Nutrient digestion, rumen fermentation and performance as ramie (Boehmeria nivea) is increased in the diets of goats

Metagenomic characterization of the cecal microbiota community and functions in finishing pigs fed fermented Boehmeria nivea

Ramie (Boehmeria nivea, BN) is used as livestock forage through suitable silage fermentation owing to its nutritional value. To date, relatively few studies have investigated the effects of dietary fermented BN (FBN) on gut health in finishing pigs. The aim of the present study was to investigate the effects of dietary supplementation with 20% FBN on intestinal morphology, gene expression, and the functional response of the gut microbiota in finishing pigs. We found that FBN did not significantly affect serum antioxidant enzyme activities, ileal morphology, or the expression of genes encoding antioxidant enzymes, inflammatory cytokines, or tight junction proteins in the liver of the pigs. However, the gene expression levels of aryl hydrocarbon receptor (AHR) and interleukin 6 (IL6) were significantly downregulated in the ileum. A metagenomic analysis demonstrated that, compared with that seen in the control group, the cecal microbiota of pigs in the FBN treatment group was more closely clustered and contained a greater number of unique microbes. Bacteria were the predominant kingdom in the cecal microbiota, while Firmicutes, Bacteroidetes, and Proteobacteria were the dominant phyla, and Streptococcus, Lactobacillus, and Prevotella were the dominant genera. Dietary FBN significantly increased the abundance of the probiotic bacterium Roseburia inulinivorans (p < 0.05). Functional analysis of the cecal microbiota showed that ABC transporter levels and glycolysis/gluconeogenesis-associated functions were diminished in FBN-fed pigs. Meanwhile, CAZyme analysis revealed that dietary FBN significantly downregulated the contents of carbohydrate-active enzymes, such as GT2, GH1, GH25, and GH13_31. In addition, cytochrome P450 analysis revealed that the abundance of CYP51 and CYP512 decreased with FBN treatment. An assessment of antibiotic resistance based on the Comprehensive Antibiotic Resistance Database (CARD) annotation indicated that the cecal microbes from pigs in the FBN treatment group had increased resistance to lincosamide, streptogramin, and chloramphenicol and reduced resistance to amikacin, isepamicin, neomycin, lividomycin, gentamicin, paromomycin, ribostamycin, and butirosin. Finally, virulence factor-related analysis showed that putative hemolysin-associated functions were decreased, whereas fibronectin-binding protein, flagella, and alginate-associated functions were increased. Taken together, our data showed that FBN supplementation exerted only minor effects on intestinal morphology and microbial community composition, suggesting that it is potentially safe for use as a supplement in the diets of finishing pigs. However, more studies are needed to validate its functionality.

Cassava Foliage Effects on Antioxidant Capacity, Growth, Immunity, and Ruminal Microbial Metabolism in Hainan Black Goats

Cassava (Manihot esculenta Crantz) foliage is a byproduct of cassava production characterized by high biomass and nutrient content. In this study, we investigated the effects of cassava foliage on antioxidant capacity, growth performance, and immunity status in goats, as well as rumen fermentation and microbial metabolism. Twenty-five Hainan black goats were randomly divided into five groups (n = 5 per group) and accepted five treatments: 0% (T1), 25% (T2), 50% (T3), 75% (T4), and 100% (T5) of the cassava foliage silage replaced king grass, respectively. The feeding experiment lasted for 70 d (including 10 d adaptation period and 60 d treatment period). Feeding a diet containing 50% cassava foliage resulted in beneficial effects for goat growth and health, as reflected by the higher average daily feed intake (ADFI), average daily gain (ADG) and better feed conversion rate (FCR), as well as by the reduced serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine (CRE), and triglycerides (TG). Meanwhile, cassava foliage improved antioxidant activity by increasing the level of glutathion peroxidase (GSH-Px), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) and lowering malondialdehyde (MDA). Moreover, feeding cassava foliage was also beneficial to immunity status by enhancing complement 3 (C3), complement 4 (C4), immunoglobulin A (IgA), immunoglobulin G (IgG), and immunoglobulin M (IgM). Furthermore, the addition of dietary cassava foliage also altered rumen fermentation, rumen bacterial community composition, and metabolism. The abundance of Butyrivibrio_2 and Prevotella_1 was elevated, as were the concentrations of beneficial metabolites such as butyric acid; there was a concomitant decline in metabolites that hindered nutrient metabolism and harmed host health. In summary, goats fed a diet containing 50% cassava foliage silage demonstrated a greater abundance of Butyrivibrio_2, which enhanced the production of butyric acid; these changes led to greater antioxidant capacity, growth performance, and immunity in the goats.

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.

Evaluation of stirring time through a rumen simulation technique: Influences on rumen fermentation and bacterial community

Introduction

Rumen motility is a key element that influences ruminant nutrition, whereas little is known about the effects of rumen contraction duration on rumen fermentation and ruminal microbiome. We previously reported that proper rotation speed of a rumen simulation technique (RUSITEC) system enhanced rumen fermentation and microbial protein (MCP) production. In the present study, different contraction durations and intervals were simulated by setting different stirring times and intervals of the stirrers in a RUSITEC system. The objective of this trial was to evaluate the influences of stirring time on rumen fermentation characteristics, nutrient degradation, and ruminal bacterial microbiota in vitro.

Methods

This experiment was performed in a 3 × 3 Latin square design, with each experimental period comprising 4 d for adjustment and 3 d for sample collection. Three stirring time treatments were set: the constant stir (CS), the intermittent stir 1 (each stir for 5 min with an interval of 2 min, IS1), and the intermittent stir 2 (each stir for 4 min with an interval of 3 min, IS2).

Results

The total volatile fatty acid (TVFA) concentration, valerate molar proportion, ammonia nitrogen level, MCP density, protozoa count, disappearance rates of dry matter, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber, emissions of total gas and methane, and the richness index Chao 1 for the bacterial community were higher (p < 0.05) in the IS1 when compared to those in the CS. The greatest TVFA, MCP, protozoa count, nutrient disappearance rates, gas productions, and bacterial richness indices of Ace and Chao 1 amongst all treatments were observed in the IS2. The relative abundance of the genus Treponema was enriched (p < 0.05) in CS, while the enrichment (p < 0.05) of Agathobacter ruminis and another two less known bacterial genera were identified in IS2.

Discussion

It could be concluded that the proper reduction in the stirring time might help to enhance the feed fermentation, MCP synthesis, gas production, and the relative abundances of specific bacterial taxa.

Tannic acid supplementation in the diet of Holstein bulls: Impacts on production performance, physiological and immunological characteristics, and ruminal microbiota

This study was conducted to evaluate the influences of supplementing tannic acid (TA) at different doses on the production performance, physiological and immunological characteristics, and rumen bacterial microbiome of cattle. Forty-eight Holstein bulls were randomly allocated to four dietary treatments: the control (CON, basal diet), the low-dose TA treatment [TAL, 0.3% dry matter (DM)], the mid-dose TA treatment (TAM, 0.9% DM), and the high-dose TA treatment (TAH, 2.7% DM). This trial consisted of 7 days for adaptation and 90 days for data and sample collection, and samples of blood and rumen fluid were collected on 37, 67, and 97 d, respectively. The average daily gain was unaffected (P > 0.05), whilst the ruminal NH3-N was significantly decreased (P < 0.01) by TA supplementation. The 0.3% TA addition lowered (P < 0.05) the levels of ruminal isobutyrate, valerate, and tumor necrosis factor alpha (TNF-α), and tended to (P < 0.1) increase the gain to feed ratio. The digestibility of DM, organic matter (OM), and crude protein, and percentages of butyrate, isobutyrate, and valerate were lower (P < 0.05), while the acetate proportion and acetate to propionate ratio in both TAM and TAH were higher (P < 0.05) than the CON. Besides, the 0.9% TA inclusion lessened (P < 0.05) the concentrations of glucagon and TNF-α, but enhanced (P < 0.05) the interferon gamma (IFN-γ) level and Simpson index of ruminal bacteria. The 2.7% TA supplementation reduced (P < 0.05) the intake of DM and OM, and levels of malondialdehyde and thyroxine, while elevated (P < 0.05) the Shannon index of the rumen bacterial populations. Moreover, the relative abundances of the phyla Fibrobacteres and Lentisphaerae, the genera Fibrobacter and Bradyrhizobium, and the species Bradyrhizobium sp., Lachnospiraceae bacterium RM29, and Lachnospiraceae bacterium CG57 were highly significantly (q < 0.01) or significantly (q < 0.05) raised by adding 2.7% TA. Results suggested that the TA addition at 0.3% is more suitable for the cattle, based on the general comparison on the impacts of supplementing TA at different doses on all the measured parameters.

Tannic acid reduced apparent protein digestibility and induced oxidative stress and inflammatory response without altering growth performance and ruminal microbiota diversity of Xiangdong black goats

The present study was performed to evaluate the impacts of tannic acid (TA) supplementation at different levels on the growth performance, physiological, oxidative and immunological metrics, and ruminal microflora of Xiangdong black goats. Twenty-four goats were randomly assigned to four dietary treatments: the control (CON, basal diet), the low-dose TA group [TAL, 0.3 % of dry matter (DM)], the mid-dose TA group (TAM, 0.6 % of DM), and the high-dose TA group (TAH, 0.9 % of DM). Results showed that the growth performance was unaffected (P > 0.05) by adding TA, whilst the 0.3 % and 0.6 % TA supplementation significantly decreased (P < 0.05) the apparent digestibility of crude protein (CP) and ruminal NH3-N concentration, and raised (P < 0.05) the level of total volatile fatty acid (TVFA) in rumen. The increments of alanine aminotransferase (ALT), triglyceride (TG), cortisol (CORT), total antioxidant capacity (T-AOC), interleukin (IL)-1β, IL-6, and serumamyloid A (SAA), and decrements of globulin (GLB), immunoglobulin G (IgG), cholinesterase (CHE), glutathione reductase (GR), creatinine (CRE), growth hormone (GH), high-density lipoprotein cholesterol (HDLC), and insulin-like growth factor 1 (IGF-1) to different extents by TA addition were observed. Although the Alpha and Beta diversity of rumen bacterial community remained unchanged by supplementing TA, the relative abundance of the predominant genus Prevotella_1 was significantly enriched (P < 0.05) in TAL. It could hence be concluded that the TA supplementation in the present trial generally decreased CP digestion and caused oxidative stress and inflammatory response without influencing growth performance and ruminal microbiota diversity. More research is needed to explore the premium dosage and mechanisms of effects for TA addition in the diet of goats.

Comparisons of Ramie and Corn Stover Silages: Effects on Chewing Activity, Rumen Fermentation, Microbiota and Methane Emissions in Goats

The study aimed to investigate the nutritional value of ramie (Boehmeria nivea) silage, and its consequences for chewing activity, rumen fermentation, and enteric methane (CH4) emissions in goats, by comparing it with corn stover (CS) silage. An in vitro ruminal experiment was firstly performed to investigate the substrate degradation and fermentation of CS and ramie silage. The ramie silage diet was formulated by replacing 60% of CS silage with ramie silage (dry matter (DM) basis). Eight female Xiangdong Black goats (a local breed in Southern China, 1 to 1.2 years of age) with BW of 21.0 ± 1.05 kg were used for this experiment and were randomly assigned to either one of the two dietary treatments in a cross-over design. The ramie silage had higher crude protein (CP) and ash content and lower hemicellulose content, together with decreased (p < 0.05) nutrient degradation and methane production and increased (p < 0.05) acetate molar percentage and acetate to propionate ratio through in vitro ruminal fermentation. Feeding the ramie silage diet did not alter feed intake (p > 0.05), decreased (p < 0.05) nutrient digestibility, and increased (p < 0.05) chewing activity and rumination activity, with reductions (p < 0.05) in eating activity and idle activity. Although feeding the ramie silage diet caused a greater (p < 0.05) molar percentage of acetate and lower molar percentage of propionate, it decreased the rumen-dissolved CH4 concentration and enteric CH4 emissions (p < 0.05). Feeding the ramie silage diet did not alter (p > 0.05) the population of bacteria, protozoa, and fungi; it increased the 16S rRNA gene copies of Ruminococcus flavefaciens (p < 0.05). Further 16SrRNA gene amplicon analysis indicated a distinct bacterial composition between the two treatments (p < 0.05). Feeding the ramie silage diet led to a lower abundance of genera Lawsonibacter, Sedimentibacter, Saccharofermentans, Sediminibacterium, and Bifidobacterium (p < 0.05). Ramie can be an alternative forage resource to stimulate chewing activity and reduce CH4 emissions in ruminants.

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.

Effect of alfalfa substituted with ramie on the expression of apoptotic genes in the gastrointestinal tracts of goats

The study investigated the effect of alfalfa hay substituted with ramie silage on the expression of apoptotic genes in the gastrointestinal tract of goats. Thirty-two goats were randomly allocated into four groups, in which the alfalfa was substituted with ramie at 0%, 35%, 75%, and 100% levels, respectively. In the rumen, the mRNA expression of Bax was significantly up-regulated (p = .0007) when alfalfa was 100% substituted by ramie; the mRNA expression of Bcl-2/Bax was significantly down-regulated (p = .02) when alfalfa was 100% substituted by ramie compared with the 75% substituted treatment; the protein expression of Bcl-xl was significantly down-regulated (p = .03) when alfalfa was 100% substituted by ramie compared with 35% and 75% substituted treatments, respectively. In the jejunum, the mRNA expression of p53 was significantly up-regulated (p = .01) when alfalfa was 100% substituted by ramie compared with 0% and 35% substituted treatments; the protein expression of p53 was significantly up-regulated (p = .001) when alfalfa was 35% substituted by ramie compared with 0% and 75% substituted treatments. However, the activity of Caspase-3 was not affected by different substituting levels of ramie in the rumen and jejunum of goats (p > .05). In conclusion, ramie with high substitution had strong antinutritional effect, which might promote the apoptosis in the gastrointestinal tract of goats in a caspase-independent manner, thus affecting the growth and development of goat. It was suggested that ramie should not replace alfalfa more than 35% in the process of goat feeding.

Genome-Wide Association Study of Six Forage Traits in Ramie (Boehmeria nivea L. Gaud)

Genome-wide association study (GWAS) of six forage traits using whole-genome sequencing data generated from 301 ramie accessions found that traits were continuously distributed; the maximum variant coefficient was fresh weight per clump (FWPC) (2019) and individual plant height (IPH) (2019) minimum. Correlation analysis demonstrated that 2019 and 2020 results were similar; all traits were correlated. GWAS analysis demonstrated that six traits exhibited consistent and precise association signals. Of the latter, 104 were significant and detected in 43 genomic regions. By screening forage trait-associated single nucleotide polymorphisms and combining Manhattan map with genome annotation, signals were categorized according to functional annotations. One loci associated with fresh weight per plant (FWP) (chromosome 5; Bnt05G007759), two associated with FWPC (chromosome 13; Bnt13G018582, and Bnt13G018583), and two associated with leaf dry weight per plant (LDWP) and dry weight per plant (DWP) (chromosome 4; Bnt04G005779 and Bnt04G005780), were identified. We describe forage trait candidate genes that are highly correlated with FWP and FWPC; Bnt05G007759 may be involved in nitrogen metabolism, while Bnt13G018582 and Bnt13G018583 may encode TEOSINTE branch 1/CYCLOIDEA/proliferating cytokine 1 (TCP) domains. Bnt04G005779 and Bnt04G005780, which may regulate growth and development, are highly related to LDWP and DWP. These genomic resources will provide a basis for breeding varieties.

Metabolomics Analysis Across Multiple Biofluids Reveals the Metabolic Responses of Lactating Holstein Dairy Cows to Fermented Soybean Meal Replacement

This experiment was performed to reveal the metabolic responses of dairy cows to the replacement of soybean meal (SBM) with fermented soybean meal (FSBM). Twenty-four lactating Chinese Holstein dairy cattle were assigned to either the SBM group [the basal total mixed ration (TMR) diet containing 5.77% SBM] or the FSBM group (the experimental TMR diet containing 5.55% FSBM), in a completely randomized design. The entire period of this trial consisted of 14 days for the adjustment and 40 days for data and sample collection, and sampling for rumen liquid, blood, milk, and urine was conducted on the 34th and 54th day, respectively. When SBM was completely replaced by FSBM, the levels of several medium-chain FA in milk (i.e., C13:0, C14:1, and C16:0) rose significantly (p < 0.05), while the concentrations of a few milk long-chain FA (i.e., C17:0, C18:0, C18:1n9c, and C20:0) declined significantly (p < 0.05). Besides, the densities of urea nitrogen and lactic acid were significantly (p < 0.05) higher, while the glucose concentration was significantly (p < 0.05) lower in the blood of the FSBM-fed cows than in the SBM-fed cows. Based on the metabolomics analysis simultaneously targeting the rumen liquid, plasma, milk, and urine, it was noticed that substituting FSBM for SBM altered the metabolic profiles of all the four biofluids. According to the identified significantly different metabolites, 3 and 2 amino acid-relevant metabolic pathways were identified as the significantly different pathways between the two treatments in the rumen fluid and urine, respectively. Furthermore, glycine, serine, and threonine metabolism, valine, leucine, and isoleucine biosynthesis, and cysteine and methionine metabolism were the three key integrated different pathways identified in this study. Results mainly implied that the FSBM replacement could enhance nitrogen utilization and possibly influence the inflammatory reactions and antioxidative functions of dairy cattle. The differential metabolites and relevant pathways discovered in this experiment could serve as biomarkers for the alterations in protein feed and nitrogen utilization efficiency of dairy cows, and further investigations are needed to elucidate the definite roles and correlations of the differential metabolites and pathways.

The expression of nutrient chemosensing gate molecules in the ileum and colon is altered for goats fed on a high-grain diet

Limited knowledge is clarified about alterations in the related expression of nutrient chemosensors in the distal small intestine and hindgut under a high-grain (HG) diet in small ruminants. Herein, this study was performed to investigate the expression changes related to nutrient sensing and transport in the ileal and colonic epithelium of goats in response to feeding an HG diet. Twelve Liuyang black goats (similar age and weight) were randomly assigned into two groups: an HG diet (concentrate: hay = 90:10) and a CON diet (concentrate: hay = 55:45). Immunohistochemistry was applied to detect morphological changes in the gut epithelium together with altered expression of chemosensors in the ileum and colon. The results showed that feeding an HG diet increased ileal villus height and depth and induced mucosal sloughing in the colon. The expressions of the nutrient transporters GLUT2, GLUT5, SGLT2, CD36, rBAT, EAAT3, and LAT2 and sensing receptors GPR43 and T1R1 were promoted in the ileum under HG conditions. Moreover, feeding an HG diet also enhanced the expression of GLUT2, SGLT2, CD36, and GPR43 in the colon. These findings indicate that adaptation of the gastrointestinal tract to the HG diet promoted the absorption of glucose, fatty acids, and amino acids in goats.

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.

Characterization of underutilized root starches from eight varieties of ramie (Boehmeria nivea) grown in China

Ramie root is an underutilized starch source. In this study, eight ramie varieties were investigated for starch properties. Starch content ranged from 18.6% to 50.1% in dry root. Starches from different varieties showed similar morphology including ellipsoidal, spherical and truncated granules with size D[4,3] from 10.1 to 14.1 μm. Starch had amylose content from 20.8% to 28.5%. All ramie varieties had B-type starches with relative crystallinity from 24.8% to 27.1%, ordered degree from 0.724 to 0.897 and lamellar thickness from 9.1 to 9.6 nm. Starches had gelatinization peak temperature from 70.5 to 73.8 °C and enthalpy from 14.9 to 15.8 J/g. Starches had swelling power and water solubility from 27.9 to 31.9 g/g and from 11.7% to 15.5%, respectively, at 95 °C, and exhibited different pasting properties with breakdown viscosity from 36 to 377 mPa s and setback viscosities from 1295 to 1863 mPa s. Starch pastes exhibited pseudoplastic behavior and different rheological properties. Native, gelatinized and retrograded starches had resistant starch from 81.7% to 83.9%, from 1.7% to 5.1% and from 5.6% to 13.3%, respectively. The eight varieties were divided into 3 groups according to starch properties. This study is helpful for selecting suitable ramie variety as starch source.

Physicochemical properties of a new starch from ramie (Boehmeria nivea) root

A new starch was isolated from ramie root, and its physicochemical properties were investigated. Ramie dry root contained 45.9% starch. Starch had truncated, ellipsoidal, and spherical granule shapes with size from 7 to 30 μm and D[4,3] about 14.1 μm. Starch contained 38.9% apparent amylose content and 22.4% true amylose content, exhibited B-type crystallinity, and had 26.6% relative crystallinity, 0.82 ordered degree, and 9.2 nm lamellar thickness. Starch had 71.8 °C gelatinization peak temperature and 15.6 J/g gelatinization enthalpy, and exhibited 31.4 g/g swelling power and 17.1% water solubility at 95 °C. Starch had peak, hot, breakdown, final, and setback viscosities at 3048, 2768, 279, 4165, and 1397 mPa s, respectively, and showed peak time at 4.36 min and pasting temperature at 75.0 °C. The native, gelatinized, and retrograded starches contained 15.1%, 94.0%, and 86.5% rapidly digestible starch and 83.3%, 4.0%, and 10.7% resistant starch, respectively. Compared with potato and rice starches, ramie starch was somewhat similar to potato starch but significantly different from rice starch in starch component, crystalline structure, and functional properties. Therefore, ramie starch exhibited the potential to be used as a thickening agent, resistant-digesting food additive, and alternative to potato starch in food and nonfood industries.

Fermented Soybean Meal Replacement in the Diet of Lactating Holstein Dairy Cows: Modulated Rumen Fermentation and Ruminal Microflora

This study was conducted to examine the influences of replacing soybean meal (SBM) with fermented soybean meal (FSBM) in the diet of lactating Holstein cattle on rumen fermentation and ruminal bacterial microbiome. Twenty-four lactating Chinese Holstein dairy cattle were assigned to each of the two treatments in a completely randomized design: the SBM group [the basal total mixed ration (TMR) diet containing 5.77% SBM] and the FSBM group (the experimental TMR diet containing 5.55% FSBM). This trial lasted for 54 days (14 days for adjustment and 40 days for data and sample collection), and samples of rumen liquid were collected on 34 d and 54 d, respectively. The results showed that replacing SBM with FSBM significantly increased the molar percentages of propionate (P < 0.01) and valerate (P < 0.05), but reduced the total volatile fatty acid (TVFA) concentration (P < 0.05), butyrate molar proportion (P < 0.05), and the acetate to propionate ratio (P < 0.01). The copy numbers of total bacteria (P < 0.05), Fibrobacter succinogenes (P < 0.01), Selenomonas ruminantium (P < 0.01), and Prevotella spp. (P < 0.05) in the FSBM group were greater, while the density of Prevotella ruminicola (P < 0.05) was lower than those in the SBM treatment. Additionally, Succiniclasticum ruminis and Saccharofermentans acetigenes were significantly enriched (P < 0.05) in the rumen fluid of FSBM-fed cows, despite the fact that there was no remarkable difference in the Alpha diversity indexes, structure and KEGG pathway abundances of the bacterial community across the two treatments. It could hence be concluded that the substitution of FSBM for SBM modulated rumen fermentation and rumen bacterial microbiota in lactating Holstein dairy cows. Further research is required to elucidate the relevant mechanisms of FSBM, and provide more insights into the application of FSBM in dairy cattle.

Modulation of rumen fermentation and microbial community through increasing dietary cation-anion difference in Chinese Holstein dairy cows under heat stress conditions

AIMS

The effect of increasing dietary cation-anion difference (DCAD) on rumen fermentation and ruminal microbial community in dairy cows under heat stress (HS) conditions were evaluated.

METHODS AND RESULTS

This study was performed as a two-period cross-over design during the summer season, with eight lactating dairy cows randomly distributed to either a control DCAD diet (CON: 33·5 mEq/100 g DM) or high DCAD diet (HDCAD: 50·8 mEq/100 g DM). Throughout the present study, the temperature and humidity index (THI; 80·2 ± 4·29) was generally elevated above the threshold (THI = 72) that is reported to cause HS in lactating dairy cows. Rumen liquid samples were collected on 15 and 21 d during each 21 d-period. The absolute concentration of ruminal total volatile fatty acid (TVFA) in HDCAD treatment was significantly (P < 0·05) higher than those in the control, whilst the ruminal pH, NH₃ -N, and VFA molar percentages were unaffected through increasing DCAD. Furthermore, the copy numbers of the cellulolytic bacteria Ruminococcus albus and Ruminococcus flavefaciens in rumen fluid significantly (P < 0·05) rose along with the increment of DCAD. Although the Alpha diversity indexes and the bacterial microbiota structure were unaffected, increasing DCAD significantly (P < 0·05) enriched the phylum Fibrobacteres and genus Fibrobacter in the microflora of rumen fluid, whilst the genera Flexilinea and Dubosiella were the most differentially abundant taxa in the control.

CONCLUSIONS

Increasing DCAD under HS conditions resulted in a greater concentration of total VFA without affecting rumen bacteria diversity or structure, although the enrichment of some cellulolytic/hemicellulolytic bacteria was observed.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present study provides information on the modulation of rumen fermentation and microbial community through the increment of DCAD in Holstein dairy cows under HS conditions.