Ruminal Short-chain Fatty Acid Research Articles

A Chiral-LC-MS Method for the Simultaneous Quantification of Short-Chain Fatty Acids and D/L-Lactate in the Ruminal Fluid of Dairy Cows.

Short-chain fatty acids (SCFA) and lactate in ruminal fluid are products resulting from the microbial fermentation of substrates and can be used to reflect the composition and activity of the ruminal microbiome. Determination of SCFA and D-/L-lactate in ruminal fluid currently requires two separate protocols, which is time-consuming and costly. In this study, we have optimised and validated a simple and unified 3-nitrophenylhydrazine (3-NPH) derivatisation protocol and a 20 min chiral-LC-MS method for the simultaneous quantification of all SCFA and D- and L-lactate in ruminal fluid. This method, which requires no sample pretreatment or purification shows adequate sensitivity (limit of detection (LOD): 0.01 µg/mL), satisfactory accuracy (recovery: 88-103%), and excellent reproducibility (relative standard deviation (RSD) for repeated analyses < 3% for most analytes). The application of this method to a cohort of 24 animals allowed us to reveal a large inter-cow variation in ruminal SCFA and lactate level, the concentration range for each species, the widespread correlation between different SCFA, and the strong correlation between D- and L-lactate.

87 Functional rumen microbiological survey of triplet-bearing Polypay ewes from parturition to weaning

Abstract Ewes transitioning from late gestation to early lactation face a number of challenges including physiological stress, dietary changes, and metabolic adaptations, particularly when bearing and rearing multiple offspring. Furthermore, rumen microbial composition and function has been correlated with milk production and nutrient density in transitioning dairy cows. However, limited research has evaluated the rumen microbial community of ewes during early lactation. The objective of this study was to conduct a functional microbiological survey of the ewe rumen from parturition to weaning. We hypothesized that ewes would experience fermentative disturbances post-parturition and that the rumen microbiota, and consequently, circulating metabolites, would recover over time. Nine multiparous Polypay ewes bearing triplets were fed a lactation diet consisting of alfalfa hay and concentrate mix to meet protein and energy requirements. One lamb of each triplet set was randomly selected and placed on milk replacer 24 h after birth. The two lambs remaining on the ewe were weaned at 56 d of age. Blood and rumen samples from ewes were collected via jugular venipuncture and oral intubation, respectively, at 2, 7, and 15 d of lactation in addition to at the time of weaning. Rumen bacterial functional guilds were enumerated via serial dilution. Ruminal short-chain fatty acids (SCFA) were quantified via HPLC and serum metabolites by LC-MS. All data were analyzed using PROC Mixed with repeated measures in SAS (v. 9.4, SAS Inst. Inc., Cary, NC). Total starch-utilizing bacteria remained steady during early lactation but increased 100-fold by weaning (P = 0.03). In contrast, the starch-utilizing guild sub-population lactobacilli increased 10-fold by d 15 of lactation (P &amp;lt; 0.01) and remained constant through weaning (P &amp;gt; 0.05). No differences were found in the viable number of rumen cellulolytic bacteria (P = 0.37) throughout the study. Ruminal propionate concentrations increased 35% (P = 0.04) from d 2 to weaning and serum propionate (36.8 ± 4.42 µM; P = 0.08) and glucose (59.8 ± 2.97 mg dL-1; P &amp;lt; 0.01) peaked on d 15 of lactation. While ruminal acetate did not fluctuate in early lactation, it increased 58% by weaning (P &amp;lt; 0.01) leading to an 88% increase in serum acetate (P &amp;lt; 0.01). Ruminal butyrate increased 49% by d 15 (P = 0.01) and this was reflected in a 7-fold increase in serum butyrate (P = 0.02). However, serum β-hydroxybutyrate did not differ from parturition through weaning (P = 0.51). Results of this experiment demonstrate that rumen bacterial functional guilds, as well as rumen and serum metabolites, were lowest two days post-parturition and increased over the course of lactation. This may suggest that ruminal fermentation is suppressed post-parturition, which could have implications for early lactation management strategies of triplet-bearing ewes.

Transcriptome profiling revealed that key rumen epithelium functions change in relation to short-chain fatty acids and rumen epithelium-attached microbiota during the weaning transition

This study aims to characterize the functional changes of the rumen epithelium associated with ruminal short-chain fatty acid (SCFA) concentration and epithelium-attached microbes during the weaning transition in dairy calves. Ruminal SCFA concentrations were determined, and transcriptome and microbiota profiling in biopsied rumen papillae were obtained from Holstein calves before and after weaning using RNA- and amplicon sequencing. Metabolic pathway analysis showed that pathways related to SCFA metabolism and cell apoptosis were up- and down-regulated postweaning, respectively. Functional analysis showed that genes related to SCFA absorption, metabolism, and protective roles against oxidative stress were positively correlated with ruminal SCFA concentrations. The relative abundance of epithelium-attached Rikenellaceae RC9 gut group and Campylobacter was positively correlated with genes involved in SCFA absorption and metabolism, suggesting that these microbes can cooperatively affect host functions. Future research should examine the contribution of attenuated apoptosis on rumen epithelial functional shifts during the weaning transition.

Effect of sodium concentration and mucosal pH on apical uptake of acetate and butyrate, and barrier function of the isolated bovine ruminal epithelium

This study was conducted to investigate the role of Na+ on ruminal short-chain fatty acid (SCFA) absorption and barrier function when isolated ruminal epithelium was exposed to high and low pH ex vivo. Nine Holstein steer calves (322 ± 50.9 kg of BW) consuming 7.05 ± 1.5 kg DM of a TMR were euthanized and ruminal tissue was collected from the caudal-dorsal blind sac. Tissues were mounted between 2 halves of Ussing chambers (3.14 cm2) and exposed to buffers that contained low (10 mM) or high (140 mM) Na+ with low (6.2) or high (7.4) mucosal pH. The same buffer solutions were used on the serosal side except that pH was maintained at 7.4. Buffers used to evaluate SCFA uptake contained bicarbonate to determine total uptake or excluded bicarbonate and included nitrate to determine non-inhibitable uptake. Bicarbonate-dependent uptake was calculated as the difference between the total and non-inhibitable uptake. Acetate (25 mM) and butyrate (25 mM) were spiked with 2-3H-acetate and 1-14C-butyrate, respectively, and were then added to the mucosal side, incubated for 1 min, and tissues were analyzed to evaluate rates of SCFA uptake. Tissue conductance (Gt) and the mucosal-to-serosal flux of 1-3H-mannitol were used to assess barrier function. There were no Na+ × pH interactions for butyrate or acetate uptake. Decreasing mucosal pH from 7.4 to 6.2 increased total acetate and butyrate uptake, and bicarbonate-dependent acetate uptake. Flux of 1-3H-mannitol was not affected by treatment. However, high Na+ concentration reduced Gt and prevented an increase in Gt from flux period 1 to flux period 2. The results of this study indicate that although providing more Na+ to the ruminal epithelium does not affect SCFA uptake or mannitol flux, it may help stabilize tissue integrity.

Trichostrongylus colubriformis infection damages intestine brush board cells and could negatively impact postabsorptive parameters of Santa Ines lambs

This study aimed to evaluate histological, digestive and postabsorptive physiological parameters in Santa Ines lambs infected with Trichostrongylus colubriformis and fed different levels of phosphorus. Therefore, eighteen Santa Ines, castrated male, six-month old, healthy lambs (initial body weight 22.4 ± 2.7 kg) were distributed in one of four treatments arranged in a 2 × 2 split-plot arrangement: Sufficient dietary P level and uninfected (SPui; n = 4), Sufficient dietary P level and infected (SPi; n = 5), Deficient dietary P level and uninfected (DPui; n = 4), Deficient dietary P level and infected (DPi; n = 5). Infected lambs received, orally, a single pulse dose of 40.000 T. colubriformis infective larval stage (L3). Animals were fed Tifton 85 hay (Cynodon ssp.; 60%), and cassava meal and maize gluten meal (40%). Measurement of nutrient apparent digestibility and nitrogen metabolism were performed in individual metabolic stalls. To achieve the trial results, it was measured methane emissions in respiratory chambers, urine purine derivatives, ruminal short-chain fatty acids (SCFA), histological cuts of duodenal mucosal tissues and passage rates fluxes, analyzed by external (Yb, Cr, and Co) and internal (iNDF) markers. Statistical procedures were performed in R studio. The fixed main effects of treatment and the interactions were tested by ANOVA, and means compared by Duncan's test at 5% significance. Apparent digestibility was not affected by treatments, however, nitrogen retained decreased (P < 0.01) and urinary nitrogen losses increased (P < 0.01) in infected animals. Small intestine digesta content, empty segment weight, and length were higher in infected animals (P < 0.05). Passage rate was not majorly affected by infection or dietary P levels. Methane emissions, SCFA concentrations, and purine derivative excretion were also not affected by treatments. Regarding the histology, the vilosity weight (P < 0.05), and crypt depth (P < 0.01) decreased in infected animals. In conclusion, T. colubriformis infection can damage intestinal mucosa and affect nitrogen metabolism, but did not affect the digesta transit, and nutrient digestibility. The P dietary levels did not promote any modification in GIT physiological parameters tested in this study.

A comparison of post-ruminal provision of Ca-gluconate and Ca-butyrate on growth performance, gastrointestinal barrier function, short-chain fatty acid absorption, intestinal histology, and brush-border enzyme activity in beef heifers.

The objective of this study was to compare the effects of post-ruminal provision of Ca-butyrate (CaB) when delivered via abomasal dosing, and Ca-gluconate (CaG) when provided ruminally using a rumen protected form or using an unprotected form via abomasal dosing on short-chain fatty acid (SCFA) concentration throughout the GIT, nutrient digestibility, GIT barrier function, ruminal SCFA absorption, ruminal morphometrics, intestinal brush border enzyme activity, and blood parameters for beef heifers. Thirty-two beef heifers fitted with ruminal cannulas were used in a randomized complete block design and assigned to one of four treatments: 1) negative control (ruminal infusion of double-distilled water; CON); 2) abomasal infusion of CaB (AB; 0.0029% of BW); 3) abomasal infusion of CaG (AG; 0.0077% of BW); and 4) ruminal infusion of a hydrogenated fat-embedded CaG (RG; 0.0192% of BW) to provide ruminal protection. Excluding CON, treatments were designed to deliver the same amount of butyrate in the small intestine. Heifers were housed in individual pens and DMI was limited to 95% of voluntary intake to minimize a potential confounding effect of DMI on treatment responses. Total GIT barrier function was assessed on day 17 and SCFA disappearance was evaluated on day 21 using the temporarily isolated and washed reticulo-rumen technique. On day 28, heifers were slaughtered, and ruminal and colonic digesta were collected to assess SCFA concentration. Additionally, ruminal, jejunal, and colonic tissues were collected to assess SCFA fluxes and regional barrier function ex vivo using the Ussing chamber technique. For colonic digesta, both AB and CaG treatments reduced the proportion of acetate (P < 0.05) and increased the proportion on propionate (P < 0.05) compared to CON. Relative to CON, AB but not CaG treatments increased in vivo ruminal disappearance of total SCFA (P = 0.01), acetate (P = 0.03), propionate (P = 0.01), and butyrate (P > 0.01). Treatments did not affect (P ≥ 0.10) acetate and butyrate fluxes in the ruminal and colonic tissues when measured ex vivo; however, when compared with CON, AB tended to decrease (P = 0.09) mannitol flux across ruminal tissue. In addition, mannitol flux was affected (P < 0.01) by region, with greater mannitol flux across the jejunum than rumen and colon. We conclude that while both abomasal infusion of CaB and CaG affect the molar proportion of acetate and propionate in the colon, only abomasal CaB stimulated ruminal SCFA absorption for growing beef heifers.

Relationships between rumen microbes, short-chain fatty acids, and markers of white adipose tissue browning during the cold season in grazing Mongolian sheep (Ovisaries)

Mongolian sheep are characteristically cold-tolerant and they partially depend on seasonal browning of white adipose tissue (WAT) to acclimate to cold environments. The present work aimed to examine the rumen microbes, rumen fermentation profile, and relationships between the rumen microbiota, short-chain fatty acids (SCFAs), and markers of WAT browning and are thus conducive to exploring the plateau environment adaptability of Mongolian sheep in the cold season. A comparative analysis of the rumen microbes and SCFAs in the cold and warm seasons was conducted. Rumen microbes were analyzed using Illumina sequencing of the 16S rRNA gene. Ruminal SCFAs were determined by gas chromatography. Spearman's correlation test was used to determine the relationships between the rumen microbiota, SCFAs, and markers of WAT browning. Microbial 16S rRNA sequencing revealed a marked shift in rumen microbiota composition between the two seasons, and the bacteria were characterized by increased levels of the Actinobacteria and genera Christensenellaceae R-7 group, Ruminococcaceae UCG-011, Rikenellaceae RC9 gut group, Papillibacter, and Butyrivibrio 2 and reduced levels of Prevotella 1 and Ruminococcaceae UCG-014 in the cold season (P<0.05). Furthermore, the concentrations of SCFAs such as acetate and butyrate were significantly increased in the cold season (P<0.001 and P<0.05, respectively). Correlation analysis demonstrated that the relative abundances of the Actinobacteria and the genera Christensenellaceae R-7 group, Butyrivibrio 2, Ruminococcaceae UCG-002, and Ruminococcaceae UCG-011, identified as members of the Christensenellaceae, Lachnospiraceae, and Ruminococcaceae families (all within Firmicutes), were positively correlated with markers of browning in either retroperitoneal WAT or perirenal WAT, and acetate was positively correlated with Ruminococcaceae UCG-011 and Butyrivibrio 2 and markers of browning in either retroperitoneal WAT or perirenal WAT. Overall, there are distinct relationships between the rumen microbiota, ruminal SCFAs and markers of WAT browning during the cold season in grazing Mongolian sheep.

PSVI-18 Effect of Processing Method and Severity for Hybrid Fall rye on dry Matter Intake, Ruminal Fermentation, and Apparent Total Tract Nutrient Digestibility in Ruminally Cannulated Beef Heifers

Abstract This study evaluated the effect of processing method and severity of hybrid fall rye on dry matter intake (DMI), ruminal fermentation, and apparent total tract nutrient digestibility for beef cattle. Ruminally cannulated Simmental heifers (n = 8; 327±33 kg) were used in a replicated 4×4 Latin square (21-d periods) balanced for carry-over effects with a 2×2 factorial treatment. Tempered rye [water added to achieve 80% dry matter (DM)] was compared with dry-rolled rye. Roller gap width of 1.23-mm and 0.8-mm were used for coarse and finely processed rye, respectively. This resulted in processing index values of: 80.9% for dry-rolled and coarse; 72.7% for dry-rolled and fine; 92.9% for tempered and coarse; and 88.2% for tempered and fine processed rye. Diets (DM basis) included hybrid rye grain (86%), barley silage (15%), mineral (6%), and dry distillers’ grain plus solubles (3%). Feeding tempered rye increased (P&amp;lt; 0.01) DMI by 0.87 kg compared with dry-rolled rye, and feeding coarse rye increased (P=0.04) DMI by 0.33 kg compared with fine rye. Cattle fed dry-rolled and finely processed rye had greater (P&amp;lt; 0.04) area that pH was &amp;lt; 5.5 compared with tempered and coarse rye, respectively. Ruminal short-chain fatty acid concentrations and ammonia were not affected (P≥0.12). Feeding dry-rolled rye increased DM digestibility by 2.4% (P=0.02), and crude protein digestibility in 3.0% (P=0.01) compared with tempered rye. Starch digestibility was not affected by processing severity of dry-rolled rye, but increased from 92.8 to 95.9% for tempered rye with increasing severity (interaction, P=0.03). Rolling tempered rye at the same roller gap as dry-rolled rye decreases processing severity but may allow for a greater severity of processing without marked reductions in DMI and ruminal pH, while achieving similar total tract starch digestibility. When increasing processing severity (81 vs. 73%), dry-rolling hybrid rye may reduce DMI and ruminal pH.

Effects of supplementation with Saccharomyces cerevisiae products on dairy calves: A meta-analysis.

Saccharomyces cerevisiae products (SCP) have the potential to promote the growth and development of the gastrointestinal tract and immunity in young livestock animals. However, the effects of SCP supplementation on calves are inconsistent among the reported studies in the literature. Hence, we performed a meta-analysis to comprehensively assess the effects of SCP on the growth performance, ruminal fermentation parameters, nutrients digestibility, ruminal histological morphology, serum immune response, and fecal pathogen colony counts in calves. We searched the Web of Science, ScienceDirect, PubMed, and China National Knowledge Infrastructure for relevant studies published up to October 1, 2021. After screening against a set of criteria, the data of 36 studies were included in our meta-analysis (2,126 calves in total). We evaluated the quality of the data using sensitivity analysis and assessed publication bias. Our meta-analysis revealed several important findings. First, SCP supplementation increased the ruminal short-chain fatty acid concentration, ruminal papilla height, and fiber digestibility, pointing toward stimulation of the development of the rumen in calves. Second, SCP supplementation increased the serum concentrations of total protein, IgA, and IgG but decreased fecal pathogen colony counts, suggesting that SCP could help calves to promote immunity (especially maintaining circulating concentrations of immunoglobulins in preweaning calves) and resistance to pathogens. Third, a subgroup analysis between preweaning and postweaning calves showed that SCP increased average daily gain and dry matter intake preweaning but not postweaning, suggesting that SCP is better supplemented to preweaning calves to achieve the best results. Forth, based on the dose-response curve, 24 to 25 g/d might be the optimal dose range of SCP supplementation (into starter feed) preweaning to achieve the best overall effect, meanwhile, we need more studies to improve the consistency and accuracy of the dose-response curve prediction. Overall, SCP supplementation improved growth performance, rumen development, and immunocompetence in calves, particularly in preweaning calves.

Different feeding strategies can affect growth performance and rumen functions in Gangba sheep as revealed by integrated transcriptome and microbiome analyses.

Due to the harsh environment in the Tibetan Plateau, traditional grazing greatly limits the growth potential of local animals and causes severe ecosystem degradation. This is an urgent issue to be solved, which requires alternative strategies for grazing animals in the Tibetan alpine pastoral livestock systems. This study aimed to investigate the effects of different feeding strategies on growth performance and ruminal microbiota-host interactions in the local breed of sheep (Gangba sheep). Thirty 9-month old Gangba sheep (n = 10 per group) were assigned to natural grazing (G), semi-grazing with supplementation (T), and barn feeding (F) groups (supplementation of concentrate and oat hay) based on body weight. At the end of the experiment (75 d), all sheep were weighed, rumen fluid was obtained from six sheep per group, and ruminal epithelium was obtained from 3 sheep per group. The results showed that: (1) Compared with the G and T groups, the F group significantly increased dry matter intake, average daily gain, and feed conversion ratio of animals. Additionally, Gangba sheep in the F group had higher concentrations of ruminal short-chain volatile fatty acids (VFAs), especially propionate and butyrate (P <0.05) than sheep in the G and T groups. (2) The principal coordinates analysis indicated a significant difference in bacterial composition among different feed strategies. More specifically, the relative abundance of propionate (unidentified F082 and Succiniclasticum) and butyrate-producing (Eubacterium_coprostanoligenes_group) genera were also observed to be increased in the F group, in which unidentified F082 was identified as a differential biomarker among the three groups according to linear discriminant analysis effect size analysis. (3) The dynamics of the rumen epithelial transcriptome revealed that ECM-receptor interactions, focal adhesion, and PI3K-Akt signaling pathways, which are critical in mediating many aspects of cellular functions such as cell proliferation and motility, were upregulated in the F group. In conclusion, under harsh conditions in the Tibetan alpine meadow, barn feeding increased ruminal VFAs concentrations (especially propionate and butyrate), which stimulated gene expression related to cell proliferation in rumen epithelium, appearing to be superior to natural grazing and semi-grazing in gaining body weight of the local Gangba sheep.

Snaplage with microbial inoculant or organic acids has altered fermentative losses, microorganism counts, starch content and improves feed intake, digestibility and modulates ruminal fermentation in lambs

ABSTRACT Two experiments were performed to evaluate snaplage ensiling additives and determine the effects of feeding snaplage to lambs. In Exp. 1, grains, ears and husk from maize harvested at the R4 phenological stage were ensiled (65.3% DM content) in 30 min-silos in a completely randomised design with the following treatments: control (CON); microbial inoculant (INO), (Lactobacillus plantarum and Propionibacterium acidipropionici) at 4 g/ton of ensiled material; and organic acids (OA), a blend of organic acids at 2 g/kg of ensiled material. In Exp. 2, nine lambs were used in a 3 × 3 Latin square design. Lambs were randomly assigned to the following diets: control (CON); rehydrated maize silage (RHC), diet containing 380 g/kg RHC; or snaplage (SNAP), diet containing 770 g/kg of SNAP. Snaplage with OA exhibited greater DM recovery, lactic acid bacteria count and DM content than other treatments. Snaplage with INO had the lowest counts of aerobic bacteria and mould. Lambs-fed SNAP had greater nutrient intake and digestibility, ruminal short-chain fatty acid concentrations, and N retention compared to other groups. Incorporating OA to snaplage decreased DM losses and improved microbiological quality and chemical composition. Feeding snaplage to lambs may improve DM intake and apparent digestibility.

Replacing concentrates with a high-quality hay in the starter feed of dairy calves: II. Effects on the development of chewing and gut fermentation, and selected systemic health variables

Early development of the rumen, rumination, and fermentation is highly important in dairy calves. Yet, common rearing practices with feeding of concentrate-rich starters may jeopardize them because of lacking physically effective fiber (peNDF). The main objective of this study was to establish the influence of the composition of the calf starter feed (only forage with 2 different qualities or concentrate-rich starter diet) on chewing behavior, rumen development, rumen and hindgut fermentation, and selected systemic health and stress variables of dairy calves. The experiment was carried out with 40 newborn Holstein-Friesian calves, randomly assigned to 4 different solid feed treatments: MQH = 100% medium-quality hay (9.4 MJ metabolizable energy, 149 g of crude protein, and 522 g of neutral detergent fiber/kg of dry matter); HQH = 100% high-quality hay (11.2 MJ of metabolizable energy, 210 g of crude protein, 455 g of neutral detergent fiber/kg of dry matter); MQH+C = 30% MQH + 70% starter concentrate; HQH+C = 30% HQH + 70% starter concentrate). All calves were up to 14 wk in the trial and received acidified whole milk ad libitum in the first 4 wk of life, thereafter in reduced quantity until weaning on 12 wk of age. Water and the solid feed treatments were available ad libitum throughout the trial. Chewing activity was measured in wk 4, 6, 10, and 12 using RumiWatch halters. Until wk 3, rumen fluid, feces and blood were sampled weekly, thereafter every 2 wk. Rumen mucosal thickness (RMT) was measured on the same days with rumen fluid samples. Data showed that calves fed the HQH diet consumed more peNDF and this was associated with longer rumination time (591 min/d) and more ruminating boli (709 boli/d) than calves fed concentrate-rich diets (MQH+C: 430 min/d, 518 boli/d; HQH+C: 430 min/d, 541 boli/d), whereas the MQH group was intermediate (539 min/d, 644 boli/d). Ruminal and fecal pH were higher in calves fed only hay (especially MQH) compared with calves with concentrate supplementation. In both hay-fed groups, ruminal and fecal short-chain fatty acids were shifted toward acetate, whereas only the HQH diet increased the butyrate proportion in the ruminal short-chain fatty acids profile. Ruminal ammonia concentration was at a high level only in the first 3 wk and decreased thereafter. Feeding HQH tended to increase ruminal ammonia, likely because of its high crude protein content and ruminal degradability as well as lower assimilation from rumen microbes. The RMT similarly, though nonlinearly, increased in all groups over the course of the experiment. When using RMT as an indicator of rumen development in dairy calves in the practice, our data suggest an RMT of 1.7mm and >2mm at wk 5 and 10 of life, respectively. Feeding did not affect the blood levels of aspartate aminotransferase, gamma glutamyl transferase, glutamate dehydrogenase, and cortisol. In conclusion, feeding high-quality hay, instead of concentrate-rich starter feeds, resulted in improved rumination and ruminal fermentation profile, without affecting ruminal pH and systemic and stress health variables.

The effects of Pinus brutia bark extract on pure and mixed continuous cultures of rumen bacteria and archaea, and fermentation characteristics in vitro

The aim of the study was to investigate the effects of Pinus brutia bark extract, which is rich in polyphenolic compounds of tannins, on both pure and mixed continuous cultures of rumen bacteria and archaea, as well as on rumen fermentation characteristics in vitro. Antimicrobial susceptibility assay with pure cultures was carried out in an anaerobic chamber. Pinus brutia bark extract exhibited a potential inhibitor activity (P&lt;0.05) against pure cultures of Ruminococcus flavefaciens, Eubacterium ruminantium, and Methanobacterium formicicum while a growth stimulatory effect (P&lt;0.05) was observed for Ruminoccocus albus, Butyrivibrio fibrisolvens, and Streptococcus bovis. Pinus brutia bark extract only had a potential inhibitor effect (P&lt;0.05) on R. albus at the highest dose (1200 µg/mL). Pinus brutia bark extract also stimulated (P&lt;0.05) the growth of pure cultures of Fibrobacter succinogenes, while it did not affect Megasphaera elsdenii, except at the highest dose. The effects of two doses (75 and 375 mg/L) of P. brutia bark extract on in vitro mixed cultures and rumen fermentation parameters were determined by the rumen simulation technique (Rusitec). Supplementation with P. brutia bark extract led to a quadratic decrease (P&lt;0.05) in the cell numbers of R. flavefaciens. Production of total and individual short chain fatty acids (SCFA), acetate to propionate ratio (C2/C3), total protozoa, ruminal pH, and dry matter digestibility (DMD) did not change in the presence of P. brutia bark extract. Supplementation with both doses of P. brutia bark extract decreased (P&lt;0.05) the ammonia-N concentrations. Ammonia-N concentration was lowest in the high-supplemented group (P&lt;0.05). As a conclusion, inhibitory effects of P. brutia bark extract on some species in the pure cultures were in the same direction as with mixed ruminal cultures, while stimulatory effects disappeared. The lack of inhibitory effects on protozoa and on a large number of Gram-positive rumen bacteria in the mixed cultures suggests that its mechanism of action is not exactly similar to antibiotics. Although P. brutia bark extract did not alter ruminal SCFA, it could have potential to improve ruminal protein utilization without depressing rumen microbial fermentation.

Effects of narasin supplementation frequency on intake, ruminal fermentation parameters, and nutrient digestibility of Bos indicus Nellore steers fed with forage-based diets.

The study aimed to evaluate if the frequency of narasin supplementation impacts dry matter intake, ruminal fermentation parameters, and apparent digestibility of nutrient in Nellore (Bos indicus) steers fed forage-based diets. A total of 32 rumen-cannulated Nellore steers (initial body weight [BW] = 317 ± 27 kg; age =18 ± 1 mo) were assigned to individual pens in a randomized complete block design according to their initial shrunk BW. Within block, steers were randomly assigned to 1 of 4 treatments: 1) forage-based diet without the addition of narasin (CON; n = 8), 2) CON diet plus 13 ppm of narasin every 24 h (N24; n = 8), 3) CON diet plus 26 ppm of narasin every 48 hours (N48; n = 8), or 4) CON diet plus 39 ppm of narasin every 72 hours (N72; n = 8). The experimental period lasted 30 d, with 18 d for diet adaptation and 12 d for sample collection. The experimental diets contained 95% of Tifton-85 (Cynodon dactylon spp.) haylage and 5% ground corn used as a delivery vehicle for narasin. Ruminal fluid was obtained from d 25 to 30 at 6 h after feeding to determine ruminal fermentation parameters. Narasin supplementation frequency did not affect (P ≥ 0.22) nutrient intake and total tract apparent digestibility. Steers fed N24 and N48 had reduced (P = 0.02) ruminal acetate concentration compared with CON and N72. Daily supply of narasin increased (P = 0.01) the molar proportion of propionate compared with CON and N72, and it did not differ between N24 vs. N48, N48 vs. N72, and N72 vs. CON. Also, N48 steers had greater (P = 0.01) rumen propionate concentration compared with CON. The N24 treatment decreased the Ac:Prop (P = 0.01) and AcBut:Prop (P = 0.02) ratio compared with CON and N72, while N48 had reduced (P = 0.01) Ac:Prop and AcBut:Prop ratio when compared with CON steers. Steers fed N24 and N48 had greater (P = 0.04) ruminal short-chain fatty acids compared with CON, but it did not differ (P > 0.11) between N24, N48, and N72. Supplementing narasin to steers fed forage-based diets decreased (P < 0.01) ruminal ammonia concentration compared with CON steers regardless of supplementation frequency, being the least result observed for N24 steers. Collectively, narasin supplementation frequency affected fermentation parameters without altering the nutrient intake and total tract apparent digestibility. Hence, decreasing frequency of narasin supplementation to Nellore steers fed a forage-based diet did not reduce the capacity to modulate rumen fermentation parameters.

Effects of mannan oligosaccharides on growth performance, nutrient digestibility, ruminal fermentation and hematological parameters in sheep.

BackgroundMannan oligosaccharides (MOS) are a promising feed additive in animal husbandry due to mainly improving animal health status. The purpose of this study was to investigate the effects of MOS on growth performance, nutrient digestibility, ruminal fermentation, and twelve hematological parameters in sheep.MethodsNinety-six healthy Hu rams with similar body weights were chosen and divided into four treatment groups (twenty-four rams in each group), in which four different doses of MOS were tested: 0%, 0.8%, 1.6% and 2.4% of the basal diet (on an as-fed basis).ResultsThe results showed that supplementation dietary MOS did not affect feed intake, body weight, average daily weight gain, or ruminal short-chain fatty acids (SCFAs) concentration; the ratio of individual fatty acids to total SCFAs, the C2/C3 ratio, and the hematological parameters in the sheep were also unaltered (P > 0.05). Conversely, supplementation dietary MOS increased the dry matter, organic matter, crude protein, neutral detergent fiber, acid detergent fiber, and ash apparent digestibility (P < 0.05), and decreased the ruminal ammonia concentration in the sheep (P < 0.05), especially at a dose of 1.6%.ConclusionsThis indicates that supplementation dietary MOS improved nutrient utilization by the sheep and nitrogen metabolism in the rumen; however, the effects are too slight to interfere with the basal metabolism in the sheep.

Effects of protein content and rumen-undegradable to rumen-degradable protein ratio in finely ground calf starters on growth performance, ruminal and blood parameters, and urinary purine derivatives

This study investigated the effects of feeding finely ground starter diets containing either 18 or 22% crude protein (CP) content [dry matter (DM) basis] and high or low ratios of rumen-undegradable protein to rumen-degradable protein (RUP:RDP) on growth performance, nutrient digestibility, ruminal fermentation, blood metabolites, and urinary purine derivatives in dairy calves. A total of 48 three-day-old female Holstein dairy calves with 40.2 ± 2.5 kg of initial body weight (BW) were randomly assigned in a complete randomized block design to a 2 × 2 factorial arrangement of treatments (12 calves/treatment). Treatments were as follows: (1) finely ground starter diet (mean particle size = 0.69 mm) with 18% CP and low RUP:RDP ratio [low ratio (LR) = 26:74; 18CP-LR]; (2) finely ground starter diet with 18% CP and high RUP:RDP ratio [high ratio (HR) = 35:65; 18CP-HR]; (3) finely ground starter diet with 22% CP and low RUP:RDP ratio (22CP-LR); (4) finely ground starter diet with 22% CP and high RUP:RDP ratio (22CP-HR) on DM bases. Blocking was based on the day of treatment assignment, and treatments were randomly assigned within each block. Calves received 4 L of milk daily from d 3 to 10, 7 L/d from d 11 to 40, 4 L/d from d 41 to 49, and 2.5 L/d from d 50 to 53, and then all calves were weaned but remained in the experiment until d 83 of age. The results showed that overall average daily gain (ADG), weaning BW, and feed efficiency (FE) were greater in 22% CP treatments than in 18% CP. Increasing the starter CP content from 18 to 22% of DM did not influence overall starter feed intake, milk intake, total dry matter intake (DMI), postweaning ADG, and FE of calves. No effect of RUP:RDP ratio was observed for starter feed intake, milk intake, total DMI, preweaning ADG, FE, and grams of CP per megacalorie of metabolizable energy. The RUP intake and postweaning ADG were greater for calves fed the HR diets than for those fed the LR diets. The digestibility of neutral detergent fiber was greater, and the digestibility of OM tended to be greater, and the ruminal concentrations of total short-chain fatty acids (SCFA), acetate proportion, and acetate-to-propionate ratio were greater in 22% CP than in 18% CP. A 2-way interaction between starter protein content and time was observed for total ruminal SCFA, acetate proportion, and acetate-to-propionate ratio, indicating that starter CP concentration had more effect on ruminal parameters. Preweaning urinary purine derivatives, preweaning microbial protein synthesis, and postweaning urinary nitrogen were greater for calves fed the 22CP diets than for those fed the 18CP diets but were not affected by the different RUP:RDP ratios. The concentrations of blood glucose and insulin were greater in 22% CP than in 18% CP diets. The blood insulin concentration was greater when calves received the HR diets compared with the LR diets. Therefore, we conclude that greater starter protein content can have beneficial effects on growth performance, probably through increased microbial protein synthesized and preweaning blood insulin concentration; however, a greater RUP:RDP ratio showed marginal effects on growth performance during the postweaning period.

Short-term screening of multiple phytogenic compounds for their potential to modulate chewing behavior, ruminal fermentation profile, and pH in cattle fed grain-rich diets

In cattle, proper rumen functioning and digestion are intimately linked to chewing behavior. Yet, high grain feeding impairs chewing activity, increasing the risk of subacute ruminal acidosis and dysfermentation. This study aimed to screen 9 different phytogenic compounds for their potential to modulate chewing activity, meal size, rumino-reticular short-chain fatty acids (SCFA), and pH during consumption in a first daily meal and shortly thereafter in cattle fed a grain-rich diet. Treatments were control (total mixed ration without phytogenic) or addition of a phytogenic compound at a low or high dose. Phytogenic compounds and doses (all in mg/kg) were angelica root (6.6 and 66), capsaicin (10 and 100), gentian root (6.6 and 66), garlic oil (0.3 and 3), ginger extract (40 and 400), L-menthol (6.7 and 67), mint oil (15.3 and 153), thyme oil (9.4 and 94), and thymol (5 and 50), for the low and high groups, respectively. Before the start of the screening experiment, cows were fed to reach subacute ruminal acidosis conditions, confirmed with the time of ruminal pH <5.8 being 655 ± 148.2 min/d. During the screening experiment, the treatments were offered in a controlled meal (2.5 kg of DM for 4 h) as part of the daily diet with 65% concentrate. Each treatment was tested in 4 of the 9 cannulated Holstein cows using an incomplete Latin square design. Ruminal and reticular fluids were sampled before and after each treatment, and data collected before the meal were used as covariates. Chewing and ruminal pH were monitored during the treatment, followed by 2 h of complete feed restriction, and then 4 h of ad libitum feed intake without phytogenic. Data showed that supplementation of angelica root tended to linearly increase rumination time immediately after the first meal when feed was restricted (27.3, 41.9, and 42.6 ± 5.99 min for control, low and high groups, respectively). Capsaicin increased eating time (43.6, 49.4, and 66.4 ± 4.93 min) during consumption but did not affect ruminal total SCFA or mean ruminal pH. Garlic oil reduced the concentration of reticular total SCFA (75.7, 71.3, and 60.1 mM) and tended to decrease ruminal acetate-to-propionate ratio (2.50, 1.78, and 1.87 ± 0.177) with no effect on ruminal pH. The L-menthol affected reticular total SCFA quadratically (76.1, 64.9, and 81.0 ± 4.22%), and ruminal pH responded quadratically when feed was reintroduced ad libitum (6.0, 6.3, and 6.1 ± 0.07). Mint oil did not affect chewing or total SCFA during consumption, but the low dose increased ruminal pH (6.5, 6.7, and 6.5 ± 0.08). Thyme oil tended to lower the severity of ruminal acidosis. Overall, phytogenic compounds demonstrated distinct dose-dependent effects to beneficially influence chewing behavior, modulate fermentation, and mitigate ruminal acidosis in dairy cows under a high-grain challenge diet.

Increasing levels of de-oiled wet distillers grains in feedlot diets on nutrient digestibility, ruminal fermentation and microbiology

The supply of wet distillers grains (WDG) has been growing in Brazil, with the increase in corn ethanol production. However, little is known about de-oiled corn WDG on nutrient digestibility, ruminal fermentation and microbiology of beef cattle. Thus, the aim of the study was to evaluate the effects of the increasing levels of de-oiled WDG replacing soybean meal and corn on dry matter (DM) intake, total tract digestibility, ruminal short chain fatty acids and microbiology. Eight ruminally cannulated Nellore bulls (BW = 453 ± 32 kg) were allocated on individual pens and distributed in 4 treatments with 0, 150, 300 and 450 g de-oiled WDG/kg DM in a 4 × 4 replicated Latin square design. The experimental period lasted 112 days, divided into 4 periods of 28 days (14 days of adaptation plus 14 days of sampling). The DM, organic matter and ether extract intake increased quadratically (P < 0.05), and were greater in animals fed 300 g/kg WDG. Intake and digestibility of crude protein and neutral detergent fiber increased, however, intake and digestibility of non-fiber carbohydrates decreased linearly (P< 0.05) with increasing levels of de-oiled WDG.Gross energy (GE) and digestible energy (DE) intake were quadratically affected by the treatments, whereby animals fed 300 g/kg WDG in the diet showed greater (P < 0.05) GE and DE intake. Moreover, propionate and butyrate concentration increased linearly (P< 0.05) in animals fed de-oiled WDG, which could be associated to greater (P< 0.10) relative abundance of Selonomonas ruminantium, resulting in higher ruminal pH in these animals. Therefore, the inclusion of de-oiled WDG might be used as replacement of soybean meal and ground corn in high concentrate diets of Nellore cattle without compromising ruminal fermentation and nutrient digestibility.

Identification of a Candidate Starch Utilizing Strain of Prevotella albensis from Bovine Rumen.

The inclusion of starch-rich feedstuffs, a common practice in intensive ruminant livestock production systems, can result in ruminal acidosis, a condition that can severely impact animal performance and health. One of the main causes of acidosis is the rapid accumulation of ruminal short chain fatty acids (SCFAs) resulting from the microbial digestion of starch. A greater understanding of ruminal bacterial amylolytic activities is therefore critical to improving mitigation of acidosis. To this end, our manuscript reports the identification of a candidate starch utilizer (OTU SD_Bt-00010) using batch culturing of bovine rumen fluid supplemented with starch. Based on 16S rRNA gene sequencing and metagenomics analysis, SD_Bt-00010 is predicted to be a currently uncharacterized strain of Prevotella albensis. Annotation of de novo assembled contigs from metagenomic data not only identified sequences encoding for α-amylase enzymes, but also revealed the potential to metabolize xylan as an alternative substrate. Metagenomics also predicted that SCFA end products for SD_Bt-00010 would be acetate and formate, and further suggested that this candidate strain may be a lactate utilizer. Together, these results indicate that SD_Bt-00010 is an amylolytic symbiont with beneficial attributes for its ruminant host.

123 Polyclonal antibody preparations from avian origin did not reduce plasmatic haptoglobin concentrations but increased ruminal NH3-N in beef steers during transition from forage to high-grain diets

Abstract This study investigated the effects of feeding an avian-derived polyclonal antibody preparation (PAP; CAMAS, Inc.) against Streptococcus bovis, Fusobacterium necrophorum, and lipopolysaccharides (40, 35, and 25% of the preparation, respectively) on plasmatic haptoglobin, ruminal short chain fatty acids (SCFA), and ammonia-N (NH3-N) concentrations of beef steers during a 21-d step-up adaptation to a high-grain diet. Eight ruminally cannulated Angus crossbred beef steers (658 ± 79 kg BW) were randomly assigned to treatments in a crossover design to be transitioned from a diet containing bermudagrass hay [Cynodon dactylon (L.) Pers.] plus 0.45 kg/d of molasses with 0 (CON) or 3 g/d of PAP (PAP) to a high-grain diet. Transition consisted of three 7-d steps of increased inclusion of cracked corn (35, 60, and 80% diet DM for STEP1, STEP2, and STEP3, respectively). On each transition d and 7 d after STEP3 (STEP3-7d), ruminal fluid samples were obtained every 3 h for 24 h. Blood samples were collected on d 0, 1, and 3 relative to each transition for haptoglobin determinations. Haptoglobin plasmatic concentrations increased (P = 0.03) on d 2 and 3 vs. d 1 during STEP2 and on STEP3 compared to STEP1 and STEP2 (P = 0.01). Steers receiving PAP had greater (P &amp;lt; 0.01) ruminal NH3-N concentration in STEP1; however, there were no effects of treatment on SCFA (P &amp;gt; 0.10). Total SCFA concentrations were affected by the step-up diets (P &amp;lt; 0.01); propionate concentration (Pro) was greater in STEP2 through STEP3-7d vs. STEP1 (P &amp;lt; 0.01), whereas acetate concentration (Ac) and Ac:Pro linearly decreased from STEP1 to STEP3-7d (P &amp;lt; 0.01). Feeding 3 g/d of polyclonal antibody preparations against Streptococcus bovis, Fusobacterium necrophorum, and lipopolysaccharides in a 21-d step-up adaptation to high-grain diets did not affect plasmatic haptoglobin or ruminal SCFA concentrations; however, it increased ruminal NH3-3 concentrations.