Effects of genetic selection and threonine on meat quality in Pekin ducks

Muscle growth affects the metabolome of the pectoralis major muscle in red-winged tinamou (Rhynchotus rufescens)

The aim of the present study was to identify and quantify the metabolites (metabolome analysis) of the pectoralis major muscle in male red-winged tinamou (Rhynchotus rufescens) selected for growth traits. A selection index was developed for females [body weight (BW), chest circumference (CC), and thigh circumference (TC)] and males [BW, CC, TC, semen volume, and sperm concentration] in order to divide the animals into 2 experimental groups: selection group with a higher index (TinamouS) and commercial group with a lower index (TinamouC). Twenty male offspring of the 2 groups (TinamouS, n = 10; TinamouC, n = 10) were confined for 350 d. The birds were slaughtered and pectoralis major muscle samples were collected, subjected to polar and apolar metabolites extractions and analyzed by proton nuclear magnetic resonance (1H NMR) spectroscopy. Analysis of the polar metabolomic profile identified 65 metabolites; 29 of them were differentially expressed between the experimental groups (P < 0.05). The TinamouS groups exhibited significantly higher concentrations (P < 0.05) of 25 metabolites, including anserine, aspartate, betaine, carnosine, creatine, glutamate, threonine, 3-methylhistidine, NAD+, pyruvate, and taurine. Significantly higher concentrations of cysteine, beta-alanine, lactose, and choline were observed in the TinamouC group (P < 0.05). The metabolites identified in the muscle provided information about the main metabolic pathways (higher impact value and P < 0.05), for example, phenylalanine, tyrosine and tryptophan biosynthesis; alanine, aspartate and glutamate metabolism; D-glutamine and D-glutamate metabolism; β-alanine metabolism; glycine, serine and threonine metabolism; taurine and hypotaurine metabolism; histidine metabolism; phenylalanine metabolism. The NMR spectra of apolar fraction showed 8 classes of chemical compounds. The metabolome analysis shows that the selection index resulted in the upregulation of polyunsaturated fatty acids, unsaturated fatty acids, phosphocholines, phosphoethanolamines, triacylglycerols, and glycerophospholipids. The present study suggests that, despite few generations, the selection based on muscle growth traits promoted changes in metabolite concentrations in red-winged tinamou.

Metabolomic comparison of meat quality and metabolites of geese breast muscle at different ages

The purpose of this study was to distinguish the effect of age on the meat quality and chemical composition of Yangzhou goose breast meat. Nontargeted metabolomics analysis (UHPLC-MS/MS) was used to distinguish the metabolic composition of goose meat at different ages, and Pearson's correlations between differential metabolites and key meat parameters were assessed. Compared with goslings, adult geese had lighter, redder and chewier meat (p < 0.05). Metabolite analysis revealed significant differences in nucleosides, organic acids, amino acids and sugars. Levels of IMP, xanthosine, pretyrosine and l-threonine were significantly higher in older meat (p < 0.05) and positively correlated with meat freshness indicators. However, pyruvic acid, l-cysteine and glucose 6-phosphate were up-regulated in gosling meat (p < 0.05), which were important flavor compounds. These results facilitate the further investigation of changes in goose meat composition and provide biomarkers for determining goose meat quality at different ages.

Proteomic and phosphoproteomic analysis reveal threonine deficiency increases hepatic lipid deposition in Pekin ducks via reducing STAT phosphorylation

Dietary threonine (Thr) deficiency enhances triglyceride (TG) deposition in the liver of Pekin ducks, which injures hepatic function and impairs growth performance. However, the underlying molecular mechanisms remain unclear. In the present study, we investigated the effects of dietary Thr deficiency on the expressions of proteins and phosphoproteins in liver of Pekin ducks, to identify the underlying molecular changes. A total of 300 one-day-old ducklings were divided into 3 groups with 10 replicates of 10 birds. All ducks were fed corn-wheat-peanut meal diets containing 0.46%, 0.71%, and 0.96% Thr, respectively, from 1 to 21 days of age. Growth performance, serum parameters, hepatic TG content, and expression of genes involved in lipid metabolism of Pekin ducks were determined. A Thr deficiency group (Thr-D, 0.46% Thr) and a Thr sufficiency group (Thr-S, 0.71% Thr) were selected for subsequent proteomic and phosphoproteomic analysis. The results showed that Thr-D reduced the growth performance (P < 0.001), and increased the plasma concentrations of cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and hepatic TG (P < 0.05). Thr-D increased gene expression related to fatty acid and TG synthesis (P < 0.05). A total of 176 proteins and 259 phosphosites (containing 198 phosphoproteins) were observed to be differentially expressed as a result of Thr-D. The upregulated proteins were enriched in the pathway related to amino acid metabolism, peroxisome. The downregulated proteins were enriched in linolenic and arachidonic acid metabolism, and the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway. The upregulated phosphoproteins were enriched in the pathways related to fatty acid biosynthesis, fructose and mannose metabolism, and glycolysis/gluconeogenesis. Thr-D reduced the phosphorylation of STAT1 at S729 and STAT3 at S728, and expression of STAT5B. In contrast, Thr-D increased non-receptor tyrosine-protein kinase (TYK2) expression and STAT1 phosphorylation at S649. Taken together, dietary Thr-D increased hepatic TG accumulation by upregulating the expression of genes and proteins, and phosphoproteins related to fatty acid and triglyceride synthesis. Furthermore, these processes might be regulated by the JAK-STAT signaling pathway, especially the phosphorylation of STAT1 and STAT3.

Alleviative Effect of Threonine on Cadmium-Induced Liver Injury in Mice

As a toxic trace element commonly found in food, cadmium (Cd) can cause severe liver injury. Our previous study showed that threonine (Thr) could significantly alleviate Cd toxicity in yeast. To investigate the effect of Thr on Cd-induced liver injury in mice, twenty-four mice were randomly divided into four groups: control, Cd, and low/high dose of Thr-treatment groups (0.04 and 0.08 mmol/kg/day, respectively). After 7 days of continuous treatment, the alleviative effect of Thr on liver injury in Cd-exposed mice was assessed. The results showed that Thr significantly reduced the elevation of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in Cd-exposed mice. Histological analysis showed that Thr decreased Cd-induced hepatic steatosis, zonal necrosis, and inflammatory cell infiltration. Thr also reduced the Cd-induced malondialdehyde (MDA) and O^2- levels and restored superoxide dismutase (SOD) and catalase (CAT) activities in the liver. Further investigation showed that Thr significantly suppressed Cd-induced inflammatory response (tumor necrosis factor-α and interleukin-6) and restored the level of anti-apoptotic protein (Blc-2) but inhibited the elevation of pro-apoptotic proteins (Bax and caspase-3), as well as the activation of the PI3K/AKT signaling pathway in Cd-exposed mice. In conclusion, Thr alleviated Cd-induced liver injury through reducing Cd-induced oxidative stress, inflammation, and attenuating hepatocyte apoptosis via PI3K/AKT-related signaling pathway.

Effects of Fatty-Type and Lean-Type on Growth Performance and Lipid Droplet Metabolism in Pekin Ducks

Simple Summary

Lipid deposition in animals is closely related to lipid anabolism. In order to further explore how differences in different metabolic types regulate lipid deposition, we compared the growth performance and lipid droplet metabolism of fatty-type ducks and lean-type ducks. The results showed that fatty-type ducks showed a faster growth rate and more fat deposition in the early growth stage after feeding the same diet, and produced more lipoproteins in serum and deposited in adipose tissue. However, fewer triglycerides accumulated in the liver. We believe that this performance of fatty-type ducks is caused by the increased expression level of lipid droplet-related genes.

Abstract

The reasons for differences in lipid depositions between fatty-type (F-T) and lean-type (L-T) ducks remain unknown. The present study aimed to compare the growth performance, lipid deposition, and gene expression related to lipid droplet formation in F-T and L-T Pekin ducks. One-day-old, 140 each L-T and F-T male ducks were selected and distributed separately into 20 replicate cages. All ducks were fed commercial diets up to 35 d of age. F-T ducks had a higher average daily gain from 21 to 28 d of age. On 35-day-old, F-T ducks had higher serum levels of high- and low-density lipoprotein cholesterol, cholesterol, albumin, and hydroxybutyrate dehydrogenase activity than L-T ducks. F-T ducks had higher abdominal fat and subcutaneous fat percentages than those in L-T ducks. Liver histological examination showed that L-T ducks contained more lipid droplets in the liver, which gradually decreased with increasing age. The average adipocyte area and diameter of abdominal fat and subcutaneous fat in the F-T and L-T ducks increased with age and were higher in F-T ducks than those in L-T ducks. Furthermore, the gene expression of perilipin 1, perilipin 2, angiopoietin-like protein 4, adipose triglyceride lipase, alpha/beta-hydrolase domain-containing protein 5 (ABHD5), and serine/threonine kinase 17a in the liver, abdominal fat, and subcutaneous fat of F-T ducks was higher than that in L-T ducks, and it increased with age. Compared to L-T ducks, F-T ducks had higher expression of ABHD5 in the abdominal fat and subcutaneous fat and lower expression in the liver. Thus, F-T ducks displayed lower hepatic lipid deposition and a higher percentage of abdominal fat and subcutaneous fat, suggesting that F-T ducks had higher lipid storage capacity due to increased gene expression related to lipid droplets.

Comparison of Cecal Microbiota and Performance Indices Between Lean-Type and Fatty-Type Pekin Ducks

Fatty-type (FT) Pekin ducks exhibit higher lipid deposition than lean-type (LT) ducks. The gut microbiota plays an important role in modulating fat metabolism. We compared the growth performance, slaughter performance, and cecal microbiota of FT and LT Pekin ducks and analyzed the role of cecal microbiota in lipid deposition in Pekin ducks. A total of 140 1-day-old FT and LT Pekin ducks with similar body weights were randomly assigned to 10 cages, with 14 ducks in each replicate. All ducks were fed commercial diets from 28 to 42 days of age. Results showed that the average body weight and feed intake of FT ducks were higher than those of LT ducks. The breast muscle and eviscerated percentages of LT ducks were higher than those of FT ducks; the abdominal fat and sebum percentages of LT ducks were lower than those of FT ducks at 6 weeks of age (P < 0.01). 16S DNA sequencing of the cecal microbiota revealed that the bacterial abundance differed between FT and LT ducks at 4 and 6 weeks of age. The abundance of Firmicutes was higher, while that of Fusobacteria and Fusobacterium was lower in LT ducks than in FT ducks at 4 weeks of age. The abundance of Spirochaetes was higher, while that of Firmicutes and Bacteroides was lower in LT ducks than in FT ducks at 6 weeks of age. The abundance of Spirochaetes and Brachyspira in LT ducks was higher at 6 weeks than at 4 weeks of age. Interestingly, the abundance of Firmicutes and Bacteroides in FT ducks was higher at 6 weeks of age than at 4 weeks of age, while that of Fusobacteria and Fusobacterium was lower at 6 weeks than at 4 weeks of age. Linear discriminant analysis effect size analysis showed that Spirochaetes, Brachyspira, Alistipes, Campylobacter, Megamonas, Butyricicoccus, and Fusobacteria may be involved in the fat metabolism pathway as specific markers. We reveal the differences in microbial abundance in the cecal microbiota between FT and LT Pekin ducks and provide an insight into the role of cecal microbiota in lipid deposition in Pekin ducks.

Distribution characteristics and regulation of amino acids and fatty acids in muscle and adipose tissues of sheep grown in natural grazing environment

The composition of amino acid and fatty acid has a vital function on meat quality and animal health. However, the underlying mechanism of amino acid and fatty acid metabolism in sheep during different grazing periods is still unclear. In this study, a total of 12 sheep were employed in different grazing periods. Our results showed that the composition of amino acids and fatty acids in muscle and adipose tissues was significantly altered between dry grass (DG) period and green grass (GG) period. Changes in the activities of the metabolism-related enzymes including BCKD, BCAT2, ACC, SCD, HSL, GSK3β, p-GSK3β, and FABP4 were observed in muscle and adipose during different grazing periods. In addition, the mRNA expression levels of ACC, FAS, SCD, HSL, LPL, and DGAT1 in muscle and adipose tissue were changed markedly in different grazing periods. Furthermore, the expression levels of mTOR and β-catenin/PPARγ/C/EBPα pathway-related proteins were predominantly altered in muscle and adipose among DG and GG. Taken together, all investigations simplified the process of amino acid and fatty acid metabolism disorders caused by different grazing periods, and the mTOR and β-catenin/PPARγ/C/EBPα play the essential role in this process, which provided an underlying mechanism of metabolism and meat quality.