Molar Proportions Of Butyrate Research Articles

Effects of extracts of Humulus lupulus (hops) and Yucca schidigera applied alone or in combination with monensin on rumen fermentation and microbial populations in vitro

β-Acids in hops (Humulus lupulus) and saponins in yucca (Yucca schidigera) have been found to possess antimicrobial properties similar to that of monensin and could be an alternative to in-feed antibiotics. The effects of monensin (MON) and ethanol extracts of hops (HE) and Y. schidigera (YE) alone and in combination with MON were assessed on ruminal microbial composition and fermentation in vitro of a barley-based diet. All treatments decreased (P < 0.05) CH4 production (per unit of dry matter), microbial protein (mg), and NH3 -N accumulation. All treatments reduced (P < 0.01) the acetate:propionate (A:P) ratio and molar proportions of butyrate, but increased (P < 0.01) those of propionate, whereas those of acetate decreased (P < 0.001) with addition of MON (10 µg mL(-1)) and combined with HE or YE. Methane produced per unit of true digested dry matter decreased (P < 0.001) with all treatments except YE. Monensin reduced (P < 0.001) proportions of 16S rRNA copies of Ruminococcus flavefaciens, but increased (P < 0.01) those of Selenomonas ruminantium. Hops extract alone or combined with MON reduced (P < 0.01) proportions of R. flavefaciens but combined with MON tended (P < 0.1) to increase those of S. ruminantium. Yucca extract combined with MON increased (P < 0.01) the proportions of R. flavefaciens and S. ruminantium. All treatments except MON (2.5 µg mL(-1)) reduced (P < 0.01) the relative abundance of methanogens. Hops extract and YE altered rumen microbes and fermentation in a manner similar to MON with many responses being additive when applied in combination.

Effect of forage conservation method on ruminal lipid metabolism and microbial ecology in lactating cows fed diets containing a 60:40 forage-to-concentrate ratio

The effect of forage conservation method on ruminal lipid metabolism and microbial ecology was examined in 2 complementary experiments in cows. Treatments comprised fresh chopped grass, barn-dried hay, or untreated (UTS) or formic acid-treated silage (FAS) prepared from the same grass sward. Preparation of conserved forages coincided with the collection of samples from cows offered fresh grass. In the first experiment, 5 multiparous Finnish Ayrshire cows (229d in milk) were used to compare the effects of feeding diets based on grass followed by hay during 2 consecutive 14-d periods separated by a 5-d transition during which extensively wilted grass was fed. In the second experiment, 5 multiparous Finnish Ayrshire cows (53d in milk) were assigned to 1 of 2 blocks and allocated treatments according to a replicated 3×3 Latin square design with 14-d periods to compare the effects of hay, UTS, and FAS. Cows received 7 or 9kg/d of the same concentrate in experiments 1 and 2, respectively. Conservation of grass by drying, but not ensiling, decreased forage fatty acid content primarily due to losses of 18:2n-6 and 18:3n-3. Compared with grass, feeding hay had no effect on dry matter intake (DMI), rumen pH, or fermentation characteristics, other than increasing ammonia content, but lowered whole-tract organic matter and fiber digestibility (experiment 1). Relative to hay, silage increased DMI, rumen volatile fatty acid (VFA) concentrations, and molar proportions of butyrate, and decreased molar acetate proportions (experiment 2). Compared with UTS, FAS increased DMI, had no effect on rumen ammonia or VFA concentrations, but tended to lower rumen pH and the molar ratio of lipogenic to glucogenic VFA. Conservation method had no substantial effect on ruminal or whole-tract digestibility coefficients. Compared with fresh grass and silages, hay decreased lipolysis and biohydrogenation (BH) of dietary unsaturates in the rumen, resulting in similar flows of 18:2n-6 and 18:3n-3, but lower amounts of trans-11 18:1 and Δ11,13 18:2 at the omasum. The extent of silage fermentation had minimal influence on ruminal lipid metabolism. Treatments were not associated with changes in the relative abundance of specific bacteria known to be capable of BH or rumen protozoal numbers. In conclusion, conservation method altered forage lipids, the extent of lipolysis and BH in the rumen, and the flow of fatty acids at the omasum, in the absence of substantial changes in ruminal Butyrivibrio populations.

The effect of different levels of molasses on the digestibility, rumen parameters and blood metabolites in sheep fed processed broiler litter

A 28-d experiment was performed to evaluate the influence of replacing dietary corn/barley with molasses at levels of 0 (M0), 50 (M50) and 100 (M100) g/kg dietary dry matter (DM), as energy sources, in the diets containing heat-processed broiler litter (HBL) (240g/kg DM) in male Moghani sheep. Digestibility, microbial protein supply (MPS), ruminal parameters and blood metabolites were measured. The digestibility of DM and crude protein (CP) in experimental sheep linearly increased (L, P=0.01) as level of molasses enhanced in the diets. Addition of molasses to diet linearly increased MPS (L, P=0.01) compared to sheep fed the control diet. Ruminal pH and ammonia concentrations linearly declined (L, P<0.05) as level of molasses increased in the diet. There was no difference (P>0.05) in ruminal volatile fatty acid concentrations, except a linear increase in the molar proportion of butyrate (L, P=0.02) among the molasses supplemented groups. Blood urea-N linearly decreased (L, P=0.02) in sheep fed molasses compared to the control group. It can be concluded that replacing corn/barley with molasses in sheep diet improved the utilization of the diet containing HBL.

Effects of nitrate adaptation by rumen inocula donors and substrate fiber proportion on in vitro nitrate disappearance, methanogenesis, and rumen fermentation acid

A study was conducted to evaluate the main effects of dietary nitrate adaptation by cattle and alfalfa cell wall to starch ratio in in vitro substrates on nitrate disappearance and nitrite and volatile fatty acid (VFA) concentrations, as well as hydrogen (H2) and methane (CH4) accumulations. Rumen fluid from steers fed diets containing urea or nitrate was added into in vitro incubations containing sodium nitrate as the sole nitrogen source and 20 cell wall : 80 starch or 80 cell wall : 20 starch as the carbohydrate source. The results showed that during 24 h incubation, rumen fluid inoculums from steers adapted to dietary nitrate resulted in more rapid nitrate disappearance by 6 h of incubation (P < 0.01), no significant effect on nitrite concentration and diminished CH4 accumulation (P < 0.05). Cell wall to starch ratio did not affect nitrate disappearance, CH4 accumulation and total VFA concentration. The higher cell wall ratio had the lower total gas production and H2 concentration (P < 0.05). Ammonia-N (NH3-N) concentration increased because of adaptation of donors to nitrate feeding (P < 0.05). Nitrate adaptation did not alter total VFA concentration, but increased acetate, and decreased propionate and butyrate molar proportions (P < 0.01).

Effects of feeding different amounts of supplemental glycerol on ruminal environment and digestibility of lactating dairy cows

A replicated 3×3 Latin square study was conducted to evaluate the effects of replacing a portion of ground corn in the diet with dietary glycerol on rumen environment, blood metabolites, and nutrient digestibility. Six rumen-cannulated Holstein cows, averaging 56±18 DIM and 38.0±8.2kg of milk/d, were used in the study. Experimental periods included 3wk for treatment adjustment period followed by 1wk for data collection. Diets were corn silage based and balanced to be isocaloric and isonitrogenous. Treatments were 0g of glycerol/d (control, CON), 200g of glycerol/d (G2), and 400g of glycerol/d (G4). Dry matter intake (DMI) decreased as the amount of glycerol fed increased. Milk yield was higher for CON and G2 cows in comparison with G4 cows. Milk fat percentage and yield were reduced when glycerol was fed compared with CON cows but increased the milk protein percentage at the highest concentration of dietary glycerol. These changes resulted in decreased energy-corrected milk yield and efficiency (milk/DMI) in diets supplemented with G4 compared with CON. No differences were observed in ruminal pH and ammonia concentrations. Molar proportions of acetate, valerate, and acetate:propionate ratio decreased, whereas propionate increased as the amount glycerol fed increased. Molar proportions of butyrate were greatest when glycerol was included in the diet compared with CON. Nutrient intake and digestion were not different among treatments. Results of this trial suggest that feeding increasing amounts of glycerol may decrease DMI and alters ruminal fermentation, resulting in reduced yield of milk, fat, and energy-corrected milk.

The relationship between rumen acidosis resistance and expression of genes involved in regulation of intracellular pH and butyrate metabolism of ruminal epithelial cells in steers

Past research has focused on the prevention and management of subacute rumen acidosis by manipulating the ration; however, the severity of acidosis varies even among animals fed a common high-grain diet. The objectives of this study were to compare the ruminal volatile fatty acid (VFA) profile and expression of genes involved in the metabolism of butyrate, the VFA most extensively metabolized by the ruminal epithelium, and intracellular pH regulation in ruminal epithelial cells between acidosis-resistant (AR) and acidosis-susceptible (AS) steers. Acidosis indexes (area per day under pH 5.8 divided by dry matter intake) were measured for 17 steers fed a common high-grain diet, and the 3 steers with the lowest (1.4±1.2 pH∙min/kg) and the 3 with the highest values (23.9±7.4 pH∙min/kg) were classified as AR and AS, respectively, and used in the subsequent study. The steers were force-fed a diet containing 85% grain at 60% of the expected daily intake (5.8±0.8 and 5.6±0.6kg for AR and AS, respectively) within 30min. Mean ruminal pH over the postprandial 6-h period was higher for AR compared with AS (6.02 vs. 5.55), and mean total VFA concentration was 74% for AR compared with AS (122 vs. 164mM). Molar proportion of butyrate in the ruminal fluid was 139% higher for AR compared with AS (17.5 vs. 7.33mol/100mol of VFA). Expression of monocarboxylate cotransporter isoform 1, sodium hydrogen exchanger isoforms 1 and 2, and anion exchangers (downregulated in adenoma and putative anion exchanger, isoform 1) did not differ between AR and AS steers. However, expression of sodium hydrogen exchanger isoform 3, which imports Na+ to the epithelial cell and exports H+ to the rumen, was 176% higher in AR steers than in AS steers. Higher ruminal pH for AR might be partly due to a faster rate of VFA absorption, lower VFA production, or both.

Vegetable oil soapstocks reduce methane production and modify ruminal fermentation

Four soapstocks from the refinery vegetable oil industry (SSpalm, SSoliv, SSsoyb and SSsunf (RIOSA, Baeza-Linares, Spain), from processing of palm, olive, sunflower, and soybean oils, respectively) and a mixture of lauric and miristic acids (4:1, LMA) added to diets with different forage proportions (50, 150 and 250g barley straw/kg diet; F5, F15 and F25 diets, respectively) were examined to assess their potential to modify ruminal fermentation in vitro, in particular CH4 production. Serum bottles containing 400mg of substrate (F5, F15, F25 diets) including 30 or 60g/kg of the materials and 50ml of buffered rumen fluid were incubated at 39°C for 24h. After incubation, gas and CH4 production, pH and volatile fatty acid (VFA) concentrations in the incubation medium were measured. All materials linearly decreased gas production (P<0.05), and SSoliv, SSsoyb and SSsunf reduced CH4 production (P<0.05) and methane produced per mol of total VFA formed (P<0.05), and LMA also reduced CH4 proportion in the gas (P<0.05), whereas SSpalm tended to decrease it. LMA linearly (P<0.05) decreased acetate production and the acetate to propionate ratio, and raised the propionate molar proportion and pH (P<0.05). SSoliv and SSsoyb caused a linear (P<0.05) decline in acetate, and rise in propionate, molar proportions, thus decreasing the acetate to propionate ratio (P<0.05), whereas SSsunf tended to have the same effects (P<0.10). As the forage proportion increased, CH4 and acetate proportion, acetate to propionate ratio and final pH increased, while gas, VFA (individual and total) and CH4 production, and propionate and butyrate molar proportions, decreased. Soapstocks, especially SSsoyb and SSsunf, are promising dietary alternatives to depress ruminal methanogenesis.

The influence of the different carbohydrate sources on utilization efficiency of processed broiler litter in sheep

In a completely randomized design, fifteen male Moghani sheep were used to determine the influence of supplementing processed broiler litter (BL) with different carbohydrate sources (i.e., corn, barley or molasses) on the nutrients digestibility, microbial protein (MP) production, ruminal parameters and blood metabolites. The three dietary treatments, which were iso-caloric and iso-nitrogenous, were corn diet (alfalfa hay, wheat straw, processed BL, corn grain), barley diet (alfalfa hay, wheat straw, processed BL, barley grain) and molasses diet (alfalfa hay, wheat straw, processed BL, molasses). The digestibility of dry matter, crude protein and neutral detergent fiber and MP in sheep fed molasses diet were higher (P<0.05) compared with those fed with diets containing corn or barley. However, sheep fed molasses diet had lower (P<0.05) ruminal pH ammonia concentration than those fed with other diets. Including various carbohydrate sources in the diets had no effect on volatile fatty acid (VFA) concentrations (P>0.05), except for total VFA and molar proportion of butyrate which increased (P<0.05) by molasses feeding. From blood metabolites only the blood urea-N concentration in sheep fed diet containing molasses was lower (P<0.05) than diet containing corn. In conclusion, adding molasses to processed BL-containing diet led to improved nutrient digestibility and MP production in sheep.

Influences of dietary nitrogen and non-fiber carbohydrate levels on apparent digestibility, rumen fermentation and nitrogen utilization in growing yaks fed low quality forage based-diet

The effects of dietary N and non-fiber carbohydrate (NFC) levels on nutrient digestibility, ruminal fermentation, and nitrogen utilization were investigated in growing yaks. Four diets (N content: 1.43%, 1.97%, 2.45% and 2.90% of DM basis; ratio of dietary NFC and RDP: 5.9, 3.2, 2.2 and 1.6) were offered to four yaks in a 4×4 Latin square design. Dietary N and NFC did not affect the gastrointestinal tract digestibility of DM, organic matter (OM), NFC, NDF, or ADF (P>0.05). Ruminal pH value, molar proportion of butyrate, and ratio of acetate to propionate were not affected by the diets (P>0.05); whereas, molar proportions of acetate, propionate, iso-butyrate, iso-valerate, valerate, and total VFA concentration in rumen fluid increased linearly (P<0.01) with increase in dietary N and decrease in dietary NFC. Except for ruminal NH3-N and soluble protein N, free amino acid-N and peptide-N maintained constantly within the sampling time (from 0 to 8h of post feeding; P>0.05). The increment of N intake linearly increased the N retention (P=0.003), but no difference (P>0.05) was observed in the ratio of N retention to the gastrointestinal trace absorbed N after dietary N reached to 2.45% of DM. Microbial N supply had linear and quadric (P<0.001) responses to the dietary N, and the highest microbial N synthesis efficiency was observed when the yaks were fed with 1.97% N diet in which ratio of NFC to RDP was 3.2, and dietary NFC and RDP were 20.2% and 6.7% of DM, respectively. Total purine derivatives excretion and microbial purine N:total N had a quadric (P<0.05) response to the dietary N. Results of the current experiment suggest that maximizing N utilization and microbial efficiency were obtained when the yaks were fed a diet with an optimal dietary ratio of NFC to RDP.

Rumen microbial variation and nutrient utilisation in mithun (Bos frontalis) under different feeding regimes

The aim of the study was to investigate the effect of feeding different diets on fermentation, enzyme activities and microbial population in the rumen fluid of mithun (Bos frontalis). In a randomized block design, 20 male mithun (6-8 months of age, 152 ± 12.6 kg body weight) were randomly divided into four experimental groups (n = 5/group) and fed experimental diets ad libitum for 180 days. The diet R1 contained tree foliages (TF), R2 comprised of 50% concentrate mixture (CM) and 50% TF, R3 contained 50% CM and 50% rice straw, and R4 contained 50% CM, 25% TF and 25% rice straw. Rumen liquor was collected at 0 and 180 days of the experiment for estimation of different ruminal parameters and a digestion trial was conducted at the end of the experiment. Rumen fluid was analysed for pH, ammonia nitrogen (NH3 -N), total-N, ruminal enzymes, short chain fatty acid (SCFA) and microbial profile. The relative quantification of ruminal microbes was carried out with real-time PCR using bacteria as the house keeping gene. The dry matter intake, nutrients digestibility, body weight gain, NH3 -N, total-N, carboxymethyl cellulase, avicelase, xylanase, amylase, protease and molar proportion of butyrate were (p < 0.05) higher in mithun fed R2 , R3 and R4 compared to those fed R1 diet. In contrast, increased (p < 0.05) ruminal pH, molar proportion of acetate and, acetate to propionate ratio was recorded in mithun fed only TF than those fed concentrate supplemented diets. Similarly, an increase (p < 0.05) in the population of Fibrobacter succinogenes, Ruminococcus flavefaciens and total bacteria were evident in mithun fed R2 , R3 and R4 compared to those fed R1 . Therefore, it is concluded that TF 25% and/or rice straw 25% along with CM 50% may be fed to the growing mithun for improved rumen ecology, nutrient utilization and thus better performance under stall fed system.

METHANOGENESIS IN RABBIT CAECUM AS AFFECTED BY THE FERMENTATION PATTERN: IN VITRO AND IN VIVO MEASUREMENTS

Methane formation and caecal fermentation patterns were studied in vivo and in vitro in 16 white New Zealand rabbits (70-80 d and 2.27 ± 0.064 kg) allocated to four diets formulated to have a similar neutral detergent fibre (33.8±0.53%) and protein (17.7±0.33%) content, with two different fibre sources (alfalfa hay, AH or sugar beet pulp, SP) and starch (wheat or maize). Animals received the diet for 16 to 20 days before methane production was measured in vivo in a respiratory chamber. Animals were subsequently slaughtered at approximately 9:00 and caecal contents were sampled and used as inoculum for in vitro incubations to determine gas and methane production. Volatile fatty acid (VFA) and purine base (PB) concentrations were determined from both caecal content and incubation medium after 6 h. Total VFA concentration in caecal content decreased (P&lt;0.05) in rabbits fed AH-maize diet compared with rabbits fed AH-wheat and SP-maize diets (37.7 vs. 59.6 mM), with those fed SP-wheat showing an intermediate value (53.0 mM). Fermentation pattern was affected when maize was the source of starch compared to wheat, with lower acetate (0.72 vs. 0.79; P&lt;0.01) and higher butyrate (0.19 vs. 0.14; P&lt;0.001) molar proportions. Fermentation in vivo vs. in vitro showed some differences (molar proportions of acetate, 0.76 vs. 0.73, P&lt;0.001, and propionate, 0.069 vs. 0.091, P&lt;0.001, in vivo and in vitro, respectively), probably due to differences in pH (6.0 vs. 6.7 in vivo and in vitro; P&lt;0.001). Only 2 out of 16 rabbits produced a substantial volume of methane in vivo (on average, 12.6 ml/BW0.75/d or 0.56 mmol/BW0.75/d), showing a high inter-individual variability that hindered comparison of treatment differences. In contrast, methane was detected in vitro in all cases and volumes were more homogenous, a higher formation (P&lt;0.05) being observed with maize compared to wheat. A similar effect was shown in total gas production. The low methane production and H2 recovery suggest the importance of H2 disposal mechanisms other than methanogenesis, such as reductive acetogenesis. PB concentration in caecal content and the incubation medium, as an index of microbial concentration, was highest when SP was added with maize (P&lt;0.05).

Effects of the inclusion of dried molassed sugar beet pulp in a low-forage diet on the digestive process and blood biochemical parameters of Holstein steers

We evaluated the effects of substituting various concentrations of dried molassed sugar beet pulp (SBP) for barley grain in low-forage diets on chewing behavior, ruminal fermentation, nutrient digestibilities and blood biochemical parameters using four ruminally cannulated Holstein steers in a 4×4 Latin square design over 28-day periods. Steers (368±8kg initial body weight) were fed 9.5kg of dietary dry matter (DM) as a total mixed ration (TMR) (containing 350g forage and 650g concentrate per kg DM) twice daily at 0800 and 1600h. The diets were formulated to supply approximately 2.3 times the maintenance requirements of the animals so that there was no refusal. Barley grain in the basal experimental diet (330g/kg DM) was replaced with 0, 110, 220 and 330g SBP on a DM basis to create the experimental diets SBP0, SBP110, SBP220 and SBP330, respectively. Ruminal fluid was collected by suction through the rumen cannula from before the morning feeding (0.0h) to 8h after feeding at 30-min intervals. Eating, ruminating and total chewing time linearly (P<0.01) increased with the proportion of SBP in the diet. Moreover, mean ruminal pH showed linear and quadratic increases (P<0.05) with the inclusion of SBP. In contrast, the substitution of SBP for barley grain resulted in a linear and quadratic decrease (P<0.01) in the mean ruminal ammonia concentration, which was highest in steers fed SBP0. In addition inclusion of SBP gave significantly (P<0.05) higher acetate and butyrate molar proportions and lower propionate and total volatile fatty acids (VFA) concentrations in the rumen fluid. Total tract apparent digestibility of DM and neutral detergent fiber (NDF) increased quadratically with the proportion of SBP in the diet, but crude protein (CP) and acid detergent fiber (ADF) digestibilities were similar among treatments. Plasma urea nitrogen (PUN) before the morning feeding decreased linearly (P<0.01) with SBP inclusion and was highest and lowest for SBP0 and SBP330, respectively (21 vs. 16.26mg/dl). Other blood biochemical parameters and venous blood gasses (including plasma glucose, blood pH, CO2 pressure, O2 pressure, oxygen saturation, base excess of extracellular fluid, base excess of blood and bicarbonate) were not affected by the treatments (P>0.05). These results suggest that partial replacement of barley grain with SBP at low and moderate inclusion rates might improve the chewing behavior, ruminal environment and nutrient digestibility of Holstein steers fed low-forage diets.

Effects of supplementation of Bacillus subtilis natto Na and N1 strains on rumen development in dairy calves

Effects of Bacillus subtilis natto Na and N1 strains on ruminal development of papillae in dairy calves were investigated. Twenty four Holstein bull calves (7 ± 1.1 d) were randomly divided into three treatments of eight calves. The natto cultures Na and N1 were mixed with milk before weaning, or mixed with the concentrate portion of the diets after weaning. All calves were weaned when starter intake reach 20 g/kg of body weight. At weaning four calves were randomly selected from each group and slaughtered, and the remaining calves were fed the basal diet for additional 44 d and then slaughtered. Rumen fluid and ventral rumen tissue samples were collected from all calves. Results show that oral supplementation of B. subtilis natto Na or N1 reduced concentrations of short chain fatty acids in the rumen at weaning and 44 d after weaning (P<0.05). B. subtilis natto N1 reduced rumen pH and molar proportion of butyrate in both experimental periods (P<0.05), while B. subtilis natto Na decreased the molar proportion of acetate and ammonia levels at weaning (P<0.05) and depressed rumen NH3 concentration 44 d post weaning (P<0.05). The number and surface area of papillae per cm 2 rumen wall for Na and N1 groups tended to be higher than the control at weaning (P<0.10) and 44 d after weaning (P<0.01). Furthermore, rumen papillae were flattened and tongue-shaped without narrow stalks, clumping or parakeratosis in the calves treated with natto culture. This study demonstrates that oral administration of B. subtilis natto Na and N1 increased rate of rumen development in dairy calves.

Long‐term in vitro fermentation of high amylose starch digestion residues by human fecal inocula

A three‐week in vitro anaerobic human fecal incubation system was used to screen fermentability of resistant starch residues (SRV, SRVI, SRVII) after amylase digestion for short chain fatty acid (SCFA) production and shifts in bacterial composition. Fermentation capacity was compared between lean (18.5&lt;BMI&lt;25, n=15) and overweight (BMI&gt;25, n=15) subjects. All three SRs significantly increased gas production and decreased pH compared to blank (P&lt;0.05), with no difference among treatments. The molar proportions of butyrate were similar among three SRs at 45%, which was significantly higher than that of the blank (20%, P&lt;0.05), measured by GC. Higher propionate production was found from SRV compared to blank (P&lt;0.05), whereas there was no significant difference between blank and SRVI or SRVII in propionate production. No significant difference was found in the individual or total SCFA production between lean and overweight subjects. Bifidobacterium, Lachnospiraceae and Bacteroidaceae spp. were enriched by SRs, revealed by PCR‐DGGE. In conclusion, a stable in vitro fermentation system was established. All three SRs increased butyrate production, but SRV differed from SRVI and SRVII with higher propionate production. No significant difference in the fermentation capacity of SRs was seen between lean and overweight subjects. Supported by Plant Sciences Institute, ISU.

Intestinal tumours, colonic butyrate and sleep in exercised Min mice

There is strong epidemiological evidence that more physical activity is associated with reduced risk of colon cancer, but the amount or type of activity necessary to invoke this protection is disputed, and the mechanism that is responsible has not been elucidated. The present study compared the effects of two contrasting exercise regimens on intestinal tumourigenesis in Min mice, and investigated two novel mechanistic factors: colonic butyrate and sleep. From 5 weeks of age, Min mice were exercised by running on a treadmill (TR; < or = 21 m/min, 30-60 min/d, 5 d/week, < or = 12 weeks). Additional groups of mice were provided with an exercise wheel (WH) or no exercise (CON). Mice had free access to a Western-style, high-fat diet. WH mice ran 3.97 km (females) and 1.92 km (males) daily (P = 0.002). There were no differences in body weight gain or body composition between treatment groups. Treadmill running reduced the numbers of larger ( > or = 2 mm diameter) tumours (P = 0.042), and tended to reduce tumour multiplicity in the colon (P = 0.049). TR mice had a higher molar proportion of butyrate in colonic digesta than CON mice (P = 0.030), and when treatment groups were combined, there was a weak negative correlation (r - 0.174, P = 0.061) between butyrate molar proportion and total tumour number. In a subset of animals in which non-exercise physical activity was monitored, there were strong positive correlations between sleep duration and both tumour multiplicity (P < 0.001) and tumour burden (P = 0.001). More studies of the effects of sleep and of colonic butyrate in mediating the effects of physical activity on intestinal tumourigenesis are warranted.

Effect of a Ruminal Buffer and Exogenous Amylolytic Enzymes on Growth and Digestion in Lambs Fed High Concentrate Diets

Lee-Rangel, H.A., Pinos-Rodríguez, J.M., Mendoza, G.D., González, S.S., Monies, M.A., Trejo, A.S. and Jasso-Pineda, Y. 2010. Effect of a ruminal buffer and exogenous amylolytic enzymes on growth and digestion in lambs fed high concentrate diets. J. Appl. Anim. Res., 37: 117–120. To evaluate a ruminal buffer and exogenous amylolytic enzymes from Bacillus licheniformis and Aspergillus niger in high concentrate diet, lambs were fed on diet with no additives, or the same diet supplemented with enzymes (0.26% of diet as DM), buffer (1% of diet as DM) or enzymes + buffer in a growth assay. The supplemented diets did not affect intake, BW changes, feed conversion, rumen digestibility and total tract digestion of DM, organic matter (OM) and starch. Ruminal pH values, ammonia N, lactic acid concentrations and molar proportion of acetate and propionate were similar among treatments. Ruminal molar proportion of butyrate of lambs fed enzymes + buffer was lower than those fed control or buffer diets. Thus exogenous amylolytic enzymes did not have any positive effect on growth, rumen digestibility or total tract digestion in lambs.

Effect of Different Rumen-degradable Carbohydrates on Rumen Fermentation, Nitrogen Metabolism and actation Performance of Holstein Dairy Cows

Four multiparous lactating Holstein cows fitted with rumen cannulae were fed diets varying in the amount and source of rumen-degradable carbohydrates (starch vs. sucrose) to examine their effects on rumen fermentation, nitrogen metabolism and lactation performance. A 4x4 Latin square with four diets and four periods of 28 days each was employed. Corn starch and sucrose were added to diets and corn starch was replaced with sucrose at 0 (0 S), 2.5 (2.5 S), 5.0 (5.0 S) 7.5% (7.5 S) of diet dry matter in a total mixed ration (TMR) containing 60% concentrate and 40% forage (DM basis). Replacing corn starch with sucrose did not affect (p> 0.05) ruminal pH which averaged 6.41, but the ruminal pH for 7.5 S decreased more rapidly at 2 h after morning feeding compared with other treatments. Sucrose reduced (p≤0.05) ruminal NH 3 -N concentration (13.90 vs. 17.09 mg/dl) but did not affect peptide-N concentration. There was no dietary effect on total volatile fatty acids (110.53 rnmol/L) or the acetate to propionate ratio (2.72). No differences (p>0.05) in molar proportion of most of the individual VFA were found among diets, except for the molar proportion of butyrate that was increased (p≤0.05) with the inclusion of sucrose. Total branched chain volatile fatty acids tended to increase (p≥0.051) for the control treatment (0 S) compared with the 7.5 S treatment. Dry matter intake, body weight changes and digestibility of DM, OM, CP, NDF and ADF were not affected by treatments. Sucrose inclusion in the total mixed ration did not affect milk yield, but increased milk fat and total solid percentage (p≤0.05). Sucrose tended (p≥0.063) to increase milk protein percentage (3.28 vs. 3.05) and reduced (p≤0.05) milk urea nitrogen concentration (12.75 vs. 15.48 mg/dl), suggesting a more efficient utilization of the rapidly available nitrogen components in the diet and hence improving nitrogen metabolism in the rumen.

Whole citrus fruits as an alternative to wheat grain or citrus pulp in sheep diet: Effect on the evolution of ruminal parameters

Five ruminally fistulated Manchega ewes were fed twice daily (0900 and 1500 h) with five experimental diets in a 5 × 5 Latin square design to determine the effect of the diets on ruminal parameters. The diets were control based on wheat grain (0WCF), three diets in which whole citrus fruits (WCF) replaced wheat grain at 13% (13WCF), 26% (26WCF) and 39% (39WCF), and one diet with 26% of citrus pulp (26CP) replacing wheat grain. After 10 days of adaptation, the rumen pH, volatile fatty acids (VFA) and NH 3-N of the experimental animal were measured at 0, 2, 4, 6, 8, 10 and 12 h after the first feeding. The 39WCF diet ingestion was significantly lower than that of the other four diets. Ruminal pH increased linearly with the inclusion of WCF (+0.05 per 10%), although it was similar 2 h after meals, while VFA concentration decreased (−2.31 mmol/l per 10%), especially 4 h after the meals. Ruminal NH 3-N concentration decreased with the inclusion of WCF (−0.61 mmol/l per 10%), especially during the first 5 h as of the first meal. The acetate proportion increased from 0.61 to 0.66 mmol/mmol, while propionate proportion reduced from 0.20 to 0.18 mmol/mol when dietary WCF was increased from 0% to 39%. Also acetate:propionate ratio increased linearly from 3.2 to 4.1, while butyrate proportion decreased linearly from 0.15 to 0.11 mmol/mmol. The concentration of i-butyrate and i-valerate also decreased while that of valerate and caproate increased. Main ruminal parameters for 26WCF and 26CP diets were similar. However, ruminal concentrations of NH 3-N and molar proportion of butyrate and caproate were significantly lower when the animals received the 26CP diet (−1.1, −0.021 and −0.003 mmol/l, respectively). Highly degradable citrus carbohydrates could be used as an alternative to cereal starch to cover the energy requirements of ewes, and did not seem to suppose a risk, as even a higher ruminal pH was maintained throughout the day. The fermentative behaviour of WCF was similar to that of CP, although higher butyrate and NH 3-N production was observed.

Dose–response effects of chitosans on in vitro rumen digestion and fermentation of mixtures differing in forage-to-concentrate ratios

The in vitro gas production technique was used to study the dose–response effects of three chitosans on rumen fermentation of three mixtures differing in their forage-to-concentrate ratio (80:20, 50:50 and 20:80). Four concentrations (0, 325, 750 and 1500 mg/l of culture fluid) for each chitosan (CHI1, CHI2, and CHI3) were incubated for 24 h in diluted ruminal fluid with three different mixtures. Samples were collected to determine pH, volatile fatty acid (VFA) and ammonia–N concentrations. Methane concentration was estimated stoichiometrically, and in vitro true organic matter digestibility (IVOMD) was calculated. In the high-forage mixture, no differences were found between additives except for propionate molar proportion, for which CHI1 showed a lower proportion than CHI2 or CHI3. Increasing doses of chitosans did not affect total VFA or acetate molar proportions, but decreased IVOMD as well as butyrate and branch-chained volatile fatty acid (BCVFA) molar proportions, and increased propionate molar proportion as well as ratios of C3:C2 and VFA to truly degraded substrate (VFA:TDS). In the medium-forage mixture, no differences were found between additives. Increasing doses of chitosan did not affect total VFA or acetate molar proportions or methane production compared to control, but decreased IVOMD as well as butyrate and BCVFA molar proportions, and increased propionate molar proportion as well as C3:C2 and VFA:TDS ratios. In the low-forage mixture, increasing doses did not reduce total VFA, but decreased IVOMD, acetate, butyrate, and BCVFA molar proportions and methane production, and increased propionate molar proportion as well as C3:C2 and total VFA:TDS ratios compared to control. No differences were found between additives in IVOMD or butyrate molar proportion, but differences were found in acetate molar proportion, with CHI1 showing a higher proportion than CHI2 or CHI3. Differences between additives were also found for propionate molar proportion, C3:C2 ratio, and methane production, and an additive × dose effect was found, with CHI1 showing a weaker response than CHI2 or CHI3 at all tested doses. Differences were found between additives for BCVFA molar proportion, with CHI1 and CHI2 showing greater production than CHI3, and for VFA:TDS ratio, with CHI1 showing a higher ratio than CHI2 or CHI3. These results indicate that chitosans affect rumen microbial fermentation in a dose-dependent manner and that the optimum dose depends on the nature of the incubated substrate and the chitosan's characteristics.

Effect of Dietary Starch or Micro Algae Supplementation on Rumen Fermentation and Milk Fatty Acid Composition of Dairy Cows

Two experiments with rumen-fistulated dairy cows were conducted to evaluate the effects of feeding docosahexaenoic acid (DHA; C22:6 n-3)-enriched diets or diets provoking a decreased rumen pH on milk fatty acid composition. In the first experiment, dietary treatments were tested during 21-d experimental periods in a 4×4 Latin square design. Diets included a control diet, a starch-rich diet, a bicarbonate-buffered starch-rich diet, and a diet supplemented with DHA-enriched micro algae [Schizochytrium sp., 43.0g/kg of dry matter intake (DMI)]. Algae were supplemented directly through the rumen fistula. The total mixed ration consisted of grass silage, corn silage, soybean meal, and a standard or glucogenic concentrate. The glucogenic and buffered glucogenic diet had no effect on rumen fermentation and milk fatty acid composition because, unexpectedly, no reduced rumen pH was detected. The algae diet had no effect on rumen pH but provoked decreased butyrate and increased isovalerate molar proportions in the rumen. In addition, algae supplementation affected rumen biohydrogenation of linoleic and linolenic acid as reflected in the modified milk fatty acid composition toward increased conjugated linoleic acid (CLA) cis-9 trans-11, CLA trans-9 cis-11, C18:1 trans-10, C18:1 trans-11, and C22:6 n-3 concentrations. Concomitantly, on average, a 45% decrease in DMI and milk yield was observed. Based on these drastic and impractical results, a second animal experiment was performed for 20 d in which 9.35g/kg of total DMI of algae were incorporated in the concentrate and supplemented to 3 rumen-fistulated cows. Algae concentrate feeding increased rumen pH, which was associated with decreased rumen short-chain fatty acid concentrations. Moreover, a different shift in rumen short-chain fatty acid proportions was observed compared with the first experiment because molar proportions of butyrate, isobutyrate, and isovalerate increased, whereas acetate molar proportion decreased. The milk fatty acid profile changed as in experiment 1. However, the decrease in DMI and milk yield was less pronounced (on average 10%) at this algae supplementation level, whereas milk fat percentage decreased from 47.9 to 22.0g/kg of milk after algae treatment. In conclusion, an algae supplementation level of about 10g/kg of DMI proved effective to reduce the milk fat content and to modify the milk fatty acid composition toward increased CLA cis-9 trans-11, C18:1 trans, and DHA concentrations.