Impact of diets with a high content of greaves-meal protein or carbohydrates on faecal characteristics, volatile fatty acids and faecal calprotectin concentrations in healthy dogs

Effects of fecal microbial transplantation on police performance and transportation stress in Kunming police dogs

Fecal microbiota transplantation (FMT) has been shown to improve gut dysbiosis in dogs; however, it has not completely been understood in police dogs. This study aimed to investigate the effects of FMT on performance and gut microflora in Kunming police dogs. Twenty Wolf Cyan dogs were randomly assigned to receive physiological saline or fecal suspension at low, medium, or high doses through oral gavage for 14 days. Growth performance, police performance, serum biochemical profiling, and gut microflora were determined 2-week post-FMT. Dogs after FMT treatment were also subjected to an hour road transportation and then were evaluated for serum stress indicators. Overall, FMT enhanced the growth performance and alleviated diarrhea rate in Kunming dogs with the greatest effects occurring in the low dose FMT (KML) group. The improvement of FMT on police performance was also determined. These above alterations were accompanied by changed serum biochemical parameters as indicated by elevated total protein and albumin and reduced total cholesterol and glycerol. Furthermore, the serum stress indicators after road transportation in dog post-FMT significantly decreased. Increased bacterial diversity and modified bacterial composition were found in the feces of dogs receiving FMT. The fecal samples from FMT dogs were characterized by higher abundances of the genera Lactobacillus, Prevotella, and Fusobacterium and lower concentrations of Cetobacterium, Allobaculum, Bifidobacterium, and Streptococcus. The present study supports a potential benefit of FMT on police performance in Kunming dogs. KEY POINTS: • FMT improves the growth performance and reduces diarrhea rates in Kunming police dogs. • FMT alleviates the serum stress profiles after road transportation in Kunming police dogs. • FMT modifies the gut microbiota composition of Kunming police dogs.

Large intestinal nutritional and physicochemical parameters from different dog sizes reshape canine microbiota structure and functions in vitro

Different dog sizes are associated with variations in large intestinal physiology including gut microbiota, which plays a key role in animal health. This study aims to evaluate, using the CANIM-ARCOL (Canine Mucosal Artificial Colon), the relative importance of gut microbes versus physicochemical and nutritional parameters of the canine colonic environment in shaping microbiota structure and functions. CANIM-ARCOL was set up to reproduce nutrient availability, bile acid profiles, colonic pH, and transit time from small, medium, or large dogs according to in vivo data, while bioreactors were all inoculated with a fecal sample collected from medium size dogs (n = 2). Applying different dog size parameters resulted in a positive association between size and gas or SCFA production, as well as distinct microbiota profiles as revealed by 16S Metabarcoding. Comparisons with in vivo data from canine stools and previous in vitro results obtained when CANIM-ARCOL was inoculated with fecal samples from three dog sizes revealed that environmental colonic parameters were sufficient to drive microbiota functions. However, size-related fecal microbes were necessary to accurately reproduce in vitro the colonic ecosystem of small, medium, and large dogs. For the first time, this study provides mechanistic insights on which parameters from colonic ecosystem mainly drive canine microbiota in relation to dog size. The CANIM-ARCOL can be used as a relevant in vitro platform to unravel interactions between food or pharma compounds and canine colonic microbiota, under different dog size conditions. The potential of the model will be extended soon to diseased situations (e.g. chronic enteropathies or obesity).

Do high-protein diets have the potential to reduce gut barrier function in a sex-dependent manner?

PURPOSE

Impaired gut barrier function is associated with systemic inflammation and many chronic diseases. Undigested dietary proteins are fermented in the colon by the gut microbiota which produces nitrogenous metabolites shown to reduce barrier function in vitro. With growing evidence of sex-based differences in gut microbiotas, we determined whether there were sex by dietary protein interactions which could differentially impact barrier function via microbiota modification.

METHODS

Fermentation systems were inoculated with faeces from healthy males (n = 5) and females (n = 5) and supplemented with 0.9 g of non-hydrolysed proteins sourced from whey, fish, milk, soya, egg, pea, or mycoprotein. Microbial populations were quantified using fluorescence in situ hybridisation with flow cytometry. Metabolite concentrations were analysed using gas chromatography, solid phase microextraction coupled with gas chromatography-mass spectrometry and ELISA.

RESULTS

Increased protein availability resulted in increased proteolytic Bacteroides spp (p < 0.01) and Clostridium coccoides (p < 0.01), along with increased phenol (p < 0.01), p-cresol (p < 0.01), indole (p = 0.018) and ammonia (p < 0.01), varying by protein type. Counts of Clostridium cluster IX (p = 0.03) and concentration of p-cresol (p = 0.025) increased in males, while females produced more ammonia (p = 0.02), irrespective of protein type. Further, we observed significant sex-protein interactions affecting bacterial populations and metabolites (p < 0.005).

CONCLUSIONS

Our findings suggest that protein fermentation by the gut microbiota in vitro is influenced by both protein source and the donor's sex. Should these results be confirmed through human studies, they could have major implications for developing dietary recommendations tailored by sex to prevent chronic illnesses.

Effects of Heat-Treated Bifidobacterium longum CECT-7384 Combined with Fibersol-2 on the Intestinal Health of Cats Submitted to an Abrupt Dietary Change: A Randomized Controlled Study

Abrupt dietary change can disrupt the intestinal balance in felines. This study aimed to assess the impact of heat-treated Bifidobacterium longum CECT-7384 combined with Fibersol-2 on the intestinal health of adult cats before and after dietary change. We selected 24 British shorthair cats, dividing them into two groups. From day 1 to day 14, the control group received a lower protein (33%) concentration (LPF) diet, while the treated group received the same LPF diet supplemented with 0.16% functional additives, consisting of Bifidobacterium longum CECT-7384 combined with Fibersol-2. Subsequently, from day 15 to day 28, the control group transitioned to a higher protein (40%) concentration (HPF) diet, while the treated group received the same HPF diet supplemented with 0.16% functional additives. Blood and fresh feces were collected on day 0, 14, 17, 21, and 28 of the experiment. The results suggest that the use of heat-treated Bifidobacterium longum CECT-7384 combined with Fibersol-2 may improve gastrointestinal function in cats by reducing serum LPS levels and fecal pH, while increasing fecal sIgA levels. In addition, the functional additive regulates the fecal microbiota and its function, promoting intestinal homeostasis and colonization with beneficial bacteria such as Blautia. Furthermore, on day 28, there was a significant difference in fecal microbiota beta diversity between the two groups. In summary, the addition of heat-treated Bifidobacterium longum CECT-7384 combined with Fibersol-2 contributes to improving the intestinal health of adult cats affected by abrupt dietary change.

Faecal metabolome responses to an altered dietary protein:carbohydrate ratio in adult dogs

High-protein diets may aid weight loss and weight maintenance programs in both humans and dogs, although the effect of dietary protein levels on gut metabolism and functionality has not been studied in depth. The current study aimed to investigate the effect of an altered dietary protein:carbohydrate ratio on gut function in adult dogs by means of faecal metabolomic fingerprinting. More specifically, functional metabolic differences in dogs fed a high-protein/low-carbohydrate (HPLC) vs. low-protein/high-carbohydrate (LPHC) diet were studied by equally allocating twelve clinically healthy (6 lean and 6 obese) Beagles into two groups in a cross-over design, with each group receiving two isocaloric diets for four weeks. The faecal metabolome revealed that different protein:carbohydrate ratio can influence host and/or gut microbiome metabolism and function, while no effect was observed on the body condition. Targeted analysis demonstrated that the HPLC diet significantly increased the concentration of indole, spermidine, and pipecolinic acid and decreased the concentration of azelaic acid, D-fructose, mannose, and galactose (p < 0.05). Multivariate modelling (OPLS-DA) of the untargeted faecal metabolome revealed distinctly different metabolomic profiles following the HPLC vs. LPHC diet, with 18 altered pathways. The HPLC diet influenced amino acid and lipid metabolism, potentially promoting weight loss and immune function, whereas the LPHC diet affected carbohydrate fermentation and may promote anti-oxidative function.

Clinical Effects of Faecal Microbiota Transplantation as Adjunctive Therapy in Dogs with Chronic Enteropathies—A Retrospective Case Series of 41 Dogs

Chronic enteropathies (CE) are common in dogs, but not all affected dogs respond to standard therapy. Successful responses to faecal microbial transplantation (FMT) in dogs with non-responsive CE have been reported in two case series. The objective of this retrospective study was to describe the clinical effects of FMT as an adjunctive therapy in a larger population of dogs with CE. Forty-one dogs aged 0.6–13.0 years (median 5.8) under treatment for CE at one referral animal hospital were included. Dogs were treated with 1–5 (median 3) FMTs as a rectal enema at a dose of 5–7 g/kg body weight. The canine inflammatory bowel disease activity index (CIBDAI) was compared at baseline versus after the last FMT. Stored faecal samples (n = 16) were analysed with the dysbiosis index. CIBDAI at baseline was 2–17 (median 6), which decreased to 1–9 (median 2; p < 0.0001) after FMT. Subsequently, 31/41 dogs responded to treatment, resulting in improved faecal quality and/or activity level in 24/41 and 24/41 dogs, respectively. The dysbiosis index at baseline was significantly lower for good responders versus poor responders (p = 0.043). Results suggest that FMT can be useful as an adjunctive therapy in dogs with poorly responsive CE.

Clostridioides difficile-mesocolonic oedema in neonatal suckling piglets develops regardless of the fibre composition in sow's diets

Maternal dietary factors have been reported to influence Clostridioides difficile colonisation in the offspring. Twenty suckling piglets from sows fed diets supplemented with high-fermentable sugar beet pulp (SBP) or low-fermentable lignocellulose (LNC) fibres during gestation and lactation were dissected in the first week after birth. Postmortem analysis included clinical mesocolon and faecal scoring, concentration of C. difficile and respective toxins in colon digesta and faeces, immunoglobulins in serum and inflammatory markers in serum and colon tissues. Sow colostrum was assessed for nutrients, immunoglobulins and biogenic amines. Toxin-neutralising IgG antibodies were measured in colostrum and serum of the sows, and in colon digesta and serum of the piglets. Mesocolonic oedema of different severity was present in most of the piglets from both sows' feeding groups. Concentrations of C. difficile, toxins and calprotectin in colon digesta and faecal contents did not differ between the study piglets. Calprotectin correlated positively with mesocolon score (rho = 413, P = 0.07). Piglets from sows fed LNC vs SBP tended to have higher IgA (P = 0.089), IgG (P = 0.053), total Ig (P = 0.053), albumin (P = 0.075) and total protein content (P = 0.007) in serum. Colon tissues of piglets from the SFB vs LNC had upregulated expression of ZO-1 (P = 0.021), PCNA (P = 0.015) and TGF-β (P = 0.014). Titers of anti-toxin-IgG-antibodies in serum and colostrum and in piglet colon digesta and serum did not differ between sows from both dietary groups, but they all showed strong positive correlations. In conclusion, dietary sugar beet pulp or lignocellulose fed to sows did not influence the concentrations of C. difficile and toxins titers in colon digesta and faeces of neonatal piglets.

Effects of hydrolyzed chicken liver on digestibility, fecal and urinary characteristics, and fecal metabolites of adult dogs

High-protein low-carbohydrate diets have been widely used for adult maintenance dogs, as well as in specific weight loss diets and maintenance programs. However, increasing dietary protein may increase undigested protein in the hindgut, modifying intestinal fermentation and fecal metabolite concentrations. The aim of this study was to evaluate the effects of protein source and concentration on apparent total tract digestibility (ATTD) of nutrients, metabolizable energy (ME), fecal and urinary characteristics, and fecal metabolites of dogs. Twelve healthy adult dogs were distributed into six treatments (n = 6 per diet) in a balanced incomplete Latin square design consisting of three periods of 30 days each. Six diets, varying in protein source [poultry byproduct meal (PBPM) and hydrolyzed chicken liver powder (HCLP)] and concentration [24, 32, and 40% crude protein (CP) on dry matter (DM) basis] were tested: PBPM24 (PBPM based diet with 24% CP); PBPM32 (PBPM with 32% CP); PBPM40 (PBPM with 40% CP); HCLP24 (HCLP based diet with 24% CP); HCLP32 (HCLP with 32% CP); HCLP40 (HCLP with 40% CP). The ATTD of CP was greater in dogs-fed HCLP and higher protein concentrations diets (P < 0.05). However, dogs-fed HCLP diets had lower ATTD of fat and carbohydrates, and ME (P < 0.05). Similarly, high-protein diets reduced the ATTD of DM, OM, fat, carbohydrates, and energy (P < 0.05). High-protein diets increased the daily fecal output and moisture (P = 0.004 and P < 0.05, respectively), as well as the fecal score (P < 0.0001), verified as soft, moist stools, but still within the ideal range. Fecal valerate concentration was greater in dogs-fed PBPM at 32% CP (P = 0.007). Fecal isobutyrate tended to increase in dogs-fed PBPM and high-protein diets (P < 0.10). Also, dogs-fed PBPM and high-protein diets had greater fecal concentrations of isovalerate, branched-chain fatty acids (BCFA), and ammonia (P < 0.05). Finally, the fecal lactate concentration increased in dogs-fed HCLP and high-protein diets (P < 0.05). The HCLP increased the ATTD of CP, being a highly digestible protein. Although the inclusion of HCLP slightly increased fecal score and moisture, it decreased the amount of fecal metabolites of protein fermentation ammonia and BCFA, both of which are associated with proteolytic fermentation in the colon.

Analysis and Comparison of Gut Microbiome in Young Detection Dogs

The detection dogs are well-known for their excellent capabilities to sense different kinds of smells, which can play an important role in completing various searching and rescuing missions. The recent studies have demonstrated that the excellent olfactory function of detection dogs might be related with the gut microbes via the bidirectional communications between the gastrointestinal tract and the brain. In this study, the gut microbial communities of three types of breeds of detection dogs (Springer Spaniel, Labrador Retriever, and German Shepherd) were studied and compared. The results revealed that the richness and the diversity of gut microbiome German Shepherd dogs were significantly higher than the Labrador Retriever dogs and the Springer Spaniel dogs. At the phylum level, the most predominant gut microbial communities of the detection dogs were comprised of Fusobacteriota, Bacteroidetes, Firmicutes, Proteobacteria, Campilobacterota, and Actinobacteriota. At the genus level the most predominant gut microbial communities were comprised of Fusobacterium, Megamonas, Prevotella, Alloprevotella, Bacteroides, Haemophilus, Anaerobiospirillum, Helicobacter, Megasphaera, Peptoclostridium, Phascolarctobacterium, and Streptococcus. However, the gut microbial communities of the three dogs group were also obviously different. The mean relative abundance of Fusobacterium, Prevotella, Alloprevotella, Megamonas, Bacteroides, and Phascolarctobacterium presented significant differences in the three groups. According to the portraits and characteristics of the gut microbiome in young detection dogs, multiple kinds of nutritional interventions could be applied to manipulate the gut microbiota, with the aim of improving the health states and the olfactory performances.

Effects of valerate on intestinal barrier function in cultured Caco-2 epithelial cell monolayers

BACKGROUND

Short-chain fatty acids (SCFAs) are a group of microbial metabolites of undigested dietary fiber, protein and unabsorbed amino acids in the colon, well-known for their gut health promoting benefits. A relatively high intestinal level of valerate was found in the healthy human subjects. However, the intestinal protection effects and the underlying mechanism of valerate are waiting to be verified and elucidated.

METHODS AND RESULTS

In the present study, valerate, a SCFAs mainly converted from proteins or amino acids, was demonstrated to promote intestinal barrier function at its physiological concentrations of 0-4 mM in the Caco-2 cell monolayer model of intestinal barrier using transepithelial electrical resistance (TEER) assay and paracellular permeability assay. Valerate achieved the maximum increase in the TEER at 2 mM and reduced the paracellular permeability. Its intestinal barrier function promoting activity is similar to that of butyrate, with a broader range of effective concentrations than the later. Through western blot analysis, this activity is linked to the valerate-induced AMPK activation and tight junctions (TJs) assembly, but not to the reinforced expression of TJs related proteins.

CONCLUSIONS

It provides direct experimental evidence supporting valerate's function in intestinal health, implying the once under-valued function of valerate and its amino acid precursors. The valerate's role in regulating intestine homeostasis and its possible synergetic effects with other SCFAs warranted to be further investigated.

Dietary Protein and Carbohydrate Levels Affect the Gut Microbiota and Clinical Assessment in Healthy Adult Cats

BACKGROUND

Relative levels of dietary protein and carbohydrate intake influence microbiota and their functional capabilities, but the effect has not been well documented in cats.

OBJECTIVES

The impact of 3 foods with different protein:carbohydrate ratios on the gut microbiota and functional attributes in healthy adult cats was evaluated.

METHODS

Male and female cats (n = 30; mean age: 5.1 y; mean body weight: 5.26 kg) were fed 1 of 3 foods [P28 (28.3% protein, dry matter basis), P35 (35.1%), and P55 (54.8%)] for 90 d in a Williams Latin Square design. Each food had a 1:1 ratio of animal (dried chicken) to plant (pea) protein; protein replaced carbohydrate as protein level increased. Fecal microbiota and their functional capability were assessed with 16S sequencing and the Kyoto Encyclopedia of Genes and Genomes database, respectively.

RESULTS

Fecal pH, ammonia, and branched-chain fatty acids (BCFAs) were higher when cats consumed P55 food than when they consumed P28 and P35. Clear separation of samples between P28 and P55 based on bacterial genera was observed, with partitioning into saccharolytic and proteolytic functions, respectively. Significantly higher α diversity was seen with P55 than with P28 and P35. Amino acid metabolism, mucin foraging pathways, and urea metabolism were higher with P55 than with P28, whereas feces from cats fed P28 had higher concentrations of carbohydrate-active enzymes and enzymes involved in SCFA pathways than with P55. Bacterial genera that showed positive associations with amino acid catabolism also showed positive associations with mucin degradation.

CONCLUSIONS

Despite higher protein digestibility and less protein arriving to the colon, when healthy adult cats consumed the highest level of protein (P55), their gut microbiota exhibited higher mucin glycan foraging and amino acid metabolism, leading to higher fecal pH, ammonia, and BCFAs. This is likely due to lower availability of carbohydrate substrates and dietary fiber as protein replaced carbohydrate in the food.

Effect of dietary inclusion of dried apple pomace on faecal butyrate concentration and modulation of gut microbiota in dogs

This research aimed to evaluate the apparent total tract digestibility (ATTD) of nutrients, metabolisable energy (ME) and palatability of the diet, as well as products of intestinal fermentation and faecal microbiota of dogs fed with dried apple. For this purpose, three experiments were performed. In Experiment I, digestibility and ME of four diets containing 0%, 3%, 6% and 9% dried apple were evaluated, in addition to the faecal characteristics of the dogs. The diets were offered to eight adult dogs, distributed in double Latin square (4 × 4), totalling eight repetitions per treatment. In Experiment II, products of intestinal fermentation and faecal microbiota from 16 adult dogs fed diets containing 0% and 9% dried apple for 30 d (n = 8) were evaluated. Finally, Experiment III compared the dietary preference of 0 vs. 9% dried apple using 15 adult dogs. The inclusion of dried apple in the diet (p < 0.05) showed a linear reduction in the ATTD of dry matter (DM), crude protein (CP), and acid hydrolysed ether extract (EEA), and a linear increase in the ATTD of total dietary fibre (TDF). Consumption of 9% of dried apple increased faecal butyrate and reduced propionate and ammonia (p < 0.05). With this diet, there was also an increase (p < 0.05) in the faecal concentration of Faecalibacterium, Erysipelatoclostridium, Blautia, and Bacteroides. No differences were found in the palatability of the diets. The inclusion of up to 9% of dried apple in the diet reduces the digestibility of nutrients and does not influence the dogs' food preference; however, it improves some indicators of dogs' intestinal functionality.

Effect of sequentially fed high protein, hydrolyzed protein, and high fiber diets on the fecal microbiota of healthy dogs: a cross-over study

Background

Dietary content and environmental factors can shape the gut microbiota, and consequently, the way the gut microbiota metabolizes fats, carbohydrates, and proteins, affecting overall health of the host. We evaluated the impact of 3 diets (all meat [raw], high-insoluble fiber dry extruded diet and hydrolyzed protein dry extruded diet) on the gut microbiota of healthy dogs in a cross-over sequential study.

Results

We showed that diet can have an effect on the gut microbiome in dogs, which was influenced by the order of feeding. High-protein (all meat) diets were characterized by an increase in bacteria belonging to the Fusobacteria and Bacteroidetes phyla, whereas a high-insoluble fiber commercial diet correlated with increases in Firmicutes and Actinobacteria phyla. However, the individual dog’s baseline microbiota had the most impact on the magnitude and nature of the changes in response to dietary intervention.

Conclusion

Our results suggest that the dog fecal microbiota is driven by protein and fiber composition to different degrees in individual animals, and targeted modification of these patterns could be useful in the modulation of the gut microbiota in different diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-021-00101-8.

A review: nutrition and process attributes of corn in pet foods

Corn is one of the largest cereal crops worldwide and plays an important role in the U.S. economy. The pet food market is growing every year, and although corn is well utilized by dogs, some marketing claims have attributed a negative image to this cereal. Thus, the objective of this work was to review the literature regarding corn and its co-products, as well as describe the processing of these ingredients as they pertain to pet foods. Corn is well digested by both dogs and cats and provides nutrients. The processing of corn generates co-products such as corn gluten meal and distillers dried grains with solubles that retain quality protein, and fibrous components that dilute dietary energy. Further, corn has much functionality in extrusion processing. It may yield resistant starch under certain processing conditions, promoting colonic health. Carotenoids in corn may enhance immune support in companion animals if concentrated. Mycotoxin contamination in grains represent a health hazard but are well controlled by safety measures. Genetically modified (GM) corn is still controversial regarding its long-term potential for mutagenicity or carcinogenicity, thus more long-term studies are needed. In conclusion, the negative perception by some in the pet food market may not be warranted in pet foods using corn and its co-products.

The Effect of Fermentation of High- or Low-Tannin Fava Bean on Glucose Tolerance, Body Weight, Cardiovascular Function, and Blood Parameters in Dogs After 7 Days of Feeding: Comparison With Commercial Diets With Normal vs. High Protein

Fava bean, which is available in high- and low-tannin varieties, is not an approved pet food ingredient and was not included in the "assumed to be safe" category based on its ability to cause favism and hemolytic anemia in susceptible humans. The effects of 7-day feeding of test canine diets containing moderate protein (~27%) were compared with two control commercial diets with normal (NP, grain-containing, ~25% protein) or high protein (HP, grain-free, ~41% protein). Fava bean diets were formulated either with or without Candida utilis fermentation processing to reduce antinutritional factors. Glucose tolerance, body weight, cardiovascular function, and blood parameters were investigated in beagles fed the NP or HP diets or a randomized, crossover, 2 × 2 Latin square design of the fava bean diets: unfermented high-tannin (UF-HT), fermented high-tannin (FM-HT), unfermented low-tannin (UF-LT), and fermented low-tannin (FM-LT). After 7 days, HP decreased red blood cells (RBC) (P < 0.05) compared with NP, while FM increased RBC compared with UF. HP increased blood bicarbonate, calcium, phosphorus, urea, cholesterol, and albumin:globulin ratio while decreasing bilirubin, liver enzymes, and total protein. Sodium:potassium ratio was increased in UF-HT, decreased in FM-HT, and intermediate in LT regardless of fermentation. Blood phosphorus was increased in HT. Blood amylase was increased in FM-HT and decreased in FM-LT, being intermediate in UF regardless of fava bean variety. Blood direct bilirubin was decreased in HT regardless of fermentation. Of note, left ventricular end-systolic volume and cardiac output were increased in NP compared with HP-fed dogs, but were normal and had no significant differences among the fava bean diets. As expected, plasma taurine, cystine, and cysteine levels were increased in HP- compared with NP-fed dogs. Plasma cysteine levels were increased in HT- compared with LT-fed dogs and in FM- compared with UF-fed dogs. Taken together, these results show that fava bean appears to be safe as a dog food ingredient at least in the short term, and its nutritional value appears improved by fermentation. Moreover, blood chemistry parameters and cardiovascular function were impacted by protein content which merits further investigation with longer term feeding trials.

The potential role of the gut microbiota in shaping host energetics and metabolic rate

It is increasingly recognized that symbiotic microbiota (especially those present in the gut) have important influences on the functioning of their host. Here, we review the interplay between this microbial community and the growth, metabolic rate and nutritional energy harvest of the host. We show how recent developments in experimental and analytical methods have allowed much easier characterization of the nature, and increasingly the functioning, of the gut microbiota. Manipulation studies that remove or augment gut microorganisms or transfer them between hosts have allowed unprecedented insights into their impact. Whilst much of the information to date has come from studies of laboratory model organisms, recent studies have used a more diverse range of host species, including those living in natural conditions, revealing their ecological relevance. The gut microbiota can provide the host with dietary nutrients that would be otherwise unobtainable, as well as allow the host flexibility in its capacity to cope with changing environments. The composition of the gut microbial community of a species can vary seasonally or when the host moves between environments (e.g. fresh and sea water in the case of migratory fish). It can also change with host diet choice, metabolic rate (or demands) and life stage. These changes in gut microbial community composition enable the host to live within different environments, adapt to seasonal changes in diet and maintain performance throughout its entire life history, highlighting the ecological relevance of the gut microbiota. Whilst it is evident that gut microbes can underpin host metabolic plasticity, the causal nature of associations between particular microorganisms and host performance is not always clear unless a manipulative approach has been used. Many studies have focussed on a correlative approach by characterizing microbial community composition, but there is now a need for more experimental studies in both wild and laboratory-based environments, to reveal the true role of gut microbiota in influencing the functioning of their hosts, including its capacity to tolerate environmental change. We highlight areas where these would be particularly fruitful in the context of ecological energetics.

Varying Protein Levels Influence Metabolomics and the Gut Microbiome in Healthy Adult Dogs

The optimal ranges of protein for healthy adult dogs are not known. This study evaluated the impact of long-term consumption of foods containing low, medium, and high levels of protein on serum, urine, and fecal metabolites, and gut microbiome in beagles. Following maintenance on a prefeed food for 14 days, dogs (15 neutered males, 15 spayed females, aged 2–9 years, mean initial weight 11.3 kg) consumed the low (18.99%, dry matter basis), medium (25.34%), or high (45.77%) protein foods, each for 90 days, in a William’s Latin Square Design sequence. In serum and/or urine, metabolites associated with inflammation (9,10-dihydroxyoctadecanoic acid (DiHOME)), 12,13-DiHOME) and kidney dysfunction (urea, 5-hydroxyindole sulfate, 7-hydroxyindole sulfate, p-cresol sulfate) increased with higher protein levels in food, while one-carbon pathway metabolites (betaine, dimethylglycine, sarcosine) decreased. Fecal pH increased with protein consumed, and levels of beneficial indoles and short-chain fatty acids decreased while branched-chain fatty acids increased. Beta diversity of the fecal microbiome was significantly different, with increased abundances of proteolytic bacteria with higher protein food. Feeding dogs a high amount of protein leads to a shift to proteolytic gut bacteria, higher fecal pH, and is associated with increased levels of metabolites linked with inflammation and kidney dysfunction.

Effects of Brewer's spent grain and carrot pomace on digestibility, fecal microbiota, and fecal and urinary metabolites in dogs fed low- or high-protein diets1

Brewer's spent grain (BSG) and carrot pomace (CAP) were used as fiber sources in low- or high-protein diets in dogs. Ten adult Beagles were involved in 5 feeding periods of 19 d in a cross-over design. Experimental diets contained 7.5% of total dietary fiber (TDF) from BSG or CAP and 20% or 40% of crude protein in dry matter. A diet with 3.5% TDF from both fiber sources and 20% crude protein was used as reference. Fecal dry matter was 27% higher for diets with BSG compared to CAP (P < 0.001). Apparent fecal digestibility of crude protein was 7% to 11% higher in diets with 40% protein concentration (P < 0.001), while apparent digestibility of crude fat was 2% to 3% higher for diets with CAP (P < 0.001). Carrot pomace increased the apparent fecal digestibility of TDF, phosphorus, and magnesium (P < 0.001), while 40% protein diets had a positive impact on TDF and sodium and a negative effect on magnesium apparent fecal digestibility (P < 0.001). Inclusion of CAP increased fecal short-chain fatty acids (P = 0.010), mainly acetate (P = 0.001). i-butyrate (P = 0.001), i-valerate (P = 0.002), biogenic amines (P < 0.001), and ammonium (P < 0.001) increased with higher dietary protein levels. Diet-induced changes in the fecal microbiome were moderate. Relative abundance of Bifidobacteriales was higher for the low-protein diets (P = 0.001). To conclude, BSG and CAP can be used as fiber sources in canine diets and are well tolerated even at higher inclusion rates, the effect on microbial protein fermentation seems to be limited compared to the dietary protein level.

Bioconversion of coal to methane by microbial communities from soil and from an opencast mine in the Xilingol grassland of northeast China

BACKGROUND

The Xilingol grassland ecosystem has abundant superficial coal reserves. Opencast coal mining and burning of coal for electricity have caused a series of environmental challenges. Biogenic generation of methane from coal possesses the potential to improve economic and environmental outcomes of clean coal utilization. However, whether the microbes inhabiting the grassland soil have the functional potential to convert coal into biomethane is still unclear.

RESULTS

Microbial communities in an opencast coal mine and in grassland soil covering and surrounding this mine and their biomethane production potential were investigated by Hiseq sequencing and anaerobic cultivation. The microbial communities in covering soil showed high similarity to those in the surrounding soil, according to the pairwise weighted UniFrac distances matrix. The majority of bacterial communities in coal and soil samples belonged to the phyla Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria. The dominant bacterial genera in grassland soil included Gaiella, Solirubrobacter, Sphingomonas and Streptomyces; whereas, the most abundant genus in coal was Pseudarthrobacter. In soil, hydrogenotrophic Methanobacterium was the dominant methanogen, and this methanogen, along with acetoclastic Methanosarcina and methylotrophic Methanomassiliicoccus, was detected in coal. Network-like Venn diagram showed that an average of 28.7% of microbial communities in the samples belonged to shared genera, indicating that there is considerable microbial overlap between coal and soil samples. Potential degraders and methanogens in the soil efficiently stimulated methane formation from coal samples by the culturing-based approach. The maximum biogenic methane yields from coal degradation by the microbial community cultured from grassland soil reached 22.4 μmol after 28 day.

CONCLUSION

The potential microbial coal degraders and methanogenic archaea in grassland soil were highly diverse. Significant amounts of biomethane were generated from coal by the addition of grassland soil microbial communities. The unique species present in grassland soil may contribute to efficient methanogenic coal bioconversion. This discovery not only contributes to a better understanding of global microbial biodiversity in coal mine environments, but also makes a contribution to our knowledge of the synthetic microbiology with regard to effective methanogenic microbial consortia for coal degradation.

In vitro evaluation of the effects of Yucca schidigera and inulin on the fermentation potential of the faecal microbiota of dogs fed diets with low or high protein concentrations

This in vitro study aimed to evaluate the effects of Yucca schidigera powder (YSP) and inulin (IN) on protein fermentation metabolites (short-chain fatty acids [SCFA] and branched-chain fatty acids, phenolic and indolic compounds, biogenic amines, ammonia and pH) by using faecal inocula from dogs fed either a low (L) or a high (H) protein diet (crude protein 201 or 377 g/kg as fed). Four treatments for each diet were evaluated in an in vitro batch culture system over 24 h: (1) control with no addition of substrates; (2) 4 g YSP/l; (3) 5 g IN/l; (4) 4 g YSP/l in combination with 5 g IN/l of faecal culture of dogs fed Diet L or H. Several changes in fermentation metabolites were analysed. Samples incubated with the faecal inocula of dogs fed Diet L produced higher concentrations of total SCFA, propionate (p = 0.001), acetate (p ≤ 0.001), d-lactate (p = 0.041) and indole (p = 0.003), whereas pH (p = 0.004) was decreased. Supplementation of IN increased the content of putrescine, d- and l-lactate, total SCFA, acetate, propionate, n-butyrate (p ≤ 0.001) and n-valerate (p = 0.003), while i-valerate, indole and pH (p ≤ 0.001) were reduced. Ammonia was lower (p = 0.013) in samples with faecal inocula from dogs fed Diet H and further reduced by the addition of IN (p ≤ 0.001). Samples with faecal inocula from dogs fed Diet L had a fewer quotient of ammonia and total SCFA (p = 0.040). Supplementation of YSP (p = 0.021), IN (p ≤ 0.001) and YSP in combination with IN (p = 0.047) led to a higher reduction of the quotient of ammonia and total SCFA. In conclusion, dietary protein concentration and the supplementation of IN resulted in a stimulation of fermentation while YSP appeared to have only minor effects.

Grain free diets for utility dogs during training work: Evaluation of the nutrient digestibility and faecal characteristics

Two different diets characterized by the absence of cereals or by the presence of conventional cereals were evaluated on the nutrient digestibility and faecal characteristics and faecal fermentative end-product concentrations of 8 neutered adult Labrador retrievers housed at the Regional Centre Helen Keller (Messina, Italy) during the training work for the service guide for the blind. Dogs (age = 17 ± 1 months, initial body weight [BW] = 26.3 ± 1 kg, and body condition score [BCS] = 4.5 ± 0.11) were divided into 2 homogeneous groups for sex (half males and half females). Dogs in the grain free (GF) group were fed a commercial diet characterized by the absence of grain cereals, and dogs in the control (CTR) group were fed a super-premium pet food characterized by conventional grains as the carbohydrate source. The trial lasted 84 d, preceded by a 7-d of adaption period. Physical examination, digestibility, and faecal characteristics were studied. The statistical model included the effects of diet (GF vs. CTR), time (from d 0 to 84, end of the trial) and the interaction (diet × time). The high-protein, low-carbohydrate dry diet (GF) offered higher apparent nutrient digestibility of protein (+10%; P = 0.002) and fat (+7%; P < 0.001) and more stable large intestinal fermentation of carbohydrate compared to the commercial high-carbohydrate dry diet, enabling dogs to use nutrients from the diet more efficiently and thus requiring less food (-13%) to satisfy their nutrient requirements, producing less excrement (-33%; P = 0.033), and reaching a higher final BW (+8%; P < 0.0001) and a higher final BCS (+15%; P = 0.003). Therefore, the GF diet appears the nutritional plan most suitable for these animals taking due account not only of the training work done by animals with their increased nutrient and energy needs, but also of the gastrointestinal disorders consequent to stress coming from work and life in kennels, which cause in the Labrador retrievers an unusual weight loss.

Fecal short-chain fatty acid concentrations and dysbiosis in dogs with chronic enteropathy

Background

Accumulating evidence shows an important relationship between the gastrointestinal (GI) microbiota and host health. Microbial metabolites are believed to play a critical role in host‐microbial interactions. Short‐chain fatty acids (SCFAs) are major end products of bacterial carbohydrate fermentation in the intestinal tract. Decreased concentrations of SCFAs have been observed in humans with GI disease. However, large‐scale clinical data in dogs are lacking.

Hypothesis/Objective

To evaluate fecal concentrations of SCFAs and the fecal microbiota in healthy control (HC) dogs and dogs with chronic enteropathy (CE).

Animals

Forty‐nine privately owned HC dogs and 73 dogs with CE.

Methods

Prospective cohort study. Fecal concentrations of SCFAs were measured using gas chromatography/mass spectrometry. Illumina sequencing and quantitative real‐time polymerase chain reaction were utilized to evaluate the fecal microbiota.

Results

Fecal concentrations (median [range] μmol/g of dry matter) of acetate were lower (P = .03) in dogs with CE (185.8 [20.1‐1042.1]) than in HC dogs (224.0 [87.7‐672.8]). Propionate were also lower (P < .001) in dogs with CE (46.4 [0.4‐227.9]) than in HC dogs (105.9 [1.6‐266.9]). Moreover, total SCFAs were lower (P = .005) in dogs with CE (268.1 [21.8‐1378.2]) than in HC dogs (377.2 [126.6‐927.0]). Dysbiosis in dogs with CE was characterized by decreased bacterial diversity and richness, distinct microbial community clustering compared with that in HC dogs, and a higher dysbiosis index.

Conclusions and Clinical Importance

Dogs with CE had an altered fecal SCFA concentration accompanied by significant changes of the fecal microbiota.

Effects of plant and animal high protein diets on immune-inflammatory biomarkers: A 6-week intervention trial

BACKGROUND & AIMS

Pro-inflammatory biomarkers are well-established contributors to insulin resistance and represent valid targets for diabetes management and prevention. Yet, little is known whether nutrition could play a role in modulating various aspects of immune-inflammatory responses. Our aim is to assess the effect of isocaloric animal and plant protein dietary interventions on selected biomarkers representing various immune-inflammatory pathways.

METHODS

We enrolled 37 participants with type 2 diabetes (age 64 ± 6 years, body mass index 30.2 ± 3.6 kg/m², glycated hemoglobin 7.0 ± 0.6%) who underwent an either high-animal protein (AP) or high-plant protein (PP) diet (30 E% protein, 40 E% carbohydrates, 30 E% fat) for 6-weeks. Clinical examinations were performed at beginning and end of the study. Levels of pro-inflammatory adipokines [chemerin, progranulin], cytokines [tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), soluble urokinase-type plasminogen activator receptor (suPAR), transforming growth factor beta 1 (TGF-β1)], and proteins [calprotectin, lactoferrin and growth differentiation factor 15 (GDF-15)] were determined in blood serum using enzyme-linked immunosorbent assay.

RESULTS

Chemerin and progranulin concentrations decreased following AP and PP diets. TGF-β1 increased in AP and decreased in PP, whereas calprotectin increased in PP and decreased in AP. No statistically significant differences in the concentrations of IL-6, TNF-α, suPAR, lactoferrin and GDF-15 could be seen in either of the protein diet arms.

CONCLUSIONS

These results suggest that both AP and PP diets may effectively reduce the levels of the pro-inflammatory adipokines chemerin and progranulin. The effects on the additional immune-inflammatory biomarkers seem to be more complex.

CLINICAL TRIAL REGISTRY NUMBER

NCT02402985 (ww.clinicaltrials.gov).

Balance of saccharolysis and proteolysis underpins improvements in stool quality induced by adding a fiber bundle containing bound polyphenols to either hydrolyzed meat or grain-rich foods

Dietary fiber is a key component in gastrointestinal health maintenance partly due to its fermentation by the gut microbiome. The food-dependent effects of a novel fiber bundle added to hydrolyzed meat (HM) or grain-rich (GR) foods in healthy dogs (n = 16) or those with chronic enteritis/gastroenteritis (n = 16) were examined. Addition of fiber to either food improved stool quality in dogs regardless of health status; microbiome diversity of dogs with chronic enteritis/gastroenteritis became more similar to healthy dogs. The abundance of bacteria mediating beneficial saccharolytic processes (eg, Lachnospiraceae) significantly increased on addition of fiber to the GR food, while those mediating detrimental proteolytic catabolism (eg, Desulfovibrionaceae) significantly decreased. Fiber addition to the HM food led to significant changes in saccharolytic/proteolytic bacteria. Higher levels of free saccharides in feces upon fiber addition to either food indicated increased saccharolysis. Fiber addition to the GR food decreased levels of fecal free amino acids, indicating decreased proteolysis. Addition of fiber decreased fecal pH for both foods but likely by different mechanisms: addition of fiber to the HM food led to increased straight-chain short-chain fatty acids (SCFAs) and no significant change in proteolytic branched-chain SFCAs, while in the GR food, fiber mainly led to decreased proteolytic branched-chain SFCAs. Other postbiotics related to intestinal health were consistently altered when fiber was added to either food. Plant-derived bioactive molecules were enriched in feces from dogs fed either food with added fiber, which could account for the observed modulation of the canine gut microbiome and shifts in metabolic capacity.

Effect of an extruded animal protein-free diet on fecal microbiota of dogs with food-responsive enteropathy

Background

Dietary interventions are thought to modify gut microbial communities in healthy individuals. In dogs with chronic enteropathies, resolution of dysbiosis, along with remission of clinical signs, is expected with treatment.

Hypothesis/Objective

To evaluate changes in the fecal microbiota in dogs with food‐responsive chronic enteropathy (FRE) and in healthy control (HC) dogs before and after an elimination dietary trial with an animal protein‐free diet (APFD).

Animals

Dogs with FRE (n = 10) and HC (n = 14).

Methods

Dogs were fed the APFD for 60 days. Fecal microbiota was analyzed by Illumina 16S rRNA sequencing and quantitative polymerase chain reaction (PCR).

Results

A significantly lower bacterial alpha‐diversity was observed in dogs with FRE compared with HC dogs at baseline, and compared with FRE dogs after the trial. Distinct microbial communities were observed in dogs with FRE at baseline compared with HC dogs at baseline and compared with dogs with FRE after the trial. Microbial communities still were different in FRE dogs after the trial compared with HC dogs at baseline. In HC dogs, the fecal microbiota did not show a significant modification after administration of the APFD.

Conclusion and Clinical Importance

Our results suggest that, in FRE dogs, treatment with the APFD led to a partial recovery of the fecal microbiota by significantly increasing microbiota richness, which was significantly closer to a healthy microbiota after the treatment. In contrast, no changes were detected in the fecal microbiota of HC dogs fed the same APFD.

Serologic and fecal markers to predict response to induction therapy in dogs with idiopathic inflammatory bowel disease

Background

Little information is available of markers that assess the disease course in dogs with idiopathic inflammatory bowel disease (IBD).

Objectives

Evaluate relationship between disease severity and serum and fecal biomarkers in dogs with idiopathic IBD before and after treatment.

Animals

Sixteen dogs with idioptahic IBD and 13 healthy dogs.

Methods

Prospective case control study. Canine IBD activity index (CIBDAI) clinical score, serum concentrations of C‐reactive protein (CRP), perinuclear antineutrophil cytoplasmic antibodies (pANCA), and serum and fecal canine calprotectin (cCP) were measured before and after 21 days of treatment.

Results

Serum CRP (median 3.5 mg/L; range: 0.1‐52.4 mg/L), fecal cCP (median 92.3 μg/g; range: 0.03‐637.5 μg/g), and CIBDAI scores significantly increased in dogs with IBD before treatment compared with serum CRP (median 0.2 mg/L; range: 0.1‐11.8 mg/L; P < .001), fecal cCP (median 0.67 μg/g; range: 0.03‐27.9 μg/g; P < .001) and CIBDAI (P < .001) after treatment. No significant associations between CIBDAI scores and before or after treatment serum biomarkers. There was a significant association between fecal cCP and CIBDAI scores before treatment (rho = 0.60, P = .01). CRP and fecal cCP significantly decreased after treatment (median 3.5 mg/L v. 0.2 mg/L; P < .001 and 92.3 μg/g v. 0.67 μg/g; P = .001, respectively).

Conclusions and Clinical Importance

Our data indicate that measurement of fecal cCP concentration is a useful biomarker for noninvasive evaluation of intestinal inflammation. Dogs with severe signs of GI disease more often have abnormal markers than dogs having less severe disease.

Influence of dietary protein and fructooligosaccharides on fecal fermentative end-products, fecal bacterial populations and apparent total tract digestibility in dogs

Background

Feeding dogs with diets rich in protein may favor putrefactive fermentations in the hindgut, negatively affecting the animal’s intestinal environment. Conversely, prebiotics may improve the activity of health-promoting bacteria and prevent bacterial proteolysis in the colon. The aim of this study was to evaluate the effects of dietary supplementation with fructooligosaccharides (FOS) on fecal microbiota and apparent total tract digestibility (ATTD) in dogs fed kibbles differing in protein content. Twelve healthy adult dogs were used in a 4 × 4 replicated Latin Square design to determine the effects of four diets: 1) Low protein diet (LP, crude protein (CP) 229 g/kg dry matter (DM)); 2) High protein diet (HP, CP 304 g/kg DM); 3) Diet 1 + 1.5 g of FOS/kg; 4) Diet 2 + 1.5 g of FOS/kg. The diets contained silica at 5 g/kg as a digestion marker. Differences in protein content were obtained using different amounts of a highly digestible swine greaves meal. Each feeding period lasted 28 d, with a 12 d wash-out in between periods. Fecal samples were collected from dogs at 0, 21 and 28 d of each feeding period. Feces excreted during the last five days of each feeding period were collected and pooled in order to evaluate ATTD.

Results

Higher fecal ammonia concentrations were observed both when dogs received the HP diets (p < 0.001) and the supplementation with FOS (p < 0.05). The diets containing FOS resulted in greater ATTD of DM, Ca, Mg, Na, Zn, and Fe (p < 0.05) while HP diets were characterized by lower crude ash ATTD (p < 0.05). Significant interactions were observed between FOS and protein concentration in regards to fecal pH (p < 0.05), propionic acid (p < 0.05), acetic to propionic acid and acetic + n-butyric to propionic acid ratios (p < 0.01), bifidobacteria (p < 0.05) and ATTD of CP (p < 0.05) and Mn (p < 0.001).

Conclusions

A relatively moderate increase of dietary protein resulted in higher concentrations of ammonia in canine feces. Fructooligosaccharides displayed beneficial counteracting effects (such as increased bifidobacteria) when supplemented in HP diets, compared to those observed in LP diets and, in general, improved the ATTD of several minerals.

Systematic review of the effects of the intestinal microbiota on selected nutrients and non-nutrients

PURPOSE

There is considerable interest in the effects of the intestinal microbiota (IM) composition, its activities in relation with the metabolism of dietary substrates and the impact these effects may have in the development and prevention of certain non-communicable diseases. It is acknowledged that a complex interdependence exists between the IM and the mammalian host and that the IM possesses a far greater diversity of genes and repertoire of metabolic and enzymatic capabilities than their hosts. However, full knowledge of the metabolic activities and interactions of the IM and the functional redundancy that may exist are lacking. Thus, the current review aims to assess recent literature relating to the role played by the IM in the absorption and metabolism of key nutrients and non-nutrients.

METHODS

A systematic review (PROSPERO registration: CRD42015019087) was carried out focussing on energy and the following candidate dietary substrates: protein, carbohydrate, fat, fibre, resistant starch (RS), and polyphenols to further understand the effect of the IM on the dietary substrates and the resulting by-products and host impacts. Particular attention was paid to the characterisation of the IM which are predominantly implicated in each case, changes in metabolites, and indirect markers and any potential impacts on the host.

RESULTS

Studies show that the IM plays a key role in the metabolism of the substrates studied. However, with the exception of studies focusing on fibre and polyphenols, there have been relatively few recent human studies specifically evaluating microbial metabolism. In addition, comparison of the effects of the IM across studies was difficult due to lack of specific analysis/description of the bacteria involved. Considerable animal-derived data exist, but experience suggests that care must be taken when extrapolating these results to humans. Nevertheless, it appears that the IM plays a role in energy homeostasis and that protein microbial breakdown and fermentation produced ammonia, amines, phenols and branch chain fatty acids, and a greater diversity in the microbes present. Few recent studies appear to have evaluated the effect of the IM composition and metabolism per se in relation with digestible dietary carbohydrate or fat in humans. Intakes of RS and prebiotics altered levels of specific taxa that selectively metabolised specific prebiotic/carbohydrate-type substances and levels of bifidobacteria and lactobacilli were observed to increase. In controlled human studies, consistent data exist that show a correlation between the intake of fibre and an increase in bifidobacteria and short-chain fatty acids, in particular butyrate, which leads to lower intestinal pH. Dietary polyphenols rely on modification either by host digestive enzymes or those derived from the IM for absorption to occur. In the polyphenol-related studies, a large amount of inter-individual variation was observed in the microbial metabolism and absorption of certain polyphenols.

CONCLUSIONS

The systematic review demonstrates that the IM plays a major role in the breakdown and transformation of the dietary substrates examined. However, recent human data are limited with the exception of data from studies examining fibres and polyphenols. Results observed in relation with dietary substrates were not always consistent or coherent across studies and methodological limitations and differences in IM analyses made comparisons difficult. Moreover, non-digestible components likely to reach the colon are often not well defined or characterised in studies making comparisons between studies difficult if not impossible. Going forward, further rigorously controlled randomised human trials with well-defined dietary substrates and utilizing omic-based technologies to characterise and measure the IM and their functional activities will advance the field. Current evidence suggests that more detailed knowledge of the metabolic activities and interactions of the IM hold considerable promise in relation with host health.

Analysis of fecal short chain fatty acid concentration in miniature dachshunds with inflammatory colorectal polyps

Short chain fatty acids (SCFAs) play an important role in the maintenance of colonic homeostasis, and their depletion has been reported in various gastrointestinal disorders. Inflammatory colorectal polyps (ICRPs) are a recently recognized disease specific to miniature dachshunds (MDs), and fecal dysbiosis with a reduction of SCFA-producing bacteria has been reported with this disease. Therefore, this study was performed based on the hypothesis that a reduced SCFA concentration associates with the development of ICRPs. We recruited 11 ICRP-affected MDs and 25 control MDs. Their fecal SCFA concentrations and bacterial proportions were quantified using high performance liquid chromatography and quantitative real-time PCR, respectively. The feces of ICRP-affected MDs contained lower amounts of propionic acid and lower proportions of Bifidobacterium than the feces of control MDs. Furthermore, fecal proportions of Bifidobacterium, Firmicutes and Lactobacillus exhibited significant positive correlations with fecal concentrations of total SCFAs and/or propionic acid; fecal Escherichia coli proportions correlated negatively with fecal concentrations of total SCFAs, as well as acetic, propionic and butyric acid. This result indicates an association between fecal dysbiosis and fecal SCFA concentrations; these phenomena may contribute to ICRP pathogenesis in MDs. Potential therapeutic targeting of the reduced propionic acid concentration using probiotics, prebiotics or SCFA enemas merits further study.

A diet change from dry food to beef induces reversible changes on the faecal microbiota in healthy, adult client-owned dogs

BACKGROUND

Diet has a major influence on the composition of the gut microbiota, whose importance for gut health and overall well-being is increasingly recognized. Knowledge is limited regarding health implications, including effects on the faecal microbiota, of feeding a diet with high content of red meat to dogs, despite some owners' apparent preference to do so. The aim of this study was to evaluate how a diet change from commercial dry food to one with a high content of boiled minced beef and vice versa influenced the faecal microbiota, and short chain fatty acid profile in healthy, adult, client-owned dogs.

RESULTS

The diet change influenced the faecal microbiota composition and diversity (Shannon diversity index). The most abundant OTUs in samples of dogs fed the dry food and high minced beef were affiliated with the species Faecalibacterium prausnitzii and Clostridia hiranonis respectively. The high minced beef diet apparently also influenced the short chain fatty acid profile, with increased isovaleric acid, as well as an increase in faecal pH. These effects were reversed when the commercial dry food was reintroduced in weeks 6 and 7.

CONCLUSIONS

Results of this study can aid in the understanding of how diet changes influence the faecal microbiota and metabolite content on a short-term basis. Long-term studies are required to investigate potential implications for canine gut and general health.

Raw meat based diet influences faecal microbiome and end products of fermentation in healthy dogs

BACKGROUND

Dietary intervention studies are required to deeper understand the variability of gut microbial ecosystem in healthy dogs under different feeding conditions and to improve diet formulations. The aim of the study was to investigate in dogs the influence of a raw based diet supplemented with vegetable foods on faecal microbiome in comparison with extruded food.

METHODS

Eight healthy adult Boxer dogs were recruited and randomly divided in two experimental blocks of 4 individuals. Dogs were regularly fed a commercial extruded diet (RD) and starting from the beginning of the trial, one group received the raw based diet (MD) and the other group continued to be fed with the RD diet (CD) for a fortnight. After 14 days, the two groups were inverted, the CD group shifted to the MD and the MD shifted to the CD, for the next 14 days. Faeces were collected at the beginning of the study (T0), after 14 days (T14) before the change of diet and at the end of experimental period (T28) for DNA extraction and analysis of metagenome by sequencing 16SrRNA V3 and V4 regions, short chain fatty acids (SCFA), lactate and faecal score.

RESULTS

A decreased proportion of Lactobacillus, Paralactobacillus (P < 0.01) and Prevotella (P < 0.05) genera was observed in the MD group while Shannon biodiversity Index significantly increased (3.31 ± 0.15) in comparison to the RD group (2.92 ± 0.31; P < 0.05). The MD diet significantly (P < 0.05) decreased the Faecal Score and increased the lactic acid concentration in the feces in comparison to the RD treatment (P < 0.01). Faecal acetate was negatively correlated with Escherichia/Shigella and Megamonas (P < 0.01), whilst butyrate was positively correlated with Blautia and Peptococcus (P < 0.05). Positive correlations were found between lactate and Megamonas (P < 0.05), Escherichia/Shigella (P < 0.01) and Lactococcus (P < 0.01).

CONCLUSION

These results suggest that the diet composition modifies faecal microbial composition and end products of fermentation. The administration of MD diet promoted a more balanced growth of bacterial communities and a positive change in the readouts of healthy gut functions in comparison to RD diet.

Calprotectin in serum and zonulin in serum and feces are elevated after introduction of a diet with lower carbohydrate content and higher fiber, fat and protein contents

Calprotectin is a marker of inflammation and zonulin is a marker of intestinal permeability. Diets with lower carbohydrate content and higher contents of fat, fiber and protein, e.g., Okinawan-based diet, are considered to reduce inflammation and intestinal permeability. The aim of the present study was to evaluate calprotectin and zonulin levels in serum and feces after intervention with an Okinawan-based Nordic diet. Thirty patients (17 women) with type 2 diabetes, mean age 57.5±8.2 years, BMI 29.9±4.1 kg/m², were served the diet during 12 weeks, and were followed for another 16 weeks. Anthropometric and metabolic parameters were registered. Fasting levels of calprotectin and zonulin in serum and feces, and hormones in plasma, were measured by Luminex or ELISA before study start and after 12 and 28 weeks. Calprotectin in serum tended to be increased (P=0.074) after 12 weeks. Zonulin in serum and feces were elevated after 12 weeks (P=0.019 vs. P<0.001), and remained elevated in serum after 28 weeks (P=0.014). In contrast to baseline, there was a correlation between calprotectin and zonulin in serum and feces after dietary intervention (P=0.025 vs. P=0.079). Energy percentage of protein in breakfast correlated with serum calprotectin (P=0.008) and tended to correlate with serum zonulin (P=0.059). Calprotectin in serum tended to be elevated, and zonulin in serum and feces are elevated after introduction of an Okinawan-based Nordic diet. These biomarkers correlate with energy percentage of protein.

Two meals with different carbohydrate, fat and protein contents render equivalent postprandial plasma levels of calprotectin, cortisol, triglycerides and zonulin

The aim was to compare postprandial plasma levels of calprotectin, cortisol, triglycerides and zonulin between a control breakfast and a moderately low-carbohydrate test breakfast, given randomly after 10-h fast. Blood samples were collected before and repeatedly after the meal. Plasma calprotectin, cortisol, triglycerides and zonulin were analyzed. The total area under the curve (tAUC) and change in AUC from baseline (dAUC) were calculated. Ratios between the test and control values were calculated to investigate equivalence. Healthy volunteers (8 men and 12 women; 46.0 ± 14.5 years) were included. tAUCs of cortisol and triglycerides did not differ between the breakfasts (p = 0.158 versus p = 0.579). Cortisol dAUCs were decreased and triglyceride dAUCs were increased after both breakfasts, with no differences between the breakfasts (p = 0.933 versus p = 0.277). Calprotectin and zonulin levels were unaffected. The meals were bioequivalent for cortisol, triglycerides and zonulin, but not for calprotectin.

In vitro influence of dietary protein and fructooligosaccharides on metabolism of canine fecal microbiota

Background

The present in vitro study investigated whether the utilization of fructooligosaccharides (FOS) may influence canine fecal microbial population in presence of diets differing in their protein content and digestibility. Fresh fecal samples were collected from five adult dogs, pooled, and incubated for 24 h with the undigested residue of three diets: 1, Low protein high digestibility diet (LP HD, crude protein (CP) 229 g/kg); 2, High protein high digestibility diet (HP HD, CP 304 g/kg); 3, High protein low digestibility diet (HP LD, CP 303 g/kg) that had been previously subjected to enzymatic digestion. In the in vitro fermentation study, there were six treatments: 1) LP HD; 2) HP HD 3) HP LD; 4) LP HD + FOS; 5) HP HD + FOS; 6) HP LD + FOS. Fructooligosaccharides were added at the final concentration of 1.5 g/L. Samples of fermentation fluid were collected at 6 and 24 h of incubation.

Results

Values of pH were reduced by FOS at 6 and 24 h (P < 0.001); conversely, low protein digestibility and high dietary protein level resulted in higher pH at both sampling times (P < 0.001). At 24 h, FOS lowered ammonia (−10 %; P < 0.001) and resulted (P < 0.05) in higher concentrations of total volatile fatty acids (VFA) (+43 %), acetic acid (+14 %), propionic acid (+75 %) and n-butyric acid (+372 %). Conversely, at 24 h, low protein digestibility resulted (P < 0.01) in lower concentrations of acetic acid (−26 %), propionic acid (−37 %) and total VFA (−21 %). Putrescine concentrations were increased at 6 and 24 h of fermentation by low protein digestibility (+21 and 22 %, respectively; P < 0.05) and FOS (+18 and 24 %, respectively; P < 0.01). After 24 h of fermentation, high dietary protein level resulted in lower counts of lactobacilli and enterococci (−0.5 and −0.7 log cells/mL, respectively; P < 0.05) whereas low protein digestibility tended to increase counts of C. perfringens (+0.2 log cells/mL; P = 0.07).

Conclusions

Results from the present study showed that diets rich in protein may exert negative influences on the canine intestinal ecosystem, slightly increasing the presence of ammonia and reducing counts of lactobacilli and enterococci. Moreover, the presence of poorly digestible protein resulted in lower concentrations of VFA. Conversely, administration of FOS may improve metabolism of canine intestinal microbiota, reducing ammonia concentrations and enhancing VFA production.

Microbiota and probiotics in canine and feline welfare

Dogs and cats have been cohabiting with us for thousands of years. They are the major human companions. Today, dogs and cats live in urban areas. Cats and most dogs are on high carbohydrate diets and face similar life-style challenges as the human beings. The health and well-being of companion animals, just as their owners, depends on the gut microbes. Providing a proper care and nutritionally balanced diet to companion animals is recognised as a part of our responsibility to maintain the health and well being of our pet. However, as microbiota differences may facilitate exposure to pathogens and harmful environmental influences, it is prudent to search for novel tools to protect dogs and cats and at the same time the human owners from pathogens. Specific probiotic strains and/or their defined combinations may be useful in the canine and feline nutrition, therapy, and care. Probiotic supplementations have been successful in the prevention and treatment of acute gastroenteritis, treatment of IBD, and prevention of allergy in companion animals. New challenges for probiotic applications include maintenance of obesity and overweight, urogenital tract infections, Helicobacter gastritis and parasitic infections. The probiotics of human origin appear to be among the new promising tools for the maintenance of pets' health. However, the host-derived microorganisms might be the most appropriate probiotic source. Therefore, more controlled trials are needed to characterise new and safe probiotic preparations with an impact on general health and well being as well as health maintenance in dogs and cats.

Effect of age, gestation and lactation on faecal IgA and calprotectin concentrations in dogs

Faecal calprotectin and IgA have been suggested as non-invasive markers of gut health. Faecal calprotectin is a marker of intestinal inflammation in adults, whereas IgA has been suggested as a marker of intestinal immunity. The purpose of the present study was to evaluate the effect of gestation, lactation and age on faecal concentrations of these biomarkers. Thirty puppies, nineteen pregnant or lactating bitches and eighty-nine healthy control adult dogs were included in the study. Faeces were collected from the fourth week of gestation until the eighth week of lactation in pregnant and lactating bitches, and between 4 and 9 weeks of age in puppies. Faeces from the eighty-nine healthy control adult dogs were also collected. Faecal calprotectin and IgA concentrations were measured. Faecal calprotectin concentrations in control dogs were significantly lower than faecal calprotectin concentrations in puppies between 4 and 6 weeks of age (P < 0·001) or between 7 and 9 weeks of age (P = 0·004). Puppies between 4 and 6 weeks of age had significantly higher faecal IgA concentrations compared with puppies between 7 and 9 weeks of age (P = 0·001). Bitches during their second month of lactation had significantly lower faecal IgA concentrations compared with their first month of lactation (P = 0·049). Faecal calprotectin and IgA have been suggested as non-invasive and easily measured biomarkers of gut health in adults. However, the present study underlines that faecal IgA and calprotectin concentrations vary markedly depending of physiologic factors such as gestation, lactation and age. These factors need to be considered when these faecal biomarkers are used for evaluation of intestinal immunity or inflammation.