Fatty Acids In Rumen Fluid Research Articles

Asparagopsis taxiformis supplementation to mitigate enteric methane emissions in dairy cows - effects on performance and metabolism.

Methane emissions from ruminant digestion contribute significantly to global anthropogenic greenhouse gas emissions. Members of the phylum Rhodophyta (red algae), particularly Asparagopsis sp., have shown promising results in reducing methane emissions in ruminants, due to their high content of halogenated methane analog compounds. However, knowledge is lacking regarding the effects of red algae on animal performance and metabolism. This study investigated the effects of dairy cow diet supplementation with Asparagopsis taxiformis on enteric methane performance, metabolism of bromine and iodine, and health status of the cows. Thirty lactating Nordic Red dairy cows fed a total mixed ration, were blocked according to parity and days in milk, and randomly assigned to one of 3 diets: a control diet with no Asparagopsis taxiformis (CON), a diet with 0.15% Asparagopsis taxiformis on an organic matter (OM) basis (L-AT), and a diet with 0.3% Asparagopsis taxiformis on an OM basis (H-AT). The cows were fed the experimental diets continuously for 13 weeks, beginning with a baseline week (wk 0), which served as covariate by week where all cows received the basal diet. Individual feed intake and milk yield were recorded automatically throughout the experiment. Milk composition was determined by collecting milk samples during each milking session on 2 consecutive days every experimental week. While enteric methane and hydrogen levels were measured continuously by the GreenFeed system. Feces grab samples were collected as spot samples from a subset of 6 cows per treatment after milking during sampling wk 0, 2, 4, 8, and 12. Urine spot samples were collected from the same subset of cows during the same weeks as fecal samples. One urine sample was taken per day on 2 consecutive days, and the samples were analyzed for wk 12. Rumen fluid was collected after morning milking using a stomach tube in wk 0, 2, 4, and 12. We observed a 30% reduction in methane production in the H-AT group, with a concomitant increase in hydrogen production by 383%. However, the interaction between treatment and week showed that the AT effect on methane reduction began to diminish by wk 9 of the experiment. In the L-AT group, methane was reduced by 7.6% and hydrogen production was increased by 70%. However, dry matter intake (DMI) was 7% lower and energy-corrected milk (ECM) yield was 2% lower in the H-AT group compared with the other 2 groups. Total concentration of volatile fatty acids in rumen fluid was lower in the H-AT group compared with CON, with a reduction in acetate concentration and an increase in propionate, butyrate and valerate in the H-AT group. Bromine concentration was 5-fold higher and iodine concentration was 9-fold higher in milk from the H-AT group compared with CON. Bromine concentration in feces and urine samples from H-AT cows was approximately 4-fold and 9-fold higher, respectively, than in samples from CON cows. Metabolic profiling revealed a reduction in cholesterol levels and a decrease in the ferric-reducing ability of plasma in the H-AT treatment group compared with the CON group, as well as an increase in plasma magnesium concentration in the H-AT group. In conclusion, using 0.3% Asparagopsis taxiformis as an additive in dairy cow feed rations can mitigate enteric methane emissions, but this reduction was observed only during the first 8 weeks of the experiment, with no effect on methane emissions from wk 9 to 12. Additionally, it may have negative effects on DMI and ECM yield. Further long-term studies on red algae as methane inhibitor is needed to examine its sustained inhibitory effects over time and its impact on various metabolic processes. The effects appear to decline after wk 8 and influence several metabolic mechanisms.

The addition of curcumin to the diet of post-weaning dairy calves: effects on ruminal fermentation, immunological, and oxidative responses.

Incorporating Curcumin into animal diets holds significant promise for enhancing both animal health and productivity, with demonstrated positive impacts on antioxidant activity, anti-microbial responses. Therefore, this study aimed to determine whether adding Curcumin to the diet of dairy calves would influence ruminal fermentation, hematologic, immunological, oxidative, and metabolism variables. Fourteen Jersey calves were divided into a control group (GCON) and a treatment group (GTRA). The animals in the GTRA received a diet containing 65.1mg/kg of dry matter (DM) Curcumin (74% purity) for an experimental period of 90 days. Blood samples were collected on days 0, 15, 45, and 90. Serum levels of total protein and globulins were higher in the GTRA group (P < 0.05) than the GCON group. In the GTRA group, there was a reduction in pro-inflammatory cytokines (IL-1ß and IL-6) (P < 0.05) and an increase in IL-10 (which acts on anti-inflammatory responses) (P < 0.05) when compared to the GCON. There was a significantly higher (P < 0.05) concentration of immunoglobulin A (IgA) in the serum of the GTRA than the GCON. A Treatment × Day interaction was observed for haptoglobin levels, which were higher on day 90 in animals that consumed Curcumin than the GCON (P < 0.05). The catalase and superoxide dismutase activities were significantly higher (P < 0.05) in GTRA, reducing lipid peroxidation when compared to the GCONT. Hematologic variables did not differ significantly between groups. Among the metabolic variables, only urea was higher in the GTRA group when compared to the GCON. Body weight and feed efficiency did not differ between groups (meaning the percentage of apparent digestibility of dry matter, crude protein, and acid detergent fiber (ADF) and neutral detergent fiber (NDF). There was a tendency (P = 0.09) for treatment effect and a treatment x day interaction (P = 0.05) for levels of short-chain fatty acids in rumen fluid, being lower in animals that consumed curcumin. There was a treatment vs. day interaction (P < 0.05) for the concentration of acetate in the rumen fluid (i.e., on day 45, had a reduction in acetate; on day 90, values were higher in the GTRA group when compared to the GCON). We conclude that there was no evidence in the results from this preliminary trial that Curcumin in the diet of dairy calves interfered with feed digestibility. Curcumin may have potential antioxidant, anti-inflammatory, and immune effects that may be desirable for the production system of dairy calves.

Effect of physically effective fibre on chewing behaviour, ruminal fermentation, digesta passage and protein metabolism of dairy cows

Dietary fibre concentration and particle size influence chewing behaviour, ruminal fermentation and digesta passage in dairy cows and through this, may impact nitrogen (N) use and excretion by the animals. The aim was thus to evaluate the effects of physically effective neutral detergent fibre (peNDF) concentration on chewing behaviour, ruminal fermentation, passage rate and protein metabolism in four lactating, rumen-cannulated Holstein cows in a 4 × 4 latin square design. Four total mixed rations with identical ingredients, chemical composition and a negative ruminal N balance (–2.1 g/kg dry matter) were tested. They varied in peNDF concentration, adjusted by feed mixing time: low (L), medium-low (ML), medium-high (MH) and high (H) peNDF. Nutrient intakes, number of total chews, organic matter digestibility and yield and efficiency of ruminal microbial protein synthesis responded quadratically to increasing peNDF concentration, with greater values for MH and ML diets. While rumination and total chewing intensity (min/kg dry matter) increased with increasing peNDF concentration, milk yield and composition, digesta passage rates and concentrations of ammonium-N and volatile fatty acids in rumen fluid were similar across diets. Energy-corrected milk yield and partitioning of N between milk and urine responded quadratically to increased peNDF concentration. Energy-corrected milk yield and the percentage of ingested N secreted via milk were lower, but the percentage of N intake excreted via urine was greater for MH and ML diets. Hence, feeding dairy cows a low-protein diet with varying peNDF concentrations affects their chewing behaviour, nutrient digestion and protein metabolism.

Rumen bacterial cluster identification and its influence on rumen metabolites and growth performance of young goats

Enterotypes, which are defined as bacterial clusters in the gut microbiome, have been found to have a close relationship to host metabolism and health. However, this concept has never been used in the rumen, and little is known about the complex biological relationships between ruminants and their rumen bacterial clusters. In this study, we used young goats (n = 99) as a model, fed them the same diet, and analyzed their rumen microbiome and corresponding bacterial clusters. The relationships between the bacterial clusters and rumen fermentation and growth performance in the goats were further investigated. Two bacterial clusters were identified in all goats: the P-cluster (dominated by genus Prevotella, n = 38) and R-cluster (dominated by Ruminococcus, n = 61). Compared with P-cluster goats, R-cluster goats had greater growth rates, concentrations of propionate, butyrate, and 18 free amino acids¸ and proportion of unsaturated fatty acids, but lower acetate molar percentage, acetate to propionate ratio, and several odd and branched chain and saturated fatty acids in rumen fluid (P < 0.05). Several members of Firmicutes, including Ruminococcus, Oscillospiraceae NK4A214 group, and Christensenellaceae R-7 group were significantly higher in the R-cluster, whereas Prevotellaceae members, such as Prevotella and Prevotellaceae UCG-003, were significantly higher in P-cluster (P < 0.01). Co-occurrence networks showed that R-cluster enriched bacteria had significant negative correlations with P-cluster enriched bacteria (P < 0.05). Moreover, we found the concentrations of propionate, butyrate and free amino acids, and the proportions of unsaturated fatty acids were positively correlated with R-cluster enriched bacteria (P < 0.05). The concentrations of acetate, acetate to propionate ratio, and the proportion of odd and branched chain and saturated fatty acids were positively correlated with P-cluster enriched bacteria (P < 0.05). Overall, our results indicated that rumen bacterial clusters can influence rumen fermentation and growth performance of young goats, which may shed light on modulating the rumen microbiome in early life to improve the growth performance of ruminant animals.

Microbial incubations of 8-phenyloctanoic acid and furan fatty acids in rumen fluid.

The digestive tract of ruminants is specialized in the digestion of various plant components. One of the largest parts of the stomach is the so-called rumen, which contains a large number of micro-organisms that may degrade or modify fatty acids, for example by β-oxidation, chain elongation and/or hydrogenation. Here we performed incubation experiments with less common fatty acids by in vitro incubations with rumen fluid of fistulated cows for 24h. Sample extracts were analysed by gas chromatography with mass spectrometry. As substrates, we selected one phenyl fatty acid and four furan fatty acids (FuFAs). All studied fatty acids were degraded by β-oxidation (two or three chain-shortening steps) while chain elongation or saturation of the aromatic part (terminal phenyl or central furan moiety) was not observed in any case. The percentage of β-oxidation products was low, especially in the case of the FuFAs. This could be due to the rather long carbon number of FuFAs (19-22 carbon atoms). In addition, compound-specific differences in the degradation rates were observed in our experiments. Our results produce evidence that FuFAs, which are valuable antioxidants that are known to be present in various feed items of the cow, can be effectively passed on the rumen into the milk.

TECHNICAL NOTE: Analysis of volatile fatty acids in rumen fluid by gas chromatography mass spectrometry using a dimethyl carbonate extraction.

Analysis of rumen fluid volatile fatty acids (VFA) is typically conducted by injecting acidified aqueous rumen fluid into a gas chromatograph (GC) with a flame ionization detector (FID). Aqueous samples are highly problematic because of the large vapor volume that can lead to poor peak shape and contamination of inlets, potentially causing sample carryover. Methods using aqueous samples are not well suited for use in a mass spectrometer (MS) detector system. The objective of this project was to validate a dimethyl carbonate (DMC) extraction process and GCMS method for rumen VFA analysis. To perform the extraction, 100 µL of sample, KHSO4 (500 g/L), and 2-ethylbutyrate (internal standard; 8.5 mM) were added to a microcentrifuge tube (in order) followed by 1 mL of DMC. The mixture was thoroughly vortexed and centrifuged. The organic layer (top) was removed and placed in a GC vial. The DMC extract was injected (0.5 µL) into an Agilent 5977B GCMS (8:1 split injection) with a polar DB-FFAP column. The column was held at 105 °C for 5 min, increased at 10 °C/min to 150 °C, then 65 °C/min to 240 °C, and held constant for 10 min. The peak area of acetate relative to the internal standard is linear from approximately 2 mM to at least 130 mM and encompasses the expected values of rumen concentrations for the other VFA. Recovery of VFA from spiked rumen fluid was tested at three concentrations in rumen fluid from steers fed a finishing diet or grazing wheat pasture. Recovery was not affected by the diet of the animals (P > 0.10) or the amount of VFA spiked (P > 0.19) for acetate, propionate, isobutyrate, or butyrate. There was an interaction of amount of VFA spiked and the diet of the animal (P = 0.021) for valerate and a tendency for an interaction (P = 0.051) for isovalerate, due to the recovery of the VFA being lower in the medium spike amount in rumen fluid from cattle on wheat pasture. Overall, recovery was greatest for propionate (101.9 ± 1.67%) and lowest for valerate (95.7 ± 1.95%). Including the 10-min hold at 240 °C at the end of each run prevented carryover from sample to sample. This method appears to perform well in a GCMS system and accurately and precisely quantifies rumen fluid VFA.

Relations of Ruminal Fermentation Parameters and Microbial Matters to Odd- and Branched-Chain Fatty Acids in Rumen Fluid of Dairy Cows at Different Milk Stages.

Simple SummaryThe objective of this study was to determine the relationships between milk odd- and branched-chain fatty acids (OBCFAs) and ruminal fermentation parameters, microbial populations, and base contents. Significant relationships existed between the concentrations of C11:0, iso-C15:0, anteiso-C15:0, C15:0, and anteiso-C17:0 in rumen and milk. The total OBCFA content in milk was positively related to the acetate molar proportion but negatively correlated with isoacid levels. The adenine/N ratio was negatively related to milk OBCFA content but positively associated with the iso-C15:0/iso-C17:0 ratio.The purpose of this research was to evaluate whether relationships exist between odd- and branched-chain fatty acids (OBCFAs) originating from milk fat and the corresponding data of ruminal fermentation parameters, microbial populations, and base contents that were used to mark microbial protein in rumen. Nine lactating Holstein dairy cows with similar body weights and parity were selected in this study, and the samples of rumen and milk were collected at the early, middle, and late stages, respectively. The rumen and milk samples were collected over three consecutive days from each cow, and the ruminal and milk OBCFA profiles, ruminal fermentation parameters, bacterial populations, and base contents were measured. The results showed that the concentrations of OBCFAs, with the exception of C11:0 and C15:0, were significantly different between milk and rumen (p < 0.05). The concentrations of anteiso-fatty acids in milk were higher than those in rumen, and the contents of linear odd-chain fatty acids were higher than those of branched-chain fatty acids in both milk and rumen. Significant relationships that existed between the concentrations of C11:0, iso-C15:0, anteiso-C15:0, C15:0, and anteiso-C17:0 in rumen and milk (p < 0.05). The total OBCFA content in milk was positively related to the acetate molar proportion but negatively correlated with isoacid contents (p < 0.05). The populations of Ruminococcus albus, R. flavefacients, and Eubacterium ruminantium were significantly related to milk C13:0 contents (p < 0.05). The adenine/N ratio was negatively related to milk OBCFA content (p < 0.05) but positively associated with the iso-C15:0/iso-C17:0 ratio (p < 0.05). Milk OBCFAs were significantly correlated with ruminal fermentation parameters, ruminal bacterial populations, and base contents. Milk OBCFAs had the potential to predict microbial nitrogen flow, and the prediction equations for ruminal microbial nitrogen flow were established for OBCFAs in dairy milk.

Effects of supplementary desalted mother liquor as replacement of commercial salt in diet for Thai native cattle on digestibility, energy and nitrogen balance, and rumen conditions.

Four Thai native cattle were used in a 4×4 Latin square design experiment to evaluate the availability of desalted mother liquor (DML) as replacement of salt in concentrate. Each cattle was assigned to one of the following concentrate feeding treatments: C1, 1% NaCl was added as salt; C2, 2% NaCl was added as salt; D1, 1% NaCl was replaced by DML; D2, 2% NaCl was replaced by DML, on a dry matter (DM) basis. The animals were fed rice straw and experimental concentrates (40:60) at 1.9% of body weight on a DM basis, daily. Acid detergent fiber expressed exclusive of residual ash (ADFom) digestibility in DML treatment was higher than salt treatment (p<.05) and D2 feeding showed the highest value (60.8%). There were no significant differences in blood metabolites, nitrogen retention, ruminal ammonia nitrogen, methane emission or energy efficiency among treatments. Molar percent of acetate on volatile fatty acids in rumen fluid 4hr post-feeding tended to be higher in DML treatment than salt treatment (p=.08). The results indicated that adding DML could improve ADFom digestibility and salt could be replaced by DML up to 2% as NaCl in concentrate without adverse effects on nitrogen balance, rumen conditions, blood metabolites and methane emission.

Effects of Leymus chinensis replacement with whole-crop wheat hay on blood parameters, fatty acid composition, and microbiomes of Holstein bulls

This study investigated the replacement of Leymus chinensis (LC) with whole-crop wheat hay (WCWH) in the diets of Holstein bulls in the fattening stage and examined the potential effects on blood parameters, fatty acids in rumen fluid and serum, and the rumen microbiomes. In this study, 12 Holstein bulls in the fattening period (body weight = 485.0 ± 40.8 kg) were assigned to 1 of 4 dietary treatments using a 4 × 4 Latin square design. Each experimental period consisted of a 17-d adaptation period and a 5-d collection period. The dietary treatments consisted of 4 proportions of WCWH (0, 33, 67, and 100%) as a substitute for LC (designated as WCWH0, WCWH33, WCWH67, and WCWH100, respectively). On d 18 and 22 of each experiment period, blood and rumen content samples were collected for analysis, respectively. Real-time quantitative PCR was used to analyze the rumen microbiomes. The results from this study revealed no differences in the saturated, monounsaturated, and polyunsaturated long-chain fatty acid proportions of rumen liquid among the treatments. It was observed in the present trial that rumen microbiotal flora were not significantly different in the bulls fed LC compared with the bulls fed WCWH. Additionally, blood sample analysis demonstrated that the concentration of urea nitrogen in the WCWH100 group was higher than that observed in the other groups. Meanwhile, no differences were detected for other serum parameters. There were no differences in the proportions of serum saturated, monounsaturated, and polyunsaturated long-chain fatty acids among the treatments. In conclusion, our data revealed that LC can be replaced with WCWH in the diet of Holstein bulls in the fattening stage with no negative effects on the blood indicators, fatty acids, and microbiomes.

Growth performance and macronutrient digestion in goats fed a rice straw based ration supplemented with fibrolytic enzymes

Supplementation of rice straw based rations (30% rice straw, dry matter basis) with fibrolytic enzymes is of potential interest to improve nutrient utilization and hence animal performance, but its efficacy is not yet demonstrated in growing goats. In a parallel design, eighteen young goats were fed a total mixed ration (TMR) based on rice straw either with or without supplemental fibrolytic enzymes. Addition of fibrolytic enzymes to the TMR increased the apparent digestibility of neutral and acid detergent fiber by 10.0 and 9.1%, respectively. Enzyme supplementation raised concentrations of total volatile fatty acids in rumen fluid with an associated increase in the proportion of acetate and total bacteria counts. Fortification of TMR with fibrolytic enymes increased average daily weight gain by 34.7% and the efficiency of feed utilization by 28%. It is concluded that the nutritive value of rice straw based rations can be upgraded by supplementation with fibrolytic enzymes, leading to enhanced ruminant production.

The effects of feeding 3-nitrooxypropanol at two doses on milk production, rumen fermentation, plasma metabolites, nutrient digestibility, and methane emissions in lactating Holstein cows

The objective of this study was to determine the effects of feeding 3-nitrooxypropanol (NOP) in the total mixed ration of lactating Holstein cows on rumen fermentation, ruminal microbial population, enteric methane production, milk production, nutrient digestibility, and blood metabolites. Fifteen ruminally cannulated Holstein cows in mid to late lactation were used in a 3 × 3 Latin square design study with 28-day periods. Cows were fed a 60%-forage diet (dry matter basis) with 2500 (HIGH), 1250 (LOW) or 0 (CON) mg/day of NOP. After a 20-day diet adaptation period, dry matter intake (DMI) and milk yield were recorded daily. Rumen digesta and rumen fluid were collected on Days 21 and 28 and ruminal pH was determined on Days 23–28. Methane emissions were measured on Days 23–27 using the sulfur hexafluoride tracer gas technique. Faecal and blood samples were taken on Days 25–27. Feeding NOP at either dose did not affect DMI, milk production or bodyweight gain. Total concentration of volatile fatty acids in rumen fluid did not differ; however, there was a decrease in molar proportion of acetate and increase in molar proportion of propionate with feeding NOP in a dose-dependent manner. Microbial profile and ruminal pH were not affected by treatment. Apparent total-tract digestibility of DM (62.7% vs 58.4%; P &lt; 0.05) and neutral detergent fibre (38.0% vs 30.7%; P &lt; 0.05) were increased with the HIGH dose compared with CON. Feeding NOP reduced methane yield from 19.9 to 15.3 g/kg DMI for CON versus LOW (P &lt; 0.05) and from 19.9 to 12.6 for CON versus HIGH (P &lt; 0.05). Feeding NOP at 1250 or 2500 mg/day reduced methane yield and affected ruminal volatile fatty acid profile without compromising DMI or apparent total-tract nutrient digestibility.

Relationship of rumen fill and fermentation to diurnal and seasonal variation of herbage intake in dairy cows grazed on perennial ryegrass pasture.

To clarify the effect of digesta weight in the reticulorumen on diurnal and seasonal fluctuations in herbage intake, six ruminally cannulated, non-lactating dairy cows were grazed on perennial ryegrass/white clover pasture during morning and evening sessions in spring and autumn. The digesta weight of fresh matter, dry matter (DM) and fiber in the reticulorumen at the beginning and the end of each grazing session was lower in spring than in autumn (P < 0.01). Although the digesta weight was similar between the sessions at the beginning of grazing, it was greater for the evening than for the morning at the end of grazing (P < 0.01). The large particles proportion in the digesta was lower for the morning than the evening (P < 0.01), and it was lower in spring than in autumn (P < 0.01). The concentrations of volatile fatty acids in rumen fluid were generally higher in spring compared with autumn. The herbage DM intake during the evening was greater compared with the morning in both seasons (P < 0.01). However, there was no difference in herbage DM intake between seasons. The results showed that the rumen digesta fill was not the sole factor explaining diurnal and seasonal variation of herbage intake in grazing dairy cows.

The effect of lipid sources on intake, rumen fermentation parameters and microbial protein synthesis in Nellore steers supplemented with glycerol

The effects of glycerol with fat sources as a feed alternative were investigated in the ration for Nellore steers (Bos indicus). Eight cannulated steers at 30 months of age with initial bodyweight of 554 ± 36.0 kg were used in a double 4 by 4 Latin square design with four consecutive 16-day periods. Treatments were three different diets with lipid sources (soybean, soybean oil and calcium salts of fatty acids) and one diet control without lipid sources. All diets formulated contained 10% crude glycerol and 5% ether extract with a forage:concentrate ratio of 35:65; corn silage was used as forage. The ruminal liquid was sampled for 24 h and ruminal fermentations were monitored by measuring pH, concentrations of ammonia nitrogenand volatile fatty acids in rumen fluid. Urine samples were obtained from the total collection for 24 h for estimation of rumen microbial protein supply using urinary purine derivatives. Our results showed that the use of lipid sources combined with glycerol did not induce significant changes in rumen pH, acetate molar proportion, ruminal microbial protein or dry matter intake. Although the acetate molar proportion was kept constant within normal parameters, the propionate molar proportion was increased by the diet containing lipid sources. Moreover, we found that there was a negative effect of lipid sources on crude protein and neutral detergent fibre corrected for ash and protein intake, and one positive effect on ether extract intake. We believe that association between fat and glycerol may affect rumen fermentation parameters through reducing fibre intake and increasing propionate production and ammonia nitrogen.

Ácidos graxos voláteis no rúmen de vacas alimentadas com diferentes teores de concentrado na dieta

Avaliou-se o efeito de teores de concentrado na dieta sobre a concentração de ácidos graxos voláteis no líquido ruminal de bovinos. Foram utilizadas quatro vacas mestiças, fistuladas no rúmen, com peso médio de 442,15kg, distribuídas em quadrado latino 4x4, divididos em quatro períodos de 14 dias, sendo 11 de adaptação e três para coleta de dados. Foi utilizada a silagem de milho, como volumoso, e milho, sorgo, farelo de soja, casca de soja, ureia e gordura protegida, como concentrado. As dietas foram formuladas para 13% de proteína bruta (PB), utilizando-se proporções de 30; 40; 50 e 60% de concentrado. Não houve influência do tratamento para concentrações de ácido acético, isobutírico, butírico, isovalérico e valérico. O ácido propiônico e a proporção acetato:propionato apresentaram concentrações máximas em 8,44 e 8,14 horas após a alimentação, respectivamente. Os ácidos graxos totais não foram influenciados pelos tratamentos, com concentração máxima em 7,68 horas após a alimentação, juntamente com valores mínimos de pH entre seis e nove horas. Dietas com até 60% de concentrado na matéria seca total não influenciaram as concentrações de ácidos graxos voláteis do rúmen.

Effects of chestnut tannins and coconut oil on growth performance, methane emission, ruminal fermentation, and microbial populations in sheep

This study was conducted to evaluate the effects of chestnut tannins (CT) and coconut oil (CO) on growth performance, methane (CH4) emission, ruminal fermentation, and microbial populations in sheep. A total of 48 Rideau Arcott sheep (average body weight 31.5±1.97kg, 16 wk old) were randomly assigned into 6 treatment groups in a 3 × 2 factorial design, with CT and CO as the main effects (8 sheep per group). The treatments were control diet (CTR), 10 or 30g of CT/kg of diet (CT10 and CT30), 25g of CO/kg of concentrate (CO25), and 10 or 30g of CT/kg of diet+25g of CO/kg of concentrate (CT10CO25 and CT30CO25). After the feeding trial (60 d), all sheep were moved to respiratory chambers to measure CH4 emission. After CH4 emission measurements, all sheep were slaughtered to obtain rumen fluid samples. Results showed that the addition of CT, CO, and CT+CO had no significant effects on growth performance of sheep but reduced CH4 emission. Addition of CT reduced the NH3-N concentration in rumen fluid in CT30. Addition of CO decreased the concentration of total volatile fatty acids in rumen fluid. No significant differences were observed in pH and molar proportion of volatile fatty acids among treatments. Addition of CT, CO, and CT+CO significantly decreased methanogen and protozoa populations. Moreover, CO decreased counts of Fibrobacter succinogenes. No significant differences were observed in populations of fungi, Ruminococcus flavefaciens, or Ruminococcus albus among treatments. In conclusion, supplementation of CT and CO seemed to be a feasible means of decreasing emissions of CH4 from sheep by reduction of methanogen and protozoa populations with no negative effect on growth performance.

Feeding value of total mixed ration silage with spent mushroom substrate

Six wethers were used in a digestibility experiment arranged as replicated 3 x 3 Latin square to evaluate the nutritive value of total mixed ration (TMR) silages that were made from ensiling of TMR containing 0, 6.5 and 13.0% (dry matter basis) of spent mushroom substrate (SMS) for 45 days (treatments denoted as CSMS, LSMS and HSMS, respectively). The amount of SMS replaced the same amount of timothy hay in the respective TMR. All TMR were well preserved as indicated by their low pH, low ammonia-N and high lactic acid contents. Increasing levels of SMS in the TMR silage quadratically reduced (P < 0.05) nutrient digestibility with the exception of ether extract. The difference of total digestible nutrients and digestible energy contents between LSMS and CSMS TMR silage were less than those between LSMS and HSMS. Increasing concentration of SMS in the ration tended to decrease content of total volatile fatty acids in rumen fluid but increased the ratio of acetate to propionate and pH. The study suggests that a SMS level of 6.5% in the diet DM can be recommended for silage based TMR.

Effects of Rumen or Duodenal Glucose Infusions on Intake in Dairy Cows Fed Fresh Perennial Ryegrass Indoors

The aim of this study was to determine whether the intake of fresh highly digestible ryegrass could be limited by the total amount of energy absorbed. Moreover, it investigated whether the limitation was more specific to energy absorbed as volatile fatty acids in the rumen compared with energy absorbed in the lower gastrointestinal tract. Four treatments were compared: infusion of 1.25kg of glucose into the rumen (R1.25), infusion of 2.5kg of glucose into the rumen (R2.5), infusion of 1.5kg of glucose into the duodenum (D1.5), and a control treatment consisting of water and salts. Treatments R2.5 and D1.5 were assumed to supply about 16.5 MJ of net energy for lactation. All treatments consisted of 2 infusions, one into the rumen and the other into the duodenum, with one of these infusions being a control. All infused solutions were isoosmotic with osmolarities around 340 and 330mmol/L for rumen and duodenum, respectively. Treatments were compared using 4 dairy cows in mid lactation according to a 4×4 Latin square design replicated twice during 8 periods of 7 d each. Cows were housed in tie stalls and fed ad libitum with fresh perennial ryegrass cut every morning during the spring at 28 d of regrowth. Intake and feeding behavior were measured, as well as concentrations of ruminal fermentation products and some blood metabolites. The pepsin-cellulase organic matter digestibility of the offered herbage averaged 0.76±0.011. The average dry matter intake of herbage was 15.5±0.52kg/d. The glucose infusions decreased dry matter intake by 0.95kg/d compared with the control, but had the same satiating effect regardless of site or dose of infusion. The average concentration of volatile fatty acids in rumen fluid was 97.9±2.03mmol/L and the molar proportion of propionate was 21.6±0.19mmol/100mmol. Glucose infusions into the rumen led to a decrease in the molar proportions of acetate from 64.4 on the control treatment to 60.9mmol/100mmol on R2.5 and increased the molar proportions of butyrate from 10.2 (control) to 13.5mmol/100mmol on R2.5, and minor acids (valerate and caproate), from 1.27 (control) to 2.54mmol/100mmol on R2.5, proportionally to the dose infused. These results suggested that energy nutrients can limit intake in dairy cows fed high-digestibility ryegrass and that butyrate and minor acids would have a limited satiating effect compared with propionate.

Prediction of short chain fatty acids in rumen fluid using near infrared reflectance spectroscopy (NIRS)

Short chain fatty acids, produced from the fermentation of feedstuffs, form the ruminant’s primary energy source, as well as being precursors of glucose, protein and milk constituents (Dijkstra et al., 2000). The analysis of rumen fluid to estimate short chain fatty acids involves the addition of internal standards and analysis by gas chromatography. NIRS has been shown to have the potential to accurately and rapidly evaluate fresh silage chemical and biological parameters, including short chain fatty acids (Park et al., 1998). This study was undertaken to evaluate the potential of NIRS to accurately estimate the chemical composition of rumen fluid when a range of diets were fed to fistulated steers.

Analysis of volatile fatty acids in rumen fluid by proton NMR spectroscopy

A study was conducted to quantify the volatile fatty acid (VFA) concentrations in aqueous and rumen fluid samples using a standard additions based quantitative proton nuclear magnetic resonance (NMR) spectroscopic method. Standard plots for acetic, propionic and butyric acids were all found to be linear (R2 &gt; 0.99). Results obtained by NMR were compared with those obtained using the conventional gas chromatographic method. No significant differences were found between the means and precisions of the two techniques (P &lt; 0.05). The method is well-suited for the routine quantification of these acids, requires no sample pretreatment and is more rapid than gas chromatography. Key words: Volatile fatty acid determination, rumen fluid, gas chromatography, nuclear magnetic resonance spectroscopy

Nutrient Fluxes in Splanchnic Tissue of Dairy Cows: Influence of Grass Quality

A crossover design was used to investigate the effects of high (450kg of N/ha) or low (150kg of N/ha) N fertilization of ryegrass on fermentation and nutrient fluxes in splanchnic tissue of dairy cows fed those grasses. Grass that was fertilized with the high amount of N contained more N and less sugar than did grass that was fertilized with less N. In rumen fluid, the concentration of NH3 N was lower for ryegrass that was fertilized with the low amount of N. The NH3 release by portal-drained viscera and urea synthesis in the liver were higher for cows fed ryegrass that was fertilized with the high amount of N.The concentration of NH3 N in rumen fluid, NH3 N release in portal-drained viscera, urea synthesis in the liver, urea release from the liver, and urea concentrations in milk were highly correlated. The release of acetate and propionate in portal-drained viscera was similar for both grasses and was well correlated with the proportion of volatile fatty acids in rumen fluid. The proportion of butyrate in rumen fluid was closely correlated with the release of butyrate and β-hydroxybutyrate in portal-drained viscera. Glucose synthesis in the liver indicated gluconeogenesis from amino acids, which corresponded well with urea synthesis in the liver. For the grass fertilized with more N, availability of energy sources for rumen microbes was low, and, therefore, cows did not use the N in that grass efficiently.