Postnatal development of the rabbit caecal microbiota composition and activity

This study describes the development of the rabbit caecum microbiota and its metabolic activities from the neonatal (day 2) until the subadult period (day 70). The caecal microbiota was analysed using 16S rRNA gene approaches coupled with capillary electrophoresis single-stranded conformation polymorphism (CE-SSCP) and qPCR. At day 2, rabbits harboured population levels up to 8.4, 7.2 and 7.4 log(10) copy number g(-1) full caecum of the total bacteria, Bacteroides-Prevotella and Firmicutes groups, respectively. These populations reached their maximum levels from day 14 for Firmicutes groups (10.8 log(10) copy number g(-1) caecal content) and day 21 (11.4 and 10.7 log(10) copy number g(-1) caecal content of the total bacteria and the Bacteroides-Prevotella group, respectively). The archaeal population could be detected only from day 7 onwards (5.5 log(10) copy number g(-1) full caecum) and reached its maximum level at day 35 (7.4 log(10) copy number g(-1) caecal content). Similarity analysis, diversity calculation and quantitative evaluation of the stability of bacterial community CE-SSCP profiles provided some evidence that the caecal microbiota develops progressively from a simple and unstable community after birth into a complex and climax community in subadult rabbits. Meanwhile, the microbial activity evolved with the progressive decrease of the propionate/butyrate ratio towards a rabbit-specific value <1.     

Effects of age and mannanoligosaccharides supplementation on production of volatile fatty acids in the caecum of rabbits

This trial studied the effect of including mannanoligosaccharides (MOS, Bio-Mos^®, Alltech Inc., USA) in the diet on the caecal volatile fatty acids (VFA) and pH of rabbits from 34 to 90 days of age. Three experimental diets were compared: control diet, zinc bacitracin (ZnBac) diet (control diet with 0.1 g ZnBac/kg feed) and MOS diet (control diet with 2.0 g MOS/kg feed). Rabbits were slaughtered at 34, 48, 69 and 90 days of age and caecal contents were collected and analyzed for dry matter, pH and VFA concentration. The empty caecum and caecal contents weights relative to live weight were also determined.Age affected (P<0.0001) VFA concentration and pH values in the caecum. The pH decreased with age whereas VFA concentration increased. Rabbits fed MOS had higher (P<0.05) VFA and tended (P=0.098) to had lower pH in the caecum than rabbits fed ZnBac and control diets. Acetic, propionic and butyric acids concentrations in the caecum increased with MOS but its molar proportions were similar among diets. Diet had no effect on empty caecum weight and caecal contents weight and dry matter concentration. There was no interaction effect between diet and age. From 34 to 90 days of age, VFA production was higher (P<0.05) in the caecum of rabbits fed MOS than in those fed ZnBac diet and control diet.The addition of MOS to the diet increased the VFA concentration in the caecum of growing rabbits from 34 to 90 days of age.     

Effect of level of fibre on performance and digestion traits in growing rabbits

An experiment was conducted to determine the effects of level of fibre on production performance, gastrointestinal tract development, caecum fermentation and fibrolytic activity in weaner to 2-month-old New Zealand rabbits. One hundred weaner rabbits were allocated in individual cages for five treatments in which they were fed each diet with ADF at 130 (NDF, 274.1; ADL, 39.7; CP, 158.4; EE, 26.8; starch, 252.5 g/kg), 160 (NDF, 292.9; ADL, 41.9; CP, 160.3; EE, 25.6; starch, 249.4 g/kg), 190 (NDF, 312.4; ADL, 50.5; CP, 157.6; EE, 24.2; starch, 218.2 g/kg), 220 (NDF, 343.9; ADL, 51.2; CP, 158.5; EE, 22.2; starch, 217.6 g/kg), and 250 g/kg (NDF, 375.7; ADL, 66.0; CP, 156.9; EE, 22.4; starch, 220.8 g/kg) original matter basis, respectively. The results were: ADG and F/G deteriorated with increasing fibre (P<0.05); ADI increased with increasing dietary ADF (P=0.002). The stomach relative weight (g/kg LW), small intestine relative weight (g/kg LW), caecum weight, caecum content weight and caecum relative weight (g/kg LW) all increased with increasing ADF (P=0.003, 0.007, 0.002, 0.010 and <0.001, respectively). Quadratic effects of level of ADF on the villus height, villus height/crypt depth of the duodenum and the villus height/crypt depth of the jejunum were obtained; cubic effects of level of ADF on the crypt depth of the jejunum and the villus height/crypt depth of the ileum were obtained. Cubic effects of level of ADF on the pH, the butyric acid (% total VFA) and C2/C4 were obtained. The NH₃–N concentration dropped and the acetic acid (% total VFA) increased when the dietary ADF increased (P<0.001). The fibrolytic activity measured in the caecal contents increased when the dietary ADF increased (P<0.001). Providing a ration consisting mainly of clover meal, wheat straw and peanut hulls, the optimum dietary ADF content for weaner to 2-month-old growing meat rabbits was shown to be 190 g/kg feed.     

Changes over time in the bacterial communities associated with fluid and food particles and the ruminal parameters in the bovine rumen before and after a dietary change

This work aimed to study the changes over time in the bacterial communities associated with the fluid and food particle fractions of the cow rumen following a change in diet. Four cannulated cows were fed a hay-based diet for 21?days and were then switched to a corn-silage-based diet for 33?days. The bacterial communities were regularly characterized by capillary electrophoresis?- single-strand conformation polymorphism (CE-SSCP) and qPCR, and the main ruminal parameters were determined. The dietary change led to slight reductions in the diversity index, bacterial concentration, pH, and NH(3)-N concentration, and to an increase in the redox potential and volatile fatty acid concentrations. CE-SSCP profiles were not significantly affected by the dietary change but did change over time, with frequent fluctuations in both fluid and food particle fractions before and after the dietary change. The food particle fraction had a higher diversity index of bacterial community (+1.2 points, P?< 0.001) and slightly more total bacteria than the fluid fraction of the rumen.     

Biological properties of fructooligosaccharides with different contents of kestose and nystose in rats

Abstract

In a four-week experiment on rats' diets containing 5% of sucrose or fructooligosaccharides (FOS) diversified in terms of kestose and nystose contents: 6:1 (FOS-K), 3:1 (FOS-KN), and 0.5:1 (FOS-N) were applied. All FOS preparations, primarily FOS-N, considerably increased the mass of caecum, lowered pH of caecal digesta, and increased concentrations of protein. The glycolytic activity of the caecal digesta was generally alike in all groups, except for the control group where the activity of β-glucosidase was negligibly lower and that of α-galactosidase higher. The administration of FOS preparation with a diet increased the concentration and the pool of total VFA in the caecal digesta, especially in the case of butyric and propionic acids and decreased the concentration of iso-butyric and valeric acids. When compared with the kestose-rich preparation, the nystose-rich preparation increased the production of total VFA in the caecum, primarily of n-butyrate and propionate. Different length of kestose and nystose chains had no effect on the activity of bacterial enzymes in the caecum nor the biochemical indices of serum, concentration of cholesterol, glucose, urea, Ca, P and Mg.     

Biological properties of fructooligosaccharides with different contents of kestose and nystose in rats

In a four-week experiment on rats' diets containing 5% of sucrose or fructooligosaccharides (FOS) diversified in terms of kestose and nystose contents: 6:1 (FOS-K), 3:1 (FOS-KN), and 0.5:1 (FOS-N) were applied. All FOS preparations, primarily FOS-N, considerably increased the mass of caecum, lowered pH of caecal digesta, and increased concentrations of protein. The glycolytic activity of the caecal digesta was generally alike in all groups, except for the control group where the activity of beta-glucosidase was negligibly lower and that of alpha-galactosidase higher. The administration of FOS preparation with a diet increased the concentration and the pool of total VFA in the caecal digesta, especially in the case of butyric and propionic acids and decreased the concentration of iso-butyric and valeric acids. When compared with the kestose-rich preparation, the nystose-rich preparation increased the production of total VFA in the caecum, primarily of n-butyrate and propionate. Different length of kestose and nystose chains had no effect on the activity of bacterial enzymes in the caecum nor the biochemical indices of serum, concentration of cholesterol, glucose, urea, Ca, P and Mg.     

Effect of decreasing dietary protein level and replacing starch with soluble fibre on digestive physiology and performance of growing rabbits

At weaning (33 days of age), 246 hybrid rabbits (782 ± 53 g live weight) were divided into six experimental groups and fed ad libitum six iso-ADF diets formulated according to a bifactorial arrangement with two protein levels (152 and 162 g/kg) and three soluble fibre-to-starch ratios (0.2, 0.6 and 1.5), the latter obtained by replacing starch (from 209 to 91 g/kg) with soluble fibre (from 48 to 136 g/kg). The trial lasted for 42 days until slaughter. The rabbits that were fed the diet with the highest protein level and the lowest soluble fibre-to-starch ratio showed the highest mortality rate (17.1% v. 1.7% on average; P < 0.001) and sanitary risk (mortality + morbidity: 20.0% v. 8.1%; P = 0.04) compared with the rabbits fed the other diets. With increasing dietary crude protein level, the digestibility of dry matter (DM; 0.615 to 0.626) and gross energy (0.620 to 0.630) as well as aNDF (without sodium sulphite; 0.298 to 0.323) and hemicelluloses (0.417 to 0.461) significantly (0.001 < P < 0.10) improved. Moreover, total volatile fatty acids (VFAs) in the caecal content increased (59.0 to 68.4 mmol/l; P = 0.01) and ileum crypt depth tended to reduce (P = 0.07). Neither growth performance nor slaughter results were affected by the protein level. When increasing soluble fibre-to-starch ratio, the digestibility of DM and gross energy did not change, whereas the digestibility of aNDF (0.264 to 0.352), ADF (0.167 to 0.267) and hemicelluloses (0.400 to 0.470) linearly increased (P < 0.001). At caecum, N-ammonia tended to decrease linearly (P = 0.08), total VFA concentration (56.0 to 67.3 mmol/l) and acetate proportion (80.4 to 83.3 mmol/100 mmol VFA) linearly increased (P < 0.01), whereas butyrate and valerate proportions decreased (0.01 < P < 0.05). Growth performance was similar among groups, whereas at slaughter the proportion of the gastrointestinal tract linearly increased (177 to 184 g/kg; P < 0.01) without effect on dressing percentage, however. As soluble fibre-to-starch ratio increased, meat pH linearly decreased and lightness (L*), redness (a*) and yellowness (b*) colour indexes increased (0.01 < P < 0.05).     

Impact of feed restriction and fragmented feed distribution on performance,intake behaviour and digestion of the growing rabbit

Postweaning feed restriction preserves rabbit digestive health after weaning, but the underlying physiological mechanisms are not yet understood. To elucidate whether the feeding intake pattern modification related to feed restriction might be involved, we studied the effects of both feed intake quantity and intake frequency. Animals were allotted at weaning (28 d old) in a 2 × 2 factorial design: feed intake quantity (AL = ad libitum vs R = 75% of AL) and fragmented feed distribution (FFD) (1 vs 13 distributions), thus forming four groups (AL1, AL13, R1 and R13). New Zealand White growing rabbits were used from weaning to slaughter (70 d old), to analyse mortality, morbidity, performance, intake behaviour, digestion and microbial activity. Seven days after starting feed restriction (35 d old, group R1), rabbits consumed 44% of the feed within 2 h, 65% in 4 h and in 7 h over 95%. Over the 28–70 d period, mortality was low (5.3%) while morbidity averaged 18.5% and neither was affected by treatment. However, FFD tended to decrease the morbidity rate during the first 14 days after weaning (P = 0.06). Feed conversion (28–70 d) was improved by restriction (+15%, P < 0.001) and by FFD (+5%, P < 0.001). Nutrient digestibility was improved by restriction (+10% for energy, P < 0.01), but not by FFD. Fragmented feed distribution led to a lower stomachal pH, in the antrum (1.48 vs 2.13, P < 0.001) and in the fundus (1.52 vs 2.63, P < 0.001), while a higher pH was found in the caecum (6.07 vs 5.86, P < 0.001). Butyrate proportion in the caecum was reduced by four units for restricted groups. Fragmented feed distribution reduced the caecal VFA concentration by 23% within restricted rabbit groups only. A similar interaction between intake level and FFD was observed for fibrolytic activity (cellulase and xylanase). The diversity of caecal bacterial community was not modified by either of the two factors studied. Globally, fragmented meals have no major impacts on the caecal microbial activity, diversity, and thus would not be implicated in the better resistance of restricted rabbit to digestive troubles.     

Nutritional and sanitary statuses alter postweaning development of caecal microbial activity in the rabbit

The postweaning development of caecal microbial activity was studied in the rabbit according to the sanitary status (conventional "C" vs. specified pathogen-free "SPF") and the nutritional status (standard-fibre "SF" vs. deficient-fibre "DF" diet). The two diets were distributed ad libitum from weaning (28 days) to 70 days of age, respectively, to 80 C and 72 SPF rabbits. From 28 to 42 days, the volatile fatty acids concentration in the caecum (tVFA) of C rabbits was 50 mM/L and increased by 46% between 42 and 56 days, without interactions with the diet effect. In parallel, the bacterial fibrolytic activity decreased for xylanase and CMCase (-32% and -60%, respectively, P<0.05), while pectinase activity decreased more regularly from 28 to 70 days (-28%, P<0.05). At weaning, tVFA was similar among C or SPF rabbits, while at 70 days, it decreased by 23% for SPF and increased in C group (+31%). Cellulasic and hemicellulasic activity of bacteria were two to three times lower, respectively, in SPF rabbits compared to conventional ones. No interaction was detected between sanitary and nutritional status at 70 days of age for the caecal fermentative activity. With the FD diet, tVFA decreased by 10%, while butyrate proportion increased by 37% (at 70 days), whatever the sanitary status. In 70-day-old rabbits (C or SPF group), pectinasic activity was reduced by 30% when rabbits were fed the FD compared to the SF one.     

Physiological effects of lactulose and inulin in the caecum of rats

A model experiment was performed on rats to evaluate the effect of partial or total substitution of saccharose (S) and cellulose (C) by preparations of lactulose and inulin on the development and metabolism of the caecum. In the experimental diets given to rats for 4 weeks, the examined preparations were administered either with an equivalent amount of cellulose (each at 4% of the diet) or as sole source of dietary fibre at 8% of the diet. Compared to the saccharose group cellulose had no effect, and low doses of lactulose and inulin in the diet increased to a medium extent the weight of the caecum wall and caecal digesta. The addition of lactulose and inulin at 8% increased significantly the content of caecal digesta (4.62 and 4.11?g/100g BW, respectively) and the weight of the caecal wall (1.10 and 0.86?g/100g BW, respectively), compared to the groups with saccharose and cellulose (0.73, 0.90 and 0.24, 0.28?g/100g BW, respectively). Cellulose and cellulose partially-substituted with lactulose and inulin caused an increase in the dry matter content of caecal digesta (26.5–27.5%), compared to other groups (21.8–22.8%). The administration of lactulose and inulin preparations was accompanied by a significant drop in pH (5.47–5.81), compared to the groups with cellulose or saccharose (6.83–6.91), and a decrease in the ammonia concentration in the caecal digesta, compared to the cellulose control (0.27–0.40 and 0.62?mg/g, respectively). The group with 8% lactulose was characterized by the highest activities of microbiological α- and β-galactosidase and β-glucosidase in the caecal digesta. Cellulose and both preparations significantly decreased the activity of β-glucuronidase, compared to the saccharose group (0.39–0.89 and 1.52?U/g, respectively). The highest concentration of VFA in the caecal digesta was observed in the saccharose group (89.2?μmol/g), and the lowest concentration in the group where cellulose was totally substituted by lactulose and inulin (55.1 and 57.5?μmol/g, respectively). The total production of VFA in the caecum was fourfold higher with 8 % lactulose and inulin (254.7 and 236.4?μmol/100g BW, respectively) than in both controls groups (65.1 and 67.8?μmol/100g BW, respectively). The high dose of inulin and lactulose increased the share of propionic acid in the VFA profile (C₂:C₃:C₄) compared to both control groups. When 4% inulin was added to the diet a significant increase of butyrate concentration in the caecum was observed.     

A Note on the Total Viable Counts and Selective Enumeration of Anaerobic Bacteria in the Caecal Content, Soft and Hard Faeces of Rabbit

Total viable counts, proteolytic, ureolytic, cellulolytic and NH⁺₄ utilizing anaerobic bacteria in caecal contents, soft and hard faeces of rabbits were studied. No significant differences between the bacterial counts from the caecum and soft faeces were observed ( P < 0·05) but there were significant differences between the bacterial counts of the soft and hard faeces ( P < 0·01).     

Effects of increasing the intake of dietary β-glucans by exchanging wheat for barley on nutrient digestibility, nitrogen excretion, intestinal microflora, volatile fatty acid concentration and manure ammonia emissions in finishing pigs

An experiment (complete randomised design) was conducted to investigate the linear and quadratic effects of barley β-glucan inclusion level on total tract nutrient apparent digestibility, nitrogen excretion, intestinal microflora, volatile fatty acid (VFA) profile and manure ammonia emissions in pigs. Twenty-four boars (66 kg) were assigned to one of four treatments: (T1) 0 g/kg barley (control diet) (5.6 g/kg β-glucan), (T2) 222 g/kg barley (12.1 g/kg β-glucan), (T3) 444 g/kg barley (18.9 g/kg β-glucan) and (T4) 666 g/kg barley (25 g/kg β-glucan). Barley was substituted for wheat in the diet. The diets were formulated to contain similar concentrations of digestible energy and digestible lysine. There was a linear decrease (P < 0.001) in the total tract apparent digestibility of dry matter, organic matter, gross energy and neutral-detergent fibre with increasing β-glucan concentration. Faecal nitrogen excretion was affected by dietary β-glucan concentration (quadratic P < 0.05). There was a linear decrease in Enterobacteria concentrations (P < 0.05) with increasing dietary β-glucan concentration. Increasing dietary barley levels caused a linear decrease in colonic (P < 0.01) and caecal pH (P < 0.001). Total caecal VFA and propionic acid were affected by dietary β-glucan concentration (quadratic, P < 0.05). There was a linear decrease in the proportion of acetic acid (P < 0.001), isobutyric acid (P < 0.01) and isovaleric acid (P < 0.05) with increasing levels of dietary barley in both the caecum and colon. There was a linear increase in the proportion of propionic acid (P < 0.001) and butyric acid (P < 0.05) with increasing barley in the colon. In conclusion, high level of dietary β-glucan (25 g/kg) is required to reduce offensive odour forming branched-chain VFAs; however, diet digestibility is compromised at such levels.     

Physiological effects of lactulose and inulin in the caecum of rats

A model experiment was performed on rats to evaluate the effect of partial or total substitution of saccharose (S) and cellulose (C) by preparations of lactulose and inulin on the development and metabolism of the caecum. In the experimental diets given to rats for 4 weeks, the examined preparations were administered either with an equivalent amount of cellulose (each at 4% of the diet) or as sole source of dietary fibre at 8% of the diet. Compared to the saccharose group cellulose had no effect, and low doses of lactulose and inulin in the diet increased to a medium extent the weight of the caecum wall and caecal digesta. The addition of lactulose and inulin at 8% increased significantly the content of caecal digesta (4.62 and 4.11 g/100g BW, respectively) and the weight of the caecal wall (1.10 and 0.86 g/100g BW, respectively), compared to the groups with saccharose and cellulose (0.73, 0.90 and 0.24, 0.28 g/100g BW, respectively). Cellulose and cellulose partially-substituted with lactulose and inulin caused an increase in the dry matter content of caecal digesta (26.5-27.5%), compared to other groups (21.8-22.8%). The administration of lactulose and inulin preparations was accompanied by a significant drop in pH (5.47-5.81), compared to the groups with cellulose or saccharose (6.83-6.91), and a decrease in the ammonia concentration in the caecal digesta, compared to the cellulose control (0.27-0.40 and 0.62 mg/g, respectively). The group with 8% lactulose was characterized by the highest activities of microbiological alpha- and beta-galactosidase and beta-glucosidase in the caecal digesta. Cellulose and both preparations significantly decreased the activity of beta-glucuronidase, compared to the saccharose group (0.39-0.89 and 1.52 U/g, respectively). The highest concentration of VFA in the caecal digesta was observed in the saccharose group (89.2 micromol/g), and the lowest concentration in the group where cellulose was totally substituted by lactulose and inulin (55.1 and 57.5 micromol/g, respectively). The total production of VFA in the caecum was fourfold higher with 8 % lactulose and inulin (254.7 and 236.4 micromol/100g BW, respectively) than in both controls groups (65.1 and 67.8 micromol/100g BW, respectively). The high dose of inulin and lactulose increased the share of propionic acid in the VFA profile (C2:C3:C4) compared to both control groups. When 4% inulin was added to the diet a significant increase of butyrate concentration in the caecum was observed.     

Effect of substitution of wheat starch by potato starch on the performance,digestive physiology and health of growing rabbits

The goal of this research was to study the effect of the substitution of wheat starch by potato starch (PS) on the performance, health and digestion of growing rabbits. Three experimental diets were formulated with 0%, 7% and 14% PS (PS0, PS7 and PS14, respectively) and similar starch contents (22% dry matter basis), proteins and fibre. The three diets were administered to three groups of 48 rabbits from weaning (28 days) to slaughter (70 days), and growth and health measurements were made. Another 10 rabbits per diet (30 rabbits at each age), reared under similar conditions, were slaughtered at 6 to 10 weeks of age, and the digesta were collected to analyse the caecal microbial activity (pH, volatile fatty acids (VFA) levels, fibrolytic activity) and the starch concentration in the ileal digesta. At the same ages, the whole tract digestibility coefficients were measured in 10 other rabbits for each treatment (30 rabbits). The feed intake between 28 and 42 days of age (days) increased by 11% (P < 0.05) in PS0 v. PS14. Over the whole growth period (28 to 70 days), weight gain was similar among diets (40.5 g/day), whereas the feed intake and feed conversion increased (8.5% and 5.2%, respectively; P < 0.05) with the PS14 diet. Mortality and morbidity were not affected by the diets. The starch concentration of the ileal contents increased (P < 0.01) with the addition of PS to the diet (0.39%, 0.77% and 1.08% for diets PS0, PS7 and PS14, respectively). Starch digestibility was 0.8 percentage units higher (99.8% v. 99.0%) with the PS0 diet than the PS14 diet (P = 0.04). The bacterial cellulolytic activity in the caecum tended to be higher with the PS14 diet (P = 0.07). The total VFA caecal concentration increased (P < 0.01) only in 6-week-old rabbits with PS7 compared with PS0 (54.7 v. 74.5 mmol/l). Protein digestibility and ileal starch concentration decreased (P < 0.05) with age (6 v. 10 weeks), and hemicelluloses digestibility increased (P < 0.05). At 10 weeks of age, rabbits showed a higher VFA pool (6.25 mol) and proportion of butyrate (15.9%) and a lower proportion of acetate (79.3%), ammonia level (7.5 mmol/l) and C3/C4 ratio (0.31) than at 6 weeks of age. The intake of potato starch had no effect on the performance, caecal microbial activity or digestive health of growing rabbits.     

Effect of concentrate feeding sequence on equine hindgut fermentation parameters

Feeding a diet with a small amount of hay and a high proportion of concentrate given in large meals entails a risk of colic to horses as this can impact the hindgut microbial ecosystem. To counteract this potential negative effect, one feeding strategy is to modify the distribution sequence of concentrate and hay. The purpose of the present study was to assess the impact of feeding the concentrate meal before or with the hay meal on fermentative parameters postprandial variations in caecum and right ventral colon contents and faeces. We focused on the comparison of pH value and volatile fatty acid (VFA) concentrations between the three compartments. Four horses fitted with two cannulas in the caecum and right ventral colon were fed a 100% hay diet (H) for a 3-week period, and then a 40% concentrate–60% hay diet for two consecutive periods of 3 weeks each. Concentrate and hay were offered simultaneously in two equal meals at 0800 and 1700 h (HC1) during one period, or separately in two equal meals at 0800 and 1600 h for the concentrate and at 1000 and 1730 h for hay (HC2) during the second one. During the 2^nd week of each diet period (H, HC1, HC2), caecal, right ventral colonic and faecal samples were collected before (0) and at 2, 4, 6 and 8 h after the morning meal. pH values and VFA concentrations were measured. Adding concentrate to the hay was associated with a decrease of pH value in the caecum, right ventral colon and faeces and an increase of faecal VFA concentrations (P<0.01). An impact of the concentrate feeding sequence was observed on caecal pH and faecal propionate concentration (P<0.001) but none on the other parameters investigated. In the caecum and right ventral colon, pH values decreased and VFA concentrations increased within the range of 4 to 8 h after the morning meal. Our data suggested that the variation of faecal pH could be an indicator of those of the caecal and right ventral colonic pH with a delay of 2 h. The present study showed that hay and commercial pelleted could be safely distributed simultaneously, thus making easier every day horse feeding.     

Caecal size and function in the rock elephant shrew Elephantulus myurus (Insectivora, Macroscelididae) and the Namaqua rock mouse Aethomys namaquensis (Rodentia, Muridae)

1. The relative size of the digestive organs and the function of the caeca of an insectivorous elephant shrew Elephantulus myurus (Macroscelididae) and of a herbivorous rodent Aethomys namaquensis (Muridae) were compared. 2. Both species had similar body mass but A. namaquensis had a significantly heavier total digestive tract, full stomach, and caecum and a longer large intestine and caecum than E. myurus. 3. Both species had similar total volatile fatty acid (VFA) concentration and VFA % composition although A. namaquensis had a significantly higher % of n-butyric acid. Both had a similar caecal NH3-N concentration. 4. The presence of a functional caecum in E. myurus supports the view that Macroscelididae have evolved from ancestral herbivores and not from insectivores.     

Faecal parameters as biomarkers of the equine hindgut microbial ecosystem under dietary change

Faeces could be used for evaluating the balance of the equine hindgut microbial ecosystem, which would offer a practical method for assessing gut health and how this relates to disease. However, previous studies concluded that faeces microbial ecosystem was not representative of the proximal hindgut (caecum and ventral colon). This study aimed to evaluate if variations of the faecal microbial ecosystem were similar to those observed in the proximal hindgut. Six horses, fistulated in the caecum and right ventral (RV) colon, were subjected to a gradual change of diet, from a 100% hay (high fibre) diet (2.2 DM kg/day per 100 kg BW) to a 57% hay+43% barley (high starch) diet (0.8 DM kg/day per 100 kg BW hay and 0.6 DM kg/day per 100 kg BW barley). The two diets were iso-energetic and fed over a 3-week trial period. Samples of digesta from the caecum, RV colon and faeces were collected two times on the 10th and 20th day of the trial, for each diet to assess the microbial ecosystem parameters by both classical culture technics and biochemical methods. The variations observed in the caecal and colonic bacterial composition (increase in total anaerobic, amylolytic and lactate-utilizing and decrease in cellulolytic bacteria concentrations) and microbial activity (changes in volatile fatty acids concentrations and increase in lactate concentrations) demonstrated that the hay+barley diet caused changes in the hindgut microbial ecosystem. Similar variations were observed in the faecal microbial ecosystem. Feeding the hay+barley diet resulted in higher concentrations of faecal lipopolysaccharides. The functional bacterial group concentrations (cellulolytics, amylolytics and lactate utilizers) were significantly correlated between caecum and faeces and between colon and faeces. From analyses of the metabolites produced from microbial activity, only valerate concentration in the caecum and the proportion of propionate were significantly correlated with the same parameters in the faeces. Results of the principal component analysis performed between all the caecal/faecal and colonic/faecal parameters revealed that the total anaerobic and cellulolytic bacteria concentrations, as well as valerate, l-lactate and lipopolysaccharide concentrations were strongly correlated with several microbial parameters in the caecum (P<0.027; r>|0.45|) and in the colon (P<0.013; r>|0.50|). This demonstrated that faecal samples and their bacterial analyses could be used to represent caecum and RV colon hindgut microbial ecosystem in terms of variations during a change from a high-fibre to a high-starch diet, and thus could be markers of particular interest to diagnostic proximal hindgut microbial disturbances.     

Effects of fibre level and dietary mannanoligosaccharides on digestibility,caecal volatile fatty acids and performances of growing rabbits

The current experiment with 3 trials aimed to study the effect of two levels of dietary fibre – high fibre (HF; 323 g aNDFom/kg) and low fibre (LF; 248 g aNDFom/kg) – and the effect of mannanoligosaccharides (MOS) addition (1 g/kg) to the LF diet (LFM) on the performances and health status of growing rabbits, digestibility and caecal fermentative characteristics. In the growth trial 132 rabbits of both sexes were used (11 cages with 4 rabbits per treatment) from weaning (32 days of age) to slaughter (67 days of age). Rabbits fed HF diet showed a significantly higher weight gain and live weight at 67 days than rabbits fed LF diet (2032 g vs. 1935 g) (P<0.05). Feed and digestible energy intake increased with dietary fibre level (P<0.05). During the growing period rabbits fed HF diet had a feed intake 26% higher than those fed LF diet. Feed efficiency ratio was worse in HF animals (0.334 vs. 0.385; P<0.05). Addition of MOS to LF diet did not affect growth performance parameters (P>0.05). Mortality and morbidity rate were not affected by treatments. In the digestibility 24 rabbits from 46 to 51 days of age trial were used. The HF diet resulted in a significant (P<0.05) decrease in digestibility of dry matter, organic matter and protein while the aNDFom digestibility was not significantly different between diets (P>0.05). Supplementation with MOS had no effects on digestibility (P>0.05). In the 3rd trial the caecal traits were measured in 30 rabbits with 46 days of age that received the experimental diets in the previous 14 days. Caecal production of total volatile fatty acids (VFA), acetate and propionate were significantly higher (P>0.05) on rabbits fed HF diets than on rabbits fed LF diets. The total VFA concentration increased 64% (from 5.01 to 8.20 mmol/100 ml) and acetate increased 73% (from 3.73 to 6.44 mmol/100 ml). Butyrate production was not different between diets (P>0.05). Fibre level did not affect proportions of VFA and caecal contents and caecal weights. Addition of MOS to LF diet did not affect any caecal trait (P>0.05). It was concluded that the reduction of dietary fibre level increases feed digestibility but worsens rabbit growth performances. Supplementation of low fibre diet with 1 g MOS/kg is not enough to reduce its negative effects on growth performances.     

Effect of mannanoligosaccharides supplementation on caecal microbial activity of rabbits

A total of 200 weaned (35 days) hybrid Hyla rabbits were randomly divided among five groups housed in bicellular cages (20 cages per group). Between 35 and 60 days of age, the groups were submitted to the following treatments: group ANT (positive control) fed a basal diet supplemented with antibiotics (colistin sulphate, 144 mg/kg; tylosin, 100 mg/kg; and oxytetracyclin, 1000 mg/kg); groups MOS_0.5, MOS_1.0 and MOS_1.5 fed the basal diet supplemented with 0.5, 1.0 and 1.5 g/kg mannanoligosaccharides (MOS), respectively; another group fed the basal diet without antibiotics or mannanoligosaccarides supplementation (negative control). Along the trial, an episode of epizootyc rabbit enteropathy occurs so that in the control group mortality rate was very high (78%) and survivor rabbits showed severe symptoms of disease (diarrhoea). Thus, the control group was discarded from the trial. At 60 days of age, samples of caecal content were collected from 10 rabbits per group and used as inocula for an in vitro gas production trial. At the end of fermentation (120 h of incubation), organic matter digestibility (OMd), cumulative gas production, fermentation kinetics, pH, volatile fatty acid (VFA) and NH3 productions were measured. Inoculum from MOS_1.0 rabbits showed the significant higher values of OMd (64.21%, P < 0.05), gas production (262.32 ml/g, P < 0.05), acetate (96.99 mmol/g OM, P < 0.05) and butyrate (26.21 mmol/g OM, P < 0.05) than the other groups. Slight differences were recorded among the groups ANT, MOS_0.5 and MOS_1.5. In addition, branched chain acids, in proportion to total VFAs, were significantly higher in MOS_1.0 inoculum (0.04, P < 0.05). MOS are able to affect fermentation activity of caecal micro-organism, but their activities seem not proportional to their level in the diet.     

The effect of high and low dietary crude protein and inulin supplementation on nutrient digestibility, nitrogen excretion, intestinal microflora and manure ammonia emissions from finisher pigs

A 2 × 2 factorial experiment was performed to investigate the interaction between a high- and low-crude-protein (CP) diet (200 v. 140 g/kg) and inulin supplementation (0 v. 12.5 g/kg) on nutrient digestibility, nitrogen (N) excretion, intestinal microflora, volatile fatty acid (VFA) concentration and manure ammonia emissions from 24 boars (n = 6, 74.0 kg live weight). The diets were formulated to contain similar concentrations of digestible energy and lysine. Pigs offered the high-CP diets had a higher excretion of urinary N (P < 0.001), faecal N (P < 0.01) and total N (P < 0.001) than the pigs offered the low-CP diets. Inulin supplementation increased faecal N excretion (P < 0.05) and decreased the urine N : faeces N ratio (P < 0.05) compared with the inulin-free diets. There was no effect (P > 0.05) of dietary treatment on N retention. There was an interaction (P < 0.05) between dietary CP concentration and inulin supplementation on caecal Enterobacteria spp. Pigs offered the diet containing 200 g/kg of CP plus inulin decreased the population of Enterobacteria spp. compared to those with the inulin-supplemented 140 g/kg CP diet. However, CP level had no significant effect on the population of Enterobacteria spp. in the unsupplemented diets. Inulin supplementation increased caecal Bifidobacteria (P < 0.01) compared with the inulin-free diets. There was no effect of inulin supplementation on VFA concentration or intestinal pH (P > 0.05). Pigs offered the 200 g/kg CP diets had higher (P < 0.05) manure ammonia emissions from 0 to 240 h of storage than pigs offered the 140 g/kg CP. In conclusion, inulin supplementation resulted in an increase in Bifidobacteria concentration and a reduction in Enterobacteria spp. at the high CP level indicating that inulin has the ability to beneficially manipulate gut microflora in a proteolytic environment.