Effect of supplementing lysins and methionine to low-protein diets on growth performance, hepatic antioxidant capacity, immune status, and glycolytic activity of tibetan sheep.

Reducing the levels of dietary protein is an effective nutritional approach in lowering feed cost and nitrogen emissions in ruminants. The purpose of this study was to evaluate the effects of dietary Lys/Met ratio in a low protein diet (10%, dry matter basis) on the growth performance and hepatic function (antioxidant capacity, immune status, and glycolytic activity) in Tibetan lambs. Ninety two-month-old rams with an average weight of 15.37 ± 0.92 kg were randomly assigned to LP-L (dietary Lys/Met = 1:1), LP-M (dietary Lys/Met = 2:1) and LP-H (dietary Lys/Met = 3:1) treatments. The trial was conducted over 100 d, including 10 d of adaption to the diets. Hepatic phenotypes, antioxidant capacity, immune status, glycolytic activity and gene expression profiling was detected after the conclusion of the feeding trials. The results showed that the body weight was higher in the LP-L group when compared to those on the LP-M group (P < 0.05). In addition, the activities of the catalase (CAT) and glutathione peroxidase (GSH-Px) in the LP-L group were significantly increased compared with the LP-M group (P < 0.05), while the malondialdehyde (MDA) levels in LP-H group were significantly decreased (P < 0.05). Compared with LP-H group, both hepatic glycogen (P < 0.01) and lactate dehydrogenase (LDH) (P < 0.05) were significantly elevated in LP-L group. For the LP-L group, the hepatocytes were arranged radially with the central vein in the center, and hepatic plates exhibited tight arrangement. Transcriptome analysis identified 29, 179, and 129 differentially expressed genes (DEGs) between the LP-M vs. LP-L, LP-H vs. LP-M, and LP-H vs. LP-L groups, respectively (Q-values < 0.05 and |log2Fold Change| > 1). Gene Ontology (GO) and correlation analyses showed that in the LP-L group, core genes (C1QA and JUNB) enriched in oxidoreductase activity were positively correlated with antioxidant indicators, while the MYO9A core gene enriched in the immune response was positively associated with immune indicators, and core genes enriched in molecular function (PDK3 and PDP2) were positively correlated with glycolysis indicators. In summary, low-protein diet with a low Lys/Met ratio (1:1) could reduce the hepatic oxidative stress and improve the glycolytic activity by regulating the expression of related genes of Tibetan sheep.

Changes in Rumen Microbiology and Metabolism of Tibetan Sheep with Different Lys/Met Ratios in Low-Protein Diets.

In ruminants, supplementing appropriate amounts of amino acids improves growth, feed utilization efficiency, and productivity. This study aimed to assess the effects of different Lys/Met ratios on the ruminal microbial community and the metabolic profiling in Tibetan sheep using 16S rDNA sequencing and non-target metabolomics. Ninety-two-month-old Tibetan rams (initial weight = 15.37 ± 0.92 kg) were divided into three groups and fed lysine/methionine (Lys/Met) of 1:1 (LP-L), 2:1 (LP-M), and 3:1 (LP-H) in low-protein diet, respectively. Results: The T-AOC, GSH-Px, and SOD were significantly higher in the LP-L group than in LP-H and LP-M groups (p < 0.05). Cellulase activity was significantly higher in the LP-L group than in the LP-H group (p < 0.05). In the fermentation parameters, acetic acid concentration was significantly higher in the LP-L group than in the LP-H group (p < 0.05). Microbial sequencing analysis showed that Ace and Chao1 indicators were significantly higher in LP-L than in LP-H and LP-M (p < 0.05). At the genus level, the abundance of Rikenellaceae RC9 gut group flora and Succiniclasticum were significantly higher in LP-L than in LP-M group (p < 0.05). Non-target metabolomics analyses revealed that the levels of phosphoric acid, pyrocatechol, hydrocinnamic acid, banzamide, l-gulono-1,4-lactone, cis-jasmone, Val-Asp-Arg, and tropinone content were higher in LP-L. However, l-citrulline and purine levels were lower in the LP-L group than in the LP-M and LP-H groups. Banzamide, cis-jasmone, and Val-Asp-Arg contents were positively correlated with the phenotypic contents, including T-AOC, SOD, and cellulase. Phosphoric acid content was positively correlated with cellulase and lipase activities. In conclusion, the Met/Lys ratio of 1:1 in low-protein diets showed superior antioxidant status and cellulase activity in the rumen by modulating the microbiota and metabolism of Tibetan sheep.

Insights into the effects of saline forage on the meat quality of Tibetan sheep by metabolome and multivariate analysis.

This work aimed to investigate how two different types of forage (saline and alkaline) impact the meat quality and muscle metabolism of Tibetan sheep. An integrative multi-omics analysis of meat quality and different metabolites was performed using untargeted and targeted metabolomics approaches. The research results indicated that GG grass (saline and alkaline forage) possessed superior characteristics in terms of apparent quality and secondary metabolite content compared with HG grass (Non saline alkali forage), regardless of the targeted metabolites or non-targeted ones. Simultaneously, under stress conditions, the carbohydrates-rich salt-alkali grass play a significant role in slowing down the decline in pH, increasing the unsaturated fatty acid content and reducing the thawing loss in Tibetan sheep. This study provides an understanding of the impact of different salt-alkali grass on the quality of Tibetan sheep meat, while providing a scientific basis for the future development of salt-alkali livestock industry.

Integrated metabolome and microbiome analysis reveals the effect of rumen-protected sulfur-containing amino acids on the meat quality of Tibetan sheep meat.

Introduction: This study investigated the effects of rumen-protected sulfur-containing amino acids (RPSAA) on the rumen and jejunal microbiota as well as on the metabolites and meat quality of the longissimus lumborum (LL) in Tibetan sheep. Methods: By combining 16S rDNA sequencing with UHPLC-Q-TOF MS and Pearson correlation analysis, the relationship between gastrointestinal microbiota, muscle metabolites and meat quality was identified. Results: The results showed that feeding RPSAA can increase the carcass weight, abdominal fat thickness (AP-2 group), and back fat thickness (AP-2 and AP-3 group) of Tibetan sheep. The water holding capacity (WHC), texture, and shear force (SF) of LL in the two groups also increased although the fatty acids content and brightness (L*) value significantly decreased in the AP-2 group. Metabolomics and correlation analysis further showed that RPSAA could significantly influence the metabolites in purine metabolism, thereby affecting L* and SF. In addition, RPSAA was beneficial for the fermentation of the rumen and jejunum. In both groups, the abundance of Prevotella 1, Lachnospiraceae NK3A20 group, Prevotella UCG-003, Lachnospiraceae ND3007 group in the rumen as well as the abundance of Eubacterium nodatum group and Mogibacterium group in the jejunum increased. In contrast, that of Turicibacter pathogens in the jejunum was reduced. The above microorganisms could regulate meat quality by regulating the metabolites (inosine, hypoxanthine, linoleic acid, palmitic acid, etc.) in purine and fatty acids metabolism. Discussion: Overall, reducing the levels of crude proteins in the diet and feeding RPSAA is likely to improve the carcass quality of Tibetan sheep, with the addition of RPMET (AP-2) yielding the best edible quality, possibly due to its ability to influence the gastrointestinal microbiota to subsequently regulate muscle metabolites.

The impact of different levels of wheat diets on hepatic oxidative stress, immune response, and lipid metabolism in Tibetan sheep (Ovis aries).

BACKGROUND: Compared with corn, wheat contains higher crude protein, amino acids concentration. However, wheat contains a mass of anti-nutritional factors, resulting in increased of the digesta viscosity and impaired the intestinal function in ruminant. OBJECTIVE: This study aimed to investigate the effects of substitution of different amounts of wheat for corn on hepatic metabolism in the Tibetan lamb. METHODS: Ninety Tibetan lambs (Body weight = 12.37 ± 0.92 kg) were randomly assigned to three groups: 0% wheat diet (Control), 10% wheat diet (Low group), and 15% wheat diet (High group). The feeding trial lasted for 130 d, including a 10 d adaption period. Hepatic gene expression profiling was performed via RNA sequencing after the conclusion of the feeding trials. RESULTS: Results showed that greater level of glutathione peroxidase levels in L group compared with those of the C and H groups (P < 0.05). The immune indexes, including interleukin-1ß (IL-1ß), immunoglobulin A (IgA), and IgM were also elevated in L group compared with the other groups (P < 0.05). Compared with H group, the hepatocytes were arranged radially, and hepatic plates anastomosed with each other to form a labyrinth-like structure in L group. Transcriptomic analysis showed 872 differentially expressed genes (DEG) between H and L group, of which 755 were down-regulated and 117 were up-regulated. Through Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, 32 pathways were significantly enriched (Q-value < 0.05), such as the cAMP signaling pathway, Th1 and Th2 cell differentiation, leukocyte transendothelial migration, platelet activation and adipocytokine signaling pathway. Additionally, the expression of comment DEGs were verified via quantitative reverse-transcription polymerase chain reaction. CONCLUSION: In summary, our findings suggest that wheat can be supplemented up to 10% in Tibetan sheep, contributing to improve the hepatic oxidative stress, immune response and lipid metabolism through regulating the expression of related genes.

Effects of dietary wheat supplementation levels on growth performance, rumen bacterial community and fermentation parameters in Chinese Tibetan Sheep.

The objective of this study was to evaluate various wheat supplementation levels on rumen microbiota and fermentation parameter in Tibetan sheep. A total of ninety ram with an average 12.37 ± 0.92 kg at the age of 2 months were randomly allocated to three treatments: 0% wheat diet (CW, N = 30), 10% wheat diet (LW, N = 30), and 15% wheat diet (HW, N = 30) on a dry matter basis. The experiment was conducted over a period of 127 days, including 7 days of adaption to the diets. Our results showed that sheep fed 10% wheat exhibited optimal average daily gain and feed gain ratio compared with HW group (p < 0.05). The serum alkaline phosphatase concentration was the lowest when fed the 10% wheat diet (p < 0.05), whereas serum aspartate aminotransferase concentration was the highest (p < 0.05). Both acetate and propionate increased with increase in dietary wheat ratio (p < 0.05), while a greater decrease in concentrations of NH3 -N was observed (p < 0.05). In rumen fluid, 3413 OTUs were obtained with 97% consistency. Phylum Firmicutes was the predominant bacteria and accounted for 49.04%. The CW groups supported significantly increased the abundance of Bacteroidetes (p < 0.05), as compared with the HW group. The abundance of Bacteroidales_UCG-001, Ruminococcus, and Mitsuokella possessed a higher relative abundance in HW group (p < 0.05). No differences in the bacterial community and fermentation parameters were observed between the sheep fed 0% and 10% wheat (p > 0.05). Ruminal bacterial community structure was significantly correlated with isobutyrite (r2 = 0.4878, p = 0.035) and valerate (r2 = 0.4878, p = 0.013). In conclusion, supplementation of 10% wheat in diet promoted the average daily gain and never altered microbial community structure and fermentation pattern, which can be effectively replace partial corn in Chinese Tibetan Sheep.

Fat deposition, fatty acid profiles, antioxidant capacity and differentially expressed genes in subcutaneous fat of Tibetan sheep fed wheat-based diets with and without xylanase supplementation.

Xylanase, an exogenous enzyme that plays an essential role in energy metabolism by hydrolysing xylan into xylose, has been shown to positively influence nutrient digestion and utilisation in ruminants. The objective of this study was to evaluate the effects of xylanase supplementation on the back-fat thickness, fatty acid profiles, antioxidant capacity, and differentially expressed genes (DEGs) in the subcutaneous fat of Tibetan sheep. Sixty three-month-old rams with an average weight of 19.35 ± 2.18 kg were randomly assigned to control (no enzyme added, WH group) and xylanase (0.2% of diet on a dry matter basis, WE group) treatments. The experiment was conducted over 97 d, including 7 d of adaption to the diets. The results showed that xylanase supplementation in the diet increased adipocyte volume of subcutaneous fat (p < 0.05), shown by hematoxylin and eosin (H&E) staining. Gas chromatography showed greater concentrations of C14:0 and C16:0 in the subcutaneous fat of controls compared with the enzyme-treated group (p < 0.05), while opposite trend was seen for the absolute contents of C18:1n9t, C20:1, C18:2n6c, C18:3, and C18:3n3 (p < 0.05). Compared with controls, supplementation with xylanase increased the activity of T-AOC significantly (p < 0.05). Transcriptomic analysis showed the presence of 1630 DEGs between the two groups, of which 1023 were up-regulated and 607 were down-regulated, with enrichment in 4833 Gene Ontology terms, and significant enrichment in 31 terms (p < 0.05). The common DEGs were enriched in 295 pathways and significantly enriched in 26 pathways. Additionally, the expression of lipid-related genes, including fatty acid synthase, superoxide dismutase, fatty acid binding protein 5, carnitine palmytoyltransferase 1 A, and peroxisome proliferator-activated receptor A were verified via quantitative reverse-transcription polymerase chain reaction. In conclusion, dietary xylanase supplementation was found to reduce subcutaneous fat deposition in Tibetan sheep, likely through modulating the expression of lipid-related genes.

Insight into the differences of meat quality between Qinghai white Tibetan sheep and black Tibetan sheep from the perspective of metabolomics and rumen microbiota.

The purpose of this study was to investigate the differences in meat quality between two local breeds of Tibetan sheep, the White Tibetan sheep and the Black Tibetan sheep in Qinghai, and to search for metabolic mechanisms that produce meat quality differences by analyzing differential metabolites and key rumen microorganisms. The meat quality results showed that one breed, SG73, was superior to the other (WG). Further investigation identified differences in the composition of muscle metabolites and rumen microorganisms between the two Tibetan sheep breeds. It also regulates muscle tenderness, water retention, fat content and the composition and content of AA and FA through two major metabolic pathways, AA metabolism and carbohydrate metabolism. These findings could be beneficial for the development of breeding strategies for Tibetan sheep in Qinghai in the future.

Exploring the effects of palm kernel meal feeding on the meat quality and rumen microorganisms of Qinghai Tibetan sheep.

Palm kernel meal (PKM) has been shown to be a high-quality protein source in ruminant feeds. This study focused on the effects of feed, supplemented with different amounts of PKM (ZL-0 as blank group, and ZL-15, ZL-18, and ZL-21 as treatment group), on the quality and flavor profile of Tibetan sheep meat. Furthermore, the deposition of beneficial metabolites in Tibetan sheep and the composition of rumen microorganisms on underlying regulatory mechanisms of meat quality were studied based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry as well as 16S rDNA sequencing. The results of the study showed that Tibetan sheep in the ZL-18 group exhibited superior eating quality and flavor profile while depositing more protein and fat relative to the other groups. The ZL-18 group also changed significantly in terms of the concentration and metabolic pathways of meat metabolites, as revealed by metabolomics. Metabolomics and correlation analyses finally showed that PKM feed mainly affected carbohydrate metabolism in muscle, which in turn affects meat pH, tenderness, and flavor. In addition, 18% of PKM increased the abundance of Christensenellaceae R-7 group, Ruminococcaceae UCG-013, Lachnospiraceae UCG-002, and Family XIII AD3011 group in the rumen but decreased the abundance of Prevotella 1; the above bacteria groups regulate meat quality by regulating rumen metabolites (succinic acid, DL-glutamic acid, etc.). Overall, the addition of PKM may improve the quality and flavor of the meat by affecting muscle metabolism and microorganisms in the rumen.

Determination of the relationship between class IV sirtuin genes and growth traits in Chinese black Tibetan sheep.

Class IV sirtuin (SIRT6 and SIRT7) played essential roles in biometabolism processes via deacetylating specific transcription factors. The present study was conducted to search for mutations in SIRT6/7 and determine their associations with growth traits in black Tibetan sheep. Via DNA sequencing methods, three single-nucleotide polymorphisms (SNPs) were identified in 427 ewes, including a mutation (g.3724C > T) in the intron 1 of SIRT6 and two mutations (g.3668G > T and g.4223C > G) in SIRT7 intron 6 and 8, respectively. Based on the χ2 test, both g.3724C > T and g.4223C > G loci fitted with Hardy-Weinberg equilibrium (p > 0.05). Compared with animals with genotype TT, the CC genotype at g.3724C > T locus (SIRT6) exhibited the highest mean for body weight (p < 0.05) and heart girth (p < 0.05). At g.3668G > T locus (SIRT7), individuals carrying the GG genotype tended to have heavier body weight than those of TT genotype (p < 0.05). With the exception of body weight, body measurement traits not affected by combinative genotype (p > 0.05). Our results could be used as genetic markers for marker-assisted selection and maybe guide sheep breeding in economic traits.

RNA-Seq revealed the effect of adding different proportions of wheat diet on fat metabolism of Tibetan lamb.

The objective of this study was to evaluate the effect of the level of wheat substitution for corn on the fat metabolism of Tibetan lamb. A total of 90 Tibetan lambs [body weight (BW) of 19.78 ± 2.45 kg] were arranged with three substitution levels of wheat: WC (100 % corn), WL (10 % wheat substitution for corn), and WH (15 % wheat substitution for corn) on a dry matter basis. After the experiment, cry section technology was used to scrutinize the subcutaneous adipose tissue morphology, and genes related to fat metabolism were excavated using high-throughput sequencing technology. According to the study results, fat diameter and fat biovolume of the WL and WH groups were less than the WC group. A total of 506 differentially expressed genes (DEGs) were identified by RNA sequencing (RNA-Seq) technology. Compared with the WC group, 66 DEGs were upregulated and 59 DEGs were downregulated in the WL group, and 179 DEGs were upregulated and 269 DEGs were downregulated in the WH group. The top 20 DEGs were analyzed by Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathway, indicating significant differences in the fat metabolism pathway. Five DEGs were randomly screened for quantitative reverse transcription-polymerase chain reaction (qRT-PCR) verification, and the results were consistent with the RNA-Seq results, which proved the accuracy of sequencing. In summary, with the increase in the proportion of supplemental wheat, the fat cells became smaller, and the genes related to fat decomposition were significantly upregulated.

Metabolomics approach reveals high energy diet improves the quality and enhances the flavor of black Tibetan sheep meat by altering the composition of rumen microbiota.

This study aims to determine the impact of dietary energy levels on rumen microbial composition and its relationship to the quality of Black Tibetan sheep meat by applying metabolomics and Pearson's correlation analyses. For this purpose, UHPLC-QTOF-MS was used to identify the metabolome, whereas 16S rDNA sequencing was used to detect the rumen microbiota. Eventually, we observed that the high energy diet group (HS) improved the carcass quality of Black Tibetan sheep and fat deposition in the longissimus lumborum (LL) compared to the medium energy diet group (MS). However, HS considerably increased the texture, water holding capacity (WHC), and volatile flavor of the LL when compared to that of MS and the low energy diet group (LS). Metabolomics and correlation analyses revealed that dietary energy levels mainly affected the metabolism of carbohydrates and lipids of the LL, which consequently influenced the content of volatile flavor compounds (VOCs) and fats. Furthermore, HS increased the abundance of Quinella, Ruminococcus 2, (Eubacterium) coprostanoligenes, and Succinivibrionaceae UCG-001, all of which participate in the carbohydrate metabolism in rumen and thus influence the metabolite levels (stachyose, isomaltose, etc.) in the LL. Overall, a high-energy diet is desirable for the production of Black Tibetan sheep mutton because it improves the mouthfeel and flavor of meat by altering the composition of rumen microbiota, which influences the metabolism in the LL.

Effects of different feeding regimes on muscle metabolism and its association with meat quality of Tibetan sheep.

This study aimed to explore the effects of different feeding regimes on muscle metabolism and its association with meat quality of Tibetan sheep through correlation analysis of meat quality and differential metabolites using untargeted and targeted metabolomics. The untargeted metabolome was detected by UHPLC-QTOF-MS, and the targeted metabolome was detected by UHPLC-QQQ-MS (amino acids) and GC-MS (fatty acids). Based on the researched results, the nutritional quality of meat, including the content of protein and fat and the edible quality of meat, including tenderness, water holding capacity (WHC), texture, and flavor of Tibetan sheep were superior in the stall-feeding group (GBZ) than in the traditional grazing group (CBZ). In the GBZ group, the key upregulated metabolites and metabolic pathways were dominated by essential amino acids (EAAs) and amino acid metabolism as well as the key downregulated metabolites and metabolic pathways were dominated by polyunsaturated fatty acids (PUFA) and lipid metabolism. Correlation analysis showed that there was a significant correlation between the results of untargeted metabolomics and some phenotypic data, including shear force, cooking loss, drip loss, chewiness, elasticity, flavor, and the content of protein and fat. Taken together, stall-feeding would be appropriate for the production of Tibetan mutton, offering better mouthfeel and higher nutrition by altering the muscle metabolism and increasing the beneficial compound deposition in the muscle.

Metabolome and microbiome analysis revealed the effect mechanism of different feeding modes on the meat quality of Black Tibetan sheep.

Introduction: Black Tibetan sheep is one of the primitive sheep breeds in China that is famous for its great eating quality and nutrient value but with little attention to the relationship between feeding regimes and rumen metabolome along with its impact on the muscle metabolism and meat quality. Methods: This study applies metabolomics-based analyses of muscles and 16S rDNA-based sequencing of rumen fluid to examine how feeding regimes influence the composition of rumen microbiota, muscle metabolism and ultimately the quality of meat from Black Tibetan sheep. Twenty-seven rams were randomly assigned to either indoor feeding conditions (SG, n = 9), pasture grazing with indoor feeding conditions (BG, n = 9) or pasture grazing conditions (CG, n = 9) for 120 days. Results: The results showed that, compared with BG and CG, SG improved the quality of Black Tibetan sheep mutton by preventing a decline in pH and increasing fat deposition to enhance the color, tenderness and water holding capacity (WHC) of the Longissimus lumborum (LL). Metabolomics and correlation analyses further indicated that the feeding regimes primarily altered amino acid, lipid and carbohydrate metabolism in muscles, thereby influencing the amino acid (AA) and fatty acid (FA) levels as well as the color, tenderness and WHC of the LL. Furthermore, SG increased the abundance of Christensenellaceae R-7 group, [Eubacterium] coprostanoligenes group, Methanobrevibacter, Ruminococcus 2 and Quinella, decreased the abundance of Lactobacillus, Prevotella 1 and Rikenellaceae RC9 gut group, and showed a tendency to decrease the abundance of Succinivibrio and Selenomonas 1. Interestingly, all of these microorganisms participated in the deposition of AAs and FAs and modified the levels of different metabolites involved in the regulation of meat quality (maltotriose, pyruvate, L-ascorbic acid, chenodeoxycholate, D-glucose 6-phosphate, glutathione, etc.). Discussion: Overall, the results suggest that feeding Black Tibetan sheep indoors with composite forage diet was beneficial to improve the mouthfeel of meat, its color and its nutritional value by altering the abundance of rumen bacteria which influenced muscle metabolism.

Effect of Different Heat Treatments on the Quality and Flavor Compounds of Black Tibetan Sheep Meat by HS-GC-IMS Coupled with Multivariate Analysis.

There are limited reports about the effect of different heat treatments on the quality and flavor of Black Tibetan sheep meat. The current study examined the effect of pan-frying, deep-frying, baking, and boiling treatment on the quality of Black Tibetan sheep meat; the amino acid, fatty acid, and volatile flavor compounds (VFCs) were investigated by a texture analyzer, ultra-high-performance liquid chromatography (UHPLC), gas chromatography (GC), and headspace-gas chromatography-ion mobility (HS-GC-IMS). The key VFCs were identified through orthogonal partial least squares discrimination analysis (OPLS-DA), and variable importance projection (VIP) values. In addition, Pearson's correlations between meat quality parameters and key VFCs were examined. The sensory scores, including texture, color, and appearance, of baked and pan-fried meat were higher than those of deep-fried and boiled meat. The protein (40.47%) and amino acid (62.93 µmol/g) contents were the highest in pan-fried meat (p < 0.05). Additionally, it contained the highest amounts of monounsaturated and polyunsaturated fatty acids, such as oleic, linoleic, and α-linolenic acids (p < 0.05). Meanwhile, pan-fried and deep-fried meat had higher amounts of VFCs than baked meat. The OPLS-DA similarity and fingerprinting analyses revealed significant differences between the three heat treatment methods. Aldehydes were the key aroma compounds in pan-fried meat. Importantly, 3-methylbutyraldehyde and 2-heptanone contents were positively correlated with eicosenoic, oleic, isooleic, linoleic, α-Linolenic, and eicosadiene acids (p < 0.05). To sum up, pan-fried Black Tibetan sheep meat had the best edible, nutritional, and flavor quality.

Altered milk yield and rumen microbial abundance in response to concentrate supplementation during the cold season in Tibetan sheep

BACKGROUND Weight loss and decline of milk yield in Tibetan sheep was a challenge for the dairy industry in Qinghai-Tibet Plateau, which were considered to be caused by underfeeding of the sheep during the harsh winter. The objective of this study was to assess the role of feed supplementation in the milk performance and rumen microbiome of ewes under forage-based diets. Based on parity, milking period, milk yield, and body weight, ten 1.5-yr-old ewes were allocated randomly into two groups. One group of ewes was fed no supplement Control group (CON) and the other group was fed with concentrate feed supplement (Treatment group, T). Individual milk yield was determined daily; both the milk composition and rumen bacterial characteristics were analyzed after the end of feeding trials. RESULTS Results showed that lactose in the milk of the CON group was significantly lower (P < 0.05) than that of the T group at days 30 and 60. Milk yield in the T group was greater than in the CON group at day 30 (P < 0.05). Additionally, the dominant ruminal bacteria (phyla Bacteroidetes, Firmicutes, and Verrucomicrobia) were shared by both groups through 16S rRNA gene pyrosequencing. Greater relative abundance of Bacteroidales RF16 group in family level, Victivallales in order level, Lentisphaeria in class level, and Lachnospiraceae bacterium in species level were observed in the T group than in the CON group (P < 0.05). CONCLUSIONS These results demonstrated that supplementation of concentrate in the cold season improved milk lactose yield and milk production, and the rumen microbial abundance of Tibetan sheep.

Variations in the insulin receptor substrate 1 (IRS1) and its association with growth traits in Chinese black Tibetan sheep (Ovis aries).

This paper presented the results on the study of insulin receptor substrate 1 (IRS1) polymorphisms in Chinese black Tibetan sheep. Via DNA direct sequencing, four variations within 3' untranslated region (UTR) of IRS1, including g.9382T > G, g.9569T > G, g.9572C > T and g.9695A > C were detected in the black Tibetan sheep population. Based on the χ2 test, those four loci deviated from Hardy-Weinberg equilibrium (p < 0.05). In g.9569T > G locus, genotype of GG possessed advantage on body weight (p < 0.05). In g.9572C > T locus, individuals with genotype of TT homozygous mutation decreased significantly on body weight, withers height, body length and chest circumference (p < 0.05 or p < 0.01). In g.9695A > C locus, the body weight and chest circumference were also higher in AA carriers than in CC carriers (p < 0.05). Our results provided evidence that polymorphisms in IRS1 were associated with growth efficiency traits by quantitative genetic analysis, and may be used for marker-assisted selection in Chinese indigenous sheep.

Association between Single Nucleotide Polymorphisms in SIRT1 and SIRT2 Loci and Growth in Tibetan Sheep.

Silent information regulator 1 and 2 (SIRT1, 2) were NAD+-dependent histone or non-histone deacetylase, which emerged as key metabolic sensors in several tissues of mammals. In the present study, the search for polymorphisms within the ovine SIRT1 and SIRT2 loci as well as association analyses between SNPs and growth-related traits were performed in Tibetan sheep. To determine the expression pattern of SIRT1 and SIRT2 genes in Tibetan sheep, the quantitative real-time polymerase chain reaction (qPCR) analysis revealed that those two genes were widely expressed in diverse tissues. Expression of SIRT1 was less in abomasum of lamb, whereas it was greater in duodenum within adult stage. In the case of SIRT2, the greatest expression was observed in reticulum (lamb) and in muscle (adult), whereas the least expression was in liver for lamb and in kidney for adult animals. The association analysis demonstrated that g.3148 C > T polymorphism of SIRT1 affected heart girth (p = 0.002). The g.8074 T > A SNP of SIRT2 had a significant correlation with body weight (p = 0.011) and body length (p = 0.008). These findings suggested that the SIRT1 and SIRT2 polymorphism was involved in growth-related traits in Tibetan sheep, which may be considered to be genetic markers for improving the growth traits of Tibetan sheep.

Dual-cross-linked dynamic hydrogels with cucurbit[8]uril and imine linkages.

The strategy of dual cross-linking was investigated by enhancing the performance of dynamic hydrogels. To this end, phenylalanine modified ε-polylysine was synthesized and employed as the polymer backbone of hydrogels. The phenylalanine moieties and amine groups of the polymer could be cross-linked with cucurbit[8]uril (CB[8]) and the dialdehyde cross-linker, respectively. Single CB[8] linkage with fast dynamics led to an increase in the viscosity of the polymer solution, and single imine linkage with slow dynamics led to the formation of weak and brittle hydrogels. However, the two linkages were combined together to form a dual-cross-linked hydrogel and the performance of the hydrogel could be well enhanced. Compared with the single imine cross-linked hydrogel, the dual-cross-linked hydrogel demonstrated a higher mechanical strength, better extensibility and faster self-healing rate. It is anticipated that this line of research could provide a useful method to enhance the performance of dynamic hydrogels.

Tunable Fluorescence-Responsive Double Hydrophilic Block Polymers Induced by the Formation of Pseudopolyrotaxanes with Cucurbit[7]Uril.

There is an urgent need for new strategies that allow the simultaneous detection and control of drug delivery. By making use of supramolecular host-guest interactions, a kind of pseudopolyrotaxanes, as a visualizable nanoscale drug carrier has been constructed by self-assembly of cucurbit[7]uril (CB[7]) with methoxy poly(ethylene glycol)-block-quaternized poly(4-vinyl pyridine) (mPEG-b-QP4VP) using 4-(chloromethyl)benzonitrile. Simple addition of CB[7] into an aqueous solution of mPEG-b-QP4VP resulted in noncovalent attachment of CB[7] to 4-cyanobenzyl-containing polymers, transforming the nonemissive mPEG-b-QP4VP micelles into highly fluorescent micelles. These pseudopolyrotaxanes micelles exhibited remarkable supramolecular assembly-induced emission enhancement and excellent biocompatibility, showing great potential for bioimaging applications. In addition, the efficient cellular uptake of the developed pseudopolyrotaxanes micelles loaded with the anticancer drug doxorubicin was a promising platform for simultaneous cell imaging and drug delivery, thereby widening their application in cancer theranostics.