Effects of the solubility of yeast cell wall preparations on their potential prebiotic properties in dogs

β-glucans from Euglena gracilis or Saccharomyces cerevisiae effects on immunity and inflammatory parameters in dogs

Considering the differences in molecular structure and function, the effects of β-1,3-glucans from Euglena gracilis and β-1,3/1,6-glucans from Saccharomyces cerevisiae on immune and inflammatory activities in dogs were compared. Four diets were compared: control without β-glucans (CON), 0.15 mg/kg BW/day of β-1,3/1,6-glucans (Β-Y15), 0.15 mg/kg BW/day of β-1,3-glucans (Β-S15), and 0.30 mg/kg BW/day of β-1,3-glucans (Β-S30). Thirty-two healthy dogs (eight per diet) were organized in a block design. All animals were fed CON for a 42-day washout period and then sorted into one of four diets for 42 days. Blood and faeces were collected at the beginning and end of the food intake period and analysed for serum and faecal cytokines, ex vivo production of hydrogen peroxide (H2O2) and nitric oxide (NO), phagocytic activity of neutrophils and monocytes, C-reactive protein (CRP), ex vivo production of IgG, and faecal concentrations of IgA and calprotectin. Data were evaluated using analysis of covariance and compared using Tukey's test (P<0.05). Dogs fed Β-Y15 showed higher serum IL-2 than dogs fed Β-S30 (P<0.05). A higher phagocytic index of monocytes was observed in dogs fed the B-S15 diet than in those fed the other diets, and a higher neutrophil phagocytic index was observed for B-S15 and B-Y15 than in dogs fed the CON diet (P<0.05). Monocytes from dogs fed B-S15 and B-S30 produced more NO and less H2O2 than those from the CON and B-Y15 groups (P<0.05). Despite in the reference value, CRP levels were higher in dogs fed B-S15 and B-S30 diets (P<0.05). β-1,3/1,6-glucan showed cell-mediated activation of the immune system, with increased serum IL-2 and neutrophil phagocytic index, whereas β-1,3-glucan acted on the immune system by increasing the ex vivo production of NO by monocytes, neutrophil phagocytic index, and serum CRP. Calprotectin and CRP levels did not support inflammation or other health issues related to β-glucan intake. In conclusion, both β-glucan sources modulated some immune and inflammatory parameters in dogs, however, different pathways have been suggested for the recognition and action of these molecules, reinforcing the necessity for further mechanistic studies, especially for E. gracilis β-1,3-glucan.

Guava fibre characterization and effects on digestibility, fermentation products, gastrointestinal transit time and palatability of dry diets for dogs

The use of fruit fibres as a way of reusing industrial waste is attractive and necessary, increasing the efficiency and reducing the environmental impact of the industry. This study characterized guava fibre as a fibrous ingredient and evaluated its effects when included in extruded diets for dogs on nutrient digestibility, faecal traits, fermentation products, gastrointestinal transit time and palatability. Four diets were formulated: CO (control diet, no fibrous ingredients added), GF3 (3% guava fibre), GF6 (6% guava fibre) and GF12 (12% guava fibre). The guava fibre was added to diets in replacement of maize, with small adjustments in the other ingredients to ensure similar contents of protein and fat. The diets were fed to 24 adult Beagle dogs (6 per diet) during 15 days for adaptation followed by 15 days for assessment of digestibility, fermentation end products and gastrointestinal transit time. The palatability of G6 and G12 treatments was evaluated against the CO by the two-pan test. Results were compared by analysis of variance and polynomial contrasts according to the guava fibre inclusion level (p < 0.05). The addition of guava fibre did not change nutrient intake except for the increase on dietary fibre (p < 0.001). Fibre inclusion resulted in a quadratic reduction in total tract apparent digestibility for dry matter, organic matter, crude protein and crude energy (p < 0.001), and on the metabolizable energy content of the foods (p < 0.001). Guava fibre addition did not change the faecal concentration of ammonia, lactic acid, faecal pH and branched chain fatty acids but it decreased acetic and propionic acids concentration (p < 0.01). The inclusion of 12% guava fibre did result in a faster transit time (p = 0.046) compared to the control diet. Guava fibre can be characterized as a novel insoluble non-fermentable fibre source that could be safely used in levels up to 12% in canine extruded diets.

Effects of Increasing Levels of Purified Beta-1,3/1,6-Glucans on the Fecal Microbiome, Digestibility, and Immunity Variables of Healthy Adult Dogs

Yeast-purified beta-1,3/1,6-glucans (BG) can modulate dogs' immune systems and microbiome, but the optimal inclusion dose remains unknown. The aim of the study was to evaluate the effects of 0.0, 0.07, 0.14, and 0.28% inclusion of BG in a dry extruded diet on the digestibility, immunity, and fecal microbiota of healthy adult dogs. Eight male and female border collies [n = 4; body condition score (BCS) = 5] and English cocker spaniels (n = 4; BCS = 5), aged 3.5 ± 0.5 years, were randomly distributed into two 4 × 4 balanced Latin squares. Fecal microbiota (using 16S rRNA sequencing, Illumina®), apparent digestibility coefficients (ADC) of nutrients, fecal concentrations of short-chain fatty acids (SCFA) and branched-chain fatty acids (BCFA), ammoniacal nitrogen, lactic acid, IgA and pH, lymphocyte immunophenotyping, intensity and percentage of phagocytosis and oxidative burst were determined. No differences were observed in Faith (p = 0.1414) and Pielou-evenness (p = 0.1151) between treatments, but beta diversity was different between 0.0% and 0.14% BG groups (p = 0.047). Moreover, the Firmicutes phylum was the most abundant in all groups and exhibited the highest relative abundance after the consumption of 0.14% BG, a finding considered beneficial for the canine microbiome. The Erysipelotrichaceae and Ruminococcaceae families, along with the Faecalibacterium and Prevotella genera, considered favorable for their involvement in butyrate production and other metabolites, showed increased abundance after the consumption of 0.14% BG. The potentially pathogenic Proteobacteria phylum displayed lower abundance after the consumption of 0.14% BG. Fecal concentrations of the evaluated compounds and pH did not differ after consumption of the BG at all percentages. Higher crude protein ADC was found after 0.14 and 0.28% BG consumption (p < 0.0001), but no differences were found for other nutrients. Phagocytosis, oxidative burst, and lymphocyte populations were not modulated by any of the treatments; however, 0.14% BG modulated the lymphocyte T CD4+:CD8+ ratio (p = 0.0368), an important marker of immune system efficiency. The inclusion of 0.14% BG resulted in the best responses and was the best dose evaluated.

Potential benefits of yeast Saccharomyces and their derivatives in dogs and cats: a review

Yeast Saccharomyces and its derivatives have been largely used in livestock and poultry nutrition for their potential positive impact on growth, performance, and general health. Originally included in animal diets as a source of protein, yeasts can also offer a wide range of by-products with interesting bioactive compounds that would confer uses beyond nutrition. Although its supplementation in livestock, poultry and even in humans is well documented, the available body of literature on the use of yeast and its derivatives in companion animals' food, mainly dogs and cats' diets, is still developing. Despite this, gut microbiota modulation, immune system enhancement or decreasing of potentially pathogenic microorganisms have been reported in pets when using these products, highlighting their possible role as probiotics, prebiotics, and postbiotics. This review attempts to provide the reader with a comprehensive on the effects of Saccharomyces and its derivatives in pets and the possible mechanisms that confer their functional properties.

Yeast Cell Wall Compounds on The Formation of Fermentation Products and Fecal Microbiota in Cats: An In Vivo and In Vitro Approach

The effects of yeast cell wall compounds (YCWs) being added to cat food on hindgut fermentation metabolites and fecal microbiota were assessed in in vivo Experiment 1 (Exp. 1) and in vitro Experiments 2 and 3 (Exp. 2 and 3). In Exp. 1, the cats' diets were supplemented with two dietary concentrations (46.2 and 92.4 ppm) of YCWs (YCW-15 and YCW-30, respectively), and a negative control diet with no compound in three groups (six cats per group) was used to assess the fecal score, pH, digestibility, fermentation products, and microbiota. In Exp. 2, feces from the cats that were not supplemented with YCWs (control) were used as an inoculum. A blend of pectin, amino acids, and cellulose was used as a substrate, and the YCW compound was added at two levels (5 and 10 mg). In Exp. 3, feces from cats fed YCWs were used as an inoculum to test three different substrates (pectin, amino acids, and cellulose). In Exp. 2 and 3, the gas production, pH, and fermentation products (ammonia, SCFAs, and BCFAs) were assessed. YCW-30 resulted in a higher digestibility coefficient of the crude protein, organic matter (OM) (p < 0.05), and energy of the diet (p < 0.10). Regarding the fermentation products, YCW-15 showed a trend toward higher concentrations of propionate, acetate, lactate, ammonia, isobutyrate, and valerate, while YCW-30 showed a trend (p < 0.10) toward higher levels of butyrate and pH values. The bacteroidia class and the genus Prevotella were increased by using YCW-30 and the control. At the gender level, decreased (p < 0.01) Megasphaera was observed with YCW inclusion. The microbiota differed (p < 0.01) among the groups in their Shannon indexes. For beta diversity, YCW-30 showed higher indexes (p = 0.008) than the control. The microbiota metabolic profile differed in the pathway CENTFERM-PWY; it was more expressed in YCW-30 compared to the control. In Exp. 2, the YCWs showed a higher ratio (p = 0.006) of the fermentation products in the treatments with additives with a trend towards a high dose of the additive (10 mg). In Exp. 3, the effects of the substrates (p < 0.001), but not of the YCWs, on the fermentation products were observed, perhaps due to the low dietary concentrations we used. However, the marked responses of the fermentation products to the substrates validated the methodology. We could conclude that the YCWs, even at low dietary concentrations, affected fecal SCFA production, reduced the fecal pH, and modulated the fecal microbiota in the cats. These responses were more pronounced under in vitro conditions.

Effects of a Saccharomyces cerevisiae fermentation product on fecal characteristics, metabolite concentrations, and microbiota populations of dogs undergoing transport stress

Previously, a Saccharomyces cerevisiae fermentation product (SCFP) positively altered fecal microbiota, fecal metabolites, and immune cell function of adult dogs. Our objective was to determine the fecal characteristics, microbiota, and metabolites of SCFP-supplemented dogs subjected to transport stress. All procedures were approved by the Four Rivers Kennel IACUC prior to experimentation. Thirty-six adult dogs (18 male, 18 female; age: 7.1 ± 0.77 yr; body weight: 28.97 ± 3.67 kg) were randomly assigned to be controls or receive SCFP supplementation (250 mg/dog/d) (N = 18/group) for 11 wk. At that time, fresh fecal samples were collected before and after transport in a hunting dog trailer with individual kennels. The trailer was driven 40 miles round trip for about 45 min. Fecal microbiota data were evaluated using Quantitative Insights Into Microbial Ecology 2, while all other data were analyzed using the Mixed Models procedure of Statistical Analysis System. Effects of treatment, transport, and treatment × transport were tested, with P < 0.05 being considered significant. Transport stress increased fecal indole concentrations and relative abundances of fecal Actinobacteria, Collinsella, Slackia, Ruminococcus, and Eubacterium. In contrast, relative abundances of fecal Fusobacteria, Streptococcus, and Fusobacterium were reduced by transport. Fecal characteristics, metabolites, and bacterial alpha and beta diversity measures were not affected by diet alone. Several diet × transport interactions were significant, however. Following transport, relative abundance of fecal Turicibacter increased in SCFP-supplemented dogs, but decreased in controls. Following transport, relative abundances of fecal Proteobacteria, Bacteroidetes, Prevotella, and Sutterella increased in controls, but not in SCFP-supplemented dogs. In contrast, relative abundances of fecal Firmicutes, Clostridium, Faecalibacterium, and Allobaculum increased and fecal Parabacteroides and Phascolarctobacterium decreased after transport stress in SCFP-supplemented dogs, but not in controls. Our data demonstrate that both transport stress and SCFP alter fecal microbiota in dogs, with transport being the primary cause for shifts. SCFP supplementation may provide benefits to dogs undergoing transport stress, but more research is necessary to determine proper dosages. More research is also necessary to determine if and how transport stress impacts gastrointestinal microbiota and other indicators of health.

Evaluation of the Influence of Coprophagic Behavior on the Digestibility of Dietary Nutrients and Fecal Fermentation Products in Adult Dogs

Coprophagia is a common and undesirable behavior observed in dogs; however, little is known about its causes or possible consequences when analysis of the animal's feces is needed for experimental purposes. Therefore, this study evaluated the effect of coprophagy on digestibility, fecal pH, and fermentative metabolites. Twelve healthy dogs with a mean age of 3.50 ± 1.45 years were included and divided into two groups: coprophagic (COP) and non-coprophagic (NCOP). The study lasted 30 days, the last 6 days being used to collect feces for the analysis of the apparent digestibility of coefficients (ADC), fecal pH, and the concentration of short- and branched-chain fatty acids, ammonia, and fecal lactic acid. Statistical analysis was performed using the SAS software. No differences were observed for most variables, except for the ADC of nitrogen-free extract (NFE), which presented the highest average for the COP. This result should be interpreted with caution, as the NFE is estimated from calculations and was not determined in the laboratory; in addition, the results represent not only starch and sugars but also some parts referring to fibers. Therefore, coprophagy seemed not to influence the fecal variables analyzed.

Evaluation of Torula yeast as a protein source in extruded feline diets

The objective of this work was to evaluate the use of a Torula yeast (TY) on diet processing, palatability, and total tract nutrient digestibility in extruded feline diets. Four dietary treatments were compared, differing by protein source: TY, pea protein concentrate (PP), soybean meal (SM), and chicken meal (CM). Diets were produced using a single-screw extruder under similar processing conditions. Palatability assessment was conducted as a split plate design where both first choice and intake ratio (IR) were determined. Apparent total tract digestibility (ATTD) of nutrients was estimated using Titanium dioxide as an indigestible marker. During diet production, specific mechanical energy of TY and SM (average of 187 kJ/kg) was greater (P < 0.05) than for PP (138 kJ/kg); however, CM was similar to all treatments (167 kJ/kg). Kibble diameter, piece volume, and sectional expansion ratio were greatest for TY (P < 0.05). Additionally, both bulk and piece density were lowest (P < 0.05) for TY. Kibble hardness was lower for TY and SM (P < 0.05; average of 2.10 Newtons) compared to CM and PP (average of 2.90 Newtons). During the palatability trial, TY was chosen first a greater number of times than CM (P < 0.05; 36 vs. 4, respectively), but differences were not found between TY and PP (25 vs. 15, respectively) or TY and SM (24 vs. 16, respectively). Cats had a greater IR (P < 0.05) of TY compared to CM and PP (0.88 and 0.73, respectively). However, there was no difference in preference between TY and SM. ATTD of dry matter (DM) and organic matter (OM) was greater (P < 0.05) for CM (87.43% and 91.34%, respectively) than other treatments. Both DM and OM ATTD of TY were similar (P < 0.05) to PP and SM (average of 86.20% and average of 89.76%, respectively). Ash ATTD was greater (P < 0.05) for cats fed TY and SM (average of 37.42%), intermediate for PP (32.79%), and lowest for CM (23.97%). Crude protein (CP) ATTD of TY was similar to all other treatments (average of 89.97%), but fat ATTD was lower (P < 0.05; 92.52%) than other treatments (93.76% to 94.82%). Gross energy ATTD was greater (P < 0.05) for CM than TY (90.97% vs. 90.18%, respectively); however, TY was similar to PP and SM (average of 90.22%). Total dietary fiber ATTD was similar between TY and CM (average of 66.20%) and greater (P < 0.05) than PP and SM (average of 58.70%). The TY used in this study facilitated diet formation, increased diet preference, and was highly digestible when fed to cats.

Effects of a Saccharomyces cerevisiae fermentation product-supplemented diet on circulating immune cells and oxidative stress markers of dogs

Feeding Saccharomyces cerevisiae fermentation product (SCFP) has previously altered fecal microbiota, fecal metabolites, and immune function of adult dogs. The objective of this study was to investigate measures of skin and coat health, changes in circulating immune cell numbers and activity, antioxidant status, and oxidative stress marker concentrations of healthy adult dogs fed a SCFP-supplemented extruded diet. Sixteen adult English Pointer dogs (8 M, 8 F; mean age = 6.7 ± 2.1 yr; mean BW = 25.9 ± 4.5 kg) were used in a randomized crossover design study. All dogs were fed a control diet for 4 wk, then randomly assigned to either the control or SCFP-supplemented diet (0.13% of active SCFP) and fed to maintain BW for 10 wk. A 6-wk washout preceded the second 10-wk experimental period with dogs receiving opposite treatments. After baseline/washout and treatment phases, skin and coat were scored, and pre and postprandial blood samples were collected. Transepidermal water loss (TEWL), hydration status, and sebum concentrations were measured (back, inguinal, ear) using external probes. Oxidative stress and immune cell function were measured by ELISA, circulating immune cell percentages were analyzed by flow cytometry, and mRNA expression of oxidative stress genes was analyzed by RT-PCR. Change from baseline data was analyzed using the Mixed Models procedure of SAS 9.4. Sebum concentration changes tended to be higher (P < 0.10; inguinal, ear) in SCFP-fed dogs than in controls. TEWL change was lower (P < 0.05) on the back of controls, but lower (P = 0.054) on the ear of SCFP-fed dogs. Delayed-type hypersensitivity response was affected by diet and time post-inoculation. Other skin and coat measures and scores were not affected by diet. Changes in unstimulated lymphocytes and stimulated IFN-γ secreting T cells were lower (P < 0.05) in SCFP-fed dogs, while changes in stimulated T cells were lower (P < 0.05) in control-fed dogs. Upon stimulation, the percentage of cytotoxic T cells delta trended lower (P < 0.10) in SCFP-fed dogs. Change in serum superoxide dismutase concentrations was higher (P < 0.05) and change in catalase mRNA expression was lower (P < 0.05) in SCFP-fed dogs. All other measurements of immune cell populations, oxidative stress markers, and gene expression were unaffected by treatment. In conclusion, our data suggest that SCFP positively impacts indicators of skin and coat health of dogs, modulates immune responses, and enhances some antioxidant defense markers.

Effect of orange fibre on nutrient digestibility and fermentation products in faeces of cats fed kibble diets

The aim of the present study was to compare orange fibre, beet pulp and inulin as fibre sources for cats. A control diet (CON) was formulated without inclusion of a fibre source. Further experimental diets were also based on diet CON but were supplemented with 1% orange fibre (diet 1%OF); 3% orange fibre (diet 3%OF); 3% beet pulp (diet 3%BP) or 1% inulin (diet 1%IN). Forty cats were used in a randomised block design (4 blocks of 10 cats, 2 animals per food in each block, totalling 8 animals per treatment). Each block lasted 20 d, with 10 d of adaptation, 10 d of faecal collection for digestibility as well as evaluation of pH-value and fermentation products. The digestibility of dry matter, organic matter, crude protein, ether extract, starch and gross energy did not vary between diets. In diet 1%OF, dietary fibre revealed a greater digestibility than in diet CON (p < 0.05). Faecal production was higher in cats fed diets 3%OF and 3%BP than in those fed diet 1%IN (p < 0.05). Faecal concentrations of acetate and total short-chain fatty acids were higher for cats fed diet 3%BP than for those fed diets 1%IN and CON (p < 0.05), while diets 1%OF and 3%OF showed intermediate results. Faecal propionate concentration was higher for cats fed diet 3%BP, intermediate for diets 1%OF, 3%OF and 1%IN and lower for animals fed diet CON (p < 0.05). Compared with diets CON and 1%IN, the faecal concentration of tyramine was higher for cats fed diet 3%OF (p < 0.05). Orange fibre was fermentable; up to 3% inclusion it did not interfere with the digestibility of nutrients, faecal score and faecal moisture content, and promoted the formation of short-chain fatty acids and tyramine by the intestinal microbiota, with possible effects on intestinal function.

Disclosing the Genomic Diversity among Members of the Bifidobacterium Genus of Canine and Feline Origin with Respect to Those from Human

In recent decades, much scientific attention has been paid to characterizing members of the genus Bifidobacterium due to their well-accepted ability to exert various beneficial effects upon their host. However, despite the well-accepted status of dogs and cats as principal companion animals of humans, the bifidobacterial communities that colonize their gut still represents a rather unexplored research area. To expand and further investigate the bifidobacterial ecosystem inhabiting the canine and feline intestine, strains belonging to this genus were isolated from fecal samples of dogs and cats and subjected to de novo sequencing. The obtained sequencing data, together with publicly available genomes of strains belonging to the same bifidobacterial species of our isolates, and of both human and animal origin, were employed for in-depth comparative genome analyses. These phylogenomic investigations highlighted a different degree of genetic variability between human- or pet-derived bifidobacteria depending on the considered species, with B. pseudocatenulatum strains of pet origin showing higher genetic variability than human-derived strains of the same bifidobacterial species. Furthermore, in silico evaluation of metabolic activities coupled with in vitro growth assays revealed the crucial role of diet in driving the genetic assembly of bifidobacteria as a result of their adaptation to the specific ecological niche they colonize. IMPORTANCE Despite cats and dogs being well recognized as the most intimate companion animals to humans, current knowledge on canine and feline gut microbial consortia is still far from being fully dissected compared to the significant advances achieved for other microbial ecosystems, such as the human gut microbiota. In this context, a combination of in silico genome-based analysis and in vitro carbohydrate growth assay allowed us to further explore the canine and feline bifidobacterial community with respect to that inhabiting the human intestine. Specifically, these data revealed how strains of different bifidobacterial species seem to have evolved a different degree of host-specific adaptation. In detail, genotypic and phenotypic evidence of how diet can be considered the main factor of this host-specific adaptation is provided.

Altered fecal microbiota, IgA, and fermentative end-products in adult dogs fed prebiotics and a nonviable Lactobacillus acidophilus

A study investigating the use of a nonviable Lactobacillus acidophilus (NVL: Culbac; TransAgra, Storm Lake, IA) and a mixed prebiotic (MP) blend (beet pulp, fructooligosaccharide (FOS), mannanoligosaccharide (MOS), inulin, and kelp) was done to evaluate changes in fecal microbiota, fermentative end products, and gut immune health in healthy female and male adult Beagle dogs (n = 24; 5.74 ± 2.18 yr; 9.30 ± 1.32 kg). The study protocol was first approved by the facility's Institutional Animal Care and Use Committee (Summit Ridge Farms; Susquehanna, PA) and followed throughout. Each of four test diets (control, NVL, MP, and MP + NVL [formulated to crude protein 25%, crude fat 14%, crude fiber 10% as-fed]) was fed once daily to maintain body weight for 21 d in a randomized-crossover design (four treatment periods and four washout periods). Fecal samples were collected on days 0 and 21 only for immunoglobulin A (IgA) and microbiota evaluation (16S rRNA V4 region and qPCR for Escherichia coli and Bifidobacterium), and fecal fermentative end-products and fecal pH were assessed only on day 21. Over the test periods, apparent total tract nutrient digestibility and stool quality were assessed. Data were analyzed by ANOVA (SAS v9.4, Cary, NC) or Kruskal-Wallis for between-diet effects, and paired t-test or Wilcoxon for time effects. Statistical significance was set at P ≤ 0.05. Apparent total tract nutrient digestibility revealed feeding MP-containing diets resulted in lower (P < 0.05) crude protein and fat digestibility vs. control and NVL diets. When dogs were fed MP, they had lower (P < 0.05) fecal pH compared with control and NVL diets, whereas fecal pH was lower in (P < 0.05) MP + NVL- vs. NVL-fed dogs. Fecal E. coli was (P < 0.05) lower at day 21 vs. day 0 when dogs were fed MP. Fecal Fusobacterium spp. was lower (P < 0.05) in both MP diets vs. control. Fecal Lactobacillus spp. increased (P < 0.05) from baseline with MP. Both diets with MP elicited greater (P < 0.05) fecal acetate and propionate concentration vs. control diet. At day 21, fecal IgA was greater (P < 0.05) in MP and MP + NVL compared with NVL diet. Only when dogs were fed MP did they have increased (P < 0.05) fecal IgA from day 21 vs. day 0. The MP + NVL diet decreased (P < 0.05) fecal isovalerate, isobutyrate, phenol, and indole vs. control. Overall, the MP elicited the most changes on microbiota, fermentative end-products, and IgA. Further investigation into NVL's gut health benefits is warranted.

Effects of Saccharomyces cerevisiae cell wall addition on feed digestibility, fecal fermentation and microbiota and immunological parameters in adult cats

Background

This study aimed to evaluate the effects of increasing dosages of a commercial product composed by Saccharomyces cerevisiae yeast (YAM), with active metabolites, which are beta glucans, nucleotides, organic acids, polyphenols, amino acids, vitamins and minerals (Original XPC^tm, Diamond V, IOWA, USA) added to a commercially available dry cat food. Apparent digestibility of dietary nutrients, fecal microbiota, fecal fermentation products and immunological parameters were evaluated. Twenty-seven healthy cats of mixed sexes, with a mean body weight of 4.19 ± 0.83 kg and a mean age of 9.44 ± 5.35 years were distributed by age in an unbalanced randomized block design, consisting of three experimental treatments: CD (control diet), YAM 0.3 (control diet with 0.3% yeast with active metabolites) and YAM 0.6 (control diet with 0.6% yeast with active metabolites).

Results

The inclusion of the additive elevated the apparent digestibility of crude fiber (p = 0.013) and ash (p < 0.001) without interfering feed consumption, fecal production and fecal characteristics. Regarding fermentation products present in the feces, prebiotic inclusion increased lactic acid concentration (p = 0.004) while reducing isovaleric acid (p = 0.014), only in the treatment YAM 0.3. No differences were noticed on biogenic amines (BA), fecal pH, ammonia concentration, total and individuals short-chain fatty acids (SCFA) and total and individuals branched-chain fatty acids (BCFA) (except isovaleric acid in YAM 0.3). As regards to fecal microbiota, prebiotic inclusion has resulted in the reduction of Clostridium perfringens (p = 0.023). No differences were found in the immunological parameters evaluated.

Conclusion

It can be concluded that the additive, at the levels of inclusion assessed shows prebiotic potential and it has effects on fecal fermentation products and microbiota without interfering on crude protein and dry matter digestibility. More studies evaluating grater inclusion levels of the prebiotic are necessary to determine optimal concentration.

Effects of thermal energy on extrusion characteristics, digestibility and palatability of a dry pet food for cats

The influence of specific thermal energy (STE) applications on extruder preconditioner was evaluated in a dry food for cats. In the first study, six STE applications were tested with mass temperatures of 45°C, 55°C, 65°C, 75°C, 85°C and 95°C. The extrusion parameters, starch gelatinization and kibble formation were evaluated. Diets were given to cats to evaluate digestibility, faecal characteristics and palatability. In the second experiment, three treatments were compared: low STE-a preconditioner temperature of 45°C (_L STE); high STE-a preconditioner temperature of 95°C (_H STE); high STE (preconditioner temperature of 95°C) combined with an increase in the mass flow rate to obtain a motor amperage similar to that of the _L STE (_H STE_flow ). Data were analysed by polynomial contrasts (Experiment 1) or Tukey's test (Experiment 2; p < 0.05). An increase in STE reduced motor amperage, mass pressure and specific mechanical energy (SME) implementation (p < 0.001) and increased total specific energy (TSE) and mass temperature (p < 0.01). The increase in STE induced greater kibble expansion and starch gelatinization (p < 0.001). No changes in apparent nutrient digestibility or faeces characteristics were observed (p > 0.05). Lower STE and starch gelatinization induced higher butyrate and total volatile fatty acid (VFA) contents in faeces (p < 0.01). Cats showed greatest preference for the formulation with the highest STE (p < 0.01). In the second experiment, when the motor amperage was increased in the _H STE_flow treatment to a value similar to that of the _L STE, the mass flow rate increased 40%, and the electric energy consumption remained unchanged (p < 0.001), with gains observed for efficiency and cost. In conclusion, STE application is important for sufficient TSE implementation, enhancing kibble expansion, starch gelatinization, cat preferences for food, extruder productivity and reducing SME application. Foods with lower starch gelatinization lead to increased VFA in faeces, with possible implications for gut health.

Seaweed Supplementation Failed to Affect Fecal Microbiota and Metabolome as Well as Fecal IgA and Apparent Nutrient Digestibility in Adult Dogs

The present study investigated in dogs the dietary effects of intact seaweeds on some fecal bacterial populations and metabolites, fecal IgA and apparent total tract digestibility (ATTD). Ten healthy adult dogs were enrolled in a 5 × 5 replicated Latin square design to evaluate five dietary treatments: control diet (CD); CD + Ascophyllum nodosum; CD + Undaria pinnatifida; CD + Saccharina japonica; CD + Palmaria palmata (n replicates per treatment = 10). Seaweeds were added to food at a daily dose of 15 g/kg. The CD contained silica as a digestion marker. Each feeding period lasted 28 d, with a 7 d wash-out in between. Feces were collected at days 21 and 28 of each period for chemical and microbiological analyses. Fecal samples were collected during the last five days of each period for ATTD assessment. Dogs showed good health conditions throughout the study. The fecal chemical parameters, fecal IgA and nutrient ATTD were not influenced by algal supplementation. Similarly, microbiological analyses did not reveal any effect by seaweed ingestion. In conclusion, algal supplementation at a dose of 15 g/kg of diet failed to exert noticeable effects on the canine fecal parameters evaluated in the present study.

Orange fibre effects on nutrient digestibility, fermentation products in faeces and digesta mean retention time in dogs

Fermentable fibres are used in commercial dog food to promote intestinal health by providing substrates for better metabolic activity of the gut microbiota. Brazil is the world's largest producer of oranges, from which it is possible to obtain fibre with a relevant soluble fraction. The present study compared the effects of two inclusions of orange fibre (1% and 3%, on as fed basis) with a negative control (without addition of fibre source) and two positive controls, beet pulp (3%) and purified inulin (1%), totalling five extruded diets for dogs. The experiment followed a randomised block design with 4 blocks of 10 dogs, 2 dogs per food in each block, totalling 8 dogs per diet. The apparent total tract nutrient digestibility was determined by total faecal collection. Faecal pH and fermentation product content were also measured. The digesta mean retention time (DMRT) was evaluated using plastic markers. The inclusion of a 3% fibre source in diets with 3% orange fibre and beet pulp reduced DM, OM, and energy digestibility (p < 0.05). Diets with 3% orange fibre, beet pulp and 1% inulin presented lower crude protein digestibility than the control (p < 0.05). Dietary fibre digestibility was higher for orange fibre-supplemented diets than inulin (p < 0.05). Beet pulp and 3% orange fibre inclusions resulted in increased moisture content in the faeces of dogs (p < 0.05) but did not alter DMRT. Total short-chain fatty acids were higher than the control in the faeces of dogs fed both orange fibre levels and the beet pulp-supplemented diet (p < 0.05), and the inulin diet-fed dogs presented intermediate values. Butyrate was higher in the faeces of dogs fed the diets supplemented with 1% and 3% orange fibre (p < 0.05), and similar values to the control were observed for beet pulp- and inulin-fed animals. Thus, it was concluded that orange fibre presented higher apparent total tract dietary fibre digestibility than beet pulp and had a fermentation profile in the colon that promoted the generation of butyrate, an effect not observed for inulin and beet pulp.

Duration of Prebiotic Intake Is a Key-Factor for Diet-Induced Modulation of Immunity and Fecal Fermentation Products in Dogs

Prebiotics promote health benefits, however, there is no consensus on the minimal intake period required in order to obtain good results. This study evaluated the effect of the time of ingestion of prebiotics on fecal fermentation products and immunological features in dogs. Twenty-four adult dogs were randomly distributed in a block design with six groups and four treatments. Diet and intake period were variation factors. Diets were either a control diet without the addition of prebiotic (CO) or with the inclusion of 1% of a commercial product containing a minimum of 0.38% galactooligosaccharides (GOS), 0.5% (B1) or 1% (B2) of a prebiotic blend. Time variable was set at 30 and 60 days for evaluation of immunity and gut health. Results were analyzed in the Statistical Analysis System software (SAS), version 9.4, considering the repeated measures over time design, and means were compared by the Tukey test and p < 0.05 was significant. Propionic acid was the only variable that had an interaction effect, with reduction of this metabolite in treatment B2 in the period of 60 days. At T60, concentrations of immunoglobulin A, lactic acid, and pH in the feces increased (p < 0.05) in all treatments regardless of prebiotic inclusion or not. GOS increased fecal score and lactic acid concentrations. Therefore, a 60-day intake period of a prebiotic blend was not sufficient to modulate fecal and immune variables and higher concentrations of a single prebiotic would be more relevant for results.

Impacts of Dietary Protein and Prebiotic Inclusion on Liver and Spleen Gene Expression in Hy-Line Brown Caged Layers

Simple Summary

Eggs are one of the most affordable and nutritious animal proteins available, and with increasing human population, there is an increased demand for production. As feed is the main expense in poultry production, novel protein sources and feed additives need to be evaluated for their benefits for poultry health and performance. In this study, we evaluated the standard soybean-based diets against an alternate source—cottonseed meal, in the context of prebiotic addition. Prebiotics putatively improves health and production. We assessed the homeostatic and immune balance by assaying the expression of select marker genes. We find that the inclusion of yeast cell wall products as prebiotic alters homeostatic balance. Particularly, the upregulation of apoptosis—a normal cell process—suggests that these products may promote homeostatic balance.

Abstract

The ingredients of poultry feeds are chosen based on the least-cost formulation to meet nutritional requirements. However, this approach can lead to the introduction of anti-nutritional ingredients in the feed. The objective of this study was to evaluate the impacts of two diets (with or without prebiotic) on homeostatic genes in the liver and spleen of laying hens. Hy-Line Brown layers were raised either on a soybean meal or cottonseed meal-based diets with and without an added prebiotic (yeast cell wall), totaling four experimental diets. A total of 120, 63-week old layers were housed individually in a wire cage system. We investigated differences in the expression of select homeostatic marker genes in the liver and spleen of hens from each treatment. We then used the ΔΔCT and generalized linear models to assess significance. Results show that the inclusion of prebiotic yeast cell-wall (YCW) increased the expression of the BAK gene in the liver tissue for both the soybean meal (SBM) and cottonseed meal (CSM) diets. For splenic tissue, the combination of YCW with the CSM diet increased the POR gene over six log2 fold. Altogether, our results suggest altered homeostasis, which can have consequences for health and performance.