Manipulation of the functional activity of the gut by dietary and other means (antibiotics/probiotics) in ruminants

Development and Evaluation of a Commercial Direct-Fed Microbial (Zymospore®) on the Fecal Microbiome and Growth Performance of Broiler Chickens under Experimental Challenge Conditions

Simple Summary

Probiotics are recognized for their beneficial health-promoting properties, through competitive exclusion, promoting maintenance of intestinal epithelial integrity and host immune system homeostasis. The use of some spore-forming bacteria from the genus Bacillus has earned interest as a direct-fed microbial in recent years as a potential alternative to antibiotic growth promoters and growth enhancers. The present study evaluates the use of a Bacillus subtilis spore-based direct-fed microbial (Zymospore^®, Vetanco, Villa Martelli, Argentina) compared to an antibiotic growth promoter on the performance of broiler chickens under experimental intestinal challenge conditions. The results suggest that Zymospore^® increases the diversity of the broiler fecal microbiota and is an acceptable substitute for commonly used antibiotic growth promoters under defined and non-defined intestinal dysbiosis conditions.

Abstract

Direct-fed microbials (DFM) are added to broiler chicken diets in order to promote the proliferation of beneficial intestinal bacterial populations, which may lead to gains in performance efficiency and, potentially, reduce the level of enteric pathogens in the broiler chickens. The selection and laboratory evaluation of Bacillus subtilis strains as well as the experimental trial results of a novel Bacillus-based commercial DFM product are described. Fifteen wild-type Bacillus subtilis strains were characterized and assayed for their enzyme production capability, spore resistance to pH, salinity, and temperature, and ability to inhibit the growth of E. coli and Salmonella spp. The final DFM formulation was evaluated and compared to an antibiotic growth promoter (AGPs) in two experimental trials. In Experiment 1, broilers were given a defined challenge of Eimeria spp. and Clostridium perfringens to induce intestinal dysbiosis. The optimal dose of the DFM was determined to be 0.3 kg/ton of feed. At this dose, the broilers fed the DFM performed as well as the Flavomycin^®-fed broilers. Further, intestinal microbiome analysis indicates that the use of the DFM enhances bacterial diversity of the gut flora by day 5 of age, increasing levels of lactic acid bacteria (LAB) and Clostridiales by 25 days of age, which may enhance the digestion of feed and promote growth of the birds. In Experiment 2, the broilers were raised on recycled litter and given an undefined challenge orally to mimic commercial growth conditions. In this trial, the DFM performed as well as the bacitracin methylene disalicylate (BMD)-11%-fed birds. The results of the present studies suggest that this novel DFM, Zymospore^®, improves the performance of broiler chickens under experimental challenge conditions as effective as an AGP, providing a safe and effective substitute to the poultry industry.

Repeated Inoculation of Young Calves With Rumen Microbiota Does Not Significantly Modulate the Rumen Prokaryotic Microbiota Consistently but Decreases Diarrhea

The complex rumen microbiota exhibits some degree of host specificity. The undeveloped simple rumen microbiota is hypothetically more amendable. The objective of this study was to investigate if the rumen prokaryotic microbial assemblage of young calves can be reprogrammed by oral inoculation with rumen microbiota of adult cows. Twenty newborn male calves were randomly assigned to four groups (n = 5 per group), with two groups being orally inoculated with rumen microbiota (fresh rumen fluid) collected from two lactating dairy cows, while the other two groups receiving autoclaved rumen fluid collected from another two donor cows. Each calf was orally drenched with 100, 200, 300, 400, and 500 mL of the rumen fluid at d3, d7, d21, d42, and d50, respectively, after birth. The inoculation with rumen microbiota did not affect (P > 0.05) feed intake, average daily gain (ADG), heart girth, or feed conversion ratio but significantly (P < 0.01) lowered instance of diarrhea. At the age of 77 days (27 days post-weaning), all the calves were slaughtered for the sampling of rumen content and determination of empty rumen weight. Rumen fermentation characteristics were not affected (P > 0.05) by the inoculation. Rumen prokaryotic microbiota analysis using metataxonomics (targeting the V4 region of the 16S rRNA genes) showed that the calf rumen prokaryotic microbiota differed from that of the donors. Two Succinivibrionaceae OTUs, two Prevotella OTUs, and one Succiniclasticum OTU were predominant (relative abundance > 2%) in the donors, but only one Succinivibrionaceae OTU was found in the calves. On the other hand, five other Prevotella OTUs were predominant (>3%) in the calves, but none of them was a major OTU in the donors. No correlation was observed in relative abundance of major OTUs or genera between the donor and the calves. Principal coordinates analysis (PCoA) based on weighted UniFrac distance showed no significant (P > 0.05) difference in the overall rumen prokaryotic microbiota profiles among the four calf groups, and principal component analysis (PCA) based on Bray-Curtis dissimilarity showed no significant (P > 0.05) difference in functional features predicted from the detected taxa. Nor the calf rumen microbiota showed any clustering with their donor's. Repeated oral inoculation with rumen microbiota probably has a limited effect on the development of rumen microbiota, and the rumen microbiota seems to develop following a program determined by the host and other factors.

Influence of Nigella sativa seeds, Rosmarinus officinalis leaves and their combination on growth performance, immune response and rumen metabolism in Dorper lambs

The objective of this study was to determine the effects of dietary supplementation of Nigella sativa L. seeds, Rosmarinus officinalis L. leaves and their combination on rumen metabolism, nutrient intake and digestibility, growth performance, immune response and blood metabolites in Dorper lambs. Twenty-four entire male Dorper lambs (18.68 ± 0.6 kg, 4-5 months old) were randomly assigned to a concentrate mixture containing on a dry matter basis either, no supplement (control, T1), 1% R. officinalis leaves (T2), 1% N. sativa seeds (T3) or 1% R. officinalis leaves +1% N. sativa seeds (T4). The lambs had ad libitum access to urea-treated rice straw (UTRS) and were raised for 90 days. Supplemented lambs had greater (P < 0.05) intake of DM and UTRS than the control lambs. The T4 lambs had lower (P < 0.05) nutrient digestibility than those fed other treatments. Total and daily weight gain was greater (P < 0.05) in T2 lambs than those fed other diets. The T3 and T4 lambs had greater (P < 0.05) ruminal pH than the T1 and T2 lambs. Supplemented lambs had lower (P < 0.05) ruminal total volatile fatty acids, acetate, propionate, NH₃-N and C18:0 than the control lambs. The T4 lambs had lower (P < 0.05) population of Fibrobacter succinogenes, Ruminococcus albus, methanogens and total protozoa compared with those fed other diets. Supplemented lambs had lower (P < 0.05) neutrophils, basophils and serum urea and greater (P < 0.05) serum IgA and IgG compared with the control lambs. The current results emphasised the variation in the efficacy of medicinal plants in ruminant nutrition.

Time dependent effect of gentamicin on enzymes of carbohydrate metabolism and terminal digestion in rat intestine

Gentamicin (GM) is an aminoglycoside antibiotic commonly used against life threatening gram negative bacterial infections, however, nephrotoxicity remains the major concern for its long term use. Although its effects on kidney are well characterized but there have been no studies regarding its effects on intestine. We hypothesize that GM causes adaptive coordinated effect on enzymes of carbohydrate metabolism and terminal digestion/ absorption in rat intestine. Rats were administerd a nephrotoxic dose of GM (80 mg /kg body weight) daily for 15 days and a time dependent effect was observed on various enzyme activities. Activities of lactate (LDH), malate (MDH) and isocitrate (ICDH) dehydrogenases, significantly increased and peaked at different time intervals of GM treatment. Whereas LDH activity remained higher, MDH and ICDH activity slowly declined from their peak values. Activities of fructose-1,6-bisphosphatase, glucose-6-phosphatase and glucose-6-phosphate dehydrogenase increased but malic enzyme decreased in a time dependent manner. Activity of alkaline phosphatase and sucrase significantly increased but γ-glutamyl transpeptidase activity decreased. GM administration increased lipid peroxidation, glutathione peroxidase but decreased superoxide dismutase and catalase activities. The results indicate that GM treatment selectively upregulated certain enzymes of carbohydrate metabolism and terminal digestion/absorption and perturbed antioxidant defenses. Human & Experimental Taxicology, ( 2007) 26, 587—593.

Controlling Salmonella infection in weanling pigs through water delivery of direct-fed microbials or organic acids: Part II. Effects on intestinal histology and active nutrient transport

The objective of this study was to evaluate the effects of water-delivered, direct-fed microbials (DFM) or organic acids on intestinal morphology and active nutrient absorption in weanling pigs after deliberate Salmonella infection. Pigs (n = 88) were weaned at 19 ± 2 d of age and assigned to 1 of the following treatments, which were administered for 14 d: 1) control diet; 2) control diet + DFM (Enterococcus faecium, Bacillus subtilis, and Bacillus licheniformis) in drinking water at 10(9) cfu/L for each strain of bacteria; 3) control diet + organic acid-based blend (predominantly propionic, acetic, and benzoic acids) in drinking water at 2.58 mL/L; and 4) control diet + 55 mg/kg carbadox. Pigs were challenged with 10(10) cfu Salmonella enterica var Typhimurium 6 d after commencement of treatments. Pigs (n = 22/d) were harvested before Salmonella challenge and on d 2, 4, and 8 after challenge. Duodenal, jejunal, and ileal mucosal tissues were sampled for measurement of villus height and crypt depth. Jejunal tissue was sampled for determination of active nutrient absorption in modified Ussing chambers. Duodenal villus height was greater in pigs fed in-feed antibiotic before infection (P < 0.05). Jejunal crypts were deeper in DFM- and acid-treated pigs on d 4 after infection compared with all other treatments (P < 0.05). Salmonella infection resulted in a linear decrease in phosphorus (P < 0.001) and glucose (P < 0.05) active transport, and an increase (P < 0.001) in glutamine uptake immediately after challenge. Salmonella infection reduced basal short-circuit current (I(sc)); however, water-delivered DFM or organic acid treatments caused greater basal I(sc) on d 2 after challenge than did carbadox. Carbachol-induced chloride ion secretion was greatest in negative control pigs before infection (P < 0.01) and DFM-treated pigs (P < 0.05) after infection. In conclusion, both the DFM and acidification treatments induced increases in basal active ion movement and jejunal crypt depth, which could be interpreted as responses consistent with increased Salmonella pathology, but none of the additives markedly affected intestinal absorptive and secretory function in response to Salmonella challenge.

Investigation of endogenous metabolic changes in the urine of pseudo germ-free rats using a metabolomic approach

Gut microflora are recognized as an active metabolic compartment in whole body systems. Understanding their impact on host physiology is an ongoing process, although many studies demonstrate that they play significant roles in host life. To assess the impact of gut microflora on host physiology in normal or close to normal conditions of the intestine, we prepared pseudo germ-free rats by antibiotic treatment, and we investigated urinary metabolite profiles of pseudo germ-free rats using UPLC-QTOF-MS based on metabolomics. The repeatability and stability of the analysis were evaluated using QC samples and testmixes in both positive and negative ionization modes. When data sets were analyzed with OPLS-DA, 25 metabolites related to the activities of gut microflora were identified. The changes of amino acid metabolism, especially aromatic or sulfur amino acids, and alternations of bioactive nutrients, such as isoflavonoid and riboflavin were observed in the pseudo germ-free rats. Among the sulfur amino acid metabolites, the metabolites reflecting oxidative stress increased in the urine of pseudo germ-free animals, which imply that the activities of intestinal microorganisms can affect the host redox homeostasis. Altered isoflavonoid metabolism due to lack of gut bacteria may impact on steroid hormone metabolism in the body, especially estrogen metabolism. These results indicate that the some essential metabolic pathways are sensitive to the activities of gut microorganism and directly or indirectly affected by the state of intestinal bacteria, thus gut microflora plays an important role in whole body physiology.

Physiology, regulation and multifunctional activity of the gut wall: a rationale for multicompartmental modelling

A rationale is given for a modelling approach to identify the mechanisms involved in the functioning and metabolic activity of tissues in the wall of the gastrointestinal tract. Maintenance and productive functions are discussed and related to the distinct compartments of the gastrointestinal tract and the metabolic costs involved. Functions identified are: tissue turnover; tissue proliferation; ion transport; nutrient transport; secretions of digestive enzymes, mucus and immunoglobulins; production of immune cells. The major nutrients involved include glucose, amino acids and volatile fatty acids.In vivomeasurements of net portal fluxes of these nutrients in pigs and ruminants are evaluated to illustrate the complexity of physiology and metabolic activity of the gastrointestinal tract. Experimental evidence indicates that high, but variable and specific, nutrient costs are involved in the functioning of the gastrointestinal tract.

the influence oflentinus edodes(shiitake mushroom) preparations on bacteriological and morphological aspects of the small intestine in piglets

Among substances intended to replace growth promoting antibiotics in pig nutrition, non-digestible oligosaccharides or polysaccharides could be potential alternative compounds. Therefore, the influence of beta-1,3-1,6 glucans on bacteriological, biochemical and morphological aspects of the small intestine in weaned piglets was investigated. As sources of beta-glucans, Lentinan (extract of Lentinus edodes mycelium) or dried L. edodes mycelium were added to the diet. Four homogenous groups of 5 newly weaned piglets (4 weeks of age) received one of four diets: control diet (C), C supplemented with Avilamycin (50 mg/kg, positive control), C supplemented with 0.1% of Lentinan and C supplemented with 5% of dried L. edodes mycelium powder. A first group of 10 piglets was euthanized after 11 days and the remaining 10 on day 12 of the experiment. The gastrointestinal tract was divided in segments and samples taken from digesta (stomach, proximal and distal jejunum, caecum), mucosal scrapings (jejunum) and ring shaped tissue samples (1 cm) of proximal and distal jejunum. Bacterial counts were made with digesta and mucosal samples, and short-chain fatty acids (SCFA), lactic acid and ammonia concentrations were determined. Tissue samples of both jejunal sites were embedded in paraffin wax for morphometrical (villus length, crypt depth) and histological observations (numbers of intraepithelial lymphocytes (IEL), goblet cells, apoptotic enterocytes on villi, mitotic cells in crypts). Only the diet containing 5% of dried L. edodes consistently resulted in lower viable counts (ca. 1-2 log10 CFU) of total bacteria, E. coli, streptococci and lactic acid bacteria, and luminal and mucosal effects agreed very well. With this diet, acetate and butyrate concentrations in the distal jejunum were doubled, which is favourable in view of the trophic effect on enterocytes and colonocytes. Villus length (V) was increased with both diets containing beta-glucans while crypt depth (C) was not altered, but V/C was higher. IEL counts were decreased by both diets although bacterial numbers, which is only one parameter of bacterial load, were only diminished with the L. edodes feed. The three supplemented feeds lowered the number of apoptotic enterocytes on the villi, but these numbers were very low (control diet : 44 cells per 100 villi), making clear interpretation difficult. The mitotic index was slightly lower with the L. edodes feed, although not statistically significant. Decreased viable counts observed with the latter diet is a favourable effect as it is accepted that a lower bacterial load causes lower turnover rates of the intestinal epithelial cells, while there is also less competition for specific substrates. A higher V/C ratio, a smaller number of IEL in the epithelium and a lower apoptotic index also indicate slower turnover rate of the mucosa when Lentinan and L. edodes diets were fed. The inconsistent effects observed with Lentinan were probably due to the low amount added to the diet. It should be taken into account that the influence of L. edodes mycelium powder was more likely due to the presence of antibacterial compounds (eg. lenthionine, lentinamycin, terpenoids, polyphenols), rather than to an immunostimulating action of beta-glucans with increased release of IgA onto the mucosa surface.

Effects of live cultures of Lactobacillus acidophilus (strains NP45 and NP51) and Propionibacterium freudenreichii on performance, carcass, and intestinal characteristics, and Escherichia coli strain O157 shedding of finishing beef steers

In Exp. 1, 240 beef steers (initial BW = 332.8 kg) were used to determine the effects of Lactobacillus acidophilus (LA) plus Propionibacterium freudenreichii (PF) on performance, carcass, and intestinal characteristics; serum IgA concentrations; and the prevalence of Escherichia coli O157 (EC). Cattle were fed a steam-flaked corn-based, 92% concentrate diet, and the four direct-fed microbial (DFM) treatments (12 pens/treatment) included in a randomized complete block design were as follows: 1) control, lactose carrier only (CON); 2) 1 x 10(9) cfu of LA NP51 plus 1 x 10(6) cfu of LA NP45 plus 1 x 10(9) cfu of PF NP24 per animal daily (LA45-51H); 3) 1 x 10(9) cfu of LA NP51 plus 1 x 10(9) cfu of PF NP24 per animal daily (LA51); and 4) 1 x 10(6) cfu of LA NP51 plus 1 x 10(6) cfu of LA NP45 plus 1 x 10(9) cfu of PF NP24 per animal daily (LA45-51L). No differences (P > 0.10) were detected for pen-based performance data. The average lamina propria thickness for LA51 and LA45-51H steers was less (P = 0.02) than the average for CON and LA45-51L steers. Moreover, LA51 and LA45-51H steers had a lower (P = 0.06) prevalence of EC shedding than CON and LA45-51L steers. In Exp. 2, 660 steers fed 91% concentrate, steam-flaked corn-based diets were used to determine the effects of the following DFM treatments (10 pens/treatment) on performance, carcass, and intestinal characteristics: 1) control, lactose carrier only (CON); 2) 5 x 10(6) cfu of LA NP51 plus 5 x 10(6) cfu of LA NP45 plus 1 x 10(9) cfu of PF NP24 per animal daily (LA45-51L); and 3) 1 x 10(9) cfu of LA NP51 plus 5 x 10(6) cfu of LA NP45 plus 1 x 10(9) cfu of PF NP24 per animal daily (LA45-51H). Steers were from two weight groups (WG). One group (SDOF; BW at arrival = 351.5 kg) had grazed before arrival, and the other group (LDOF; BW at arrival = 314 kg) had been in a grower yard. A split plot was used with WG as the whole-plot factor and DFM in the split plot. There was an interaction of WG and DFM for ADG (P = 0.05) and for carcass-adjusted ADG (P = 0.08). The simple-effect ADG and carcass-adjusted ADG means for DFM treatments differed (P < or = 0.01) between WG classifications. Within SDOF, ADG for CON and LA45-51L did not differ (P = 0.70), but both were less (P < or = 0.08) than for LA45-51H. Overall, these data indicate that live cultures of LA plus PF did not greatly affect feedlot performance and carcass characteristics. Some of the DFM used decreased fecal EC shedding, which might be related to the results for ileal lamina propria thickness.

Glucose and [13C]leucine metabolism by the portal-drained viscera of sheep fed on dried grass with acute intravenous and intraduodenal infusions of glucose

The effect of exogenous glucose supply by either intrajugular (IJG) or intraduodenal (IDG) infusion at 2.0 mg glucose/kg body weight per min was investigated in four wether sheep (average weight 44 (SD 4) kg) chronically catheterized in the carotid artery and portal veins. Sheep were fed on a dried grass pellet diet hourly using continuous belt feeders. Whole-body glucose irreversible loss (IL) rate, measured with [6-3H]glucose, was increased by 0.5 and 0.8 of exogenous supply for IJG and IDG infusions respectively. Portal glucose utilization, measured by isotope dilution across the portal-drained viscera, was unaffected by additional glucose regardless of the route of glucose supply (P = 0.76 for control v. glucose infusions) and was a constant proportion of glucose IL (0.28) for all treatments. Portal plasma flow was higher during IDG infusions compared with IJG infusions (1.65 v. 1.44 litres/min, P = 0.055). Circulating total free amino acid concentrations fell during glucose infusions (2146, 1808 and 1683 mumol/l for control, IJG and IDG treatments respectively, P = 0.067 for treatment effect) but net portal absorption was not affected by increased glucose supply. Recovery in the portal vein of [1-13C]leucine infused into the duodenum averaged 0.65 and was not affected by increasing glucose supply to the gut tissues. The results show that glucose utilization by gut tissues is responsive to changes in both vascular and luminal glucose supply. The effects of changing gut tissue use of glucose and increased whole body glucose IL on metabolism of nutrients is discussed.

Amino acid use by the gastrointestinal tract of sheep given lucerne forage

Essential amino acid (EAA) utilization by gastrointestinal tract (GIT) tissues has been investigated in sheep given 800 and 1,200 g/day lucerne pellets. Animals prepared with indwelling catheters into the aorta and the portal drained viscera plus cannulas into the small intestine were infused with mixed U-13C-labeled amino acid or (1-13C]leucine tracers into the jugular vein or directly into the small intestine. GIT sequestration of EAA from arterial and luminal AA pools was determined from tracer and tracee arterioportal concentration differences at both levels of intake. Proportional tracer 13C-labeled EAA extraction of the arterial supply, on first pass across the GIT during jugular infusion, ranged from 0.063 for histidine to 0.126 for leucine. Recovery of intestinally infused tracer 13C-EAA at the portal vein ranged from 0.61 for histidine to 0.83 for valine. These data were independent of intake. Calculated rates of tracee sequestration by GIT tissues represented 0.45-0.65 of whole body EAA flux, except for histidine, for which the values were much lower (0.25-0.32). With the exception of phenylalanine, more than 0.8 of the EAA used by the GIT was extracted from circulating blood, thus calling into question the theory that GIT tissues make preferential use of EAA during absorptive metabolism, restricting supply to peripheral tissues such as skeletal muscle (growth) or mammary glands (lactation). Instead the GIT seems to compete very successfully with these tissues for circulating blood EAA.

A clinical trial of probiotic administration for prevention of Salmonella shedding in the postoperative period in horses with colic

The purpose of this study was to evaluate the effects of probiotic administration on the prevalence of fecal shedding of Salmonella, the prevalence of postoperative diarrhea, the length of antimicrobial therapy, and the length of the hospitalization stay during the postoperative period in horses with colic. Two commercially available probiotics for horses were used in a double-blind prospective study of 200 horses undergoing surgery for colic. Probiotic or placebo was administered PO once a day for 7 days postoperatively, and fecal cultures for Salmonella were obtained daily for 10 days. After selection of 186 patients completing the treatment protocol, the results indicated that the commercial probiotic formulations had no effect on Salmonella shedding, prevalence of diarrhea, length of antimicrobial therapy, or length of hospitalization (P > .05). Twenty percent of the horses yielded 1 or more positive fecal cultures for Salmonella; of these horses, 74% were classified as asymptomatic shedders. Twenty-six percent of all horses had fluid diarrhea postoperatively, with only 12% of these horses having positive fecal cultures for Salmonella. The most common isolate was Salmonella krefeld (24 of 39 isolates). Among the different gastrointestinal disorders, horses with feed and sand impactions appeared to be more prone to shed Salmonella.

Nutrient metabolism by gut tissues

The gut uses a disproportionate amount of energy (about 25% of total oxygen consumption) for the size of the tissue (about 6% of body weight). Therefore, knowledge of metabolites used in gut tissues is important to assess nutrient needs. The VFA produced intraruminally are used to varying degrees by rumen epithelial tissue. A review of net portal absorption data essentially confirms earlier studies that show acetate, propionate, and butyrate metabolism by stomach tissue to be 30, 50, and 90%, respectively, of ruminant production. Glucose also is used by rumen epithelial tissue; however, glutamine appears to be a poor substrate for energy production. Tissue of the small intestine uses glutamine, glucose, and ketones but does not use VFA very well for energy. Cecal and colonic tissues can use glucose and glutamine for energy, but butyrate is the preferred substrate in both tissues.

Glutamine is a potentially limiting amino acid for milk production in dairy cows: a hypothesis

Recently, extensive research has been focused on glutamine because of its key position between energy and protein metabolism. Evidence is growing that glutamine is essential in situations of metabolic stress; practical application of this knowledge can already be found in parenteral nutrition of severely ill patients. Furthermore, glutamine is claimed to increase muscle protein synthesis. Glutamine and its counterpart, glutamic acid, are the most abundant amino acids in milk protein. Nevertheless, the role of nonessential amino acids (NEAA) in milk protein synthesis in high-yielding dairy cows has been practically neglected during the past 20 years. Evaluating current literature on glutamine metabolism in ruminants with emphasis on data related to milk protein production, we conclude the following: (1) Ruminants have a relatively low glutamine synthetase capacity compared with monogastric species, reflected in relatively low plasma glutamine levels; (2) The uptake of glutamine by the mammary gland is effectively 100% of the arterial supply; (3) Milk production in high-yielding dairy cows represents a metabolic stress comparable to fasting or acidosis; and (4) Responses of plasma and tissue glutamine pools in conditions of "metabolic stress," including high milk production, resemble those of most essential amino acids (EAA). Therefore we hypothesize that glutamine, although regarded as a NEAA, limits milk protein synthesis in high-yielding dairy cows.