Molar Proportion Of Propionate Research Articles

Yak rumen microbiome elevates fiber degradation ability and alters rumen fermentation pattern to increase feed efficiency.

Rumen microbes play an important role in ruminant energy supply and animal performance. Previous studies showed that yak (Bos grunniens) rumen microbiome and fermentation differ from other ruminants. However, little is understood about the features of the rumen microbiome that make yak adapted to their unique environmental and dietary conditions. This study was to investigate the rumen microbiome and metabolome to understand how yak adapt to the coarse forage and harsh environment in the Qinghai-Tibetan plateau. Nine female Qaidam yellow cattle (Bos taurus), 9 dzomo (hybrids of cattle and yak) and 9 female plateau yak (B. grunniens), about 5 to 6 years old, were used in this study. Rumen fermentation parameters, fibrolytic enzyme activities, and rumen metataxonomic were determined. Then 18 (6 samples per group) were selected for rumen metagenomic and metabolome analysis. Metataxonomic analysis revealed that the rumen microbiota was significantly different among plateau yak, Qaidam yellow cattle, and dzomo (P < 0.05). Metagenomic analysis displayed a larger gene pool encoding a richer repertoire of carbohydrate-active enzymes in the rumen microbiome of plateau yak and dzomo than Qaidam yellow cattle (P < 0.05). Some of the genes encoding glycoside hydrolases that mediate the digestion of cellulose and hemicellulose were significantly enriched in the rumen of plateau yak than Qaidam yellow cattle, but glycoside hydrolase 57 that primarily includes amylases was abundant in Qaidam yellow cattle (P < 0.05). The rumen fermentation profile differed also, Qaidam yellow cattle having a higher molar proportion of acetate but a lower molar proportion of propionate than dzomo and plateau yak (P < 0.05). Based on metabolomic analysis, rumen microbial metabolic pathways and metabolites were different. Differential metabolites are mainly amino acids, carboxylic acids, sugars, and bile acids. Changes in rumen microbial composition could explain the above results. The present study showed that the rumen microbiome of plateau yak helps its host to adapt to the Qinghai-Tibetan plateau. In particular, the plateau yak rumen microbiome has more enzymes genes involved in cellulase and hemicellulase than that of cattle, resulting higher fibrolytic enzyme activities in yak, further providing stronger fiber degradation function.

Effects of Barley Starch Level in Diet on Fermentation and Microflora in Rumen of Hu Sheep.

Simple SummaryIncreasing the starch level in the diet of ruminants can promote rumen fermentation to a certain extent and improve production performance. However, the degradation of rapidly fermentable carbohydrates in the rumen can lead to the accumulation of large amounts of organic acids (mainly volatile fatty acids and lactic acid), increasing the risk of subacute ruminal acidosis (SARA) in high-yielding ruminants. By changing the fermentation sites of rapidly fermentable carbohydrates, the rumen environment and feed efficiency could be effectively improved. The object of this study was to explore the effects of replacing corn starch with barley starch in the diet of Hu sheep on the fermentation and microflora in the rumen. Our results showed that, starch in the diet cannot be derived entirely from barley, and it is feasible to replace 33% of the corn with barley in the diet for Hu sheep.This study aimed to explore the effects of different levels of barley starch instead of corn starch on the rumen fermentation and microflora when feeding a corn-based diet to Hu sheep. Thirty-two male Hu sheep equipped with permanent rumen fistulas were selected and fed in individual metabolic cages. All sheep were randomly divided into four groups (eight sheep in each group) and fed with four diets containing a similar starch content, but from different starch sources, including 100% of starch derived from corn (CS), 33% of starch derived from barley + 67% of starch derived from corn (33 BS), 67% of starch derived from barley + 33% of starch derived from corn (67 BS) and 100% of starch derived from barley (100 BS). The experimental period included a 14 d adaptation period and a 2 d continuous data collection period. The results showed that the molar proportions of acetate, isobutyrate, butyrate and isovalerate and the ratio of acetate to propionate in the 67 BS and 100 BS groups decreased compared with the CS and 33 BS groups (p < 0.001), while the molar proportions of propionate and valerate increased (p < 0.001). The combination of 33% barley starch and 67% corn starch in the diet improved the production of TVFAs (p = 0.007). The OTUs and Shannon indexes of the CS and 33 BS groups were higher than the 67 BS and 100 BS groups (p < 0.001), and the Chao1 and Ace indexes were higher than the 100 BS group (p < 0.05). In addition, the 33 BS group had increased the relative abundances of Bacteroidetes, Prevotella and Ruminococcus and the abundances of Fibrobacter succinogenes, Ruminococcus flavefaciens, Streptococcus bovis, Selenomonas ruminantium and Prevotella brevis relative to the CS group (p < 0.05). These results indicate that the substitution of 33% of the CS with BS did not change the rumen fermentation pattern relative to the CS group, and increased the richness and diversity of the rumen microbes in Hu sheep compared with other two starch substitute groups.

Effect of Clostridium butyricum Supplementation on in vitro Rumen Fermentation and Microbiota With High Grain Substrate Varying With Media pH Levels.

Clostridium butyricum (C. butyricum) can survive at low pH, and it has been widely used as an alternative to antibiotics for the improvement of feed efficiency and animal health in monogastrics. A recent study suggested that the improved ruminal fermentation with supplementing C. butyricum is may be associated with increasing the abundance of rumen microbiota in Holstein heifers, as ruminal pH plays a key role in rumen microbiota and the probiotics are often active in a dose-dependent manner. The objective of this study was to determine the effects of increasing the doses of C. butyricum on gas production (GP) kinetics, dry matter disappearance (DMD), fermentation characteristics, and rumen microbiota using a high grain substrate in batch culture varying with media pH levels. The doses of C. butyricum were supplemented at 0 (control), 0.5 × 106, 1 × 106, and 2 × 106 CFU/bottle, respectively, at either media pH 6.0 or pH 6.6. The fermentation microbiota at 0 and 1 × 106 CFU/bottle were determined using the 16S rRNA high throughput sequencing technology. Overall, the GP, DMD, total volatile fatty acid (VFA) concentration, and the ratio of acetate:propionate were higher (P <0.01) at media pH 6.6 than at pH 6.0. However, there was interaction between pH × dose of C. butyricum for rate constant of GP (P = 0.01), average GP rate (P = 0.07), and volume of GP (P = 0.06); with the increase in C. butyricum supplementation, the GP kinetics were not changed at media pH 6.0, but the volume (P = 0.02), rate of GP (P = 0.01), and average GP rate (P = 0.01) were quadratically changed at media pH 6.6. The DMD was not affected by increasing the supplementation of C. butyricum. The molar proportions of propionate (P <0.09), butyrate (P <0.06), and NH3-N concentration (P = 0.02) were quadratically changed with increasing supplementation of C. butyricum regardless of media pH levels. The interactions between media pH level and dose of C. butyricum supplementation were noticed for alpha diversity indexes of Shannon (P = 0.02) and Evenness (P = 0.04). The alpha diversity indexes increased (P <0.05) except for Chao1 with supplementation of C. butyricum. The unweighted uniFrac analysis showed that the group of control at media pH 6.0 and control at media pH 6.6, and supplementation of C. butyricum and control at media pH 6.0 clustered separately from each other. At the phylum level, relative abundance (RA) of Bacteroidota was lower (P <0.01) and Firmicutes was higher (P <0.01) at media pH 6.6 than pH 6.0. Moreover, RA of Proteobacteria decreased (P <0.05) with supplemented C. butyricum at either media pH 6.6 or pH 6.0. At media pH 6.6, RA of Rikenellaceae_RC9_gut_group and Prevotella were decreased, and CAG-352 was increased (at genus level) compared to pH 6.0. Supplementation of C. butyricum decreased RA of Rikenellaceae_RC9_gut_group and increased CAG-352 at media pH 6.0. It could hence be concluded that manipulating media pH level and supplementation of C. butyricum effectively modulated in vitro rumen fermentation characteristics and microbiota but in a dose depending manner of C. butyricum addition.

Microbiome-Metabolome Responses in Ruminal Content and Feces of Lactating Dairy Cows With N-Carbamylglutamate Supplementation Under Heat Stress.

The objective of the present study was to investigate the effects of N-carbamylglutamate (NCG) supplementation on metabolic profile and microbiota in ruminal content and feces of lactating dairy cows under heat stress (HS). Forty-eight lactating Holstein cows (154 ± 13.6 days in milk) were assigned randomly to four treatments (n = 12), to receive 0, 15, 20, or 25 g/day of commercial NCG (proportion: 97.7%) for the period of 60 days. The recorded ambient temperature–humidity index (THI) suggested that the cows were exposed to HS for almost the entire experimental period (average THI: 80.6). Samples of ruminal content and feces were collected at the end of the trial (day 60) to determine the biological effects of NCG supplementation on metabolome and microbiota using mass spectrometry-based metabolomics and 16S rRNA gene sequencing techniques, respectively. Results showed that NCG supplementation enhanced the levels of ruminal microbial protein, total volatile fatty acids (VFAs), and the molar proportion of propionate in the rumen, but lowered the ruminal pH, ammonia nitrogen (NH3-N), and the ratio of acetate to propionate. NCG at doses of 20 and 25 g/day reduced the community richness and diversity of ruminal microbiota with the decrease of Shannon and Simpson diversity. Compositions of ruminal and fecal microbiotas were altered by NCG, and the PICRUSt results revealed that metabolic pathways of the bacteria, such as amino acid metabolism, energy metabolism, and pyruvate metabolism, were enriched in NCG groups. Distinct changes in the metabolomic profile of ruminal fluid were observed between the control and NCG groups. Changes of 26 metabolites mainly involved in arginine metabolism, glutamate metabolism, and nitrogen metabolism were observed associated with NCG supplementation. These results provided new insights into the effects of NCG on metabolomic profile and microbiota in ruminal content and feces, and the optimal dose of NCG supplemented to dairy cows was 20 g/hd/day, which contributed to understanding the effects of NCG on HS in lactating dairy cows.

Partial Substitution of Corn Grain in the Diet with Beet Pulp Reveals Increased Ruminal Acetate Proportion and Circulating Insulin Levels in Korean Cattle Steers.

Simple SummaryIntramuscular fat content is one of the important beef quality traits due to its contribution to beef palatability, including flavor, tenderness, and juiciness. Intramuscular fat content is determined by fat synthesis using substrates such as acetate and glucose in ruminants. Beet pulp is a byproduct of sugar beet processing and contains abundant neutral detergent fiber and pectin, with these two components readily fermentable in the rumen. Beet pulp may be a useful energy source in cattle to produce acetate during ruminal fermentation, thereby aiding in lipogenesis (fatty acid synthesis). In this study, partial substitution of corn grain in the diet with beet pulp increased ruminal acetate proportion and circulating insulin levels in beef cattle. Beet pulp could be used as a lipogenic energy source without affecting growth performance in cattle.We investigated the effects of the partial substitution of corn grain in the diet with beet pulp on growth performance, ruminal fermentation characteristics, microbial profiles, and blood lipogenic parameters in fattening steers. Twelve Korean cattle steers (body weight, 485 ± 19.32 kg; age, 18.0 ± 0.17 months) were equally divided into corn grain (CG) and beet pulp (BP) groups. Approximately 75% of dry matter of the requirement was offered as a concentrate portion, and the remaining 25% was offered as oat straw. Eighty percent of the concentrate portion was provided by a pelleted basal concentrate, and the remaining 20% with corn grain for the CG group, or 18% beet pulp plus 2.0% rumen-protected fat for the BP group, respectively, by top dressing. The experiment was conducted for 14 weeks, including a 2-week acclimation period. Growth rate was not affected by beet pulp feeding (p = 0.55). The molar proportions of ruminal acetate (p < 0.05) on wk 4, the relative abundances of ruminal cellulolytic bacteria, including Fibrobacter succinogenes (p = 0.01) and Ruminococcus albus (p = 0.04) on wk 12, and serum insulin concentrations (p < 0.05) on wk 12 were higher in the BP group than in the CG group, whereas the molar proportions of propionate (p < 0.05) on wks 8 and 12 and serum nonesterified fatty acids (p < 0.05) on wk 12 were lower in the BP group. Beet pulp could be used as a lipogenic energy source without affecting growth performance during the fattening period of cattle.

Application of 3-nitrooxypropanol and canola oil to mitigate enteric methane emissions of beef cattle results in distinctly different effects on the rumen microbial community

BackgroundThe major greenhouse gas from ruminants is enteric methane (CH4) which in 2010, was estimated at 2.1 Gt of CO2 equivalent, accounting for 4.3% of global anthropogenic greenhouse gas emissions. There are extensive efforts being made around the world to develop CH4 mitigating inhibitors that specifically target rumen methanogens with the ultimate goal of reducing the environmental footprint of ruminant livestock production. This study examined the individual and combined effects of supplementing a high-forage diet (90% barley silage) fed to beef cattle with the investigational CH4 inhibitor 3-nitrooxypropanol (3-NOP) and canola oil (OIL) on the rumen microbial community in relation to enteric CH4 emissions and ruminal fermentation.Results3-NOP and OIL individually reduced enteric CH4 yield (g/kg dry matter intake) by 28.2% and 24.0%, respectively, and the effects were additive when used in combination (51.3% reduction). 3-NOP increased H2 emissions 37-fold, while co-administering 3-NOP and OIL increased H2 in the rumen 20-fold relative to the control diet. The inclusion of 3-NOP or OIL significantly reduced the diversity of the rumen microbiome. 3-NOP resulted in targeted changes in the microbiome decreasing the relative abundance of Methanobrevibacter and increasing the relative abundance of Bacteroidetes. The inclusion of OIL resulted in substantial changes to the microbial community that were associated with changes in ruminal volatile fatty acid concentration and gas production. OIL significantly reduced the abundance of protozoa and fiber-degrading microbes in the rumen but it did not selectively alter the abundance of rumen methanogens.ConclusionsOur data provide a mechanistic understanding of CH4 inhibition by 3-NOP and OIL when offered alone and in combination to cattle fed a high forage diet. 3-NOP specifically targeted rumen methanogens and partly inhibited the hydrogenotrophic methanogenesis pathway, which increased H2 emissions and propionate molar proportion in rumen fluid. In contrast, OIL caused substantial changes in the rumen microbial community by indiscriminately altering the abundance of a range of rumen microbes, reducing the abundance of fibrolytic bacteria and protozoa, resulting in altered rumen fermentation. Importantly, our data suggest that co-administering CH4 inhibitors with distinct mechanisms of action can both enhance CH4 inhibition and provide alternative sinks to prevent excessive accumulation of ruminal H2.

Diet Type Impacts Production Performance of Fattening Lambs by Manipulating the Ruminal Microbiota and Metabolome.

The pelleted total mixed ration (PTMR) has a positive effect on the productivity of fattening lambs. However, whether the beneficial effects are underpinned by altering the rumen microbiota and metabolome that remain unclear. This study aimed to investigate correlations among growth performance, ruminal microbiota, and ruminal metabolome of lambs fed PTMR diet. A total of 100 crossbred (Dorper sheep × Fine-wool sheep) ram lambs at 55 days of age with similar body weight (BW) (13.2 ± 0.5 kg) were randomly allocated to 10 pens that were fed either PTMR (PTMR group) or unpelleted total mixed ration (UPTMR group) with the same dietary ingredients and nutritional contents. The average daily gain (ADG) and average daily feed intake (ADFI) were determined during the 62-day experimental period and ruminal pH, volatile fatty acid (VFA) concentrations, microbiota, and metabolome in the rumen of the lambs were examined at the end of the experiment. Compared to those of the UPTMR group, the PTMR group had greater ADFI (P = 0.002), ADG (P = 0.003), and feed efficiency (G/F) (P < 0.05). Similarly, feeding PTMR increased the concentration of total VFA (TVFA) and the molar proportion of propionate, but decreased the proportion of butyrate and acetate to propionate ratio in the rumen of lambs compared to that in lambs from the UPTMR group (P < 0.05). In addition, the PTMR group demonstrated lowered alpha-diversity of the ruminal microbiota and enhanced the relative abundance of Fibrobacter (P < 0.05), Veillonellaceae (P < 0.05), and the abundance of Rikenellaceae (P = 0.064) in the rumen compared with those in the UPTMR group. Feeding lambs with PTMR significantly upregulated the metabolic pathways involving tryptophan, histidine, cysteine and methionine, β-alanine, tyrosine metabolisms, and steroid biosynthesis. Moreover, the abundance of the microbiota strongly correlated with the altered performance, ruminal VFA, metabolites, and metabolic pathways of lambs. Taken together, feeding PTMR shaped the ruminal microbiota of lambs with decreased diversity, while improving relative abundance of some specific microbes and upregulating certain growth-related metabolic pathways, which contributed to the augmented growth performance and G/F of fattening lambs. Thus, feeding PTMR to fattening lambs for superior production performance and G/F is recommended.

Effects of red cabbage extract rich in anthocyanins on rumen fermentation, rumen bacterial community, nutrient digestion, and plasma indices in beef bulls

Dietary anthocyanins (ATH) have probiotic and antioxidant functions in humans. They may also have beneficial impacts on rumen microorganisms and subsequently nutrient digestion in cattle. The experiment aimed to study the effects of dietary red cabbage extract (RCE) rich in ATH on rumen fermentation, rumen bacterial community, and nutrient digestibility in beef bulls. Eight Simmental beef bulls and two RCE levels (0 and 120 g/d) were allocated in a replicated 2 × 2 crossover design. Each experimental period included 15 days for adaptation and subsequent 5 days for sampling. The results showed that dietary addition of RCE increased the ruminal concentration of total volatile fatty acids and the molar proportion of propionate, decreased the acetate to propionate ratio, and tended to decrease the molar proportion of acetate, but it did not affect the ruminal pH and the concentrations of ammonia N, microbial CP, monophenols, polyphenols, and total phenolics. ATH was undetectable in the ruminal fluid of beef bulls in both groups. RCE did not affect the alpha diversity of rumen bacterial community, and the relative abundances of major rumen bacteria at the phylum level, but it increased the relative abundances of Ruminobacter and Anaerovibrio and tended to increase the relative abundances of Oribacterium and Monoglobus at the genus level. RCE tended to increase the plasma concentrations of globulin and total protein, but it did not affect the plasma albumin, urea, triglyceride, glucose, and antioxidant activities. Dietary addition of RCE did not affect the apparent nutrient digestibility. In conclusion, the ATH in RCE was highly hydrolysable in rumen fluid. Dietary addition of RCE increased the ruminal concentration of total volatile fatty acids, decreased the acetate to propionate ratio, and slightly modified the rumen bacterial community, but it did not affect the nutrient digestibility and the plasma antioxidants in beef bulls.

Effects of cyclic monensin feeding on ruminal function in cannulated beef steers consuming low-quality forage

The aim of this research was to evaluate the effects of cyclically feeding monensin (Rumensin 90, Elanco Animal Health) to ruminally cannulated steers (12 Bos taurus; 260 kg of BW) consuming low-quality forage (4.9% CP) on measures of intake, digestion, and ruminal function. Twelve steers were randomly assigned to 1 of 3 treatments in a completely randomized design: (1) no monensin (CON); (2) 200 mg·head−1·d−1 monensin (MON); or (3) 200 mg·head−1·d−1 monensin for 14 d and 0 mg·head−1·d−1 monensin for the subsequent 14 d (CYC; recurrent cycle). Hay and ort samples were collected d 10 through 13 for intake determination during each of the four 28-d replicated cycles. Rumen fluid was collected with a suction strainer 0, 2, 4, 8, and 12 h after feeding on d 14 for pH and VFA analysis. Data were analyzed using the MIXED procedure of SAS 9.4 (SAS Institute Inc.). Treatment × cycle interactions or treatment effects were not observed for any measure of intake (OM intake, NDF intake; P ≥ 0.17) or pH (P = 0.13). A tendency for a treatment × cycle interaction was observed (P = 0.08) for OM digestion but not for NDF digestion (P = 0.37). Treatment × cycle interactions were observed (P < 0.01) for molar proportions of acetate, propionate, and acetate:propionate ratio. Because these treatment × cycle interactions occurred, treatment × hour interactions, treatment effects, and hour effects were evaluated within cycles for these parameters. Treatment × hour interactions (P ≤ 0.02) occurred for molar proportion of propionate in cycle 1 and propionate and acetate:propionate ratio in cycle 3, and there was a tendency (P = 0.09) for a treatment × hour interaction for acetate:propionate in cycle 4. Although treatment effects were observed for molar proportions of acetate, propionate, and acetate:propionate ratio in cycle 1 (P ≤ 0.01), these effects had diminished by cycle 4 (P ≥ 0.39). An effect of hour after feeding was observed (P ≤ 0.02) in all 4 cycles for acetate, propionate, acetate:propionate, and ruminal pH. Further evaluation of monensin feeding methods that vary duration of feeding and withdrawal periods may be warranted. Additionally, further study concerning differences in the effect of these methods on a diet bases on concentrate versus low-quality forage warrant investigation.

Effects of choline chloride on the ruminal microbiome at 2 dietary neutral detergent fiber concentrations in continuous culture

Our objective was to evaluate the effects of unprotected choline chloride (Cho) on the ruminal microbiome at 2 dietary neutral detergent fiber (NDF) concentrations. We hypothesized that the effects of Cho on ruminal bacterial populations would depend on NDF. Eight dual-flow continuous-culture fermentors were arranged in a duplicated 4 × 4 Latin square as a 2 × 2 factorial with the following treatments: (1) 30% NDF-control (30% NDF diet, no supplemental choline); (2) 30% NDF-Cho (30% NDF diet plus 1.9 g of choline ion per kg of dry matter); (3) 40% NDF-control (40% NDF diet, no supplemental choline); and (4) 40% NDF-Cho (40% NDF diet plus 1.9 g of choline ion per kg of dry matter). We did 4 fermentation periods of 10 d each and used the last 3 d for collection of samples of solid and liquid digesta effluents for DNA extraction. Overall, 32 solid and 32 liquid samples were analyzed by amplification of the V4 variable region of bacterial 16S rRNA. Data were analyzed with R (R Project for Statistical Computing) and SAS (SAS Institute Inc.) to determine effects of Cho, NDF, and NDF × Cho on taxa relative abundance. The correlation of propionate molar proportion with taxa relative abundance was also analyzed. At the phylum level, relative abundance of Firmicutes in the liquid fraction tended to be greater when Cho was supplemented with a 30% NDF diet. At the order level, Cho increased Coriobacteriales in solid fraction and decreased Fibrobacterales in liquid fraction. Moreover, Cho decreased abundance of Clostridiales and increased Selenomonadales in the solid fraction, only with the 30% NDF diet. For genera, lower abundance of Pseudobutyrivibrio resulted from Cho in solid and liquid fractions. Greater abundance of Succinivibrio in solid and Selenomonas and Selenomonas 1 in liquid resulted from Cho with the 30% NDF diet. Propionate molar proportion was positively correlated with relative abundance of order Selenomonadales in solid and liquid fractions, and with genus Succinivibrio in solid and genera Selenomonas and Selenomonas 1 in liquid. Our results indicate that Cho primarily decreases abundance of bacteria involved in fiber degradation and increases abundance of bacteria mainly involved in nonstructural carbohydrate degradation and synthesis of propionate, particularly when a diet with 30% NDF is provided.

Supplementation of Ascophyllum nodosum meal and monensin: Effects on diversity and relative abundance of ruminal bacterial taxa and the metabolism of iodine and arsenic in lactating dairy cows

Previous research has shown that the brown seaweed Ascophyllum nodosum (ASCO) has antimicrobial and antioxidant properties and also increases milk I concentration. We aimed to investigate the effects of supplementing ASCO meal or monensin (MON) on ruminal fermentation, diversity and relative abundance of ruminal bacterial taxa, metabolism of I and As, and blood concentrations of thyroid hormones, antioxidant enzymes, and cortisol in lactating dairy cows. Five multiparous ruminally cannulated Jersey cows averaging (mean ± standard deviation) 102 ± 15 d in milk and 450 ± 33 kg of body weight at the beginning of the study were used in a Latin square design with 28-d periods (21 d for diet adaptation and 7 d for data and sample collection). Cows were fed ad libitum a basal diet containing (dry matter basis) 65% forage as haylage and corn silage and 35% concentrate and were randomly assigned to 1 of the following 5 dietary treatments: 0, 57, 113, or 170 g/d of ASCO meal, or 300 mg/d of MON. Supplements were placed directly into the rumen once daily after the morning feeding. Diets had no effect on ruminal pH and NH3-N concentration, which averaged 6.02 and 6.86 mg/dL, respectively. Total volatile fatty acid concentration decreased linearly in cows fed incremental amounts of ASCO meal. Supplementation with ASCO meal did not change the ruminal molar proportions of volatile fatty acids apart from butyrate, which responded quadratically with the lowest values observed at 56 and 113 g/d of ASCO supplementation. Compared with the control diet or diets containing ASCO meal, cows fed MON showed greater molar proportion of propionate. Diets did not affect the α diversity indices Shannon, Simpson, and Fisher for ruminal bacteria. However, feeding incremental levels of ASCO meal linearly decreased the relative abundance of Tenericutes in ruminal fluid. Monensin increased the relative abundance of the CAG:352 bacterial genus in ruminal fluid compared with the control diet. Linear increases in response to ASCO meal supplementation were observed for the concentrations and output of I in serum, milk, urine, and feces. Fecal excretion of As increased linearly in cows fed varying amounts of ASCO meal, but ASCO did not affect the concentration and secretion of As in milk. The plasma activities of the antioxidant enzymes and the serum concentrations of thyroid hormones did not change. In contrast, circulating cortisol decreased linearly in diets containing ASCO meal. The apparent total-tract digestibilities of dry matter, organic matter, and crude protein increased linearly with ASCO meal, but those of neutral and acid detergent fiber were not affected. In summary, feeding incremental amounts of ASCO meal decreased serum cortisol concentration, and increased I concentrations and output in serum, milk, feces, and urine.

Effects of Pistacia atlantica gum essential oil on ruminal methanogen, protozoa, selected bacteria species and fermentation characteristics in sheep

The objective of the current research was to investigate the effects of Pistacia atlantica subspecies Kurdica gum essential oil (PAKEO) on ruminal methanogen, protozoa, selected bacteria species, feed intake, and ruminal microbial fermentation in sheep. Six rumen-cannulated male Sanjabi sheep (average BW = 49 ± 2.4 kg) were used in a crossover design with two periods and 2 treatments: control (CON, without additive) and PAKEO (1.2 ml/sheep/day of PAKEO). Voluntary feed intake and ruminal ammonia-N concentration were not affected, but ruminal pH decreased by PAKEO. Total VFA concentration (P = 0.06) and propionate molar proportion (P < 0.05) increased, but acetate molar proportion not affected in PAKEO treatment compared to the CON. Also, PAKEO supplementation decreased the acetate: propionate ratio (P = 0.05). Results showed that PAKEO supplementation increased (P < 0.01) the relative abundance of total bacteria and Ruminococcus flavefaciens, and decreased (P < 0.05) Fibrobacter succinogenes abundance, but not influenced Ruminococcus albus. The ruminal relative population of methanogens was dramatically decreased by PAKEO (P < 0.01). Protozoa population was not affected by the addition of PAKEO. Results suggest that PAKEO could have the potential as feed additives to change the rumen microbial population and subsequently improve the ruminal fermentation characteristics. The decrease in ruminal methanogens and enhanced production of the gluconeogenesis precursor, propionic acid, demonstrated that PAKEO could be used to improve ruminal fermentation.

Evaluating the effect of finely ground, dry-rolled, and crumbled corn grain on performance, feeding behavior, and starch digestion in Holstein dairy heifers

Corn processing methods including finely ground (FGC), dry rolled (DRC), and crumbled corn (CRC) were evaluated to determine their effects on average daily gain (ADG), structural growth, starch digestibility, feeding behavior, and blood metabolites of young dairy heifers. In this study, 36 Holstein heifers [91 ± 4 d of age, 105 ± 6.5 kg of body weight (BW); mean ± standard deviation] housed in 9 pens (4 heifers per pen) were fed diets (dry matter basis) containing 20% forage (wheat straw) and 80% corn-based concentrate for 60 d. Pens were randomly assigned to 1 of 3 dietary treatments based on the type of corn grain used for the diets: (1) ground corn (FGC; fine: 1.11 ± 0.52 mm); (2) dry-rolled corn (DRC; 2.30 ± 0.68 mm); and (3) crumbled corn (CRC; 2.54 ± 0.70 mm). Heifers had ad libitum access to diets and water throughout the experiment and the feed intake was measured daily. Animals were weighed at the beginning (91 d of age) and end (151 d of age) of the study. The ADG (kg of BW/d) was calculated at the end of experiment at an individual level. Feeding behavior was recorded based on direct observation by monitoring each heifer every 5 min during a 22-h period at 150 d of age. The CRC and DRC tended to increase feed intake compared with FGC, whereas heifers fed CRC tended to have a greater withers height compared with other treatments. Feed efficiency was not affected; however, ADG and final BW increased in heifers fed the CRC diet compared with other diets. Feeding CRC increased total-tract starch digestibility compared with FGC and DRC diets (97.8 vs. 93.1 and 89.5%, respectively). Compared with FGC diet, feeding DRC and CRC tended to increase rumination time. The molar proportion of propionate was greater, and the molar proportion of acetate and acetate-to-propionate ratio were lower in heifers fed CRC than in those fed DRC. The blood glucose and insulin-like growth factor concentrations increased in heifers fed CRC compared with feeding DRC; however, blood urea concentrations decreased by CRC feeding. In conclusion, thermal processing (CRC diet) improved total-tract starch digestibility, ADG, feed intake, and skeletal growth, but had no effect on feed efficiency during the experimental period. Our results indicated that the thermal processing of corn grain improved growth performance of weaned heifers; however, the performance of heifers over a 60-d period did not differ between mechanical processing methods (grinding and dry rolling).

Associations among nutrient concentration, silage fermentation products, in vivo organic matter digestibility, rumen fermentation and in vitro methane yield in 78 grass silages

Grass-clover silage constitutes a large part of ruminant diets in Northern and Western Europe, but the impact of silage quality on methane (CH4) production is largely unknown. This study was conducted to identify the quality attributes of grass silage associated with variation in CH4 yield. We expected that silage nutrient concentrations and silage fermentation products would affect CH4 yield, and that these factors could be used to predict the methanogenic potential of the silages. Round bales (n = 78) of grass and grass-clover silage from 37 farms in Norway were sampled, incubated, and screened for in vitro CH4 yield, i.e. CH4 production expressed on the basis of incubated organic matter (CH4-OM) and digestible OM (CH4-dOM) using sheep. Concentration of indigestible neutral detergent fiber (iNDF) was quantified using the in situ technique. The data were subjected to correlation and principal component analyses. Stepwise multiple regression was used to model methanogenic potential of silages. Among all investigated silage composition variables, neutral detergent fiber (aNDFom) and water-soluble carbohydrate (WSC) concentrations obtained the greatest correlations to CH4-OM (r = −0.63 and r = 0.57, respectively, P < 0.001), while concentration of iNDF negatively correlated with CH4-OM (r = −0.48, P < 0.001). In vivo organic matter digestibility (OMD) and concentration of ammonia-N (NH3-N) in silages were also correlated to CH4-OM (r = 0.44 and r = −0.32, P < 0.001 and P < 0.01, respectively). The stepwise regression using CH4-OM as response variable included aNDFom, WSC, iNDF, silage propionic acid and pH in descending order. The stepwise regression using CH4-dOM as response variable included WSC, aNDFom and iNDF in descending order. Among in vitro rumen short chain fatty acids (SCFA), molar proportion of butyrate was the most prominent in increasing CH4-OM and CH4-dOM (r = 0.23 and r = 0.36, P < 0.05 and P < 0.01, respectively), while molar proportion of propionate was the most prominent SCFA in reducing CH4-OM and CH4-dOM (r = −0.23 and r = −0.26, respectively, P < 0.05). Regression models that account for silage quality attributes can be used to predict CH4 yield from silages with a coefficient of determination (R2) between 0.33 (CH4-dOM) and 0.65 (CH4-OM). In conclusion, concentration of WSC increased in vitro CH4-OM and CH4-dOM, while concentration of aNDFom and iNDF decreased CH4-OM and CH4-dOM in grass silages.

Effects of Dietary Barley Starch Contents on the Performance, Nutrient Digestion, Rumen Fermentation, and Bacterial Community of Fattening Hu Sheep.

The objective of this experiment was to investigate the effects of substituting corn starch (CS) with barley starch (BS) on the growth performance, nutrient digestion, rumen fermentation, and bacterial community of fattening Hu sheep. Seventy-two Hu lambs with similar initial body weight (BW, 29.70 ± 1.70 kg) were randomly assigned to four treatments, with 18 lambs per group. The four experimental diets have identical starch contents but with different starch sources as 100% starch from corn (BS-0), 33% starch from barley and 67% starch from corn (BS-33), 67% starch form barley and 33% starch from corn (BS-67), and 100% starch from barley (BS-100). All lambs were reared in individual units and fed high-concentrate diets (85% concentrate in diets based on dry matter [DM]). The experimental period included 7 days for adaptation and 63 days for data collection. Sixteen ruminal cannulated Hu sheep were divided into 4 groups and received the four experimental diets to determine the dynamics of ruminal pH. The average daily gain (ADG), and BW gain of lambs linearly decreased (p < 0.05), whereas the feed to gain ratio linearly increased (p < 0.05) with increasing dietary proportions of BS. Digestibility of DM, organic matter, neutral detergent fiber, acid detergent fiber, starch, and gross energy (GE) decreased (p < 0.05) with increasing dietary BS contents. Ruminal mean pH decreased (p < 0.05) with increasing proportions of dietary BS, accompanied with linearly increased (p < 0.05) time and area of ruminal pH below 5.80 or 5.60. Increasing dietary proportions of BS linearly decreased (p < 0.05) the molar proportion of acetate, but linearly increased (p < 0.05) the molar proportion of propionate. Sheep of the BS-0 and BS-33 treatments had a less (p < 0.05) relative abundance of Selenomonas ruminantium than that of sheep of the BS-67 treatment, but a greater (p < 0.05) relative abundance of Ruminococcus albus than that of sheep of the BS-100 treatment (p < 0.05). In conclusion, feeding a high-concentrate corn-based diet for fattening Hu sheep improved the performance and rumen fermentation parameters when compared to the barley-based diet.

Effect of heat-treated green tea waste feeding on fermentation kinetics, in vitro degradability, in vivo apparent digestibility, nitrogen balance, and blood metabolites in Black Bengal goat.

The study was conducted to examine the effect of heat treatment of green tea waste (GTW) on rumen degradability, apparent digestibility, and plasma metabolites in Black Bengal goat based on in vitro and in vivo studies. The in vitro incubation was performed with autoclaved, oven, and freeze-dried GTW, whereas animal study was conducted using 12 Black-Bengal goats in a 3×3 Latin-square design. Goats were fed a total-mixed-ration without (control) or with the partial replacement of soybean meal and barley with 50 g/kg dry matter (DM) of either oven-dried or autoclaved GTW. Heat treatments reduced ether extract and tannins concentration but increased the effective DM and crude protein (CP) degradability of GTW. The highest values of in vitro volatile fatty acid concentration, molar proportion of propionate, ammonia-nitrogen concentration, and cumulative gas production were observed for oven-dried GTW among the tested GTW. Dietary treatment did not alter the DM intake, but apparent CP digestibility and retained nitrogen (N) were increased in goats fed control or oven-dried GTW incorporated diets. Feeding autoclaved GTW diet increased the urinary and fecal N excretion in goats. In contrast, plasma glucose concentration was highest in goats fed control or oven-dried GTW diet. In conclusion, oven drying could be a practical approach to increase protein digestibility and retained N in goats.

Characterization of various wheat types and processing methods using in vitro ruminal batch cultures

This study investigated the effect of kernel hardness, processing method, and their interaction on particle size, dry matter (DM) disappearance (DMD), and fermentation characteristics of wheat grain in batch cultures. The study was a completely randomized design with 3 wheat classifications (soft, medium, hard) × 3 processing methods (grinding, dry- and temper-rolling). Fifty-five wheat samples were characterized for chemical traits and classified for kernel hardness. Samples were either ground through 1-mm screen, dry-rolled or temper-rolled to a constant processing index (PI) of 0.80. In vitro gas production (GP) kinetics, fermentation characteristics and DMD at 6, 24 and 48 h of incubation were measured. Crude protein (CP) (g/kg) was lower and starch (g/kg) was higher for soft than medium and hard wheat. The PSD of rolled wheat was affected (P < 0.01) by a wheat hardness × processing interaction. With dry-rolling, soft wheat had more particles retained on the 2.36-mm sieve and less on the 1.18-mm sieve, while, with temper-rolling, soft wheat had more particles retained on the 3.35-mm sieve and less on the 2.36-mm sieve than those for dry- or temper-rolled medium and hard wheat. Kernel hardness × processing was observed (P < 0.01) for DMD and CPD after 24 h and 48 h of incubation; the DMD and CPD were higher (P < 0.01) with dry- than temper-rolled hard or medium wheat, but no differences in DMD and CPD were observed between dry- and temper-rolled soft wheat. A kernel hardness × processing interaction was also noted for total VFA production and molar proportions of propionate after 24 h of incubation (P < 0.05). Dry-rolled soft wheat had a higher (P = 0.04) total VFA concentration and molar proportion of propionate after 24 h of incubation as compared to dry-rolled hard wheat. Compared to grinding, VFA concentrations and proportion of propionate were all reduced by both dry- and temper rolling with the magnitude of these differences generally being greater for soft as compared to medium and hard wheat. In conclusion, regardless of kernel hardness, PSD of dry- and temper-rolled wheat had a significant impact on DMD. Tempering was more effective at reducing the generation of fine particles than dry-rolling, particularly with hard wheat, a factor that may reduce the risk of digestive disturbances in ruminants fed wheat.

Effects of Selenium Supplementation on Rumen Microbiota, Rumen Fermentation, and Apparent Nutrient Digestibility of Ruminant Animals: A Review

Enzymes excreted by rumen microbiome facilitate the conversion of ingested plant materials into major nutrients (e.g., volatile fatty acids (VFA) and microbial proteins) required for animal growth. Diet, animal age, and health affect the structure of the rumen microbial community. Pathogenic organisms in the rumen negatively affect fermentation processes in favor of energy loss and animal deprivation of nutrients in ingested feed. Drawing from the ban on antibiotic use during the last decade, the livestock industry has been focused on increasing rumen microbial nutrient supply to ruminants through the use of natural supplements that are capable of promoting the activity of beneficial rumen microflora. Selenium (Se) is a trace mineral commonly used as a supplement to regulate animal metabolism. However, a clear understanding of its effects on rumen microbial composition and rumen fermentation is not available. This review summarized the available literature for the effects of Se on specific rumen microorganisms along with consequences for rumen fermentation and digestibility. Some positive effects on total VFA, the molar proportion of propionate, acetate to propionate ratio, ruminal NH3-N, pH, enzymatic activity, ruminal microbiome composition, and digestibility were recorded. Because Se nanoparticles (SeNPs) were more effective than other forms of Se, more studies are needed to compare the effectiveness of synthetic SeNPs and lactic acid bacteria enriched with sodium selenite as a biological source of SeNPs and probiotics. Future studies also need to evaluate the effect of dietary Se on methane emissions.

Effects of partially replacing dietary corn with molasses, condensed whey permeate, or treated condensed whey permeate on ruminal microbial fermentation

Corn is a feedstuff commonly fed to dairy cows as a source of energy. The objective of this study was to evaluate whether partially replacing dietary corn with molasses or condensed whey permeate, in lactating dairy cow diets in a dual-flow continuous culture system, can maintain nutrient digestibility by ruminal microorganisms. Furthermore, this study evaluated whether treating condensed whey permeate before feeding could aid the fermentation of the condensed whey permeate in the rumen. Eight fermentors were used in a 4 × 4 replicated Latin square with 4 periods of 10 d each. The control diet (CON) was formulated with corn grain, and the other diets were formulated by replacing corn grain with either sugarcane molasses (MOL), condensed whey permeate (CWP), or treated condensed whey permeate (TCWP). Diets were formulated by replacing 4% of the diet dry matter (DM) in the form of starch from corn with sugars from the byproducts. Sugars were defined as water-soluble carbohydrates (WSC) in the rations. The fermentors were fed 52 g of DM twice daily of diets containing 17% crude protein, 28% neutral detergent fiber, and 45% nonfiber carbohydrates. Liquid treatments were pipetted into each fermentor. After 7 d of adaptation, samples were collected for analyses of volatile fatty acids (VFA), lactate, and ammonia, and fermentors' pH were measured at time points after the morning feeding for 3 d. Pooled samples from effluent containers were collected for similar analyses, nutrient flow, and N metabolism. Data were statistically analyzed using Proc MIXED of SAS version 9.4 (SAS Institute Inc.); fixed effects included treatment and time, and random effects included fermentor, period, and square. The interaction of treatment and time was included for the kinetics samples. The TCWP and MOL treatments maintained greater fermentor pH compared with CWP. Total VFA concentration was increased in CWP compared with MOL. The acetate:propionate ratio was increased in TCWP compared with CON, due to tendencies of increased acetate molar proportion and decreased propionate molar proportion in TCWP. Lactate concentration was increased in MOL. Digestibility of WSC was increased in the diets that replaced corn with byproducts. The partial replacement of 4% of DM from corn starch with the sugars in byproducts had minimal effects on ruminal microbial fermentation and increased pH. Treated CWP had similar effects to molasses.

Effects of seaweed extracts on in vitro rumen fermentation characteristics, methane production, and microbial abundance

Several seaweed extracts have been reported to have potential antimethanogenic effects in ruminants. In this study, the effect of three brown seaweed species (Undaria pinnatifida, UPIN; Sargassum fusiforme, SFUS; and Sargassum fulvellum, SFUL) on rumen fermentation characteristics, total gas, methane (CH4), carbon dioxide (CO2) production, and microbial populations were investigated using an in vitro batch culture system. Seaweed extract and its metabolites, total flavonoid and polyphenol contents were identified and compared. For the in vitro batch, 0.25 mg∙mL−1 of each seaweed extract were used in 6, 12, 24, 36 and 48 h of incubation. Seaweed extract supplementation decreased CH4 yield and its proportion to total gas production after 12, 24, and 48 h of incubation, while total gas production were not significantly different. Total volatile fatty acid and molar proportion of propionate increased with SFUS and SFUL supplementation after 24 h of incubation, whereas UPIN was not affected. Additionally, SFUS increased the absolute abundance of total bacteria, ciliate protozoa, fungi, methanogenic archaea, and Fibrobacter succinogenes. The relative proportions of Butyrivibrio fibrisolvens, Butyrivibrio proteoclasticus, and Prevotella ruminicola were lower with seaweed extract supplementation, whereas Anaerovibrio lipolytica increased. Thus, seaweed extracts can decrease CH4 production, and alter the abundance of rumen microbial populations.