Molar Proportions Of Butyrate Research Articles

Effects of calcium-magnesium carbonate and calcium-magnesium hydroxide as supplemental sources of magnesium on ruminal microbiome.

Our objective was to evaluate the inclusion of calcium-magnesium carbonate [CaMg(CO3)2] and calcium-magnesium hydroxide [CaMg(OH)4] in corn silage-based diets and their impact on ruminal microbiome. Our previous work showed a lower pH and molar proportion of butyrate from diets supplemented with [CaMg(CO3)2] compared to [CaMg(OH)4]; therefore, we hypothesized that ruminal microbiome would be affected by Mg source. Four continuous culture fermenters were arranged in a 4 × 4 Latin square with the following treatments defined by the supplemental source of Mg: 1) Control (100% MgO, plus sodium sesquicarbonate as a buffer); 2) CO3 [100% CaMg(CO3)2]; 3) OH [100% CaMg(OH)4]; and 4) CO3/OH [50% Mg from CaMg(CO3)2, 50% Mg from CaMg(OH)4]. Diet nutrient concentration was held constant across treatments (16% CP, 30% NDF, 1.66 MCal NEl/kg, 0.67% Ca, and 0.25% Mg). We conducted four fermentation periods of 10 d, with the last 3 d for collection of samples of solid and liquid digesta effluents for DNA extraction. Overall, 16 solid and 16 liquid samples were analyzed by amplification of the V4 variable region of bacterial 16S rRNA. Data were analyzed with R and SAS to determine treatment effects on taxa relative abundance of liquid and solid fractions. Correlation of butyrate molar proportion with taxa relative abundance was also analyzed. Treatments did not affect alpha and beta diversities or relative abundance of phylum, class and order in either liquid or solid fractions. At the family level, relative abundance of Lachnospiraceae in solid fraction was lower for CO3 and CO3/OH compared to OH and Control (P < 0.01). For genera, abundance of Butyrivibrio (P = 0.01) and Lachnospiraceae ND3007 (P < 0.01) (both from Lachnospiraceae family) was lower and unclassified Ruminococcaceae (P = 0.03) was greater in CO3 than Control and OH in solid fraction; while abundance of Pseudobutyrivibrio (P = 0.10) and Lachnospiraceae FD2005 (P = 0.09) (both from Lachnospiraceae family) and Ruminobacter (P = 0.09) tended to decrease in CO3 compared to Control in liquid fraction. Butyrate molar proportion was negatively correlated to Ruminococcaceae (r = –0.55) in solid fraction and positively correlated to Pseudobutyrivibrio (r = 0.61) and Lachnospiraceae FD2005 (r = 0.61) in liquid. Our results indicate that source of Mg has an impact on bacterial taxa associated with ruminal butyrate synthesis, which is important for epithelial health and fatty acid synthesis.

Impact of concentrations of camphor on the in vitro mixed ruminal microorganism fermentation from goats selected for consumption of low and high levels of Juniperus spp.-2.

The microbial population in the gastrointestinal tract of ruminant animals aids in the utilization of forages with high levels of secondary plant compounds. Two divergent bloodlines of meat goats have been selected by screening fecal samples with near-infrared reflectance spectroscopy to assess the goat’s consumption of high or low levels of Juniperus sp. leaves containing several monoterpenes, including camphor. The mechanism by which these goats can consume greater concentrations of Juniperus spp. leaves than their counterparts is unclear, and therefore, this study was designed to determine if differences existed between the ruminal microbial populations of the low and high juniper-consuming bloodlines (LJC vs. HJC) by analyzing their ruminal microbiota and fermentation end products. In the present study, concentrations (0.00, 0.5, 0.99, 1.97, or 5.91 mM) of camphor were added to mixed ruminal microorganism fermentation. Five LJC and five HJC goats were fed a juniper-free diet (n = 10), and five LJC and five HJC goats (n = 10) were fed a diet that contained 30% fresh Juniperus ashei leaves for 21 d prior to ruminal fluid collection. In vitro fermentations used LJC and HJC, ruminal fluid inoculum added (33% v/v) to anoxic media in sealed Balch tubes. Camphor increased (P < 0.05) total short-chain fatty acid (SCFA) concentrations for all but one experimental group. Between the main dietary and bloodline goat effects, the diet was significant for all SCFA results except butyrate. In contrast, bloodline was only significant for acetate and butyrate molar proportions. Rumen fluid from juniper-free-fed goats exhibited greater concentrations of Ruminococcaceae, whereas juniper-fed goats contained more Coriobacteriaceae. Results demonstrated that mixed ruminal microorganisms fermentations from HJC goats did not produce greater concentrations of SCFAs or have the ability to degrade camphor at a higher rate than did that from LJC goats. Results suggest that camphor tolerance from J. ashei, was related to hepatic catabolic mechanisms instead of ruminal microbial degradation; however, further in vivo work is warranted.

Effect of Caragana korshinskii Kom. as a partial substitution for sheep forage on intake, digestibility, growth, carcass features, and the rumen bacterial community

The aim of this study was to verify that Caragana korshinskii Kom. (CK) as a component of sheep forage influences lamb digestibility and rumen fermentation by altering the rumen microbial community. Hence, 12 female Tan sheep were allocated into 2 groups: receiving (CK group) or not (control group) 10% of the diet forage fraction with CK. During the 60-day experiment, growth performance, apparent digestibility, rumen volatile fatty acids (VFAs), and nitrogen balance were measured. Meanwhile, the rumen bacterial community diversity and composition were detected by the 16S rRNA sequence. The results indicated that the apparent digestibility of acid detergent fibre (ADF) tended to be higher (0.05 < P < 0.10), and the feed conversion efficiency was improved (P < 0.05) when CK was offered. Compared to those under alfalfa, the composition and abundance of the rumen microbial community were altered in the CK group, and the phylum Firmicutes, which is involved in promoting fibre digestion, increased in abundance. Moreover, VFAs tended to decrease (0.05 < P < 0.10), and the molar proportion of butyrate declined; similarly, levels of hypoxanthine and xanthine were lower (P < 0.05) in the sheep fed CK and may have been responsible for the decreased abundance of Fibrobacter spp., which are cellulolytic ruminal bacteria associated with VFA production.

Polyclonal antibody preparations from avian origin as a feed additive to beef cattle: ruminal fermentation during the step-up transition diets.

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 ruminal fermentation [pH, ammonia-N (NH3-N), lactate, and volatile fatty acids (VFA)] of beef steers during a 21-d step-up diet adaptation. Eight ruminally cannulated Angus crossbred beef steers (658 ± 79 kg of body weight) were assigned in a crossover design to be transitioned from a diet containing ad libitum bermudagrass hay [Cynodon dactylon (L.) Pers.] plus 0.45 kg/d (as fed) of molasses with 0 (CON) or 3 g of PAP (PAP) to a high-grain diet. Transition consisted of three 7-d steps of increased inclusion of cracked corn (35%, 60%, and 82% of the diet DM for STEP1, STEP2, and STEP3, respectively). On each transition day and 7 d after STEP3 (STEP3-7d), ruminal fluid samples were obtained every 3 h for 24 h. Feeding 3 g of PAP daily increased (P < 0.01) average ruminal pH during STEP3 compared with CON steers (5.6 vs. 5.4 ± 0.05, respectively). During STEP1, NH3-N concentration was greater (P < 0.01; 9.4 vs. 6.8 ± 0.74 mM, respectively), and time (min/d) and area (time × pH) of ruminal pH below or equal to 5.2 was lesser (P ≤ 0.03) for steers consuming PAP compared with steers assigned to CON treatment (33.4 vs. 73.3 ± 21.7 min/d and 187.4 vs. 406.3 ± 119.7 min × pH/d, respectively). Steers consuming PAP had greater acetate:propionate ratio at 0, 3, and 6 h relative to diet change compared with CON (2.42, 2.35, 2.29 vs. 1.66, 1.79, and 1.72 ± 0.17, respectively), whereas butyrate molar proportions increased (P = 0.02; 17.1 vs. 11 ± 1.58 mol/100 mol for CON and PAP, respectively) when PAP was not fed at STEP2. Total ruminal lactate concentrations were not affected by PAP feeding (P > 0.11). In conclusion, feeding 3 g/d of polyclonal antibody preparation against S. bovis, F. necrophorum, and lipopolysaccharides was effective in increasing ruminal pH, A:P ratio, and NH3-N concentrations, possibly attenuating the risks of ruminal acidosis in steers during the step-up transition from forage to high-grain diets.

Substitution of molasses for corn grain at two levels of degradable protein. II. Effects on ruminal fermentation, digestion, and nitrogen metabolism

Our objective was to evaluate cow N metabolism and ruminal measures with diets containing 3 different levels of molasses or finely ground dry corn grain with 2 levels of ruminally degradable protein (RDP). Twelve lactating, ruminally cannulated Holstein cows (parity 2.25 ± 0.62; 185 ± 56 DIM; 41.3 ± 6.3 kg of milk initially) were individually fed in an experiment designed as a split-plot, replicated 3 × 3 Latin square, where each period lasted 28 d. Six diets were formulated according to a 2 × 3 factorial arrangement of treatments, where 2 levels of RDP (+RDP and -RDP) were fed throughout the experiment as the whole plot, and 3 levels of molasses (0, 5.25, or 10.50% of dry matter replacing finely ground dry corn grain) were fed in sequences of the Latin squares. Dry matter intake did not differ by diet, although ash intake increased linearly with increasing molasses. Ruminal pH, organic acid concentration, and ammonia concentration were not affected by diet. Molar percentages of ruminal acetate decreased and butyrate increased linearly with increasing levels of molasses. Ruminal free amino acid concentration was greater for +RDP, whereas branched-chain volatile fatty acids declined linearly with increasing molasses. Rumen content mass, ruminal liquid, and ruminal acetate pool size was greater for -RDP, although ruminal lactate pool size tended to be greater with +RDP. Increased ruminal lactate when increasing molasses with high RDP should be explored further, to optimize microbial efficiency and rumen health. Total-tract apparent dry matter digestibility based on spot sampling was not affected by diet; however, ash digestibility increased linearly with increasing levels of molasses. Calculated urine output was greater for cows fed diets with increasing levels of molasses and for cows fed +RDP. Grams of N distributed to excretion pools were not different across diets, although, as molasses increased, a lower proportion of N intake was excreted in urine. Overall, the results from this experiment showed that dairy cows used dietary carbohydrates differently during ruminal fermentation, with increasing molasses resulting in increased butyrate molar proportions at the expense of acetate. Additionally, RDP tended to modify the effects of carbohydrate fermentation, resulting in a tendency for increasing lactate molar pool size only in diets with greater RDP, although this did not ultimately affect ruminal pH.

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.

In vitro Inoculation of Fresh or Frozen Rumen Fluid Distinguishes Contrasting Microbial Communities and Fermentation Induced by Increasing Forage to Concentrate Ratio.

In vitro rumen batch culture is a technology to simulate rumen fermentation by inoculating microorganisms from rumen fluids. Although inocula (INO) are commonly derived from fresh rumen fluids, frozen rumen fluids are also employed for the advantages of storing, transporting, and preserving rumen microorganisms. The effects of frozen INO on microbial fermentation and community may be interfered with by substrate type, which has not been reported. This study was designed to test whether rumen fluid treatments (i.e., fresh and frozen) could interact with incubated substrates. A complete block design with fractional arrangement treatment was used to investigate the effects of INO (fresh or frozen rumen fluids) and concentrate-to-forage ratios (C/F, 1:4 or 1:1) on rumen fermentation and microbial community. The effects of increasing C/F were typical, including increased dry matter (DM) degradation and total volatile fatty acids (VFA) concentration (P < 0.001), and decreased acetate to propionate ratio (P = 0.01) and bacterial diversity of richness and evenness (P ≤ 0.005) with especially higher fermentative bacteria such as genus Rikenellaceae_RC, F082, Prevotella, Bacteroidales_BS11, Muribaculaceaege, and Christensenellaceae_R-7 (P ≤ 0.04). Although frozen INO decreased (P < 0.001) DM degradation and altered rumen fermentation with lower (P ≤ 0.01) acetate to propionate ratio and molar proportion of butyrate than fresh INO, typical effects of C/F were independent of INO, as indicated by insignificant INO × C/F interaction on substrate degradation, VFA profile and bacterial community (P ≥ 0.20). In summary, the effect of C/F on fermentation and bacterial diversity is not interfered with by INO type, and frozen INO can be used to distinguish the effect of starch content.

Dietary supplementation with Macleaya cordata extract inclusion affects growth performance, rumen fermentation, bacterial communities, and immune responses of weaned lambs

The objective of this study was to evaluate the effects of supplementing the diet of weaned lambs with Macleaya cordata extract (MCE) on growth performance, rumen fermentation, and immune responses. Twenty-four female crossbred (Dorper × Mongolian sheep) lambs with initial body weight (BW) of 21.5 ± 1.43 kg were randomly assigned to one of 3 groups (n = 8): control (CON), control supplemented with 0.5 g/d/lamb MCE (LMCE), and control supplemented with 1.0 g/d/lamb MCE (HMCE) with a 14-d adaptation period and 42-d experimental period. The basal diet consisted of 400 g/kg roughage and 600 g/kg concentrate (dry matter basis). Increasing the supplemental dose of MCE quadratically changed final BW (P = 0.02), dry matter intake (P = 0.03), average daily gain (P < 0.01) and feed conversion ratio of lambs (P = 0.04). Ruminal pH and total volatile fatty acid (VFA) concentration did not differ among treatments, whereas supplementation of MCE increased (P = 0.03) molar proportion of butyrate. The concentration of NH3-N was lower (P = 0.04) with supplementation of MCE at a low dose compared with CON. At the phylum-level, the relative abundance of Bacteroidetes and ratio of Firmicutes: Bacteroidetes tended (P < 0.10) to decrease with supplementing MCE. At the genera-level, the relative abundances of Bacteroidetes BF311 and Fibrobacteres Fibrobacter quadratically (P < 0.01) increased and linearly (P < 0.01) decreased with supplementation of MCE, respectively. Additionally, supplementation of MCE decreased blood concentrations of alanine aminotransferase (P < 0.01), blood urea nitrogen (P < 0.01), total protein (P < 0.01), interleukin-1β (P < 0.01), interleukin- 6 (P < 0.01), and tumor necrosis factor-α (P < 0.01), and increased blood concentrations of glucose (trend; P = 0.06), immunoglobulin A (P < 0.01), immunoglobulin G (P < 0.01), immunoglobulin M (P = 0.02), interleukin-10 (P < 0.01), catalase (P < 0.01), glutathione peroxidase (P < 0.01), malondialdehyde (P < 0.01) and superoxide dismutase (P < 0.01). In conclusion, MCE supplementation has the potential to improve growth performance and feed efficiency. Moreover, supplementation of MCE improved immune responses and antioxidant status and the bacterial community composition in the rumen of lambs.

PSXVI-23 The influence of trace mineral source on digestion, ruminal fermentation characteristics, and mineral solubility in beef cattle fed a high concentrate feedlot diet

Abstract Twelve Angus steers (BW 530.9 ± 22.7kg) fitted with ruminal cannulae were used to determine the impact of trace mineral (TM) source on digestibility and ruminal VFA and soluble concentrations of Cu, Mn, and Zn. Steers were fed a high concentrate diet balanced to meet the requirement of finishing feedlot steers for 21d. Treatments consisted of Cu, Mn, and Zn supplemented at 18, 40, and 90 mg/kg DM, respectively, from either sulfate (STM) or hydroxy trace mineral (HTM) sources (n = 6 steers/treatment; experimental unit = steer). Following a 21-d adaptation period total fecal output was collected for 5 d. Trace mineral sources had no impact on nutrient digestibility. On d 6, rumen fluid was collected at 0, 2, and 4 h post-feeding for VFA analysis. There were no treatment x time interactions for any VFA measured. However, HTM steers had greater (P &amp;lt; 0.05) ruminal molar proportions of propionate and tended (P &amp;lt; 0.07) to have greater molar proportions of valerate compared to STM steers. Steers fed STM had greater (P &amp;lt; 0.05) molar proportions of butyrate compared to HTM steers. Steers were then fed the same high concentrate diet without supplemental Cu, Zn, or Mn for 14 d. On d 15 steers received a pulse dose (via rumen cannula) from either STM or HTM. Ruminal samples were obtained at 2 h intervals starting at -4 and ending at 24 h relative to dosing. There was a treatment x time interaction (P &amp;lt; 0.05) for ruminal soluble Cu concentrations. Ruminal soluble mineral concentrations were greater (P &amp;lt; 0.05) for Cu at 4, 6, 8, and 16 h post-dosing in STM compared to HTM supplemented steers. Results indicate that ruminal solubility of Cu differs between STM and HTM sources and may impact rumen fermentation characteristics.

Effects of single or combined supplementation of probiotics and prebiotics on ruminal fermentation, ruminal bacteria and total tract digestion in lambs

Probiotics (beneficial living microorganisms) and prebiotics (fiber, cell wall material, mannan polysaccharides derived through hydrolysis of yeast cell walls) are feed additives that may have beneficial extra-nutritional pharmaceutical and/or metabolic effects on livestock health and growth performance. Due to differences in modes of action, their combination may have additive effects on digestion and fermentation in ruminants. For this reason, four male lambs (Dorper; 45.1 ± 2.7 kg initial weight) with “T” cannulas in the rumen were used in a 4 × 4 Latin square experiment to evaluate the effects of single or combined supplementation of probiotics and prebiotics on ruminal fermentation and total tract digestion. Dietary treatments consisted of a cracked corn-based basal finishing diet supplemented with: 1) no eubiotics (Control); 2) 3 g of live saccharomyces cerevisiae /lamb/day (2 × 1010 cfu/g, SC), 3) 3 g of mannan oligosaccharide (30 % w/w) plus b-glucans (20 % w/w) /lamb/day (MOS), and 4) combination of 1.5 g/day SC and 1.5 g/day MOS (SCMOS). Compared to controls, SC supplementation tended (P = 0.09) to increase total tract digestion of DM and OM, and increased (P < 0.05) total tract digestion of N, starch, and digestible energy (DE). Compared with Control, MOS increased total tract NDF (7.9 %, P < 0.01) and starch digestion, and tended to improve total tract digestion of (P = 0.09), N (P = 0.07), and DE diet (P = 0.07). Compared to Control, SCMOS increased (P ≤ 0.03) total tract digestion of all fractions evaluated, including a 4.2 % (P < 0.01) increase in DE. Although lambs fed MOS had greater (6.7 %, P = 0.02) NDF digestion than those fed SC, differences in total tract digestion of DM, OM, N, starch and DE diet were not appreciable (P ≥ 0.24). Compared with SC and MOS fed separately, SCMOS increased (P < 0.05) total tract digestion of N and NDF. Supplemental MOS and SCMOS tended (P = 0.09) to promote greater ruminal pH than the Control. Combining supplementation decreased (P ≤ 0.03) the molar proportion of butyrate and ruminal ammonia, consistent with decreased of ruminal concentration of C. aminophilum. Probiotic/prebiotic supplementation of high-energy lamb finishing diets enhances total tract digestion and digestible energy. Reduction hyper-ammonia producing ruminal bacteria with the combination probiotic plus prebiotic may contribute to improved dietary N economy. The combination of probiotics with prebiotics potentiate positive effects on digestion and ruminal fermentation in lambs fed a high-energy diets.

Lactational performance, rumen fermentation, and enteric methane emission of dairy cows fed an amylase-enabled corn silage

This study investigated the effects of an amylase-enabled corn silage on lactational performance, enteric CH4 emission, and rumen fermentation of lactating dairy cows. Following a 2-wk covariate period, 48 Holstein cows were blocked based on parity, days in milk, milk yield (MY), and CH4 emission. Cows were randomly assigned to 1 of 2 treatments in an 8-wk randomized complete block design experiment: (1) control corn silage (CON) from an isogenic corn without α-amylase trait and (2) Enogen hybrid corn (Syngenta Seeds LLC) harvested as silage (ECS) containing a bacterial transgene expressing α-amylase (i.e., amylase-enabled) in the endosperm of the grain. The ECS and CON silages were included at 40% of the dietary dry matter (DM) and contained, on average, 43.3 and 41.8% DM and (% DM) 36.7 and 37.5% neutral detergent fiber, and 36.1 and 33.1% starch, respectively. Rumen samples were collected from a subset of 10 cows using the ororuminal sampling technique on wk 3 of the experimental period. Enteric CH4 emission was measured using the GreenFeed system (C-Lock Inc.). Dry matter intake (DMI) was similar between treatments. Compared with CON, MY (38.8 vs. 40.8 kg/d), feed efficiency (1.47 vs. 1.55 kg of MY/kg of DMI), and milk true protein (1.20 vs. 1.25 kg/d) and lactose yields (1.89 vs. 2.00 kg/d) were increased, whereas milk urea nitrogen (14.0 vs. 12.7 mg/dL) was decreased, with the ECS diet. No effect of treatment on energy-corrected MY (ECM) was observed, but a trend was detected for increased ECM feed efficiency (1.45 vs. 1.50 kg of ECM/kg of DMI) for cows fed ECS compared with CON-fed cows. Daily CH4 emission was not affected by treatment, but emission intensity was decreased with the ECS diet (11.1 vs. 10.3 g/kg of milk, CON and ECS, respectively); CH4 emission intensity on ECM basis was not different between treatments. Rumen fermentation, apart from a reduced molar proportion of butyrate in ECS-fed cows, was not affected by treatment. Apparent total-tract digestibility of nutrients and urinary and fecal nitrogen excretions, apart from a trend for increased DM digestibility by ECS-fed cows, were not affected by treatment. Overall, ECS inclusion at 40% of dietary DM increased milk, milk protein, and lactose yields and feed efficiency, and tended to increase ECM feed efficiency but had no effect on ECM yield in dairy cows. The increased MY with ECS led to a decrease in enteric CH4 emission intensity, compared with the control silage.

Diet supplementation with canola meal improves milk production, reduces enteric methane emissions, and shifts nitrogen excretion from urine to feces in dairy cows

The objective of this study was to examine the effect of isonitrogenous substitution of solvent-extracted soybean meal (SBM) with solvent-extracted canola meal (CM) on enteric CH4 production, ruminal fermentation characteristics (including protozoa), digestion (in situ and apparent total-tract digestibility), N excretion, and milk production of dairy cows. For this purpose, 16 lactating Holstein cows, of which 12 were ruminally cannulated, were used in a replicated 4 × 4 Latin square (35-d periods; 14-d adaptation). The cows averaged (mean ± SD) 116 ± 23 d in milk, 692 ± 60 kg of body weight, and 47.5 ± 4.9 kg/d of milk production. The experimental treatments were control diet (no CM; 0%CM) and diets supplemented [dry matter (DM) basis] with 7.9% CM (8%CM), 15.8% CM (16%CM), or 23.7% CM (24%CM) on a DM basis. The forage:concentrate ratio was 52:48 (DM basis) and was similar among the experimental diets. Canola meal was included in the diet at the expense of SBM and soybean hulls, whereas the percentages of the other diet ingredients were the same. Intake of DM increased linearly, whereas apparent total-tract digestibility of DM, crude protein, neutral detergent fiber, and gross energy (GE) declined linearly as CM inclusion in the diet increased. Total volatile fatty acids concentration and butyrate molar proportion decreased linearly, whereas molar proportion of propionate increased linearly, and that of acetate was unaffected by CM inclusion in the diet. Ruminal ammonia concentration was not affected by inclusion of CM in the diet. Energy-corrected milk (ECM) yield increased linearly (up to 2.2 kg/d) with increasing CM percentage in the diet, whereas milk production efficiency averaged 1.63 kg of ECM/kg of DM intake and was unaffected by CM inclusion in the diet. Daily CH4 production decreased linearly with increasing CM percentage in the diet (489, 475, 463, and 461 g/d for 0%CM, 8%CM, 16%CM and 24%CM diets, respectively). As a consequence, CH4 emission intensity (g of CH4/kg of ECM) also declined linearly by up to 10% as the amount of CM increased in the diet. Methane production also decreased linearly when expressed relative to GE intake (5.7, 5.2, 5.1, and 4.9% for 0%CM, 8%CM, 16%CM and 24%CM diet, respectively). Quantity of manure N excretion was not affected by replacing SBM with CM; however, N excretion shifted from urine to feces as dietary percentage of CM increased, suggesting reduced potential for N volatilization. Results from this study show that replacing SBM with CM as a protein source in dairy cow diets reduced enteric CH4 emissions (g/d, % of GE intake, and adjusted for milk production) and increased milk production. The study indicates that CM can successfully, partially or fully, replace SBM in lactating dairy cow diets, with positive effects on animal productivity and the environment (i.e., less enteric CH4 emission and urinary N excreted). We conclude that compared with SBM, inclusion of CM meal in dairy cow diets can play a key role in reducing the environmental footprint of milk production.

A Metagenomic Insight Into the Hindgut Microbiota and Their Metabolites for Dairy Goats Fed Different Rumen Degradable Starch.

High starch diets have been proven to increase the risk of hindgut acidosis in high-yielding dairy animals. As an effective measurement of dietary carbohydrate for ruminants, studies on rumen degradable starch (RDS) and the effects on the gut microbiota diversity of carbohydrate-active enzymes (CAZymes), and Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology functional categories are helpful to understand the mechanisms between gut microbiota and carbohydrate metabolism in dairy goats. A total of 18 lactating goats (45.8 ± 1.54 kg) were randomly divided equally into three dietary treatments with low dietary RDS concentrations of 20.52% (LRDS), medium RDS of 22.15% (MRDS), and high RDS of 24.88% (HRDS) on a DM basis for 5 weeks. Compared with the LRDS and MRDS groups, HRDS increased acetate molar proportion in the cecum. For the HRDS group, the abundance of family Ruminococcaceae and genus Ruminococcaceae UCG-010 were significantly increased in the cecum. For the LRDS group, the butyrate molar proportion and the abundance of butyrate producer family Bacteroidale_S24-7, family Lachnospiraceae, and genus Bacteroidale_S24-7_group were significantly increased in the cecum. Based on the BugBase phenotypic prediction, the microbial oxidative stress tolerant and decreased potentially pathogenic in the LRDS group were increased in the cecum compared with the HRDS group. A metagenomic study on cecal bacteria revealed that dietary RDS level could affect carbohydrate metabolism by increasing the glycoside hydrolase 95 (GH95) family and cellulase enzyme (EC 3.2.1.4) in the HRDS group; increasing the GH13_20 family and isoamylase enzyme (EC 3.2.1.68) in the LRDS group. PROBIO probiotics database showed the relative gene abundance of cecal probiotics significantly decreased in the HRDS group. Furthermore, goats fed the HRDS diet had a lower protein expression of Muc2, and greater expression RNA of interleukin-1β and secretory immunoglobulin A in cecal mucosa than did goats fed the LRDS diet. Combined with the information from previous results from rumen, dietary RDS level altered the degradation position of carbohydrates in the gastrointestinal (GI) tract and increased the relative abundance of gene encoded enzymes degrading cellulose in the HRDS group in the cecum of dairy goats. This study revealed that the HRDS diet could bring disturbances to the microbial communities network containing taxa of the Lachnospiraceae and Ruminococcaceae and damage the mucus layer and inflammation in the cecum of dairy goats.

Short communication: Saliva and salivary components affect goat rumen fermentation in short-term batch incubations

The research about the role of saliva in ruminants has been mainly focused on its buffering capacity together with facilitation of the rumination process. However, the role of salivary bioactive components on modulating the activity of the rumen microbiota has been neglected until recently. This study developed an in vitro approach to assess the impact of different components in saliva on rumen microbial fermentation. Four different salivary fractions were prepared from four goats: (i) non-filtrated saliva (NFS), (ii) filtrated through 0.25 µm to remove microorganisms and large particles (FS1), (iii) centrifuged through a 30 kDa filter to remove large proteins, (FS2), and (iv) autoclaved saliva (AS) to keep only the minerals. Two experiments were conducted in 24 h batch culture incubations with 6 ml of total volume consisting of 2 ml of rumen fluid and 4 ml of saliva/buffer mix. In Experiment 1, the effect of increasing the proportion of saliva (either NFS or FS1) in the solution (0%, 16%, 33% and 50% of the total volume) was evaluated. Treatment FS1 promoted greater total volatile fatty acids (VFA) (+8.4%) and butyrate molar proportion (+2.8%) but lower NH3-N concentrations than NFS fraction. Replacing the bicarbonate buffer solution by increasing proportions of saliva resulted in higher NH3-N, total VFA (+8.0%) and propionate molar proportion (+11%). Experiment 2 addressed the effect of the different fractions of saliva (NFS, FS1, FS2 and AS). Saliva fractions led to higher total VFA and NH3-N concentrations than non-saliva incubations, which suggests that the presence of some salivary elements enhanced rumen microbial activity. Fraction FS1 promoted a higher concentration of total VFA (+7.8%) than the other three fractions, and higher propionate (+26%) than NFS and AS. This agrees with findings from Experiment 1 and supports that ‘microbe-free saliva’, in which large salivary proteins are maintained, boosts rumen fermentation. Our results show the usefulness of this in vitro approach and suggest that different salivary components can modulate rumen microbial fermentation, although the specific metabolites and effects they cause need further research.

Effect of exogenous glucoamylase inclusion on in vitro fermentation and growth performance of feedlot steers fed a dry-rolled corn-based diet.

The objective was to evaluate the effect of adding an exogenous glucoamylase (GA) enzyme from the fungus Trichoderma reesei on in vitro fermentation, growth performance, and carcass characteristics of feedlot steers fed a dry-rolled corn (DRC)-based diet. Experiment 1 evaluated three levels of added enzyme (0, 0.24, and 0.72 GA enzyme units) and two corn particle sizes (CPS; 2 and 4 mm) in a factorial arrangement using a 7 h in vitro batch culture fermentation. Addition of GA increased (P < 0.01) in vitro dry matter disappearance by 13% and decreased final pH (P < 0.01). Molar proportion of propionate increased with GA inclusion (P < 0.01). A smaller CPS increased (P < 0.01) in vitro dry matter disappearance and total volatile fatty acid and decreased final pH (P < 0.01). A smaller CPS also decreased (P < 0.01) the molar proportion of acetate and increased (P < 0.01) the molar proportion of butyrate. In experiment 2, Angus × Simmental steers (n = 105; initial body weight [BW] = 329 ± 38 kg) were used to evaluate the inclusion of an exogenous GA on growth performance and carcass characteristics. Steers were fed a basal diet consisting of 60% DRC, 17.5% modified distillers grains with solubles, 12.5% corn silage, and 10% dry supplement on a dry matter basis for 136 d. Steers were blocked by weight and allotted to pens. Pens were randomly assigned to one of three treatments (5 pens/treatment): diet with no GA (CON), low inclusion of GA (122 enzyme units/kg dry matter [DM]; LGA), or high inclusion of GA (183 enzyme units/kg DM; HGA). Inclusion of GA did not affect (P ≥ 0.23) final BW, dry matter intake (DMI), or average daily gain (ADG) for the 136-d feeding period. Feed conversion was affected (P = 0.02) by treatment with steers fed HGA having ~8% greater G:F compared with LGA and CON. Treatment did not affect (P = 0.32) fecal starch. Inclusion of GA did not affect (P ≥ 0.19) carcass traits including hot carcass weight, 12th rib fat thickness, yield grade, longissimus muscle area, or marbling score. Overall, results suggest inclusion of exogenous GA enzyme increased in vitro dry matter disappearance in batch culture and improved feed conversion in steers fed 183 enzyme units/kg DM during the finishing phase.

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

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

Effects of diets with different solid-to-liquid feed ratios with the same dry matter intake on the growth performance and gastrointestinal development of male Holstein calves

This study investigated the effects of diets with different solid-to-liquid feed ratios with the same dry matter intake on growth performance, blood metabolites, rumen development, and gastrointestinal development in male Holstein calves. Calves (n = 36; average 28 ± 2 days of age; 46.4 ± 0.78 kg body weight) were randomly assigned to three groups: the control group (n = 12; solid to liquid feed ratio = 1:2 at 28 days of age (d 28), then, the solid feed supply was increased by 200 g per week until the ratio was changed to about 1:1 at d 56), high liquid (HL) group (n = 12; solid to liquid feed ratio = 1:2 at d 28, then, the solid feed supply was increased by 100 g per week until the ratio was still about 1:2 at d 56), and high solid (HS) group (n = 12; solid to liquid feed ratio = 1:2 at d 28, then, the solid feed supply was increased by 400 g per week until the ratio was changed to about 1:0 at d 56). The calves were reared with three different feed types while maintaining the same dry matter feed supply and dry matter intake among the three groups before weaning. The calves from both the control and HL groups were weaned at 56 days of age with approximately 1 kg and 0.5 kg of daily solid feed intake, respectively. The calves from the HS group were weaned at 42 days of age with approximately 1 kg of daily solid feed intake. Calves were weighed at 2-week intervals, and both blood and rumen fluid samples were also collected at 2-week intervals. Calves were slaughtered, and various organs were collected for analysis. Compared with the control and HL diets, the HS diet increased the daily solid feed intake. The average daily gain did not differ among the three groups until 56 days of age, but the HS diet increased the average daily gain compared to the HL diet from 56 to 84 days of age. Compared with the HL diet, the HS diet increased the ruminal molar proportion of acetate and butyrate and the total volatile fatty acid concentration at 84 days of age. Compared with the HL diet, the HS diet improved blood IgG and insulin-like growth factor 1 concentrations, and increased the weights of the rumen and whole stomach and increased the papilla length and tunica muscularis thickness of the rumen, especially the tunica muscularis thickness of the duodenum. In conclusion, feeding an HS diet along with early weaning at 42 days of age increased solid feed intake and resulted in improved growth performance, molar proportion of butyrate in the rumen, blood immune index levels and gastrointestinal development of post-weaned Holstein male calves.

Effects of diet fermentability and supplementation of 2-hydroxy-4-(methylthio)-butanoic acid and isoacids on milk fat depression: 2. Ruminal fermentation, fatty acid, and bacterial community structure

The experiment was conducted to understand ruminal effects of diet modification during moderate milk fat depression (MFD) and ruminal effects of 2-hydroxy-4-(methylthio)-butanoic acid (HMTBa) and isoacids on alleviating MFD. Five ruminally cannulated cows were used in a 5 × 5 Latin square design with the following 5 dietary treatments (dry matter basis): a high-forage and low-starch control diet with 1.5% safflower oil (HF-C); a low-forage and high-starch control diet with 1.5% safflower oil (LF-C); the LF-C diet supplemented with HMTBa (0.11%; 28 g/d; LF-HMTBa); the LF-C diet supplemented with isoacids [(IA) 0.24%; 60 g/d; LF-IA]; and the LF-C diet supplemented with HMTBa and IA (LF-COMB). The experiment consisted of 5 periods with 21 d per period (14-d diet adaptation and 7-d sampling). Ruminal samples were collected to determine fermentation characteristics (0, 1, 3, and 6 h after feeding), long-chain fatty acid (FA) profile (6 h after feeding), and bacterial community structure by analyzing 16S gene amplicon sequences (3 h after feeding). Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC) in a Latin square design. Preplanned comparisons between HF-C and LF-C were conducted, and the main effects of HMTBa and IA and their interaction within the LF diets were examined. The LF-C diet decreased ruminal pH and the ratio of acetate to propionate, with no major changes detected in ruminal FA profile compared with HF-C. The α-diversity for LF-C was lower compared with HF-C, and β-diversity also differed between LF-C and HF-C. The relative abundance of bacterial phyla and genera associated indirectly with fiber degradation was influenced by LF-C versus HF-C. As the main effect of HMTBa within the LF diets, HMTBa increased the ratio of acetate to propionate and butyrate molar proportion. Ruminal saturated FA were increased and unsaturated FA concentration were decreased by HMTBa, with minimal changes detected in ruminal bacterial diversity and community. As the main effect of IA, IA supplementation increased ruminal concentration of all branched-chain volatile FA and valerate and increased the percentage of trans-10 C18 isomers in total FA. In addition, α-diversity and the number of functional features were increased for IA. Changes in the abundances of bacterial phyla and genera were minimal for IA. Interactions between HMTBa and IA were observed for ruminal variables and some bacterial taxa abundances. In conclusion, increasing diet fermentability (LF-C vs. HF-C) influenced rumen fermentation and bacterial community structure without major changes in FA profile. Supplementation of HMTBa increased biohydrogenation capacity, and supplemental IA increased bacterial diversity, possibly alleviating MFD. The combination of HMTBa and IA had no associative effects in the rumen and need further studies to understand the interactive mechanism.

Effects of calcium-magnesium carbonate and calcium-magnesium hydroxide as supplemental sources of magnesium on microbial fermentation in a dual-flow continuous culture.

Supplemental sources of Mg can also aid in ruminal pH regulation due to their alkaline properties. Magnesium oxide (MgO) is the most common source of Mg for ruminants and can help controlling ruminal pH; however, the alkaline potential of other sources of Mg has not been evaluated. We aimed to evaluate the inclusion of calcium–magnesium carbonate (CaMg(CO3)2) and calcium–magnesium hydroxide (CaMg(OH)4) alone or in combination as supplemental sources of Mg in corn silage-based diets and its impact on ruminal microbial fermentation. We hypothesized that inclusion of CaMg(OH)4 would allow for ruminal fermentation conditions resulting in a greater pH compared to the inclusion of CaMg(CO3)2. Four treatments were defined by the supplemental source of Mg in the diet: 1) Control (100% MgO, plus sodium sesquicarbonate as a buffer); 2) CO3 [100% CaMg(CO3)2]; 3) OH [100% CaMg(OH)4]; and 4) CO3/OH [50% Mg from CaMg(CO3)2, 50% Mg from CaMg(OH)4]. Nutrient concentration was held constant across treatments (16% CP, 30% NDF, 1.66 Mcal NEl/kg, 0.67% Ca, and 0.21% Mg). Four fermenters were used in a 4 × 4 Latin square design with four periods of 10 d each. Samples were collected for analyses of nutrient digestibility, soluble Mg, VFA, and NH3, while pH was measured at 0, 1, 2, 4, 6, 8, and 10 h post morning feeding to estimate % time when pH was below 6 (pH-B6) and area under the pH curve for pH below 6.0 (pH-AUC). Bacteria pellets were harvested for 15N analysis and estimates of N metabolism. Treatment effects were analyzed with the mixed procedure of SAS, while effects of using either CaMg(CO3)2 or CaMg(OH)4 as Mg source in comparison to Control treatment were evaluated by orthogonal contrasts. Similar pH-related variables were observed for Control, OH, and CO3/OH treatments, which had smaller pH-AUC and pH-B6 than CO3 (P ≤ 0.01). Butyrate molar proportion was greater in Control and CO3/OH than in CO3 and OH (P = 0.04). Orthogonal contrasts showed lower flow of bacterial N (P = 0.04), lower butyrate molar proportion (P = 0.08) and greater pH-AUC (P = 0.05) for diets with CaMg(CO3)2 in comparison with the Control. Concentration of soluble Mg in ruminal fluid (P = 0.73) and nutrient digestibility (P ≥ 0.52) were similar across treatments. Under the conditions of this experiment, using CaMg(OH)4 alone or combined with CaMg(CO3)2 allowed for a less acidic ruminal fermentation pattern than a diet with only CaMg(CO3)2.

PSII-17 Program Chair Poster Pick: Effect of ruminal protozoa on methane emissions in ruminants – a meta-analysis

Abstract The effects of ruminal protozoa (RP) concentration on methane emissions from ruminants were evaluated in a meta-analysis using 67 publications reporting data from 85 in vivo experiments. Experiments included in the database reported methane emissions (g/kg DMI) and RP (log10 cells/mL) from the same group of animals. Quantitative data including diet chemical composition, ruminal fermentation, total tract digestibility, and milk production; and qualitative information including methane mitigation strategies, animal type, and methane measurement methods were also collected. The studies were conducted in dairy cows (51%), beef steers (32%) and small ruminants (32%). 70% of the studies reported a reduction in methane emissions. Supplemental lipids reduced methane emissions 95% of the time. The relationship between methane emissions and RP concentration was evaluated as a random coefficient model with the experiment as a random effect and weighted by the inverse pooled SEM squared, including the possibility of covariance between the slope and the intercept. A quadratic effect of RP concentration on methane emissions was detected: CH4= -28.8 + 12.2 × RP-0.64 × RP2. To detect potential interfering factors in the relationship, the influence of several qualitative and quantitative factors were separately tested. Acetate, butyrate, and isobutyrate molar proportions had positive relationships with methane emissions and influenced the relationship between RP concentration and methane emissions, where the presence of ruminal fermentation variables reduced the effects of RP concentration in methane emissions. Total tract digestibility of DM, OM, and CP had negative relationships while NDF digestibility had a positive relationship with methane emissions; however, they only changed the magnitude of intercept and slope of RP and RP2 for the relationship. For dairy cows, milk fat and protein concentrations had positive relationships and milk yield had a negative relationship with methane emissions and changed the magnitude of intercept and slope of RP and RP2 for the relationship.