Fermentation Variables Research Articles

Use of gallic acid and hydrolyzable tannins to reduce methane emission and nitrogen excretion in beef cattle fed a diet containing alfalfa silage1,2.

The objective of this study was to determine the effects of different forms of hydrolyzable tannin [HT; source (chestnut, CN; tannic acid, TA); subunit (gallic acid, GA)] on apparent total-tract digestibility, methane (CH4) production, and nitrogen (N) utilization in beef cattle fed an alfalfa silage-based diet. Eight ruminally cannulated heifers with an initial BW of 480 ± 29.2 kg (mean ± SD) were used in a double 4 × 4 Latin square experiment. The experiment consisted of four 28-d periods (14-d adaptation, 14-d measurements) and a 7-d washout between periods. The animals received a basal diet with 19.8% CP (DM basis) content containing 75% alfalfa silage, 20% barley silage, and 5% supplement (DM basis) with or without different forms of HT. The dietary treatments were as follows: control (no HT), GA (1.5% of diet DM), TA (1.5% of diet DM), and CN (2% of diet DM). Animals were fed 95% of their ad libitum intake during the measurement phase. Total fecal excretion was collected for 4 d, CH4 was measured for 72 h using respiration chambers, and ruminal fermentation variables and plasma urea N (PUN) concentration were measured on 2 nonconsecutive days before and after feeding. The restricted DM (DMI; 10.79 ± 1.076 kg/d) and nutrient intakes did not differ (P ≥ 0.22) among treatments. Furthermore, apparent DM digestibility (60.3 ± 0.86%) was not affected (P = 0.20) by treatment, but CP digestibility decreased for TA and CN compared with control and GA treatments (63.1 vs. 69.0%; P < 0.001). Total VFA concentration tended (P = 0.089) to increase for GA compared with control and TA (134 vs. 125 and 126 mM) and intermediate for CN (129 mM). The PUN concentration was lower for all HT treatments compared with control (196 vs. 213 mg/L; P = 0.02). Both TA and CN increased the proportion of N excreted in feces and decreased the proportion in urine compared with control and GA (43.9% vs. 37.8% and 56.1% vs. 62.2%; respectively; P < 0.001). However, the proportion of urea N in urinary N decreased for all HT treatments compared with control (47.2% vs. 51.2%; P = 0.02). Also, GA tended to decrease CH4/DMI (20.4 vs. 22.3 g/kg DMI; P = 0.07) and decreased the proportion of GE intake emitted as CH4 (5.16 vs. 5.71%; P = 0.04) compared with control. Thus, among the different forms of HT applied to a high-protein alfalfa silage-based diet, both TA and CN had no effect on CH4 production, but decreased CP digestibility and shifted N excretion from urine to feces, whereas GA (i.e., HT subunit) decreased CH4 production and decreased the proportion of urea N in urinary N in beef cattle without affecting CP digestibility. Thus, feeding the HT subunit, GA, has the potential to decrease environment impact of ruminants (lower CH4 and ammonia emissions), without decreasing animal performance.

Variability in the Chemical Composition and In Vitro Ruminal Fermentation of Olive Cake By-Products.

Simple SummaryOlive cake is a by-product of oil production that can be used in ruminant feeding, but its composition can vary with multiple factors. The objective of this study was to determine the variability in the chemical composition and in vitro ruminal fermentation of 42 olive cake samples to evaluate their nutritive value for ruminants. The results showed that the chemical composition of olive cake is highly variable and is markedly affected by processing type and its storage time before processing. Cyclone olive cake had greater nutritive value for ruminants than both crude and extracted olive cake. All olive cake types were poorly degraded in vitro and, therefore, their nutritive value is highly dependent on their ether extract content. Statistical models using olive cake processing type, and either the chemical composition or storage time before processing as covariates, can be used in the practice to predict in vitro ruminal fermentation variables of olive cake samples. The obtained information may contribute to increase the use of olive cake in ruminant feeding.The objective of this study was to determine the variability in the chemical composition and in vitro ruminal fermentation of olive cake (OC) by-products. Forty-two OC samples with different storage times (1–14 months) and processing (25 crude (COC), 9 exhausted (EOC) and 9 cyclone (CYOC)) were fermented in vitro with sheep ruminal fluid. Exhausted OC samples had a lower ether extract content than COC and CYOC (15.9, 110 and 157 g/kg dry matter (DM), respectively), but greater neutral detergent fiber (NDF; 645, 570 and 441 g/kg DM) and acid insoluble nitrogen (9.76, 8.10 and 8.05 g/kg DM) content. Exhausted OC had the greatest (p < 0.05) average gas production rate (AGPR), whereas the greatest fermented organic matter (FOM) was obtained for EOC and CYOC. The best single predictor of the AGPR was total sugars content (R2 = 0.898), whereas NDF was the best one for FOM (R2 = 0.767; p < 0.001). Statistical models using storage time as a predictor variable had lower accuracy and R2 values than those from the chemical composition. In summary, the nutritive value of OC was highly dependent on its processing, but its ether extract content did not negatively affect ruminal fermentation parameters, which could be estimated from either carbohydrate composition or storage time.

Temporal fermentation and microbial community dynamics in rumens of sheep grazing a ryegrass-based pasture offered either in the morning or in the afternoon

Eight ruminally-fistulated wethers were used to examine the temporal effects of afternoon (PM; 1600h) v. morning (AM; 0800 h) allocation of fresh spring herbage from a perennial ryegrass (Lolium perenne L.)-based pasture on fermentation and microbial community dynamics. Herbage chemical composition was minimally affected by time of allocation, but daily mean ammonia concentrations were greater for the PM group. The 24-h pattern of ruminal fermentation (i.e. time of sampling relative to time of allocation), however, varied considerably for all fermentation variables (P⩽0.001). Most notably amongst ruminal fermentation characteristics, ammonia concentrations showed a substantial temporal variation; concentrations of ammonia were 1.7-, 2.0- and 2.2-fold greater in rumens of PM wethers at 4, 6 and 8h after allocation, respectively, compared with AM wethers. The relative abundances of archaeal and ciliate protozoal taxa were similar across allocation groups. In contrast, the relative abundances of members of the rumen bacterial community, like Prevotella 1 (P=0.04), Bacteroidales RF16 group (P=0.005) and Fibrobacter spp. (P=0.008) were greater for the AM group, whereas the relative abundance of Kandleria spp. was greater (P=0.04) for the PM group. Of these taxa, only Prevotella 1 (P=0.04) and Kandleria (P<0.001) showed a significant interaction between time of allocation and time of sampling relative to feed allocation. Relative abundances of Prevotella 1 were greater at 2h (P=0.05), 4h (P=0.003) and 6h (P=0.01) after AM allocation of new herbage, whereas relative abundances of Kandleria were greater at 2h (P=0.003) and 4h (P<0.001) after PM allocation. The early post-allocation rise in ammonia concentrations in PM rumens occurred simultaneously with sharp increases in the relative abundance of Kandleria spp. and with a decline in the relative abundance of Prevotella. All measures of fermentation and most microbial community composition data showed highly dynamic changes in concentrations and genus abundances, respectively, with substantial temporal changes occurring within the first 8h of allocating a new strip of herbage. The dynamic changes in the relative abundances of certain bacterial groups, in synchrony with a substantial diurnal variation in ammonia concentrations, has potential effects on the efficiency by which N is utilised by the grazing ruminant.

Exopolysaccharides production by Lactobacillus acidophilus LA5 and Bifidobacterium animalis subsp. lactis BB12: Optimization of fermentation variables and characterization of structure and bioactivities

In this study, the most important variables (incubation temperature, fermentation time and yeast extract concentration) responsible for the exopolysaccharides (EPSs) production by Lactobacillus acidophilus LA5 and Bifidobacterium animalis subsp. lactis BB12 were screened. The EPSs synthesize by LA5, BB12, and their co-culture were successfully optimized and were 349.82 ± 5.39, 146.83 ± 3.99 and 187.02 ± 1.54 mg/L, respectively. GC–MS analysis indicated that the purified EPSs are heteropolysaccharide and consisted of glucose, galactose, glucuronic acid, and xylose. The FT-IR analysis was used to investigate functional groups of purified EPSs and NMR analysis was used to study the structure of them. The DSC, TGA and DTG analysis of the extracted EPSs showed that they had high thermal stability and degradation temperature. The results of bioactivity analysis indicated that maximum DPPH and hydroxyl radicals scavenging activity were 59.30 ± 1.95, 56.76 ± 0.79, 62.33 ± 1.02% and 59.94 ± 1.68, 46.40 ± 0.73, 53.54 ± 0.76%, respectively for the EPSs of LA5, BB12, and their co-culture. Additionally, reducing power of the produced EPSs by LA5, BB12, and their co-culture were 1.047 ± 0.001, 1.270 ± 0.045 and 1.139 ± 0.018, respectively. Consequently, all these results showed that the EPSs produced by LA5, BB12, and their co-culture had a high potential as natural antioxidants or bioactive additive in the food industry.

Development of vinegar obtained from lemon juice: Optimization and chemical characterization of the process

A research on the production of lemon vinegar directly from lemon juice was conducted. For the alcoholic fermentation, two different strains of Saccharomyces cerevisiae, as well as two types of cultures (submerged culture and yeasts immobilized in alginate beads) were used. A microbiological control was also implemented during this stage. Acetic fermentation variables were optimized for a semi-continuous process. The whole process was monitored by means of volatile (SBSE/GC-MS), polyphenolic composition (UPLC-DAD), and sensory analysis was also conducted for the optimization procedure. The best conditions for alcoholic fermentation were obtained when Saccharomyces cerevisiae var. bayanus strain was used under a submerged culture, where a content of 13.53 mL ethanol/100 mL of wine was obtained. With regards to acetic fermentation, the use of an unloading volume of 33.33% of the total volume produced lemon vinegar in 20–24 h with an acidity of 13.29 g/100 mL of vinegar (expressed as acetic acid). The chemical monitoring of the process demonstrated that the majority of volatile compounds and polyphenols studied decreased during alcoholic and acetic fermentations. Multivariate statistical analysis such as principal component analysis allowed the classification of the samples according to the matrix (juice, wine and vinegar).

Optimization and partial characterization of ca-independent α-amylase from Bacillus amyloliquefaciens BH1

Strain Bacillus amyloliquefaciens BH1 was evaluated for the generation of α-amylase. Culture conditions and medium components were optimized by a statistical approach for the optimal generation of α-amylase with response surface methodology (RSM) method. The Plackett–Burman (PB) design was executed to select the fermentation variables and Central composite design (CCD) for optimizing significant factors influencing production. The optimum levels for highest generation of α-amylase activity (198.26 ± 3.54 U/mL) were measured. A 1.69-fold improve generation was acquired in comparison with the non-optimized. Partial characterization of the α-amylase indicated optimal pH and temperature at 7.0 and 40 °C, respectively. Crude α-amylase maintained a constant pH range 5.0–8.0 and 30–70 °C. The α-amylase was independent of Ca2+, and the activity was inhibited by Fe3+, Co2+, Cu2+, and Hg2+. The thermo and pH stability of the α-amylase indicate its extensive application in the food and pharmaceutical industries.

Effects of dietary adsorbent on milk aflatoxin M1 content and the health of lactating dairy cows exposed to long-term aflatoxin B1 challenge

The objective of this study was to evaluate the effects of Solis Mos (Novus International Inc., St. Charles, MO) on milk aflatoxin M1 (AFM1) content, lactation performance, plasma biochemical parameters, and ruminal fermentation in dairy cows exposed to long-term aflatoxin B1 (AFB1) challenge. Forty dairy cows were grouped according to days in milk (33 ± 7 d; mean ± SD) and milk production (33.9 ± 3.1 kg) and randomly assigned to 1 of 4 treatments: control (no additive), 20 μg of AFB1/kg of diet dry matter (AF), addition of Solis Mos at 0.25% of diet dry matter (SM), and MIX (AF + SM). The experiment lasted 9 wk, including an adaptation period during the first week. Dry matter intake, milk yield, and milk composition were measured on d 6 and 7 of each week. Milk AFM1, plasma biochemical parameters, and ruminal fermentation variables were analyzed on the last days of wk 1 and 9. No differences were observed in dry matter intake, milk yield, percentages of milk protein, milk fat, and lactose, and somatic cell counts across the treatments. Addition of adsorbent in the AFB1-contaminated diet significantly reduced the milk AFM1 concentrations (0.19 vs. 0.13 μg/kg) and transfer rates (1.38 vs. 0.89%). Dairy cows fed an AFB1-contaminated diet had lower superoxide dismutase activity, total antioxidant capacity, glutathione peroxidase, and levels of IgG and IgA, and higher levels of malondialdehyde in the plasma. Inclusion of Solis Mos in the diet increased the plasma superoxide dismutase activity, total antioxidant capacity, and IgG levels, and decreased the malondialdehyde level. Neither AFB1 nor Solis Mos affected the plasma levels of glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, alkaline phosphatase, or IgM. Long-term inclusion of adsorbent Solis Mos in the diet did not affect lactation performance or liver function, but it reduced milk AFM1 concentrations and oxidative stress and improved the immunological condition and ruminal fermentation in lactating dairy cows exposed to long-term AFB1 challenge.

CD Obesity-Prone Rats, but not Obesity-Resistant Rats, Robustly Ferment Resistant Starch Without Increased Weight or Fat Accretion.

ObjectiveWe used CD obese prone (OP) and obese resistant (OR) rats to examine how weight gain and fat accretion relate to fermentation levels and microbiota composition after feeding resistant starch (RS).MethodsAfter feeding OP rats and OR rats a high fat (HF) diet for 4 weeks, rats were stratified into three groups: fed either a HF diet (HF), switched to a low fat (LF) diet or a LF diet supplemented with RS (LF-RS, 20% wt) for 4 weeks. Energy intake, body weight, fermentation variables and microbiota composition were determined.ResultsIn OP rats, RS elicited robust fermentation (increased cecal contents, short chain fatty acids and serum GLP-1). Total bacteria, species of the Bacteroidales family S24-7 and the archaea Methanobrevibacter smithii increased. The robust fermentation did not elicit higher weight or fat accretion compared to control rats fed the same isocaloric diets (HFLF±RS). In OR rats, body weight and fat accretion were also not different between HFLF±RS diets, but RS elicited minimal changes in fermentation and microbiota composition.ConclusionsRobust fermentation did not contribute to greater weight. Fermentation levels and changes in microbiota composition in response to dietary RS differ by obese phenotype.

Monitoring the convection coefficient in fermentative processes using numerical methods.

This work is based on the importance of monitoring the thermodynamic variables of sugarcane juice fermentation by Saccharomyces cerevisiae, using a numerical technique, and providing artifices that lead to the best performance of this bioprocess. Different combinations of yeast quantity were added to diverse dilutions of cane juice, allowing the evaluation of the fermentation performance. This was conducted by observing the temperature signal obtained from thermal probes inserted in the experimental set up. The best performances are utilized in the mathematical model evaluation. Thus, the signal reconstructed by the appropriate inverse problem and subsequently, regularized by the simplified method of least squares (the method used for adjusting the defined parameters) allows a common method to process the convection coefficient that can be monitored and controlled within an actuation range. This leads to an increased level of refinement in the technique. Results show that it is possible to determine the best parameters for this technique and observe the occurrence of fermentation by monitoring the temperature signal, thereby ensuring the realization of a high-quality and high-performance bioprocess.

Glutamate Fermentation Process Model Based on Gams with Double Penalty Approach

There are many fermentation variables which can influence fermentation product during fermentation process, including fermentation time, temperature, pH, oxygen uptake rate (OUR), carbon dioxide evolution rate (CER), dissolved oxygen (DO) and stirring speed. For understanding the relationship between fermentation product and associated fermentation variables, one current interest is the investigation of significant fermentation variables to construct an interpretable and stable fermentation model. In this study, the significant variables in the fermentation process of glutamate were selected based on the generalized additive models through a shrinkage approach. The GAM2 which is based on less fermentation variables after variable selection has the same value of adjusted Rsquare (0.972) and deviance explained (97.6%) as GAM1 which includes all the measuring fermentation variables. Results showed that the proposed approach not only can identify the significant variables in the fermentation process of glutamate, but also can improve the performance of the fermentation model.

Microfermentation of Cacao: The CTAHRBag System

Standardized and repeatable techniques for microfermentation and drying small samples (&lt;100 g) of cacao (Theobroma cacao), also known as cocoa, are necessary to identify new varieties having high yield and quality. Sensory analyses of the processed cacao seed (bean) are a critical component to develop varieties for Hawaii’s cacao to chocolate industry. A microfermentation and drying system capable of processing multiple samples of mucilage-covered cacao beans ranging from 60 to 6000 g was developed. The effects of fermentation variables, genetic background, management, site, and season on quantitative and qualitative attributes can be studied using this protocol. Beans processed using the College of Tropical Agriculture and Human Resources (CTAHR) bag system (CBS) are inoculated with microorganisms on their fruit (pod) surface. This enables a better assessment of the terroir of sites when the dried fermented beans are roasted and processed. Clean, inexpensive, disposable polyethylene bags serve as fermentation vessels. The fermentery has a temperature controller that follows a fermentation temperature profile. Sun drying is replaced by drying in the laboratory. Two-month storage in ambient outdoor humidity and temperature completes the protocol. The CBS is an improvement to existing cacao microfermentation methods because beans from single pods can be fermented. No microbial isolates, inoculums, or foreign pulp from other trees and sites are used. Less labor is required to maintain the fermentation. In laboratory drying is less variable than sun drying. The CBS is a flexible and reliable method to microferment cacao for scientists, small growers, and hobbyists.

Study of Fermentation Variables for the Preparation of Wine from Jamun Fruit

Study of Fermentation Variables for the Preparation of Wine from Jamun Fruit

Monensin and a blend of castor oil and cashew nut shell liquid used in a high-concentrate diet abruptly fed to Nellore cattle1

Monensin and functional oils (FO) were supplemented to a high-concentrate diet abruptly fed to 12 ruminally cannulated Zebu steers to study their effects on rumen fermentation, blood metabolites, and , , and relative population. A randomized complete block design with repeated measures over time within 2 experimental periods of 21 d each was used. Treatments were a control (CTR; with no additives), FO (included at 400 mg/kg), and monensin included at 30 mg/kg (M30) or 40 mg/kg (M40). All steers were fed the same high-concentrate basal diet, which consisted of 92.25% concentrate. The first 60 h after transition showed a treatment and hour interaction for ruminal propionate proportion ( = 0.028), and no change in acetate molar proportion ( = 0.633), rumen pH ( = 0.370), and time the rumen pH remained below 5.6 ( = 0.242) were observed. The acetate:propionate ratio decreased ( = 0.020) when monensin was fed in both concentrations (2.30 for the M30 treatment and 2.32 for the M40 treatment) compared with when the CTR was fed (2.85), without being different when the FO (2.71) treatment was fed. Only the M30 treatment did not show pH below 5.2 (P=0.047) over the 60 h after the abrupt transition. Within the entire period, DMI ( = 0.008) and mean ruminal pH ( = 0.040) as well as molar proportions of propionate ( = 0.034) and valerate ( = 0.031) had significant interactions between treatment and day. Total VFA concentration was greater ( = 0.017) for the M30 (117.36 m) and CTR treatments (115.77 m) compared with the M40 treatment (105.02 m), without being different for the FO treatment (111.55 m). Treatments did not change feed behavior parameters. Blood HCO ( = 0.006) and total carbon dioxide ( = 0.003) were greater for the M30 (27.8 and 29.3 mmol/L, respectively) and FO treatments (28.3 and 29.7 mmol/L, respectively) compared with the CTR treatment (25.7 and 26.9 mmol/L, respectively). ( < 0.0001) and ( < 0.0001) decreased their population throughout days, whereas ( = 0.026) increased its population. Independent of ciliated protozoa genera, the greatest ( < 0.0001) protozoa counts were observed for the CTR treatment (52.7 × 10/mL), intermediate for the FO treatment (35.3 x10/mL), and least for steers fed monensin in both concentrations (15 × 10/mL for the M30 treatment and 14 × 10/mL for the M40 treatment). Feed additives had different effects to reduce the subacute acidosis. The use of the FO and M40 treatments did not change most of the rumen fermentation variables, especially in the first week after abrupt transition, when the M30 treatment provided higher protection against acidosis.

Statistical optimization of fermentation conditions for the improved production of poly-β-hydroxybutyrate from Bacillus subtilis

ABSTRACTPoly-β-hydroxybutyrate (PHB) has been an effective biodegradable plastic obtained by microbial fermentation. Batch fermentation of Bacillus subtilis features an attractive system for the production of PHB. Identification of appropriate media components and cultivation conditions are extremely important for the optimal production of biomass and/or PHB production. Statistical media design was utilized for the optimization of different fermentation variables (glucose, peptone, sodium chloride, K2HPO4, KH2PO4, ammonium sulfate, ammonium chloride, sodium sulfate, temperature, inoculum size, and pH). The optimized media predicted the optimal dry cell weight of 7.54 g L−1 and PHB production of 77.2 mg L−1 at 1 g L−1 of peptone, 1.46 g L−1 sodium sulfate, and pH 6.8 in 24 h. Glucose utilization, batch growth, and PHB production kinetics of B. subtilis were determined experimentally. The effect of substrate inhibition on specific growth rate was also determined experimentally for B. subtilis. The values of kinetic and substrate inhibition parameters obtained from this study shall be utilized to develop a mathematical model for PHB production for further improving the production of PHB.

Modeling and optimization of fermentation variables for enhanced production of lactase by isolated Bacillus subtilis strain VUVD001 using artificial neural networking and response surface methodology.

Modeling and optimization were performed to enhance production of lactase through submerged fermentation by Bacillus subtilis VUVD001 using artificial neural networks (ANN) and response surface methodology (RSM). The effect of process parameters namely temperature (°C), pH, and incubation time (h) and their combinational interactions on production was studied in shake flask culture by Box-Behnken design. The model was validated by conducting an experiment at optimized process variables which gave the maximum lactase activity of 91.32U/ml. Compared to traditional activity, 3.48-folds improved production was obtained after RSM optimization. This study clearly shows that both RSM and ANN models provided desired predictions. However, compared with RSM (R 2=0.9496), the ANN model (R 2=0.99456) gave a better prediction for the production of lactase.

Optimization of Culture Conditions for Production of Xanthine Oxidase by Arthrobacter sp. MU12

Xanthine oxidase is a key enzyme catalyzing the metabolism of purine bases. The present study isolated a new Arthrobacter strain with an ability of synthesizing high activity xanthine oxidase and diversity of stereo-specific properties. Statistical experimental designs were applied for the optimization of xanthine oxidase production by Arthrobacter sp. MU12 in shake-flask cultivation. The fermentation variables were selected in accordance with the Plackett-Burman design and were further optimized via response surface methodology. The most significant variables influencing xanthine oxidase production were (NH4) 2SO4, xanthine and CaCl2 and these factors were subsequently optimized using a Box-Behnken design. The predicted results indicated that the maximum enzyme yield(4.835 U/mL) could be obtained under the optimized conditions of (NH4) 2SO4 3.01482 g.L-1, xanthine 0.67538 g.L-1, CaCl2 4.48724 mg.L-1, which was considerably higher than results obtained using the original conditions. This environment friendly method(biological treatment) can be regarded as an effective way to produce xanthine oxidase.

Changes in the relative population size of selected ruminal bacteria following an induced episode of acidosis in beef heifers receiving viable and non-viable active dried yeast.

To characterize the changes in the relative population size (RPS) of select ruminal bacteria and rumen fermentation variables in beef heifers supplemented with a strain of Saccharomyces cerevisiae as viable active dried (ADY) or killed dried (KDY) yeast following an induced episode of ruminal acidosis. Six ruminally cannulated beef heifers fed a diet consisting of 50% forage and 50% grain (dry matter basis) were used in a replicated 3×3 Latin square design with three 28-day periods. Treatments were: (i) control (CTRL; no yeast); (ii) ADY (4gday-1 providing 1010 CFU per g; AB Vista, UK); and (iii) KDY (4gday-1 autoclaved ADY). The acidosis challenge was induced on day 22 and rumen samples were collected on day 15 (baseline; BASE), day 22 (challenge day; CHAL), and on day 29 (168th hour post acid challenge or recovery, REC) of each period. Over the study, duration of pH <5·8 (indicative of subacute ruminal acidosis) was less for ADY and KDY than CTRL, with ADY less than KDY. No treatment effects were observed on relative abundance of ruminal bacteria, but the day effect was significant. The RPS of lactate producers and utilizers was greater while RPS of fibrolytic bacteria was lower during CHAL than BASE and REC. Yeast supplementation, irrespective of its viability, showed beneficial effects on ruminal pH variables in animals more susceptible to acidosis. Rumen microbial population was altered with the induction of severe acidosis. Most of the changes reverted back to baseline values during the recovery phase. Yeast supplementation reduced subacute rumen acidosis in the most susceptible cattle, but failed to attenuate severe acidosis induced by a grain challenge. The study provided valuable insight into the mechanism by which acidosis affects cattle performance. Individual animal variation in ruminal fermentation partly explained the variability in response to yeast supplementation in the study.

Increasing dietary doses of an Aspergillus oryzae extract with alpha-amylase activity on nutrient digestibility and ruminal fermentation of lactating dairy cows

This study was designed to evaluate increasing dietary doses of an Aspergillus oryzae extract with alpha-amylase activity on nutrient intake and total tract digestion, sorting index, ruminal fermentation, milk yield and composition, blood metabolites and nitrogen utilization of mid- to late lactating dairy cows. Twenty-four multiparous Holstein cows (162.3±107.9days in milk, 636±62kg of live weight, and 31.6±6.5kg/d of milk yield) were used in a replicated 4×4 Latin square design experiment. Eight cows used in the experiment had rumen cannulas to assess ruminal fermentation variables. Periods had 21days, in which 14days were allowed for treatment adaptation and 7days for sampling. Cows were randomly assigned to the following treatments: control (A0), and Aspergillus oryzae extract to supply 150,300 or 450FAU/kg DM. One FAU (fungal amylase unit) is the amount of enzyme which will dextrinize soluble starch at the rate of 1-mg per minute at 30°C and pH 4.8. Treatments did not affect DM and nutrient intake, as well as the sorting index of cows. Alpha-amylase supplementation linearly increased (P=0.031) crude protein digestibility and tended to linearly increase (P=0.060) DM digestibility. Treatments did not affect ruminal pH, acetate, butyrate, propionate and total branched-chain fatty acids. Alpha-amylase linearly increased (P=0.023) isovalerate production and tended to quadratically affect (P=0.065) ammonia nitrogen concentration in rumen. Milk yield and composition, and efficiency of milk production were not affected (P≥0.275) by alpha-amylase supplementation. Treatments tended to linearly decrease (P=0.061)N excreted in feces. Treatments linearly increased (P≤0.039) live weight and body condition score of cows. Finally, alpha-amylase supplementation did not affect (P≥0.234) serum glucose, urea, and hepatic enzymes concentration. Increasing doses of an Aspergillus oryzae extract up to 450FAU/kg DM did not alter starch digestibility, ruminal propionate production, microbial protein synthesis, and milk yield and composition of mid-lactating cows.

Between-cow variation in digestion and rumen fermentation variables associated with methane production

A meta-analysis based on an individual-cow data set was conducted to investigate the effects of between-cow variation and related animal variables on predicted CH4 emissions from dairy cows. Data were taken from 40 change-over studies consisting of a total of 637 cow/period observations. Animal production and rumen fermentation characteristics were measured for 154 diets in 40 studies; diet digestibility was measured for 135 diets in 34 studies, and ruminal digestion kinetics was measured for 56 diets in 15 studies. The experimental diets were based on grass silage, with cereal grains or by-products as energy supplements, and soybean or canola meal as protein supplements. Average forage:concentrate ratio across all diets on a dry matter basis was 59:41. Methane production was predicted from apparently fermented substrate using stoichiometric principles. Data were analyzed by mixed-model regression using diet and period within experiment as random effects, thereby allowing the effect of experiment, diet, and period to be excluded. Dry matter intake and milk yield were more repeatable experimental measures than rumen fermentation, nutrient outflow, diet digestibility, or estimated CH4 yield. Between-cow coefficient of variation (CV) was 0.010 for stoichiometric CH4 per mol of volatile fatty acids and 0.067 for predicted CH4 yield (CH4/dry matter intake). Organic matter digestibility (OMD) also displayed little between-cow variation (CV = 0.013), indicating that between-cow variation in diet digestibility and rumen fermentation pattern do not markedly contribute to between cow-variation in CH4 yield. Digesta passage rate was much more variable (CV = 0.08) between cows than OMD or rumen fermentation pattern. Increased digesta passage rate is associated with improved energetic efficiency of microbial N synthesis, which partitions fermented substrate from volatile fatty acids and gases to microbial cells that are more reduced than fermented carbohydrates. Positive relationships were observed between CH4 per mol of volatile fatty acids versus OMD and rumen ammonia N concentration versus OMD; and negative relationships between the efficiency of microbial N synthesis versus OMD and digesta passage rate versus OMD, suggesting that the effects of these variables on CH4 yield were additive. It can be concluded that variations in OMD and efficiency in microbial N synthesis resulting from variations in digesta passage contribute more to between-animal variation in CH4 emissions than rumen fermentation pattern.

Growth performance, rumen fermentation, bacteria composition, and gene expressions involved in intracellular pH regulation of rumen epithelium in finishing Hu lambs differing in residual feed intake phenotype.

The objective of this study was to evaluate the effect of residual feed intake (RFI) on rumen function in finishing lambs. A total of 60 male Hu lambs (average initial BW = 25.2 ± 2.5kg) were used and were offered a pelleted high-concentrate diet, of which the forage to concentrate ratio was 25:75. Individual feed intake was recorded over a period of 42 d, then 10 lambs with the lowest RFI and the highest RFI were selected, respectively. The rumen fluid used for fermentation variables and relative abundance of bacteria measurement was obtained on d 10 and 20 after RFI measurement. At the end of this experiment, the selected lambs were slaughtered and rumen epithelium and liver tissues were collected for RNA extraction. Low-RFI lambs had lower ( < 0.01) DMI and greater ( < 0.05) G:F than the high-RFI ones, while the RFI groups did not differ in ADG and BW ( > 0.05). Additionally, RFI was positively ( = 0.57; < 0.01) correlated with DMI and negatively ( = -0.53; < 0.05) correlated with G:F. Total VFA and individual VFA decreased ( < 0.05) over time. The concentrations of total VFA, acetate, valerate, isobutyrate, isovalerate, and rumen pH ( > 0.05) were not affected by RFI classification. Nonetheless, low-RFI group lambs had a greater ( < 0.05) concentration of propionate, a lower ( < 0.05) concentration of butyrate, and a lower ( < 0.05) acetate to propionate ratio compared with the high-RFI group. There was a significant ( < 0.05) effect of RFI on the relative abundance of and . The relative abundance of , , and decreased ( < 0.05) over time in high-RFI group. And the relative abundance of in high-RFI group was greater ( < 0.05) than its low-RFI counterpart. Furthermore, RFI had no effect ( > 0.05) on gene expression associated with intracellular pH regulation (, , , , , , , and ) in rumen epithelium and β-hydroxybutyrate metabolism () in both rumen epithelium and liver tissues. In conclusion, even though low-RFI lambs had lower DMI, however, the number of was lower. Additionally, there was no difference in gene expressions level associated with intracellular pH regulation in rumen epithelium between RFI groups.