- Invited Review - Understanding the functionality of the rumen microbiota: searching for better opportunities for rumen microbial manipulation.

Rumen microbiota play a central role in the digestive process of ruminants. Their remarkable ability to break down complex plant fibers and proteins, converting them into essential organic compounds that provide animals with energy and nutrition. Research on rumen microbiota not only contributes to improving animal production performance and enhancing feed utilization efficiency but also holds the potential to reduce methane emissions and environmental impact. Nevertheless, studies on rumen microbiota face numerous challenges, including complexity, difficulties in cultivation, and obstacles in functional analysis. This review provides an overview of microbial species involved in the degradation of macromolecules, the fermentation processes, and methane production in the rumen, all based on cultivation methods. Additionally, the review introduces the applications, advantages, and limitations of emerging omics technologies such as metagenomics, metatranscriptomics, metaproteomics, and metabolomics, in investigating the functionality of rumen microbiota. Finally, the article offers a forward-looking perspective on the new horizons and technologies in the field of rumen microbiota functional research. These emerging technologies, with continuous refinement and mutual complementation, have deepened our understanding of rumen microbiota functionality, thereby enabling effective manipulation of the rumen microbial community.

The epithelial transcriptome and mucosal microbiota are altered for goats fed with a low-protein diet.

Introduction: Feeding low protein (LP) diet to animals impose severe challenge to animals' immune homeostasis. However, limited knowledge about the underlying adaption mechanism of host and ruminal microbiota responding to LP diet were well understood. Herein, this study was performed to examine the changes in relative abundance of ruminal microbiota and host ruminal mucosal transcriptome profiles in response to a LP diet. Methods: A total of twenty-four female Xiangdong balck goats with similar weight (20.64 ± 2.40 kg) and age (8 ± 0.3 months) were randomly assigned into two groups, LP (5.52% crude protein containing diet) and CON (10.77% crude protein containing diet) groups. Upon completion of the trial, all goats were slaughtered after a 16-hour fasting period in LiuYang city (N 28°15', E 113°63') in China. HE staining, free amino acids measurement, transcriptome analysis and microbiome analysis were applied to detect the morphology alterations, free amino acids profile alterations and the shift in host ruminal mucosal transcriptome and ruminal microbiota communities. Results: Firstly, the results showed that feeding LP diet to goats decreased the rumen papilla width (P = 0.043), surface area (P = 0.013) and total ruminal free amino acids concentration (P = 0.016). Secondly, microbiome analysis indicated that 9 microbial genera, including Eubacterium and Prevotella, were enriched in LP group while 11 microbial genera, including Butyrivibrio and Ruminococcus, were enriched in CON group. Finally, in terms of immune-related genes, the expression levels of genes involved in tight junction categories (e.g., MYH11, PPP2R2C, and MYL9) and acquired immunity (e.g., PCP4 and CXCL13) were observed to be upregulated in the LP group when compared to the CON group. Conclusion: Under the LP diet, the rumen exhibited increased relative abundance of pathogenic microbiota and VFA-degrading microbiota, leading to disruptions in immune homeostasis within the host's ruminal mucosa. These findings indicate that the ruminal microbiota interacts with host results in the disruption in animals' immune homeostasis under LP diet challenge.

Amino acid profiles, amino acid sensors and transporters expression and intestinal microbiota are differentially altered in goats infected with Haemonchus contortus.

Infection with the nematode Haemonchus contortus causes host malnutrition and gastrointestinal injuries. The objective of this study was to investigate the effects of H. contortus infection on gastrointestinal contents of free amino acids (AA), the expression of AA transporters and microbiota with a focus on amino acid metabolism. Twenty-four Xiangdong black goats (13 ± 1.5 kg, 6 months old) were randomly assigned into the control group (n = 8) and the infected group (n = 16). The results showed that H. contortus infection increased (P < 0.05) the free AA contents in jejunum and ileum digesta. The concentrations of blood threonine, phenylalanine and tyrosine were lower (P < 0.05) in the infected group as compared to the control group. In the jejunum and ileum epithelium, H. contortus infection significantly (P < 0.05) down-regulated the expression of AA transporter b0,+AT/rBAT and B0AT1, but up-regulated (P < 0.05) the expression of transporter CAT2 and xCT. Furthermore, microbiota in both jejunum (Bifidobacteriaceae, Lachnospiraceae, Bacteroidaceae, Enterobacteriaceae, and Micrococcaceae) and ileum (Acidaminococcaceae, Desulfovibrionaceae, Bacteroidaceae, and Peptostreptococcaceae) were also altered at the family level by H. contortus infection. The  commensal bacteria of jejunum showed a close correlation with amino acids, AA transporters, and amino acid metabolism, especially cystine. In conclusion, H. contortus infection affected the intestinal AA contents and the expression of intestinal AA transporters, suggesting altered AA metabolism and absorption, which were accompanied by changes in the relative abundances of gut bacteria that mediate amino acid metabolism.

Replacing ZnSO4 with Zn-glycine in the diet of goat promotes the pancreatic function of the offspring.

Zinc supplementation in the diet of goats affects pancreas development in offspring. However, the impact of maternal inorganic and organic zinc supplementation in offspring is poorly defined. In this study, 14 late-pregnant goats were assigned at random to the zinc sulfate group (ZnSO4, n = 7) and the zinc-glycine chelate group (Zn-Gly, n = 7), respectively. Serum samples and pancreas tissue were collected from kids whose mothers were fed ZnSO4 and Zn-Gly at the late pregnancy, respectively. Histologic examination showed no morphologic differences between the 2 groups. Pancreatic zinc content in kids tended to be increased when replacing ZnSO4 with Zn-Gly. The serum insulin concentration was greater and glucagon less in the Zn-Gly group when compared to the ZnSO4 group. The activities of lipase and chymotrypsin were enhanced when replacing ZnSO4 with Zn-Gly. Proteomics results showed that 234 proteins were differentially expressed between the 2 groups, some of which were associated with the secretion of insulin, enzyme activity and signal transduction. The results suggested that supply of dietary Zn-Gly to goats during late pregnancy promoted pancreatic function in offspring compared with dietary ZnSO4 supplementation. This provides new information about pancreatic function when supplementing different zinc sources in the diets of late pregnant goats.

Alterations in nutrient digestibility and performance of heat-stressed dairy cows by dietary L-theanine supplementation.

The purpose of this study was to investigate the effects of dietary L-theanine supplementation on apparent nutrient digestibility, milk yield, milk composition, and blood biochemical indices of dairy cows under heat stress. Thirty Chinese Holstein cows (19.84 ± 2.42 kg milk/d, 192.36 ± 40.77 d in milk and 2 ± 0.93 parities) were divided into 3 groups of 10 animals each. The control group was fed a basal total mixed ration (TMR) diet, while treatment 1 (LTA16) and treatment 2 (LTA32) groups were fed a basal TMR diet supplemented with L-theanine at 16 and 32 g/cow per day, respectively. The results showed that feeding the dairy cows with LTA16 treatment decreased (P < 0.05) their rectal temperature, whereas feeding with LTA32 treatment decreased (P < 0.05) their rumen fluid ammonia nitrogen content. In comparison to the control group, the supplementation of L-theanine had no significant effect (P > 0.05) on the dry matter intake, nutrient digestibility, total volatile fatty acid (TVFA) concentration and molar proportion of volatile fatty acid, milk yield, milk composition, feed efficiency and antioxidant capacity of the dairy cows. The triglyceride (TG) content of the LTA32 group was significantly greater (P = 0.014) than that of the control group. With the increase in L-theanine dosage, the serum cholesterol (CHOL) content significantly increased (P = 0.013). The serum albumin (ALB; P = 0.067), low-density lipoprotein cholesterol (LDL-C; P = 0.053), and high-density lipoprotein cholesterol (HDL-C; P = 0.067) contents showed an upward trend as L-theanine dosage increased. Ultimately, the results of this study show that supplementing dairy cow diet with L-theanine could decrease dairy cow rectal temperature, affect lipid metabolism, and potentially relieve the heat stress of dairy cows to some extent.

Elucidating the underlying mechanism of amino acids to regulate muscle protein synthesis: Effect on human health.

Maintaining muscle quality throughout life is crucial to human health and well-being. Muscle is the most extensive form of protein storage in the human body; skeletal muscle mass is determined by the balance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). MPB provides amino acids needed by various organs; however, excessive MPB, especially with aging, may cause loss of muscle mass and a decline in motor function, even threatening life. The turnover of muscle protein is vital to the health of humans. Thus, although the study of MPS and MPB has theoretical and practical significance, the network that controls MPS is very complicated and we cannot discuss both MPS and MPB in a single review. Therefore, the aim of this review is to discuss the regulation of MPS, especially by amino acids. Amino acids regulate protein synthesis in cell and animal models, but compelling evidence for amino acids promoting protein synthesis in human muscles is ambiguous. Studies on the stimulation of human MPS by branched-chain amino acids (BCAAs) have been inconsistent. Amino acids other than BCAAs such as threonine and tryptophan may also have MPS-stimulating effects, and alternatives to BCAAs, such as ß-hydroxy-ß-methyl butyrate and branched-chain keto acids are also worthy of further investigation. Amino acids coordinate protein synthesis and degradation through the mechanistic target of rapamycin complex 1 (mTORC1); however, the amino acid-mTORC1-protein synthesis pathway is complex, and new insights into amino acid control continue to emerge. Understanding how amino acids control MPS is of forward-looking significance for treating muscle mass loss during human aging.

Lipid metabolism and m6A RNA methylation are altered in lambs supplemented rumen-protected methionine and lysine in a low-protein diet.

BACKGROUND: Methionine or lysine has been reported to influence DNA methylation and fat metabolism, but their combined effects in N6-methyl-adenosine (m6A) RNA methylation remain unclarified. The combined effects of rumen-protected methionine and lysine (RML) in a low-protein (LP) diet on lipid metabolism, m6A RNA methylation, and fatty acid (FA) profiles in the liver and muscle of lambs were investigated. Sixty-three male lambs were divided into three treatment groups, three pens per group and seven lambs per pen. The lambs were fed a 14.5% crude protein (CP) diet (adequate protein [NP]), 12.5% CP diet (LP), and a LP diet plus RML (LP + RML) for 60 d. RESULTS: The results showed that the addition of RML in a LP diet tended to lower the concentrations of plasma leptin (P = 0.07), triglyceride (P = 0.05), and non-esterified FA (P = 0.08). Feeding a LP diet increased the enzyme activity or mRNA expression of lipogenic enzymes and decreased lipolytic enzymes compared with the NP diet. This effect was reversed by supplementation of RML with a LP diet. The inclusion of RML in a LP diet affected the polyunsaturated fatty acids (PUFA), n-3 PUFA, and n-6 PUFA in the liver but not in the muscle, which might be linked with altered expression of FA desaturase-1 (FADS1) and acetyl-CoA carboxylase (ACC). A LP diet supplemented with RML increased (P < 0.05) total m6A levels in the liver and muscle and were accompanied by decreased expression of fat mass and obesity-associated protein (FTO) and alkB homologue 5 (ALKBH5). The mRNA expressions of methyltransferase-like 3 (METTL3) and methyltransferase-like 14 (METTL14) in the LP + RML diet group were lower than those in the other two groups. Supplementation of RML with a LP diet affected only liver YTH domain family (YTHDF2) proteins (P < 0.05) and muscle YTHDF3 (P = 0.09), which can be explained by limited m6A-binding proteins that were mediated in mRNA fate. CONCLUSIONS: Our findings showed that the inclusion of RML in a LP diet could alter fat deposition through modulations of lipogenesis and lipolysis in the liver and muscle. These changes in fat metabolism may be associated with the modification of m6A RNA methylation. A systematic graph illustrates the mechanism of dietary methionine and lysine influence on lipid metabolism and M6A. The green arrow with triangular heads indicates as activation and brown-wine arrows with flat heads indicates as suppression.

Developmental Alterations of Colonic microRNA Profiles Imply Potential Biological Functions in Kid Goats.

The colon is a crucial digestive organ of the hind gut in ruminants. The bacterial diversity and mucosal immune maturation in this region are related to age. However, whether the microRNA expression in the colon of goats is affected by age is still unclear. In the current study, we analyzed the transcriptomes of colon microRNAs during preweaning (Day 10 and Day 25) and postweaning (Day 31). A total of 1572 microRNAs were identified in the colon tissues. Of these, 39 differentially expressed microRNAs (DEmiRNAs) and 88 highly expressed microRNAs (HEmiRNAs) were screened. The target genes regulated by the DEmiRNAs and HEmiRNAs were commonly enriched in the MAPK signaling pathway, Wnt signaling pathway, Hippo signaling pathway, cell adhesion molecules, focal adhesion, and adherens junction. Remarkably, the targeted genes of the DEmiRNAs were highly enriched for the prevention of microbial invasion via the Erbb-MAPK network while the targeted genes of HEmiRNAs contributed to the permeable barrier maintenance and cell damage surveillance. Additionally, there were eight different expression profiles of 87 dynamic miRNAs, in which approximately half of them were affected by age. Taken together, our study reveals the different roles of DEmiRNAs, HEmiRNAs, and dynamic microRNAs in the development of the colon and gives new insights into the regulatory mechanism of colon development in goats.

Effects of maternal feed intake restriction on the blood parameters, fatty acid profile and lipogenetic genes expression of perirenal fat in offspring kids.

Maternal nutritional restriction impacted lipogenic gene expression in adipose tissue of offspring, but the association of this programming with DNA methylation is not yet clear. Therefore, this experiment aimed to investigate the effects of maternal feed intake restriction on offsprings' blood indexes, lipid metabolism of perirenal adipose tissue (PAT) and DNA methylation of lipogenic genes. Blood and PAT were collected from the fetuses (at d 100 of gestation) and kids (at d 90 after birth). Maternal undernutrition (at d 45 to d 100) decreases heart and kidney weight of kid goats after birth. Maternal undernutrition decreased the content of leptin in the umbilical cord blood of fetuses. The expression of uncoupling protein 1 (UCP1) was decreased in fetal PAT of the restriction group, but fatty acid synthetase (FASN) was increased. Protein abundance of UCP1 and FASN was down-regulated in the fetal PAT from the restriction group. Furthermore, only the methylation level of the CpG site (from -756 to -757 bp) in the promoter region of FASN gene was increased for the fetal PAT from the restriction group. These results revealed that maternal feed intake restriction influenced the leptin secretion, changed the expression of FASN and UCP1 gene of fetal PAT. This alteration was able to recover in the kids after removing intake restriction, but the growth performance and visceral organ mass were still impaired, suggesting abnormal fat metabolism may happen in the future.

Effects of substituting soybean meal with corn on immune function and gene expression of gut TLR4 pathway of growing goats.

BACKGROUND: Protein malnutrition remains a severe problem in ruminant production and can increase susceptibility to infection, especially during the growth stage. This study aimed to explore substituting soybean meal with corn on activation of the TLR pathway and potential impact on immune response bias towards Type 1 or Type 2 using growing female goats as experimental animals. METHODS: Twenty-four Xiangdong black goats (initial BW = 19.83 ± 0.53 kg, about 8 ± 0.3 months old) were selected and randomly divided into the corn-soybean meal basal diet group (CON, 10.77% protein) and replacing soybean meal with 100% of corn group (CRS, 5.52% protein). EDTA whole blood and serum samples were collected prior to slaughter for determinations of blood cell counts, anti-inflammatory cytokines and antibodies. The duodenum, jejunum, ileum and colon tissues were collected after formal trial to study the effect of CRS diet on the expression of TLR4 pathway. RESULTS: Our results showed CRS diet did not induce a significant change in immune function, as evidenced by the observations that white blood cell (WBC), neutrophil (Neu), lymphocyte (Lym), monocyte (Mon), eosinophil (Eos), interleukin-4 (IL-4), IL-5, IL-13, immunoglobin G (IgG), IgA, and IgM levels in serum were similar between the two groups. RT-PCR results showed the expression of tumor necrosis factor-α (TNF-α) (P < 0.01) and interferon-ß (IFN-ß) (P < 0.01) were up-regulated in the colon of goats in the CRS group. No differences in the expression of myeloid differentiation factor 88 (MyD88) adaptor-like protein (TIRAP), IL-1 receptor-associated kinase 1 (IRAK1), TNF receptor related factor 6 (TRAF6), NF-kappa B (NF-κB), mitogen-activated protein kinase 1 (MAPK1) or activator protein-1 (AP-1) in the TLR4/MyD88 dependent pathway were observed between the two groups for any of the tested tissue. However, the expression of NF-κB activator (TANK) binding kinase 1 (TBK1) in TLR4/MyD88 independent pathway was up-regulated in the duodenum and colon (P < 0.01), and the expression of interferon regulatory factor-3 (IRF3) was up-regulated (P < 0.01) in colon. CONCLUSIONS: Our results suggested that the CRS diet failed to induce a significant change in innate immunity and adaptive immunity in growing goats. However, the up-regulated TBK1 and IRF3 in the colon from the CRS goats suggests that the CRS diet may induce the expression of Th1-type proinflammatory cytokines and inflammatory response through a TLR4-MyD88-independent pathway, and the colon may be the easiest targeted section in the intestinal tract.

Maternal undernutrition alters the skeletal muscle development and methylation of myogenic factors in goat offspring.

OBJECTIVE: The effects of maternal undernutrition during midgestation on muscle fiber histology, myosin heavy chain (MyHC) expression, methylation modification of myogenic factors, and the mammalian target of rapamycin (mTOR) signaling pathway in the skeletal muscles of prenatal and postnatal goats were examined. METHODS: Twenty-four pregnant goats were assigned to a control (100% of the nutrients requirement, n = 12) or a restricted group (60% of the nutrients requirement, n = 12) between 45 and 100 days of gestation. Descendants were harvested at day 100 of gestation and at day 90 after birth to collect the femoris muscle tissue. RESULTS: Maternal undernutrition increased (p<0.05) the fiber area of the vastus muscle in the fetuses and enhanced (p<0.01) the proportions of MyHCI and MyHCIIA fibers in offspring, while the proportion of MyHCIIX fibers was decreased (p<0.01). DNA methylation at the +530 cytosine-guanine dinucleotide (CpG) site of the myogenic factor 5 (MYF5) promoter in restricted fetuses was increased (p<0.05), but the methylation of the MYF5 gene at the +274,280 CpG site and of the myogenic differentiation (MYOD) gene at the +252 CpG site in restricted kids was reduced (p<0.05). mTOR protein signals were downregulated (p<0.05) in the restricted offspring. CONCLUSION: Maternal undernutrition altered the muscle fiber type in offspring, but its relationship with methylation in the promoter regions of myogenic genes needs to be elucidated.

Maternal intake restriction programs the energy metabolism, clock circadian regulator and mTOR signals in the skeletal muscles of goat offspring probably via the protein kinase A-cAMP-responsive element-binding proteins pathway.

The biological mechanism by which maternal undernutrition increases the metabolic disorder risk of skeletal muscles in offspring is not fully understood. We hypothesize that maternal intake restriction influences metabolic signals in the skeletal muscles of offspring via a glucagon-mediated pathway. Twenty-four pregnant goats were assigned to the control group (100% of the nutrients requirement, n = 12) and restricted group (60% of the control feed allowance from pregnant days 45 to 100, n = 12). Blood and L ongissimus thoracis muscle were sampled from dams (100 d of gestation), fetuses (100 d of gestation), and kids (90 d after birth) in each group. The data were analyzed using the linear MIXED model, with the multiple comparison method of SIDAK applied. Intake restriction reduced (P < 0.05) the total blood protein of dams and fetuses. Maternal restriction decreased (P < 0.05) the cAMP-responsive element-binding protein 1 (CREB1), CREB-binding protein (CREBBP), protein kinase A (PKA), aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1), protein kinase B (AKT1), mammalian target of rapamycin (mTOR), and regulatory-associated protein of mTOR (RPTOR) mRNA expression in the fetuses, and reduced (P < 0.05) the CREBBP, nuclear receptor subfamily 1 group H member 3 (NR1H3), D-box binding PAR bZIP transcription factor (DBP) and PKA mRNA levels in the kids, but increased (P < 0.05) the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1 A) and tuberous sclerosis 2 (TSC2) mRNA levels in the fetuses. The mRNA expression of clock circadian regulator (CLOCK) and TSC2 genes was increased (P < 0.05) in the restricted kids. The protein expression of total PKA and phosphorylated PKA in the restricted fetuses and kids were downregulated (P < 0.05), and the protein expression of total mTOR and phosphorylated mTOR were reduced (P < 0.05) in the restricted fetuses and kids. Maternal intake restriction regulated fat oxidation, protein synthesis, and circadian clock expression in the muscles of the offspring probably via the glucagon-mediated PKA-CREB pathway, which reveals a noteworthy molecular pathway that maternal undernutrition leads to metabolic adaptation of skeletal muscle in offspring.

The Regulatory Mechanism of Feeding a Diet High in Rice Grain on the Growth and microRNA Expression Profiles of the Spleen, Taking Goats as an Artiodactyl Model.

Several researchers have testified that feeding with diets high in rice grain induces subacute ruminal acidosis and increases the risk of gastrointestinal inflammation. However, whether diets high in rice grain affect spleen growth and related molecular events remains unknown. Therefore, the present study was conducted to investigate the effects of feeding a high-concentrate (HC) diet based on rice on the growth and microRNA expression profiles in goat spleen. Sixteen Liuyang black goats were used as an artiodactyl model and fed an HC diet for five weeks. Visceral organ weight, LPS (lipopolysaccharide) concentration in the liver and spleen, and microRNA expression were analyzed. The results showed that feeding an HC diet increased the heart and spleen indexes and decreased the liver LPS concentration (p < 0.05). In total, 596 microRNAs were identified, and twenty-one of them were differentially expressed in the spleens of goats fed with the HC diet. Specifically, several microRNAs (miR-107, miR-512, miR-51b, miR-191, miR-296, miR-326, miR-6123 and miR-433) were upregulated. Meanwhile, miR-30b, miR-30d, miR-1468, miR-502a, miR-145, miR-139, miR-2284f, miR-101 and miR-92a were downregulated. Additionally, their target gene CPPED1, CDK6, CCNT1 and CASP7 expressions were inhibited (p < 0.05). These results indicated that the HC diet promoted the growth of the heart and spleen. The HC diet also regulated the expression of miR-326, miR-512-3p, miR-30b, miR-30d, miR-502a and their target genes (CPPED1, CDK6 and CCNT1) related to the enhancement of splenocyte proliferation. The HC diet also modulated the expression of miR-15b-5p, miR-1468 and miR-92a, related to the suppression of splenocyte apoptosis.

Substitution of ramie (Boehmeria nivea) for alfalfa in improving the carcass and meat quality of Liuyang Black goats.

Ramie (Boehmeria nivea) is noted for the production of a large biomass that has a high protein content and is rich in antioxidants. It may thus serve as a high-quality forage material to replace alfalfa and improve the meat quality of farmed animals. In this study, we evaluated the carcass characteristics and meat quality of goats when 0, 35%, 75%, and 100% of dietary alfalfa was replaced with ramie. Crude protein content (linear, P < 0.0001) and key muscle color values at 24 h after slaughter decreased with increasing ramie levels. The content of most individual amino acids, non-essential amino acids (NEAA), total amino acids (TAA), branched chain amino acids (BCAA), functional amino acids (FAA), and flavor amino acids (DAA) decreased (P < 0.05) with increasing dietary ramie. The diet in which 35% of alfalfa was replaced with ramie yielded meat with the highest amino acid content, whereas the fatty acid profile was unaffected by the inclusion of ramie. These results indicate that ramie could be used as a potential dietary forage resource for goats, and that substituting 35% of alfalfa with ramie, which is equivalent to 126 g/kg DM content, would be optimal in terms of goat meat quality.

Transcriptome analysis reveals liver metabolism programming in kids from nutritional restricted goats during mid-gestation.

BACKGROUND: Maternal nutrient restriction during pregnancy causes a metabolic disorder that threatens the offspring's health in humans and animals. However, the molecular mechanism of how undernutrition affecting hepatic metabolism of fetal or postnatal offspring is still unclear. We aimed to investigate transcriptomic changes of fetal livers in response to maternal malnutrition in goats during mid-gestation and to explore whether these changes would disappear when the nutrition was recovered to normal level during mid-gestation using goats (Capra hircus) as the experimental animals. METHODS: Fifty-three pregnant goats were subjected to a control (100% of the maintenance requirements, CON) or a restricted (60% of the maintenance requirements on day 45 to day 100 of gestation and then realimentation, RES) diet. A total of 16 liver samples were collected from fetal goats on day 100 of gestation and goat kids of postnatal day 90 to obtain hepatic transcriptional profiles using RNA-Seq. RESULTS: Principal component analysis of the hepatic transcriptomes presented a clear separation by growth phase (fetus and kid) rather than treatment. Maternal undernutrition up-regulated 86 genes and down-regulated 76 genes in the fetal liver of the FR group as compared to the FC group. KEGG pathway analysis showed the DEGs mainly enriched in protein digestion and absorption, steroid biosynthesis, carbohydrate digestion and absorption and bile secretion. A total of 118 significant DEGs (fold change > 1.2 and FDR < 0.1) within KR vs. KC comparison was identified with 79 up-regulated genes and down-regulated 39 genes, and these DEGs mainly enriched in the biosynthesis of amino acids, citrate cycle, valine, leucine and isoleucine biosynthesis and carbon metabolism. CONCLUSION: Hepatic transcriptome analysis showed that maternal undernutrition promoted protein digestion and absorption in the fetal livers, while which restrained carbohydrate metabolism and citric acid cycle in the livers of kid goats after realimentation. The results indicate that maternal undernutrition during mid-gestation causes hepatic metabolism programming in kid goats on a molecular level.

Effects of Dietary Zinc-Methionine Supplementation During Pregnancy on the Whole-Genome Methylation and Related Gene Expression in the Liver and Spleen of Growing Goats: a Short Communication.

The effect of replacing inorganic zinc with organic zinc in diets of pregnant goats was investigated on the development of the liver and spleen of offspring. Pregnant goats (n = 14; Xiangdong black goat, local breed) of similar parity and body weight (BW, 37.17 ± 5.28 kg) were selected and divided randomly into two groups: the zinc sulfate group (ZnSO4; n = 7) and the methionine-chelated zinc group (Zn-Met; n = 7). Goats were fed for 45 days (day 106 of gestation to delivery). After delivering, lactating goats were fed a diet without extra zinc supplement. Kid goats were weaned at 2 months of age and both the groups were fed the same diet. All goats were fed a mixed diet and had free access to fresh water. Kid goats were slaughtered on day 100, and the liver and spleen were collected, weighed, and stored in liquid nitrogen for genomic DNA methylation and related gene expression determination. In the Zn-Met group, the liver organ index of kid goats showed an increasing trend (P < 0.10), but the methylation of the whole genome was not affected both in the liver and spleen (P > 0.10). Furthermore, the blood zinc content of the offspring was reduced (P < 0.05), and the expression of genes related to methylation were downregulated (P < 0.05) or showed a downward trend (P < 0.10) in the liver and spleen. These data indicated that goats feeding Zn-Met during pregnancy increased the offspring liver organ index without change in the genomic DNA methylation. It is speculated that the regulation of zinc finger protein Sp3 adjusted by blood zinc indirectly regulated the expression of methylation-related genes in the liver and spleen of the kid goats, thus enhancing the development and function of the immune system of the offspring.

Calcium Homeostasis and Bone Metabolism in Goats Fed a Low Protein Diet.

The objective of this study was to investigate the effects of low-protein diets on blood calcium (Ca) level, bone metabolism, and the correlation between bone metabolism and blood calcium in goats. Twenty-four female Xiangdong black goats with similar body weight (19.55 ± 3.55 kg) and age (8.0 ± 0.3 months) were selected and allocated into two groups: control group (CON, 10.77% protein content) and low-protein group (LP, 5.52% protein content). Blood samples were collected on days 1, 4, 7, 16 and 36 before morning feeding to determine the concentration of calcium (Ca), parathyroid hormone (PTH), bone gla protein (BGP), C-terminal telopeptide of type 1 collagen (CTX-1), bone alkaline phosphatase (BALP), and 1, 25-dihydroxyvitamin D3 [1,25(OH)2D3]. Liver samples were collected to determine the expression of bone metabolism-related genes. There was no difference observed between LP and CON in concentration of plasma Ca or any of bone metabolism markers (P > 0.05). In the liver, the mRNA expression of bone gamma carboxyglutamate protein (BGLAP), alkaline phosphatase (ALPL), and mothers against decapentaplegic homolog-1 (SMAD1) were increased (P < 0.05) in LP as compared with CON. The correlation analysis of Ca and bone metabolism markers showed no significant correlation between Ca and bone metabolism. These results suggest that the blood Ca concentration in mature goats may keep at a stable level through nitrogen cycling when the providing protein is not enough.

Novel Linkages Between Bacterial Composition of Hindgut and Host Metabolic Responses to SARA Induced by High-Paddy Diet in Young Goats.

At present, feeding a high-corn diet to goats is used to provide enough protein and energy supply to meet their higher dietary requirements. In fact, because corn grain is commonly scarce in the traditional rice cropping region of southern Asia, paddy is thereby used as an alternative feed applied in goat diets. However, the effects of the high paddy proportion on the microbiota and metabolites of the intestine are unclear. Here, we investigate the effects of high paddy proportion on bacterial community, potential function, and metabolic reaction in the cecum of goats. Sixteen Liuyang black goats were divided into two groups fed either a normal-paddy (NP) diet (55% concentrate) or a high-paddy (HP) diet (90% concentrate) for 5 weeks. Total short-chain fatty acid (SCFA) concentration was higher in the hindgut chyme of the HP-fed goats than in that of the NP-fed goats (p = 0.001). The acetic proportion was significantly decreased and the propionic proportion was increased in the HP group (p < 0.05). The HP diet decreased the value of pH, lactic acid concentration, and lactate dehydrogenase activity but increased the activity of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and amylase, together with lipopolysaccharide concentration in the hindgut chyme of goats (p < 0.05). The abundance rates of the Eubacterium_coprostanoligenes_group was increased (p = 0.050), whereas the abundance of Prevotellaceae_UCG_004, dgA-11_gut_group, Christensenellaceae_R-7_group, Ruminococcaceae_UCG-010, and Desulfovibrio were significantly decreased with the HP diet (p < 0.05). These results suggested that the HP diet altered the microbiota and metabolites, which negatively modified intestinal epithelial health in goats.

Diet with a High Proportion of Rice Alters Profiles and Potential Function of Digesta-Associated Microbiota in the Ileum of Goats.

Effects of a high proportion of concentrate in the diet on the ileal microbiota and metabolites in small ruminants are rarely reported. This study was designed to investigate the ileal microbiota and its relationship with host metabolic function in goats and aimed to elucidate the mechanisms involving in the ileal adaptation to a diet containing a high proportion of rice. Sixteen goats were equally divided into two groups and fed a diet with a normal concentrate proportion (NC, 55% concentrate) or a high-concentrate diet (HC, 90% concentrate). Results showed that the HC diet decreased bacterial diversity and elevated the abundance of five genera (Clostridium_sensu_stricto_1, Eubacterium_nodatum_group, Ruminococcus_gauvreauii_group, Eubacterium_coprostanoligenes_group and Ruminococcus 1), but reduced the number of Anaerotruncus. Microbial functional potentials indicated that the HC diet activated the pathways related to metabolism of carbohydrate, glycan, lipid and vitamins, but inhibited the pathways associated with cell motility and signal transduction. The activities of amylase and alkaline phosphatase were greater (p < 0.05) in the intestinal digesta of the HC-fed goats. However, there were no differences in the villus height, crypt depth and the ratio of villus height to crypt depth in the ileum between the two groups. These results indicate that the HC diet alters the bacterial community and pathways related to the metabolism of dietary nutrients and cell motility and signal transduction of bacteria in the ileum of goats.

Protective effects of L-theanine on rats with dextran sulfate sodium-induced inflammatory bowel disease.

The aim of this study is to evaluate the anti-inflammatory and protective effects of L-theanine in inflammatory bowel disease (IBD) and to identify the underlying molecular mechanisms. Rats were pre-treated with L-theanine at 0, 50, 200, or 800 mg/kg/day. IBD was induced in rats using dextran sulfate sodium (DSS). Histopathological analysis suggests that L-theanine can suppress DSS-induced IBD with significant inhibition of inflammation in large and small intestinal tissues. Moreover, the 200 mg/kg/day L-theanine-treated DSS group had higher body and small intestine weights, a lower disease activity index and expression of inflammatory factors than the DSS group without pre-treatment. In RNA sequencing and tandem mass tag labeling analyses, large number of mRNAs and proteins expression level differed when compared with the DSS-induced rats with and without 200 mg/kg/day L-theanine pre-treatment. Moreover, Kyoto Encyclopedia of Genes and Genomes pathway analysis indicates the anti-inflammatory activities of L-theanine in DSS-induced IBD, with a high representation of genes in "Cholesterol metabolism" and "Retinol metabolism" pathways. Analysis of protein-protein interaction networks further indicates the involvement of these two pathways. These studies suggest that medium-dose L-theanine pre-treatment could ameliorate DSS-induced IBD through molecular mechanisms involving cholesterol and retinol metabolism.