Liquid Digesta Research Articles

Examination of the molecular control of ruminal epithelial function in response to dietary restriction and subsequent compensatory growth in cattle.

BackgroundThe objective of this study was to investigate the effect of dietary restriction and subsequent compensatory growth on the relative expression of genes involved in volatile fatty acid transport, metabolism and cell proliferation in ruminal epithelial tissue of beef cattle. Sixty Holstein Friesian bulls (mean liveweight 370 ± 35 kg; mean age 479 ± 15 d) were assigned to one of two groups: (i) restricted feed allowance (RES; n = 30) for 125 d (Period 1) followed by ad libitum access to feed for 55 d (Period 2) or (ii) ad libitum access to feed throughout (ADLIB; n = 30). Target growth rate for RES was 0.6 kg/d during Period 1. At the end of each dietary period, 15 animals from each treatment group were slaughtered and ruminal epithelial tissue and liquid digesta harvested from the ventral sac of the rumen. Real-time qPCR was used to quantify mRNA transcripts of 26 genes associated with ruminal epithelial function. Volatile fatty acid analysis of rumen fluid from individual animals was conducted using gas chromatography.ResultsDiet × period interactions were evident for genes involved in ketogenesis (BDH2, P = 0.017), pyruvate metabolism (LDHa, P = 0.048; PDHA1, P = 0.015) and cellular transport and structure (DSG1, P = 0.019; CACT, P = 0.027). Ruminal concentrations of propionic acid (P = 0.018) and n-valeric acid (P = 0.029) were lower in RES animals, compared with ADLIB, throughout the experiment. There was also a strong tendency (P = 0.064) toward a diet × period interaction for n-butyric with higher concentrations in RES animals, compared with ADLIB, during Period 1.ConclusionsThese data suggest that following nutrient restriction, the structural integrity of the rumen wall is compromised and there is upregulation of genes involved in the production of ketone bodies and breakdown of pyruvate for cellular energy. These results provide an insight into the potential molecular mechanisms regulating ruminal epithelial absorptive metabolism and growth following nutrient restriction and subsequent compensatory growth.

Effects of Partial Replacement of Corn with Glycerin on Ruminal Fermentation in a Dual-Flow Continuous Culture System.

The objective of this study was to evaluate the effects of partially replacing dry ground corn with glycerin on ruminal fermentation using a dual-flow continuous culture system. Six fermenters (1,223 ± 21 ml) were used in a replicated 3x3 Latin square arrangement with three periods of 10 d each, with 7 d for diet adaptation and 3 d for sample collections. All diets contained 75% concentrate and three dietary glycerin levels (0, 15, and 30% on dry matter basis), totaling six replicates per treatment. Fermenters were fed 72 g of dry matter/d equally divided in two meals/d, at 0800 and 2000 h. Solid and liquid dilution rates were adjusted daily to 5.5 and 11%/h, respectively. On d 8, 9, and 10, samples of 500 ml of solid and liquid digesta effluent were mixed, homogenized, and stored at -20°C. Subsamples of 10 ml were collected and preserved with 0.2 mL of a 50% H2SO4 solution for later determination of NH3-N and volatile fatty acids. Microbial biomass was isolated from fermenters for chemical analysis at the end of each experimental period. Data were analyzed using the MIXED procedure in SAS with α = 0.05. Glycerin levels did not affect apparent digestibility of DM (P Lin. = 0.13; P Quad. = 0.40), OM (P Lin. = 0.72; P Quad. = 0.15), NDF (P Lin. = 0.38; P Quad. = 0.50) and ADF (P Lin. = 0.91; P Quad. = 0.18). Also, glycerin inclusion did not affect true digestibility of DM (P Lin. = 0.35; P Quad. = 0.48), and OM (P Lin. = 0.08; P Quad. = 0.19). Concentrations of propionate (P < 0.01) and total volatile fatty acids (P < 0.01) increased linearly and concentrations of acetate (P < 0.01), butyrate (P = 0.01), iso-valerate (P < 0.01), and total branched-chain volatile fatty acids, as well as the acetate: propionate ratio (P < 0.01) decreased with glycerin inclusion. Linear increases on NH3-N concentration in digesta effluent (P < 0.01) and on NH3-N flow (P < 0.01) were observed due to glycerin inclusion in the diets. Crude protein digestibility (P = 0.04) and microbial N flow (P = 0.04) were greater in the control treatment compared with the other treatments and responded quadratically with glycerin inclusion. Furthermore, the inclusion of glycerin linearly decreased (P = 0.02) non-ammonia N flow. Glycerin levels did not affect the flows of total N (P Lin. = 0.79; P Quad. = 0.35), and dietary N (P Lin. = 0.99; P Quad. = 0.07), as well as microbial efficiency (P Lin. = 0.09; P Quad. = 0.07). These results suggest that partially replacing dry ground corn with glycerin may change ruminal fermentation, by increasing total volatile fatty acids, and propionate concentration without affecting microbial efficiency, which may improve glucogenic potential of beef cattle diets.

Effects of duration of moderate increases in grain feeding on endotoxins in the digestive tract and acute phase proteins in peripheral blood of yearling calves

Effects of duration of grain feeding on the concentration of endotoxic lipopolysaccharide (LPS) in digesta throughout the digestive tract and on acute phase proteins and LPS in peripheral blood were determined in Holstein yearling calves. Twenty-five Holstein yearling steer calves received either a forage-based diet containing 92% hay and 8% of a mineral and vitamin pellet on a dry matter basis (CON) or a moderate-grain diet, obtained by replacing 41.5% of the hay in the forage-based diet with barley grain, for 3 (MG3), 7 (MG7), 14 (MG14), or 21 d (MG21) before slaughter. Immediately before slaughter, blood samples were collected from the jugular vein. Immediately after slaughter, digesta samples were collected from the rumen, jejunum, ileum, cecum, colon, and rectum. Rumen liquid digesta, digesta from the intestines, and peripheral blood plasma were analyzed for LPS. Peripheral blood plasma and serum were analyzed for the acute phase proteins amyloid A, haptoglobin, and LPS-binding protein. Feeding the grain diet increased the LPS concentration in rumen fluid linearly from 15,488 endotoxin units (EU)/mL for CON to 70,146 EU/mL for MG7. Concentrations of LPS in rumen fluid in MG14 and MG21 were 61,944 and 56,234 EU/mL, respectively, and did not differ. The LPS concentrations in jejunal digesta were much lower than that in digesta elsewhere in the digestive tract, which suggests that ruminal LPS is broken down in the abomasum or proximal jejunum. The concentration of digesta LPS in the ileum was higher than that of digesta elsewhere in the intestines and similar to that in rumen fluid. The duration of grain feeding increased the LPS concentration in digesta in the ileum and cecum and tended to increase that in the colon cubically. Concentrations of LPS in this part of the digestive tract were highest in the MG3 and MG21 groups. The highest concentrations of LPS in digesta in the cecum, colon, and rectum were 3.7, 3.8, and 5.6 times higher than that in CON, respectively. Grain feeding and the increase in LPS in digesta were not accompanied by an acute phase response or a detectable concentration of LPS in peripheral blood. The absence of LPS in peripheral blood and the lack of increase in acute phase proteins indicated that the grain feeding protocol used in the current study and the accompanying changes in LPS concentrations of the digesta did not result in systemic inflammation.

Effects of grinding intensity and pelleting of the diet – fed either dry or liquid – on intragastric milieu, gastric lesions and performance of swine

The risk of pigs developing gastric ulcers is higher when fed finely ground and pelleted diets, the supposed mechanism being the liquid gastric digesta – resulting in a consistent pH level in all areas of the stomach. In order to better understand the mechanisms involved in the higher incidence of impaired epithelium of pars nonglandularis (PN) after intake of finely ground and pelleted diets, the present study aimed at generating detailed information regarding the local intragastric milieu in pigs. In addition, the effects of the water content of the offered diet on dry matter (DM), pH, buffering capacity (BC) and chloride (Cl) content of gastric digesta of pigs were investigated as several studies had implied that a liquid gastric digesta is a major risk factor for the development of gastric ulcers in pigs. Both diets (coarsely ground fed as meal (CM) vs. finely ground, pelleted (FP)) were identical in botanical and chemical composition and were either offered dry or in liquid form (250g DM/kg) ad libitum to 24 piglets. Weight gain and gain:feed ratio were not affected by the grinding intensity of the diet (P>0.05). However, a higher daily feed intake (P=0.015) and weight gain were observed in pigs fed liquid diets (P=0.009). After six weeks the animals were slaughtered and samples of gastric digesta were taken from different areas (pars nonglandularis, fundus, cardia and pylorus). The moisture content of the diet did not influence the pH (P≥0.1), whereas the structure of the diet (particle size and form of compaction) had a significant effect on the pH in the fundic area (P≤0.001). The FP diet caused a more liquid digesta (P≤0.05) in most areas and very homogenous pH values within the gastric digesta of different regions. In contrast, CM resulted in marked differences in the pH (P<0.05) in different areas with the highest values at PN and the lowest values at the fundus. None of the pigs fed CM showed gastric ulcers while the score of macroscopical evaluation of the epithelium at the PN was higher in pigs fed FP (P≤0.001) regardless of whether diets were fed dry or liquid. The BC at the PN was lower (P≤0.001) while Cl content at PN was higher (P≤0.001) in pigs fed FP. Particle size distribution of the diet seemed to be the predominant factor for intragastric milieu, while the moisture content of the offered diet had no effect (P>0.05) on observed parameters.

Characterization of the core rumen microbiome in cattle during transition from forage to concentrate as well as during and after an acidotic challenge.

This study investigated the effect of diet and host on the rumen bacterial microbiome and the impact of an acidotic challenge on its composition. Using parallel pyrosequencing of the V3 hypervariable region of 16S rRNA gene, solid and liquid associated bacterial communities of 8 heifers were profiled. Heifers were exclusively fed forage, before being transitioned to a concentrate diet, subjected to an acidotic challenge and allowed to recover. Samples of rumen digesta were collected when heifers were fed forage, mixed forage, high grain, during challenge (4 h and 12 h) and recovery. A total of 560,994 high-quality bacterial sequences were obtained from the solid and liquid digesta. Using cluster analysis, prominent bacterial populations differed (P≤0.10) in solid and liquid fractions between forage and grain diets. Differences among hosts and diets were not revealed by DGGE, but real time qPCR showed that several bacteria taxon were impacted by changes in diet, with the exception of Streptococcus bovis. Analysis of the core rumen microbiome identified 32 OTU's representing 10 distinct bacterial taxa including Bacteroidetes (32.8%), Firmicutes (43.2%) and Proteobacteria (14.3%). Diversity of OTUs was highest with forage with 38 unique OTUs identified as compared to only 11 with the high grain diet. Comparison of the microbial profiles of clincial vs. subclinical acidotic heifers found a increases in the relative abundances of Acetitomaculum, Lactobacillus, Prevotella, and Streptococcus. Increases in Streptococcus and Lactobacillus likely reflect the tolerance of these species to low pH and their ability to proliferate on surplus fermentable carbohydrate. The acetogen, Acetitomaculum may thereforeplay a role in the conversion of lactate to acetate in acidotic animals. Further profiling of the bacterial populations associated with subclinical and clinical acidosis could establish a microbial fingerprint for these disorders and provide insight into whether there are causative microbial populations that could potentially be therapeutically manipulated.

Low-methane yield sheep have smaller rumens and shorter rumen retention time

In the present study, following the measurement of methane emissions from 160 mature ewes three times, a subset of twenty ewes was selected for further emission and physiological studies. Ewes were selected on the basis of methane yield (MY; g CH4/kg DM intake) being low (Low MY: >1 sd below the mean; n 10) or high (High MY: >1 sd above the mean; n 10) when fed a blended chaff ration at a fixed feeding level (1·2-fold maintenance energy requirements). The difference between the Low- and High-MY groups observed at the time of selection was maintained (P= 0·001) when remeasured 1-7 months later during digesta kinetics studies. Low MY was associated with a shorter mean retention time of particulate (P< 0·01) and liquid (P< 0·001) digesta, less amounts of rumen particulate contents (P< 0·01) and a smaller rumen volume (P< 0·05), but not apparent DM digestibility (P= 0·27) or urinary allantoin excretion (P= 0·89). Computer tomography scanning of the sheep's rumens after an overnight fast revealed a trend towards the Low-MY sheep having more clearly demarcated rumen gas and liquid phases (P= 0·10). These findings indicate that the selection of ruminants for low MY may have important consequences for an animal's nutritional physiology.

Mucosal microfolds augment mixing at the wall of the distal ileum of the brushtail possum

Recent work suggests that mixing in the small intestine takes place in central luminal and peripheral compartments. However, while movements of villi have been described, the mechanisms by which peripheral mixing are engendered remain unclear. We examined the disposition and movement of mucosa and associated villi during contractions of the everted terminal ileum of the brushtail possum. We then simulated the effect of these movements on peripheral mixing. Compression of the intestinal mucosa by phasic longitudinal or radial contractions created short-lived microfolds, which were of similar scale to the attached villi. The packing density of the villous tips increased in the concavities and decreased on the crests of these microfolds. Simulations showed that these caused liquid digesta to be expelled from, or drawn into, intervillous spaces, significantly augmenting peripheral, but not bulk, luminal mixing. We describe a mechanism by which peripheral mixing may be engendered by mucosal microfolds without requiring the coordinated contraction of individual villi or groups of villi.

Effect of D‐mannitol on nitrogen retention, fiber digestibility and digesta transit time in adult rabbits

The aim of the current study was to elucidate the effect of gastrointestinal retention time of digesta on fiber digestibility in adult rabbits fed indigestible, but fermentable, sugar D-mannitol. Six adult rabbits were fed alternately a commercial diet containing 5% glucose and a diet containing D-mannitol. Total feces and urine were collected during the experimental period. Nitrogen (N) balance, digestibility of nutrients, and gastrointestinal mean retention time (MRT) were measured. The results indicated that urinary excretion was significantly lowered, whereas N retention and N accumulation rates were significantly increased in the D-mannitol group compared with the glucose group (P < 0.05). However, fecal N excretion was unaffected. Absorption of crude ash (CA) and acid detergent fiber (ADF) digestibility were significantly higher in the D-mannitol group compared with the glucose group (P < 0.05). The addition of D-mannitol to the diet did not affect the MRT of liquid digesta, but increased the MRT of solid digesta compared with the glucose group (P < 0.05). These results suggest that the addition of D-mannitol to the diet stimulates cecal bacterial growth, thereby increasing N utilization and digesta retention time.

Determination and comparison of digestion kinetics of two fibre sources in geese (Anseris)

The aim of this study was to determine and compare the digestion kinetics of two fibre sources (lucerne, maize stalk) in different segments of the digestive tract of geese. Sixty Jilin nongan white geese were divided into two groups and fed with a lucerne or maize stalk diet. After 30 days of feeding, all of the geese were fed with Co-EDTA as the marker of liquid digesta, and n-alkane was used as an internal marker. At 1.0 h, 2.0 h, 3.0 h, 4.0 h and 5.0 h after Co-EDTA was fed, five geese per treatment per time period were sacrificed by cervical dislocation. Content of the glandular stomach, gizzard, duodenum, jejunum, ileum, caecum and rectum were collected for the evaluation of the parameters of digestion kinetics. The results showed that digestion kinetics of fibre in geese fed with a lucerne diet is consistent with that of a maize stalk diet. Within the digestive tract, digesta flow was the highest in the jejunum, and the slowest in the gizzard. Mean retention time of the digesta was the longest in the gizzard and duodenum. The digestibility of NDF, ADF and HC was the highest in duodenum, gizzard and duodenum and caecum respectively. Collectively, these findings suggest that the gizzard and duodenum might play important roles in the digestion of crude fibre in geese. Keywords: Goose, fibre, lucerne, maize stalk, digestion flow markers, n-alkanes, Co-EDTA

Digestion in the common marmoset (Callithrix jacchus), a gummivore–frugivore

Wild common marmosets (Callithrix jacchus) feed on fruits, insects, and gums, all of which provide different digestive challenges. Much of the ingested mass of fruits consists of seeds. In general, seeds represent indigestible bulk to marmosets and could inhibit feeding if they are not eliminated rapidly. In contrast, gums are beta-linked polysaccharides that require microbial fermentation. Their digestion would benefit from an extended residence time within the gut. Earlier research found that mean retention time (MRT) for a liquid digestive marker (cobalt EDTA) was significantly longer than MRT for a particulate marker (chromium-mordanted fiber), suggesting that common marmosets preferentially retain liquid digesta. We conducted two four-day-long digestion trials on 13 individually housed adult common marmosets fed a single-item, purified diet in order to examine the relations among MRT of cobalt EDTA and chromium-mordanted fiber, food dry matter intake (DMI), and apparent digestibility of dry matter (ADDM). We compared the MRT values with the data from the previous study mentioned above and a study using polystyrene beads. There were no significant correlations among MRT, ADDM, or DMI, although increases in DMI between trials were associated with decreases in MRT. ADDM was consistent within individuals between trials; but the mean values ranged from 75.0 to 83.4% among individuals. We found no difference in MRT between the liquid (17.5 + or - 1.6 hr) and particulate (17.9 + or - 1.4 hr) markers. Although these values were not significantly different than found previously, the MRT for chromium-mordanted fiber tended to be longer. This probably reflects the relatively small size of the chromium-mordanted fiber particles used in this study. An inverse relationship between particle size and MRT was evident; the mean MRT of polysterene beads, the largest marker, was only 8.3 + or - 1.5 hr. Marmosets appear to retain liquids and small particles within the gut longer than large particles.

Development of a Dynamic System Simulating Pig Gastric Digestion

The objective of this study was to develop a model for simulating gastric digestion in the pig. The model was constructed to include the chemical and physical changes associated with gastric digestion such as enzyme release, digestion product removal and gastric emptying. Digesta was collected from the stomach cannula of pigs to establish system parameters and to document the ability of the model to simulate gastric digestion. The results showed that the average pH of gastric digesta increased significantly from 2.47 to 4.97 after feed consumption and then decreased 140 min postprandial. The model described the decrease in pH within the pigs' stomach as pH t = 5.182e -0.0014t , where t represents the postprandial time in minutes. The cumulative distribution function of liquid digesta was V t = 64.509e 0.0109t . The average pepsin activity in the liquid digesta was 317Anson units/mL. There was significant gastric emptying 220 min after feed consumption. The cybernetic dynamic system of gastric digestion was set according to the above data in order to compare with in vivo changes. The time course of crude protein digestion predicted by the model was highly correlated with observed in vivo digestion (r = 0.97; p = 0.0001), Model prediction for protein digestion was higher than that observed for a traditional static in vitro method (r = 0.89; p = 0.0001).

The nutritive value of forage sorghum genotypes developed for the dry tropical highlands of Kenya as feed source for ruminants

In vitro studies were conducted on five sorghum genotypes developed for the dry tropical highland climate of Kenya and which can be fed to ruminants fresh or as silage. The five sorghum genotypes consisted of two normal white mid-rib (WMR) genotypes, coded E1291 and E6518l, and three brown-midrib (BMR) genotypes, coded Lan-5, Lan-6 and Lan-12. Whole mature plants (herbage plus grain) and silage made from E1291 were used in the study. An in vitro manual gas production technique was used to compare the nutritive characteristics of these genotypes for ruminants. These sorghums differed significantly in true organic matter degraded (OMDeg), which ranged from 520 to 678 g/kg after 24 h incubation and 706 to 805 g/kg after 72 h incubation. All the BMR sorghums had a higher degradability than the WMR genotype, E6518, and the silage, with Lan-5 having the highest degradability. Methane produced per g OMDeg ranged from 40.6 to 46.4 mL/g after 24 h incubation and from 53.1 to 62.6 mL/g after 72 h incubation. It was similar for all genotypes after 24 h incubation but Lan-12 had the highest methane production after 72 h incubation. After 24 h and 72 h incubation all the genotypes produced a similar total amount of gas per OMDeg (293 to 309 and 357 to 385 mL/g, respectively) with similar total short chain fatty acid concentrations in the liquid digesta (7.8 to 10.4 and 9.5 to 10.3 mmol, respectively) and acetate to propionate ratios of 2.16 to 2.49 and 2.35 to 2.87, respectively. The sorghums showed great potential as ruminant feed sources in the region.

PCR-DGGE analysis reveals a distinct diversity in the bacterial population attached to the rumen epithelium

Bacteria attached to the rumen epithelium (or epimural community) are not well characterised and their role in rumen functioning is not totally understood. There is just one published report of a clone library from one cow that suggests that this epimural community differs from the bacteria associated with the rumen digestive contents. However, this time-consuming approach is not adapted for examining microbial population changes in groups of animals. In in vivo studies, when samples from several animals have to be analysed simultaneously, a simpler technique has to be used. In this study, a genetic fingerprinting technique, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), was used to characterise the structure of the bacterial population attached to the rumen epithelium. This community was compared with that present in the solid and liquid phases of rumen content under two contrasting diets. Rumen samples were obtained from four forage-fed and four high-concentrate-fed (80 : 20, wheat grain : hay) 5-month-old lambs. After slaughter, samples from five epithelial sites and the solid and liquid digesta phases were taken for DNA extraction and analysis. Bacterial communities were profiled by PCR-DGGE using bacterial-specific 16S rDNA primers. Analysis of the fingerprint revealed that the epithelial community differed from those of rumen content in both diets. As expected, the nature of the feed influenced the bacterial communities from the solid and liquid rumen phases but no diet effect was observed in the rumen epithelial profiles suggesting a strong host effect on this bacterial population. Additionally, no differences were observed among the five epithelial sampling sites taken from each animal. The profile of the bacterial population attached to the rumen epithelium presented a high inter-animal variation, whether this difference has an influence in the function of this community remains to be determined.

Comparison of purines and nitrogen-15 as microbial flow markers in beef heifers fed barley- or corn-based diets

The objective of this study was to estimate the contribution of microbial purine bases to duodenal purines and to purine derivatives [allantoin and uric acid (PD)] excreted in the urine. Additionally, microbial protein (MCP) flow estimated using duodenal flow of purine bases was compared to estimates using 15N as a microbial marker. Four beef heifers were fed two diets, barley silage/barley grain/soybean meal (diet B) or corn silage/corn grain/corn gluten meal (diet C), in a cross-over design study. (15NH4)2SO4 was infused in the rumen for 8 d to label ruminal microorganisms and their purine bases. Rumen contents, duodenal digesta, urine, and feces were sampled during the last 2 d of tracer infusion and for 48 h after the infusion ceased. The animals consumed more (P &lt; 0.01) dry matter (DM), organic matter (OM), N, and neutral detergent fiber (NDF) with diet B than with diet C. Total tract digestibilities of DM, OM, and NDF were also higher (P &lt; 0.01) with diet B. Ruminal ammonia (P &lt; 0.01), volatile fatty acids (P &lt; 0.05), and acetate (P &lt; 0.01) concentrations and xylanase activity (P &lt; 0.05) were higher with diet B compared with diet C. Flow of MCP to the duodenum was estimated from duodenal samples using purines or 15N as microbial markers, or from urinary PD excretion. The effects of diet or method of measurement on MCP flow were not significant. However, when the urinary PD method was excluded from the analysis, MCP flow was greater (by 26%; P = 0.01) when estimated using 15N vs. the purine-based method. The difference was mainly due to underestimation of the proportion of microbial N in the liquid duodenal digesta with the purine method. Feed purines contributed from 3.5 (liquid digesta phase) to 19.7% (solid digesta phase) of the total purine flow at the duodenum. 15N enrichment of urinary PD was 1.08 of the enrichment of duodenal purines, suggesting that feed purines contributed little N to urinary allantoin and uric acid in cattle. Key words: Allantoin, cattle, microbial protein synthesis, nitrogen-15, purine derivative

Effect of a cell preparation ofEnterococcus faecalisstrain EC-12 on digesta flow and recovery from constipation in a pig model and human subjects

The effects of a cell preparation of Enterococcus faecalis strain EC-12 (EC-12) on the digesta flow in a pig model and its oral administration to humans were examined for its effect on frequency of defecation and faecal consistency. Latin square model was used in the pig study. Three sows fistulated at the caecum were fed a diet supplemented with either EC-12 or yeast cell wall (10 mg/kg body weight per day) for 9 days. An untreated control (C) was also obtained. Four markers (two were liquid and others solid markers) were used to determine the transit time of the liquid and solid phases of digesta in the gastrointestinal tract. The use of a dual marker system was for the better understanding of the digesta kinetics. YbCl3 and Co-EDTA were given with a morning meal, and CeCl3 and Eu-EDTA were given with a night meal on day 8. Caecal digesta were sampled every 2 h for 48 h after morning dosing. The total bioavailabilities of the liquid markers were lower in the EC-12 group than in the C group (Co-EDTA, 72%; Eu-EDTA, 63%). The relative concentrations of chloride to the liquid markers were higher in the EC-12 group than in other groups. Eleven volunteers ingested EC-12 (600 mg/day) for 30 days. EC-12 administration increased the frequency of defecation on day 30 in comparison with day 0. EC-12 stimulates the inflammatory reactions that relate ion and water secretion from the intestine. Accordingly, EC-12 may aid in the recovery from constipation through an acceleration of the liquid digesta flow in the large intestine. Key words: acceleration of liquid digesta flow, cell wall preparation, chloride secretion, constipation, Enterococcus faecalis strain EC-12, frequency of defecation, transit time in the pig caecum

Digesta passage and fiber digestibility in captive white-faced sakis (Pithecia pithecia).

Wild white-faced sakis (Pithecia pithecia) ingest primarily seeds that provide a diet that is lipid-rich and moderately high in dietary fiber. Although little anatomical information is available on sakis, evidence from other vertebrate seed predators suggests that such a diet is correlated with adaptations in gut morphology or physiology. Milton [1984] reported a 20 hr transit time (TT=transit time or time of first appearance in feces) of a particulate marker for a single monk saki (Pithecia monachus). This suggests that TT for Pithecia sakis may be four to five times longer than what has been reported for soft-fruit-eating platyrrhines, such as Ateles and Cebus. During a captive study, we calculated an average TT of 14.7+/-0.4 hr (n=5 trials started in the evening) for a chromic oxide (Cr(2)O(3)) marker that follows liquid digesta and TTs of 14.5 hr (trial started the previous evening) and 23.0 hr (trial started the previous morning) for two trials using particulate markers. Mean retention time (MRT) for the liquid marker ranged from 15.3 hr to 37.7 hr in four trials that lasted longer than 90 hr. Marker recovery was incomplete for the particulate markers in these trials, and thus MRT could only be determined for the liquid phase marker. Three 5-day trials on a low-fiber, blended diet revealed high fiber fraction digestibilities (neutral detergent fiber (NDF)=77.4% and acid detergent fiber (ADF)=74.4%). Data collected for this study and nutritional data from wild sakis suggest that pitheciin seed predators may have a potential for fiber digestibility that is intermediate between ripe-pulp frugivores and folivores.

Impact of diets varying in dietary fibre characteristics on gastric emptying in pregnant sows

The effects of feeding two fibre‐rich diets with contrasting solubility and a concentrated low dietary fibre on the rate of gastric emptying were examined in six gastric cannulated pregnant sows. Additionally, it was examined whether any effect could be related to the physico‐chemical properties of digesta, i.e. viscosity and/or water binding capacity. The sows were fed each diet for one week in a 3 x 3 Latin Square design and the samples were taken in a randomised order 0.5, 1, 2, 3, 5 and 15.5 h after the morning meal. The stomach contents were evacuated through the gastric cannula once daily. The evacuated gastric digesta was quantified and a representative sample was taken to determine its viscosity, water binding capacity and its content of dry matter, dietary components and solid (Cr2O3) and liquid (polyethylene glycol) phase markers. The flow of liquid digesta was calculated as the difference between digesta and dry matter. Increasing the content of dietary fibre in the diet led to higher recovery of liquid digesta but did not have any significant effect on the gastric emptying of dry matter and dietary components. The effect of dietary fibre could not be attributed to the viscosity of the liquid phase of digesta but might be related to the ability of the increased gastric dietary fibre content to hold water. The stomach selectively retained the insoluble dietary fibre components most noticeably seen with the bran‐supplemented diet where the concentration of insoluble NSP in digesta increased significantly from 2 hours and onward.

Dietary effects on the microbiological safety of food.

The high mortality rate associated with human infections caused by Escherichia coli strains of the serotype O157:H7 has brought to public attention the importance of ruminants as reservoirs of food-borne pathogens. In addition to established examples such as salmonella, campylobacter and listeria, recent evidence is emerging of the role of food in the transmission of Helicobacter pylori and Mycobacterium paratuberculosis. Food-borne pathogens harboured by ruminants are spread through shedding in the faeces and subsequent faecal contamination of raw food. Ruminant shedding appears to be affected by diet and, of particular concern, may be increased during fasting regimens imposed during transport to the slaughterhouse. The survival of food-borne pathogens in the ruminant gut is affected by many factors including microbe-microbe interactions, interactions involving plant metabolites and the presence of inhibitory end-product metabolites such as short-chain fatty acids. The potential importance of digesta flow and bacterial detachment in shedding of food-borne pathogens is discussed. Experimental procedures with dangerous pathogens have constraints, particularly in animal experimentation. This situation may be overcome by the use of rumen-simulating fermentors. One such system which, like the natural rumen, has a different turnover rate for solid and liquid digesta, was found to maintain rumen-like variables over an 11 d period. This system may prove useful for the study of dietary effects on food-borne pathogens.

Degradabilidade in situ da matéria seca, proteína bruta e fibra em detergente neutro do capim-furachão (Panicum repens, L.) submetido à adubação e em diferentes idades de corte

O objetivo deste estudo foi avaliar as degradabilidades potencial e efetiva da matéria seca (MS), proteína bruta (PB) e fibra em detergente neutro (FDN) do capim-furachão (Panicum repens, L.) em diferentes idades de corte (15, 30, 45, 60 e 75 dias) sob presença ou ausência de adubação. As taxas de passagem das fases líquida e sólida da digesta foram também avaliadas. Cinco bovinos machos, 7/8 Holandês/Zebu, entre 30 e 36 meses de idade, com média de 545 kg PV foram distribuídos em delineamento em quadrado latino em esquema de subparcelas. As parcelas foram as cinco idades de corte; as subparcelas, os dois níveis de adubação; e as subsubparcelas, os seis tempos de incubação. Idade de corte, adubação, tempo de incubação e interações entre idade e adubação e entre tempo de incubação e adubação influenciaram a degradabilidade ruminal da MS, PB e FDN. A degradabilidade potencial da MS aumentou com o tempo de incubação. A adubação melhorou e as idades de corte reduziram a degradabilidade efetiva da MS, PB e FDN. As taxas de degradação da matéria seca variaram de 0,0481 a 0,0299h-1.

Composição químico-bromatológica e degradabilidade In Situ da matéria seca, proteína bruta e fibra em detergente neutro da casca do fruto de três variedades de maracujá (Passiflora spp)

O objetivo deste trabalho foi avaliar a composição químico-bromatológica e as degradabilidades potenciais e efetivas da matéria seca (MS), proteína bruta (PB) e fibra em detergente neutro (FDN) do resíduo (casca) das variedades de maracujá amarela (Passiflora edulis f. Flavicarpa Degener), roxa (Passiflora edulis Sims) e doce (Passiflora alata) e da mistura das variedades amarela e roxa. Calcularam-se, também, o consumo de MS e as concentrações de amônia, ácidos graxos voláteis e pH no líquido ruminal e a taxa de passagem das fases líquida e sólida da digesta no rúmen de bovinos. Os resíduos (casca) in natura apresentaram grande quantidade de água, enquanto a variedade roxa apresentou o maior teor de matéria seca (17,01%) e o amarelo, o menor (10,78%). O teor de proteína bruta variou de 9,82% na MS, para a variedade amarela, a 7,53%, para a doce. O teor de fósforo foi 0,13% na MS para a variedade doce, chegando a 0,09, para a roxo, e 0,08%, para a amarelo. Os teores de cálcio, FDN e FDA não diferiram entre as variedades. Às 48 horas de incubação no rúmen, a degradabilidade atingiu ponto máximo para o teor de MS, PB e FDN. Houve interação de tempo e variedade na degradabilidade de MS, PB e FDN. As degradabilidades de PB e FDN foram influenciadas pelas variedades. A DE da FDN foi maior para a mistura (45,85%) e menor para a doce (34,61%). O consumo médio de MS foi de 16,90 kg/animal, equivalente a 3,27% do peso vivo ou 156,11 g/kg0,75, quando se utilizou farelo de casca (resíduo) com 90% de MS. As concentrações de ácidos graxos voláteis mantiveram-se na faixa de 7,76 a 10,87 mmoles/100 mL. O pH do líquido ruminal variou de 6,03 a 6,75 e o N-amoniacal, de 4,93 a 9,86 mg/100 mL.