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 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.     

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.     

Effects of feeding a Lactobacillus plantarum JL01 diet on caecal bacteria and metabolites of weaned piglets

Currently, knowledge is limited concerning the impact of a Lactobacillus plantarum JL01 diet for weaned piglets on caecal bacteria and metabolite profiles. In our experiments, 24 weaned piglets were randomly divided into two groups; each piglet in the treatment groups (Cec-Lac) was fed a basic diet and administered 10 ml of L. plantarum JL01 (1·0 × 10⁹ CFU per ml) every day. The control group (Cec-Con) was fed a basic diet. After feeding for 28 days, we analysed the parameters of the caecal digesta of weaned piglets. We used 16S rDNA gene sequencing and mass spectrometry (MS)-based metabolomics techniques to investigate the effect of a L. plantarum JL01 diet on intestinal microbial composition and its metabolite profiles in the caecum contents of weaned piglets. The results showed that the richness estimators (ACE and Chao indices) in the caecal bacteria increased in the Cec-Lac group. Prevotella_2 and Desulfovibrio decreased significantly, while Pantoea and Rectale_group increased in the caecum of weaned piglets in the Cec-Lac group. Furthermore, Pearson's correlation analysis revealed that the genus Rectale_group was positively correlated with indole-3-acetic acid (P < 0·05), and the genus Pantoea had the same correlation with 1-palmitoyl lysophosphatidic acid. The metabolomics analysis revealed that the L. plantarum JL01 diet supplementation had significant effects on tryptophan metabolism and fat digestion and absorption. The results indicated that the L. plantarum JL01 dietary supplementation not only altered the microbial composition but also mediated tryptophan metabolism and fat digestion and absorption in the caecum, factors that may further affect the health of the host.     

Maturation of the intestinal digestion and of microbial activity in the young rabbit: impact of the dietary fibre:starch ratio

The developmental changes of intestinal digestive potential and caecal microbial activity were described in suckling and weaned rabbits according to two feeding programmes. Two groups of thirteen litters were fed from 18 to 42 days old a “High” or a “Medium” NDF:starch ratio diet (resp. 2.7 vs 2.0, groups HL and ML) with similar protein and lipid levels, and from 42 to 70 days old the two groups were fed a “Low” NDF:starch ratio diet (1.7). From 25 to 32 days (weaning), the milk and solid feed intake were 22% and 41% higher in ML group (P < 0.05), and the mortality by diarrhoea was 4 units lower (P < 0.01). The whole tract digestive efficiency increased by 10% before weaning, and remained steady (organic matter) or decreased (lipids, protein) after weaning. Energy digestibility was 0.623 and 0.686 for High and Medium diets respectively. From 25 to 42 days, total enzymatic activity in intestinal content increased for chymotrypsin (5-fold, P < 0.001), lipase (10-fold, P < 0.001), amylase (17-fold, P < 0.01) and maltase (11-fold, P < 0.001), while trypsin doubled after weaning. The feeding programme only affected the amylase and maltase activities, that were higher in HL group (P < 0.05). The volatile fatty acids concentration in the caecum was not significantly different among the groups, but it increased by 44% 10 days after weaning. The bacterial fibrolytic enzymes, increased by 30% after weaning and were similar among the two groups. The study revealed that the intestinal digestive maturation and the caecal microbial activity of the rabbit evolved markedly between 3 and 5 weeks of age, and was weakly affected when the NDF:starch ratio decreased from 2.7 to 2.0.     

Modulation of bacterial translocation in mice mediated through lactose and human milk oligosaccharides

Massive resection of the small intestine in infants is imposed to the regulation of several intestinal pathological situations, as intestinal adaptation cannot be relied upon. Many nutritional disturbances are occurring following surgery procedure. In this vein, long-term parenteral feeding is adopt to improve prognosis not always successfully. Clostridia and more specifically Clostridium perfringens, are suspected to participate in the physiopathology of the rising situation. In order to investigate the effect of lactose and human milk neutral oligosaccharides (HMNOs) on Clostridia, germfree mice were inoculated either with enterotoxigenic C.perfringens strain isolated from a patient with NEC, or with a human microbiota harboring C.clostridioforme group(HF). In this vein, different doses of lactose were administrated during 2 weeks in adult mice on an attempt to evaluate the lactase activity. Intake of lactose (70 g/L) and HMNOs (7 g/L) in C.perfringens monoassociated mice induced mortality within a week. In HF mice, no mortality was observed. An increase in Clostridia occurrence was observed in the median ileum after intake of 7 g lactose (p = 0.017). Higher clostridial numbers occurred in caecum following intake of 70 g lactose (p < 0.05) and HMNOs (p < 0.025). Bifidobacteria were found increased from distal ileum to colon following 70 g of lactose intake, whereas they decreased in the caecum of mice drinking lower lactose concentrations. Finally, bacteremia was more frequent in 70 g lactose/L mice (p < 0.02), whereas at lower doses of lactose bifidobacterial translocation was observed.As a result, human milk oligosaccharides could favor clostridial population when reaching the lower intestine. The shortness of the small intestine in infants underwent massive intestinal resection seems to be associated to an incomplete breakdown of lactose. Enteral feeds formulas deprived in lactose would be more suitable in enteral feeding of infants.     

The influence of mannan oligosaccharides, acidifiers and their combination on caecal microflora of Japanese quail (Coturnix japonica)

The aim of this study was to investigate the effects of the dietary supplementation of mannan oligosaccharides (MOS) extracted from yeast Saccharomyces cerevisiae, acidifiers -calcium formate (CF), calcium propionate (CP)- and their combination on the caecal microflora of Japanese quail (Coturnix japonica). Four hundred and fifty 1-day old quail where divided in six groups with three replicates each. One group that served as control received the basal diet. The five experimental diets consisted of the basal diet to which either 1 g MOS/kg, or 6 g CF/kg, or 6 g CP/kg, or 1 g MOS plus 6 g CF/kg or 1 g MOS plus 6 g CP/kg were added. The body weight was examined at weekly intervals and mortality was recorded daily. At days 21 and 42 of age, the total count of aerobic bacteria, lactic acid bacteria, enterobacteriaceae and coliforms in the caecal content of one bird of each replicate was determined. Also, at day 42 of age, two birds of each replicate were slaughtered and their carcass weight was determined. The results showed that MOS significantly (P ≤ 0.050) increased the total aerobic plate and lactic acid bacteria counts on day 21. Furthermore, CP significantly (P ≤ 0.050) decreased the total aerobic plate and lactic acid bacteria counts compared to controls on day 21. Significant interaction between MOS and acidifiers was noticed on total aerobic plate count on day 21. No significant (P > 0.050) difference was found in the caecal microflora on day 42. Finally, no significant (P > 0.050) difference was noticed on mortality, body and carcass weight.     

Effect of Ascophyllum nodosum extract on growth performance, digestibility, carcass characteristics and selected intestinal microflora populations of grower–finisher pigs

The effects of an extract of the brown seaweed Ascophyllum nodosum (AN) in grower–finisher pigs are reported. In Experiment 1, the effect of dietary supplementation with increasing levels of AN extract (ANE) on growth performance, carcass characteristics and gastrointestinal microflora was investigated. A total of 360 pigs were randomly allocated, based on initial live-weight and sex, to one of four experimental treatments as follows; control diet (no ANE), control diet plus 3 g ANE/kg, control diet plus 6 g ANE/kg and control diet plus 9 g ANE/kg. These diets were fed ad libitum up to slaughter. In Experiment 2, eight male pigs were allocated to a control diet (no ANE) or the control diet plus 2.5 g ANE/kg to determine effects of ANE on coefficient of total tract apparent digestibility (CTTAD) of nutrients and nitrogen (N) balance. Supplementation with increasing levels of ANE in Experiment 1 resulted in reduced daily gain, carcass weight and kill-out yield during the combined grower–finisher period (P<0.05); however, there were no effects of treatment on feed intake, feed conversion ratio or carcass characteristics. Increasing levels of dietary ANE resulted in decreased ileal coliform counts (P<0.05). Increasing dietary ANE also tended to increase adherent lactobacilli in the colon (P=0.080) but caecal bifidobacteria declined (P<0.05). There were trends towards a linear reduction in colonic bifidobacteria (P=0.077) and towards a quadratic effect on rectal lactobacilli (P=0.077). Intestinal pH was unaffected by ANE supplementation (P>0.05). In Experiment 2, the CTTAD was unaffected by the inclusion of ANE (P>0.05). Overall, the intestinal coliform reductions obtained suggest that ANE may provide a dietary means to improve gut health and potentially reduce pathogen carriage in finishing pigs. However, the negative effects on growth performance observed in healthy animals will most likely limit the commercial use of dietary ANE as a feed additive.     

Comparison of alternatives to in‐feed antimicrobials for the prevention of clinical necrotic enteritis

Aims: The capacity for Lactobacillus johnsonii and an organic acid (OA) blend to prevent Clostridium perfringens‐induced clinical necrotic enteritis (NE) in chickens was studied. Methods and Results: Cobb 500 birds were allocated into six groups (n = 25 birds/pen, eight pens/treatment); Unchallenged, Challenged, Antimicrobial (zinc bacitracin (ZnB)/monensin), OA, probiotic Lact. johnsonii and probiotic sham (Phosphate–buffered saline). All birds were challenged with Eimeria spp. and Cl. perfringens except for unchallenged controls. Birds fed antimicrobials were protected from NE development as indicated by maintenance of body weight, low mortality and clostridium levels, and decreased intestinal macroscopic lesion scores compared to challenged controls (P < 0·05). Lactobacillus johnsonii‐fed birds had reduced lesion scores, whilst OA‐fed birds had decreased Cl. perfringens levels. Both Lact. johnsonii and OA‐fed birds had improved feed efficiency between days 0 and 28 compared to challenged controls; however, mortality and body weights were not improved by either treatment. Microbial profiling indicated that the challenge procedure significantly altered the jejunal microbiota. The microbiota of antimicrobial‐fed birds was significantly different from all other groups. Conclusions: Whilst Lact. johnsonii and OA altered specific intestinal parameters, significant protection against NE was not observed. Significance and Impact of the Study: Lactobacillus johnsonii and OA did not prevent NE; however, some improvements were evident. Other related treatments, or combinations of these two treatments, may provide greater protection.     

Rapid adaptation of the bacterial community in the growing rabbit caecum after a change in dietary fibre supply

This work aimed to study the response of the growing rabbit caecal ecosystem (bacterial community and caecal environmental parameters) after a switch from a control to a low-fibre diet (LFD). A group of 160 rabbits were fed ad libitum a control diet (ADF: 20.4%) from weaning (36 days). At 49 days of age (day 0), 75 rabbits were switched to a LFD group (ADF: 10.7%), whereas 85 others (control group) remained on the control diet, for 39 days. Caecal contents were regularly sampled throughout the trial (60 rabbits per group). The bacterial community structure was characterized using CE-SSCP (capillary electrophoresis single strand conformation polymorphism) and total bacteria were quantified using real-time PCR. Redox potential (Eh), pH, NH(3)-N, volatile fatty acid (VFA) were measured in the caecum to characterize environmental parameters. The reduction of fibre in the diet modified the CE-SSCP profiles (P < 0.001) but not the diversity index (5.6 ± 0.8, ns). The number of 16S rRNA gene copies of total bacteria decreased (P < 0.01) in LFD rabbits compared with controls. In LFD rabbits, the caecal environment was less acid (+0.2 units; P < 0.01), more reductive (-11 mV; P < 0.05) and drier (+3.4 g 100 per g; P < 0.001), with an increase in NH3-N (+77%; P < 0.001) and a decrease in total VFA concentration (-17%; P < 0.001). We found significant correlations between the bacterial community, the quantity of bacteria and the caecal traits of the caecal ecosystem. Indeed, in both groups, the caecal traits barely constrained the total inertia of the CE-SSCP profile set (less than 14%), whereas total bacteria were positively related to total VFA, acetic acid and butyric acid levels, and Eh, and negatively related to pH. All the microbial and environmental modifications had occurred by day 2 and remained stable thereafter. These results suggest that the bacterial community in the growing rabbit caecum is able to adapt quickly after a change to in the dietary fibre supply to reach a new steady-state equilibrium.     

Effect of pig faecal donor and of pig diet composition on in vitro fermentation of sugar beet pulp

Two experiments were undertaken to investigate the influence of (1) pig bodyweight and (2) dietary fibre content of the diet on the in vitro gas production of sugar beet pulp fibre using faecal inoculum.In the first experiment, inocula prepared from young pigs (Y; 16–50 kg), growing pigs (G; 62–93 kg) and sows (S; 216–240 kg) were compared. Sugar beet pulp, hydrolysed in vitro with pepsin and then pancreatin, was used as the fermentation substrate. The cumulated gas productions over 144 h were modelled and the kinetics parameters compared. Lag times (Y: 4.6 h; G: 6.4 h; S: 9.2 h) and half-times to asymptote (Y: 14.7 h; G: 15.9 h; S: 20.8 h) increased with pig bodyweight (P<0.001) and the fractional degradation rates of the substrate differed between the pig categories (Y: 0.110 h⁻¹; G: 0.115 h⁻¹; S: 0.100 h⁻¹; P<0.001). The final gas production was not affected (P=0.10) by the inoculum source.In the second experiment hydrolysed sugar beet pulp was fermented with four inocula prepared from pigs fed diets differing in their total and soluble dietary fibre contents, i.e. low fibre diet rich in soluble fibre (LOW-S) or in insoluble fibre (LOW-I) or high fibre diet rich in soluble fibre (HIGH-S) or in insoluble fibre (HIGH-I). The total and the soluble dietary fibres influenced the kinetics of gas production. The presence of soluble fibres decreased the lag times, whatever the total dietary fibre content (2.7 h for LOW-S versus 3.5 h for LOW-I, 4.0 h for HIGH-S versus 4.4 h for HIGH-I; P<0.001). The half-times to asymptote were higher with the low fibre diets (P<0.001) and, for similar total dietary fibre contents, they were lower when the proportion of soluble fibres increased (LOW-S: 9.9 h; LOW-I: 11.4 h; HIGH-S: 8.9 h; HIGH-I: 10.1 h; P<0.001). The fractional degradation rates of the substrate were the highest with the fibre-rich diet containing a high proportion of soluble fibres (0.158 h⁻¹; P<0.001).In conclusion, the bodyweight of the faeces donors and the dietary fibre composition of the pig diet influence the in vitro fermentation kinetics of hydrolysed sugar beet pulp, but not the final gas production.     

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.     

Oral Administration of <Emphasis Type="Italic">Clostridium butyricum</Emphasis> for Modulating Gastrointestinal Microflora in Mice

This study aimed to evaluate the safety of Clostridium butyricum and to investigate the effect of C. butyricum on mice ecosystem in the intestinal tract by way of examining the population of different microorganisms isolated from caecal contents. We firstly evaluated the safety of C. butyricum using acute toxicity test and Ames test. Then forty male BALB/c mice were divided into the following four treatment groups, each consisting of ten mice: normal group, low-dose group, medium-dose group and high-dose group. Caecal contents were removed aseptically, immediately placed into an anaerobic chamber, and dissolved in sterile pre-reduced PBS. The determination of Enterococcus spp., Enterobacter spp., Lactobacillus spp., Bifidobacterium spp. and Clostridium perfringens was analyzed by the spread plate method, cell morphologies and biochemical profiles. The results showed the oral maximum tolerated dose of C. butyricum was more than 10 g/kg body weight in mice and no mutagenicity judged by negative experimental results of Ames test. And in medium- and high-dose groups, the populations of Bifidobacterium spp. and Lactobacillus spp. increased in caecum, as well as the ratios of Bifidobacterium spp. and Lactobacillus spp. to Clostridium perfringens (P < 0.01) as compared with the normal group. This research showed the intake of C. butyricum significantly improved the ecosystem of the intestinal tract in BALB/c mice by increasing the amount of probiotics and reducing the populations of unwanted bacteria.     

Silver nanoparticles as a potential antimicrobial additive for weaned pigs

Three experiments were carried out in order to determine the potential of silver nanoparticles as an additive in diets for weanling pigs. In Experiment 1, ileal contents of 4 pigs weaned 7 days before were incubated in vitro for 4 h at 37 °C with 0, 25, 50 and 100 μg Ag/g. Metallic silver (in colloidal form) linearly reduced coliforms (P=0.003) and lactobacilli (P=0.041) concentration, but did not affect the lactobacilli proportion compared with the control. In Experiment 2, three groups of 5 weaned pigs were given a diet with 0, 20 or 40 mg Ag/kg. The second week after weaning daily growth of pigs increased linearly (P=0.007) with the dose of silver nanoparticles. A trend (P=0.073) for a linear reduction in the ileal concentration of coliforms was observed by culture counts, but lactobacilli remained unaffected. There were no differences among treatments in the ileal concentration of coliforms or lactobacilli measured by FISH. However, the concentration of total bacteria (P=0.010) and Atopobium (P=0.001) decreased at a decreasing rate. No differences were detected in the other bacterial groups tested, except for a lowest concentration of the Clostridium perfringens/Clostridium histolyticum group in 20 mg Ag/kg (P=0.012). No treatment effect was detected in histological examination of ileal mucosa. In Experiment 3, productive performance and silver retention in tissues with 0, 20 or 40 mg Ag/kg diet were studied with 6 lots of 4 piglets per treatment in five weeks after weaning. Feed intake was highest in treatment with 20 mg Ag/kg (P<0.05). No effect was observed on apparent digestibility coefficients. After 5 weeks, there was no silver retention in skeletal muscles or kidneys, but it was observed, although in minimal proportions, in liver (1.354 and 2.445 μg Ag/g dry liver for 20 and 40 mg Ag/kg). The potential effect of metallic silver as a dietary additive on intake and growth of weaned piglets could be mediated through its antimicrobial properties, either against certain bacterial groups or reducing the microbial load of the small intestine; however, other beneficial effects over the host metabolism cannot be discarded.     

Different effects of difructose anhydride III and inulin-type fructans on caecal microbiota in rats

Abstract

The effects of different kinds of inulin-type fructans on caecal microbiota were evaluated in rats. Four groups of male Wistar rats were fed either a control diet, or diets containing 5% inulin, 5% fructooligosaccharides (FOS), or 5% difructose anhydride III (DFAIII) for two weeks. In the DFAIII group, caecal propionate, butyrate, counts of bifidobacteria, and total anaerobes were lower than in the inulin group, while caecal propionate, succinate, counts of bifidobacteria, and total anaerobes were lower than in the FOS group. Compared to controls, in the DFAIII group the counts of clostridia in caecum were increased by 3 log units. However, this change was statistically not significant. There were no differences between inulin and FOS groups for the pool of short chain fatty acids in caecum and bacterial counts. Results indicate that DFAIII has different effects on caecal microbiota compared to inulin and FOS and that these differences are most likely due to the α(3→2) bonds in DFAIII.     

Effects of dietary grape pomace on the intestinal microbiota and growth performance of weaned piglets

ABSTRACT

Grape pomace (GP) is an abundant by-product from wine production and is rich in phenolic compounds, unsaturated fatty acids, dietary fibre and beneficial bacteria. In this study, weaned piglets were fed a basic diet supplemented with 5% GP for 4 weeks. Compared with those in the control (CON) group, it was found that the proportion of Lactobacillus delbrueckii, Olsenella umbonata and Selenomonas bovis in the caecum and the villus height and villus height/crypt depth ratio (VCR) of the jejunum were both significantly increased in the GP group (p < 0.05). Meanwhile, at the mRNA expression level, several proinflammatory cytokines (IL-1β, IL-8, IL-6 and TNF-α) were significantly downregulated (p < 0.05) in piglet caecal tissue, and the short-chain fatty acid receptors (GPR41 and GPR43) were not significantly upregulated. In contrast, the levels of IgG was significantly increased (p < 0.05) in the sera of weaned piglets in the GP group. However, no difference in growth performance between the two groups of piglets was detected. These results show that GP had no adverse effects on the growth performance of piglets, but GP can promote the content of some beneficial bacteria in the caecum; this effect is conducive to improving the disease resistance potential of piglets.     

In vitro fermentability and physicochemical properties of fibre substrates and their effect on bacteriological and morphological characteristics of the gastrointestinal tract of newly weaned piglets

Abstract

Fermentability of fibre has a great impact on the bacterial flora along the gastrointestinal tract of newly weaned piglets. Therefore, this parameter was determined by incubating in vitro different fibre substrates (chicory roots, sugar beet pulp, wheat bran and corn cobs) with contents of jejunum or caecum sampled from slaughtered pigs. Incubating with small intestinal contents, lactic acid was the only fermentation product. Fermentability was highest for chicory roots, followed by wheat bran and sugar beet pulp, while corn cobs were not fermented. Based on SCFA formed in the incubations with caecal contents, ranking of the fermentability of the fibre substrates was in the same order. The effect of adding different fibre substrates to diets of newly weaned piglets on bacteriological and morphological aspects of the gastrointestinal tract was also investigated. In Experiment 1 three groups of five piglets, weaned at four weeks of age, received a control feed (C), C supplemented with corn cobs (50 g/kg) or with chicory roots (20 g/kg). In Experiment 2, diet C was supplemented with sugar beet pulp (120 g/kg) or with wheat bran (75 g/kg). After three weeks animals were euthanized and digesta were sampled from stomach, proximal and distal jejunum, caecum and colon. Furthermore, mucosal scrapings were prepared and tissue samples were taken from jejunum, caecum and colon. Viscosity was determined for jejunal, caecal and colon contents. Corn cobs in the feed increased the number of total bacteria, lactobacilli and bifidobacteria in the stomach and proximal duodenum, while a decreased count of streptococci in distal jejunum contents was noted. Chicory roots increased the counts of Escherichia coli in the distal jejunum and on the mucosa, while sugar beet pulp decreased the number of lactobacilli on the mucosa only. Wheat bran seemed to increase the count of E. coli in jejunal digesta and on the mucosa, and also the number of lactobacilli in the stomach and jejunum. Bifidobacterial numbers were increased but only in the proximal part of the jejunum. Fibre substrates affected the concentration of lactate and SCFA in different parts of the intestinal tract. Feeding corn cobs increased villus length in the proximal jejunum by 13%. The number of intra-epithelial lymphocytes in the villous epithelium of proximal and distal jejunum was decreased by corn cobs and chicory roots supplementation while beet pulp and wheat bran had the opposite effect. In Experiment 1, apoptotic index of the mucosa of the distal jejunum was very low and decreased when corn cobs were fed. Mitotic index in the crypts was only affected by the wheat bran diet and a small decrease was noted. It was concluded that the fermentability of fibre was not an ideal criterion for predicting its effects on the flora. The effect of fibres on viscosity of digesta was negligible probably explaining the lack of clear and consistent influences on the intestinal mucosa.     

Spatiotemporal mapping of the motility of the isolated chicken caecum

We studied the caecal contractile activity of the chicken (Gallus gallus) using single caeca that had been cannulated at their proximal and distal ends, and in paired caeca, maintained in situ on excised segments of gut that were cannulated at the colonic and small intestinal ends. Longitudinal and circular contractile patterns were characterised using high-definition spatiotemporal mapping. Low amplitude longitudinal contraction waves of frequency 14.1 cycles/min occurred in the absence of major contractile events. These were termed fast phasic and appeared to be mediated by slow waves. The nature of major spontaneous contractions occurring in the single caecum varied with the level of caecal distension. Type A contractions occurred when the caecum was not distended, originated from variable sites and propagated in both directions. Type B or C contractile events occurred when the caecum was moderately or fully distended, originated from a predominantly distal site and propagated proximally. On diameter maps, each type B event comprised a succession of contractions which had similar propagation speeds, frequency and direction to fast phasic contractions. Type C events were comprised of a succession of higher amplitude contractions with no appreciable propagation. Perfusion of saline via the colon resulted in fluid entering both caeca and the onset of aborad contractions in their proximal canals. Saline was also seen to flow between caeca during contractile events however no saline was seen to enter the small intestine as has been postulated by other workers.     

Effects of source of fibre on the development and pH of the gastrointestinal tract of broilers

The effects of different sources of dietary fibre on gastrointestinal tract (GIT) development and digesta pH were studied in 25-day-old broilers. There were four diets: a control diet low in fibre content (37.3 g neutral detergent fibre and 16.0 g acid detergent fibre/kg) and three additional diets in which 30 g/kg of cellulose (CEL), sugar beet pulp (SBP) or oat hulls (OH) were included at the expenses of sepiolite (a complex magnesium silicate clay). The relative weight (RW, %BW) of the GIT was greater with the SBP – than with the CEL – and the control diets. Also, gizzard RW was higher with the diet containing OH than with the diet containing CEL or the control diets, with the SBP diet being intermediate (P≤0.001). Fibre inclusion modified the pH of the GIT (P≤0.05) but the effects depended on the type of fibre. Crop pH was higher and proventriculus pH lower with SBP than with the other diets. However, gizzard pH was reduced with SBP and OH but not with CEL (P≤0.05). The pH of the digesta of the duodenum was similar for all diets but that of the jejunum, Meckel's diverticulum and ileum increased with SBP and decreased with CEL inclusion (P≤0.05). We concluded that dietary fibre affects the development and pH value of the different segments of GIT and that the effects differ according to the physico-chemical characteristics of the source of fibre used.     

A polymorphism in the porcine miR‐208b is associated with microRNA biogenesis and expressions of SOX‐6 and MYH7 with effects on muscle fibre characteristics and meat quality

MicroRNAs (miRNAs) encoded by the myosin heavy chain (MHC) genes are muscle‐specific miRNAs (myomiRs) and regulate the expression of MHC isoforms in skeletal muscle. These miRNAs have been implicated in muscle fibre types and their characteristics by affecting the heterogeneity of myosin. In pigs, miR‐208b and miR‐499 are embedded in introns of MYH7 and MYH7b respectively. Here, we identified a novel single nucleotide polymorphism (SNP) in intron 30 of MYH7 by which porcine miR‐208b is encoded. Based on the association study using a total of 487 pigs including Berkshire (n = 164), Landrace (n = 121) and Yorkshire (n = 202), the miR‐208b SNP (g.17104G>A) had significant effects on the proportions of types I and IIb fibre numbers (P < 0.010) among muscle fibre characteristics and on drip loss (P = 0.012) in meat quality traits. Moreover, the SNP affected the processing of primary miR‐208b into precursor miR‐208b with a marginal trend towards significance (P = 0.053), thereby leading to significant changes in the levels of mature miR‐208b (P = 0.009). These SNP‐dependent changes in mature miR‐208b levels were negatively correlated with the expression levels of its target gene, SOX‐6 (P = 0.038), and positively associated with the expression levels of its host gene, MYH7 (P = 0.046). Taken together, our data suggest that the porcine miR‐208b SNP differentially represses the expression of SOX‐6 by regulating miRNA biogenesis, thereby affecting the expression of MYH7 and the traits of muscle fibre characteristics and meat quality.