino acid transporter 2 inhibits cell growth and mammalian target of rapamycin complex 1 pathway in skeletal muscle cells

Sodium-coupled neutral amino acid transporter 2 (SNAT2), also known as solute carrier family 38 member 2 (SLC38A2), is expressed in the skeletal muscle. Our research previously indicated that SNAT2 mRNA expression level in the skeletal muscle was modulated by genotype and dietary protein. The aim of this study was to investigate the key role of the amino acid transporter SNAT2 in muscle cell growth, differentiation, and related signaling pathways via SNAT2 suppression using the inhibitor α-methylaminoisobutyric acid (MeAIB). The results showed that SNAT2 suppression down-regulated both the mRNA and protein expression levels of SNAT2 in C2C12 cells, inhibited cell viability and differentiation of the cell, and regulated the cell distribution in G0/G1 and S phases (P < 0.05). Meanwhile, most of the intercellular amino acid content of the cells after MeAIB co-culturing was significantly lower (P < 0.05). Furthermore, the mRNA expression levels of system L amino acid transporter 1 (LAT1), silent information regulator 1, and peroxisome proliferator-activated receptor-gamma co-activator 1 alpha, as well as the protein expression levels of amino acid transporters LAT1 and vacuolar protein sorting 34, were all down-regulated. The phosphorylated protein expression levels of mammalian target of rapamycin (mTOR), regulatory-associated protein of mTOR, 4E binding protein 1, and ribosomal protein S6 kinase 1 after MeAIB treatment were also significantly down-regulated (P < 0.05), which could contribute to the importance of SNAT2 in amino acid transportation and skeletal muscle cell sensing. In conclusion, SNAT2 suppression inhibited C2C12 cell growth and differentiation, as well as the availability of free amino acids. Although the mTOR complex 1 signaling pathway was found to be involved, its response to different nutrients requires further study.

Dietary mulberry leaf powder affects growth performance, carcass traits and meat quality in finishing pigs

This study was conducted to evaluate the effect of mulberry leaves as an alternative source of protein on growth performance, carcass traits and meat quality in finishing pigs. A total of 180 Xiangcun Black pigs were randomly assigned to five treatment groups with six pens of six pigs per pen. The pigs were provided with a basal diet or a diet contained 3%, 6%, 9% or 12% of mulberry leaf powder during a 50-day experiment period. The results showed that dietary mulberry leaf powder had no negative effect on growth performance in Xiangcun Black pigs, except in the 12% mulberry group, where final body weight and average daily gain decreased (p < .05) and feed to gain ratio of the pigs increased (p < .05). Dietary mulberry inclusion decreased (quadratic, p < .05) the back fat thickness, fibre mean cross-sectional area (CSA) in the longissimus dorsi (LD) muscle and mRNA expression levels of myosin heavy chain (MyHC) IIb in LD and biceps femoris (BF) muscles, while increased (linear or quadratic, p < .05) the plasma concentration of albumin, levels of crude protein (CP), inosine monophosphate (IMP) and several amino acids in muscle tissues. When compared with the other groups, the 9% mulberry diet increased (p < .05) loin-eye area and contents of CP and IMP in muscles, while decreased (p < .05) plasma activity of cholinesterase and concentrations of uric acid and urea. The 6% mulberry diet had the lowest fibre mean CSA and shear force and increased total fibre number of the LD muscle, when compared with the other groups. These results suggest that including mulberry in the diet at <12% is an effective feed crop to improve meat quality and the chemical composition of muscle without negatively affecting growth performance.

Effects of n-acetyl-cysteine supplementation in late gestational diet on maternal-placental redox status, placental NLRP3 inflammasome, and fecal microbiota in sows1

Although n-acetyl-cysteine (NAC) has been shown to efficiently alleviate oxidative stress, inflammatory response, and alter gut microbiota, little attention has been focused on their interactions with placental metabolic status of sows. The effects of NAC on the placental redox status, function, inflammasome, and fecal microbiota in sows were explored to clarify the correlation between the fecal microbiota and placenta. Sows were divided into either the control group or the NAC group which received dietary 0.5% NAC supplementation from day 85 of gestation to delivery. Plasma redox status, placental growth factors, nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome, fecal microbial metabolites, and communities were evaluated. Compared with the control group, although NAC did not ameliorate reproductive performance of sows (P > 0.05), it significantly improved maternal-placental health, which was accompanied by increased activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD), decreased level of malondialdehyde (MDA), and lowered expression of interleukin (IL)-1β and IL-18 through inhibiting NLRP3 inflammasome (P < 0.05). Additionally, NAC significantly increased placental insulin-like growth factors (IGFs) and E-cadherin contents (P < 0.05), elevated the expression of genes involved in angiogenesis and amino acids transporters (P < 0.05), and decreased the microtubule-associated protein light chain 3B (LC3B) and Beclin-1 protein expression (P < 0.05). Furthermore, NAC increased the relative abundances of fecal Prevotella, Clostridium cluster XIVa, and Roseburial/Eubacterium rectale (P < 0.05), which were negatively correlated with placental NLRP3 and positively with solute carrier family 7, member 8 (Slc7a8; P < 0.05). In conclusion, NAC supplementation during late gestation alleviated maternal-placental oxidative stress and inflammatory response, improved placental function, and altered fecal microbial communities.

Negative effects on newborn piglets caused by excess dietary tryptophan in the morning in sows

BACKGROUND

This study investigated the effect of dynamic feeding models of dietary tryptophan on sows' performance during late pregnancy.

RESULTS

The average piglet birth weight and live farrowing rate from sows consuming a high-low tryptophan diet (0.39% Trp in the morning and 0.13% Trp in the afternoon) were decreased compared with those fed a 2×tryptophan diet (0.26% Trp in the morning and afternoon). Compared with the 2×tryptophan group, sow serum kynurenic acid and the newborn liver n-6:n-3 polyunsaturated fatty acid ratio were significantly higher, and sow serum taurine and newborn serum taurine, phosphoserine, cysteine and proline were lower in the high-low tryptophan diet group. Eighty-eight genes were differentially expressed in newborn piglets' livers between the 2×tryptophan and high-low groups. Genes related to cytotoxic effector regulation (major histocompatibility complex class I proteins), NADH oxidation, reactive oxygen species (ROS) metabolism and tissue development were differentially expressed between these two groups.

CONCLUSION

Together, the results provide information on new biomarkers in serum or liver and provide novel insights into variations in the fetal liver during exogenous stimulus response and biological processes of ROS metabolism in fetuses during late pregnancy caused by a single excessive tryptophan ingestion daily in the morning. © 2018 Society of Chemical Industry.

Leucine alone or in combination with glutamic acid, but not with arginine, increases biceps femoris muscle and alters muscle AA transport and concentrations in fattening pigs

Forty-eight Duroc × Large White × Landrace pigs with an average initial body weight of 77.09 ± 1.37 kg were used to investigate the effects of combination of leucine (Leu) with arginine (Arg) or glutamic acid (Glu) on muscle growth, free amino acid profiles, expression levels of amino acid transporters and growth-related genes in skeletal muscle. The animals were randomly assigned to one of the four treatment groups (12 pigs/group, castrated male:female = 1:1). The pigs in the control group were fed a basal diet (13% Crude Protein), and those in the experimental groups were fed the basal diet supplemented with 1.00% Leu (L group), 1.00% Leu + 1.00% Arg (LA group) or 1.00% Leu + 1.00% Glu (LG group). The experiment lasted for 60 days. Results showed an increase (p < 0.05) in biceps femoris (BF) muscle weight in the L group and LG group relative to the basal diet group. In longissimus dorsi (LD) muscle, Lys, taurine and total essential amino acid concentration increased in the LG group relative to the basal diet group (p < 0.05). In LG group, Glu and carnosine concentrations increased (p < 0.05) in the BF muscle, when compared to the basal diet group. The Leu and Lys concentrations of BF muscle were lower in the LA group than that in the L group (p < 0.05). A positive association was found between BF muscle weight and Leu concentration (p < 0.05). The LG group presented higher (p < 0.05) mRNA levels of ASCT2, LAT1, PAT2, SANT2 and TAT1 in LD muscle than those in the basal diet group. The mRNA levels of PAT2 and MyoD in BF muscle were upregulated (p < 0.05) in the LG group, compared with those in the basal diet group. In conclusion, Leu alone or in combination with Glu is benefit for biceps femoris muscle growth in fattening pig.

TRIENNIAL GROWTH AND DEVELOPMENT SYMPOSIUM: Genetics and breeding for intramuscular fat and oleic acid content in pigs

The intramuscular fat (IMF) and oleic acid (OL) content have been favorably related to pork quality and human health. This influences the purchasing behavior of consumers and, therefore, also shifts the attention of breeding companies toward whether these traits are included into the breeding goal of the lines producing for high-valued markets. Because IMF and OL are unfavorably associated with lean content, a key economic trait, the real challenge for the industry is not simply to increase IMF and OL, but rather to come up with the right trade-off between them and lean content. In this paper we review the efforts performed to genetically improve IMF and OL, with particular reference to the research we conducted in a Duroc line aimed at producing high quality fresh and dry-cured pork products. Based on this research, we conclude that there are selection strategies that lead to response scenarios where IMF, OL, and lean content can be simultaneously improved. Such scenarios involve regular recording of IMF and OL, so that developing a cost-efficient phenotyping system for these traits is paramount. With the economic benefits of genomic selection needing further assessment in pigs, selection on a combination of pedigree-connected phenotypes and genotypes from a panel of selected genetic markers is presented as a suitable alternative. Evidence is provided supporting that at least a polymorphism in the leptin receptor and another in the stearoyl-CoA desaturase genes should be in that panel. Selection for IMF and OL results in an opportunity cost on lean growth. The extent to which it is affordable relies on the consumers' willingness to pay for premium products and on the cost to benefit ratio of alternative management strategies, such as specific dietary manipulations. How the genotype can influence the effect of the diet on IMF and OL remains a topic for further research.

Genome-Wide Analysis Reveals Extensive Changes in LncRNAs during Skeletal Muscle Development in Hu Sheep

As an important type of noncoding RNA molecules, long non-coding RNAs (lncRNAs) act as versatile players in various biological processes. However, little is known about lncRNA regulators during sheep muscle growth. To explore functional lncRNAs during sheep muscle growth, we systematically investigated lncRNAs using strand-specific Ribo-Zero RNA sequencing at three key developmental stages in Hu sheep. A total of 6924 lncRNAs were obtained, and the differentially expressed lncRNAs and genes were screened from (control vs. experiment) fetus vs. lamb, lamb vs. adult, and fetus vs. adult comparisons, respectively. The quantitative real-time polymerase chain reaction (qRT-PCR) analysis results correlated well with the sequencing data. Moreover, functional annotation analysis based on the Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases showed that the target genes of the differentially expressed lncRNAs were significantly enriched in organ morphogenesis, skeletal system development as well as response to stimulus and some other terms related to muscle. Furthermore, a co-expression network of the differentially expressed target genes and lncRNAs was constructed and well-known muscle growth regulators such as retrotransposon-like 1 and Junctophilin-2 were included. Finally, we investigated the expression profiles of seven lncRNAs and their target genes, and found that they played vital roles in muscle growth. This study extends the sheep muscle lncRNA database and provides novel candidate regulators for future genetic and molecular studies on sheep muscle growth, which is helpful for optimizing the production of mutton.

Increases in circulating amino acids with in-feed antibiotics correlated with gene expression of intestinal amino acid transporters in piglets

In-feed antibiotics have been commonly used to promote the growth performance of piglets. The antibiotics can increase protein utilization, but the underlying mechanism is largely unknown. The present study investigated the effects of in-feed antibiotics on intestinal AA transporters and receptors to test the hypothesis that the alteration of circulating AA profiles may be concomitant with the change of intestinal AA transporters and receptors. Sixteen litters of piglets at day 7 started to receive creep feed with (Antibiotic) or without (Control) antibiotic. Piglets were weaned at day 23 after birth, and fed the same diets until day 42. In-feed antibiotics did not affect the BW of 23-day-old (P = 0.248), or 42-day-old piglets (P = 0.089), but increased the weight gain to feed ratio from day 23 to 42 (P = 0.020). At day 42 after birth, antibiotic treatment increased the concentrations of most AAs in serum (P < 0.05), and decreased the concentrations of most AAs in jejunal and ileal digesta. Antibiotics upregulated (P < 0.05) the mRNA expression levels for jejunal AAs transporters (CAT1, EAAC1, ASCT2, y⁺LAT1), peptide transporters (PepT1), and Na⁺-K⁺-ATPase (ATP1A1), and ileal AA transporters (ASCT2, y⁺LAT1, b^0,+AT, and B⁰AT1), and ATP1A1. The antibiotics also upregulated the mRNA expression of jejunal AAs receptors T1R3 and CaSR, and ileal T1R3. Protein expression levels for jejunal AA transporters (EAAC1, b^0,+AT, and ASCT2) and PepT1 were also upregulated. Correlation analysis revealed that the alterations of AA profiles in serum after the in-feed antibiotics were correlated with the upregulations of mRNA expression levels for key AA transporters and receptors in the small intestine. In conclusion, the in-feed antibiotics increased serum level of most AAs and decreased most AAs in the small intestine. These changes correlated with the upregulations of mRNA expression levels for key AA transporters and receptors in the small intestine. The findings provide further insights into the mechanism of in-feed antibiotics, which may provide new framework for designing alternatives to antibiotics in animal feed in the future.

Animal Models for the Study of the Relationships between Diet and Obesity: A Focus on Dietary Protein and Estrogen Deficiency

Obesity is an increasing major public health concern asking for dietary strategies to limit weight gain and associated comorbidities. In this review, we present animal models, particularly rats and mice, which have been extensively used by scientists to understand the consequences of diet quality on weight gain and health. Notably, modulation of dietary protein quantity and/or quality has been shown to exert huge effects on body composition homeostasis through the modulation of food intake, energy expenditure, and metabolic pathways. Interestingly, the perinatal window appears to represent a critical period during which the protein intake of the dam can impact the offspring’s weight gain and feeding behavior. Animal models are also widely used to understand the processes and mechanisms that contribute to obesity at different physiological and pathophysiological stages. An interesting example of such aspect is the situation of decreased estrogen level occurring at menopause, which is linked to weight gain and decreased energy expenditure. To study metabolic disorders associated with such situation, estrogen withdrawal in ovariectomized animal models to mimic menopause are frequently used. According to many studies, clear species-specific differences exist between rats and mice that need to be taken into account when results are extrapolated to humans.

Effects of supplementation with branched-chain amino acids to low-protein diets on expression of genes related to lipid metabolism in skeletal muscle of growing pigs

Branched-chain amino acids (BCAA), including leucine (Leu), isoleucine (Ile), and valine (Val), play critical roles in energy homeostasis and lipid metabolism in addition to their other functions, such as in protein metabolism. This study investigated the effects of different dietary BCAA ratios on the intramuscular fat (IMF) content and fatty acid composition in different location of skeletal muscles, including the longissimus dorsi (LD), biceps femoris (BF), and psoas major (PM) muscles of growing pigs, and also examined the mRNA expression levels of genes involved in lipid metabolism in these muscle tissues. The experiment was performed on 40 growing pigs (Large White × Landrace) with a similar initial weight (9.85 ± 0.35 kg). The pigs were randomly assigned to one of five diets: diet A was a positive control and contained 20 % crude protein (CP) with a Leu:Ile:Val ratio of 1:0.51:0.63 according to the recommendation of the National Research Council (NRC); for diets B to E, the CP level was reduced to 17 %, and the Leu:Ile:Val ratios were 1:1:1, 1:0.75:0.75, 1:0.51:0.63, and 1:0.25:0.25, respectively. No significant difference was observed in the average feed intake and feed efficiency of the pigs fed the low protein diet (17 % CP) with BCAA treatments relative to the positive control. However, there was a tendency for increased feed efficiency of the 1:0.75:0.75 group compared with the 1:1:1 group (P = 0.09). The BCAA ratio of 1:0.75:0.75 (17 % CP) increased the IMF content of BF muscle (P < 0.01). Moreover, varied dietary BCAA supplementation with a reduced protein level had different effects on the fatty acid composition of the LD, BF, and PM muscles. The BCAA ratio of 1:0.51:0.63-1:0.75:0.75 (17 % CP) significantly lowered the ratio of n-6 to n-3 polyunsaturated fatty acid in these muscles compared with the positive control group (20 % CP). This effect was associated with an increase in mRNA expression levels of acetyl-CoA carboxylase, lipoprotein lipase, fatty acid transport protein, and fatty acid binding protein 4 in the muscles (P < 0.05). The results indicated that the reduced protein diet (17 % CP) with the BCAA ratio within 1:0.25:0.25-1:0.75:0.75 could increase the IMF content in BF muscle and significantly improve the fatty acid composition in different skeletal muscles accompanied by changes in the expression of genes involved in lipid metabolism, compared with those in the pigs that received adequate dietary protein (20 %), which might result in improved eating quality and nutritional value of the meat.

Amino acid composition in eyes from zebrafish (Danio rerio) and sardine (Sardina pilchardus) at the larval stage

A comparative study was performed to identify differences in the amino acid composition of the eyes from zebrafish (Danio rerio) and sardine (Sardina pilchardus) larvae and their link to the environmental adaption of the species. Amino acids in the acidic hydrolysates of eyes from 11 zebrafish and 12 sardine were determined with the use of high-performance liquid chromatography involving precolumn derivatization with ortho-phthalaldehyde. Differences in the content of most amino acids were detected between zebrafish and sardine. These amino acids were aspartate, glutamate, serine, glycine, threonine, arginine, methionine, valine, phenylalanine, isoleucine, leucine and lysine. Of particular note, the percentage of methionine in zebrafish eyes was much higher than that in sardine, whereas the opposite was observed for glutamate and glycine. These results indicate that zebrafish and sardine likely have experienced differences in adaptation to environmental changes. We suggest that the amino acid composition of eyes represents a powerful tool to discriminate between species characterized by different lifestyle and inhabiting different environments.