Apparent Total Tract Macronutrient Digestibility Research Articles

Effects of dietary fiber and biotic supplementation on apparent total tract macronutrient digestibility and the fecal characteristics, metabolites, and microbiota of healthy adult dogs.

Dietary fibers and biotics have been shown to support gastrointestinal health in dogs, but are usually tested individually. There is value in testing fiber-biotic combinations that are commonly used commercially. Therefore, this study was conducted to determine the apparent total tract macronutrient digestibility (ATTD) of diets supplemented with fibers or biotics and to evaluate their effects on the fecal characteristics, metabolites, microbiota, and immunoglobulin A (IgA) concentrations of dogs. Twelve healthy adult female beagle dogs (age= 6.2 ± 1.6 yr; body weight = 9.5 ± 1.1kg) were used in a replicated 3 x 3 Latin square design to test three treatments: 1) control diet based on rice, chicken meal, tapioca starch, and cellulose + a placebo treat (CT); 2) diet based on rice, chicken meal, garbanzo beans, and cellulose + a placebo treat (GB); 3) diet based on rice, chicken meal, garbanzo beans, and a functional fiber/prebiotic blend + a probiotic-containing treat (GBPP). In each 28-day period, a 22-day diet adaptation was followed by a 5-day fecal collection phase. Fasted blood samples were collected on day 28. Data were analyzed using the Mixed Models procedure of SAS 9.4, with P<0.05 being significant and P<0.10 being trends. ATTD of dry matter, organic matter, and energy were lower (P<0.001) and DM fecal output was higher (P<0.01) in dogs fed GBPP than CT or GB, whereas ATTD of crude protein was higher (P<0.001) in dogs fed CT and GBPP than GB. ATTD of fat was higher (P<0.001) and wet fecal output was lower (P<0.01) in dogs fed CT than GB or GBPP. Fecal DM% was higher (P<0.001) in dogs fed CT than GBPP or GB, and higher in dogs fed GBPP than GB. Fecal short-chain fatty acid concentrations were higher (P<0.001) in dogs fed GB than CT or GBPP, and higher in dogs fed GB than GBPP. Fecal IgA concentrations were higher (P<0.01) in dogs fed GB than CT. Fecal microbiota populations were affected by diet, with alpha diversity being higher (P<0.01) in dogs fed GB than CT, and beta diversity shifting following dietary fiber and biotic supplementation. The relative abundance of 24 bacterial genera were altered in dogs fed GB or GBPP than CT. Serum triglyceride concentrations were lower in dogs fed GB than GBPP or CT. Our results demonstrate that legume-based dietary fibers, with or without prebiotics and probiotics, reduce ATTD, increase stool output, beneficially shift fecal metabolites and microbiota, and reduce blood lipids of adult dogs.

193 Apparent Total Tract Nutrient Digestibility of Frozen Raw, Freeze-Dried Raw, Fresh, and Extruded Dog Foods and Their Effects on Fecal Characteristics and Metabolites of Adult Dogs

Abstract Various pet food diet formats are now available. Processing methods are known to impact nutrient digestibility and are thought to affect pet health but are poorly studied. Therefore, the objective of this study was to determine the apparent total tract macronutrient digestibility (ATTD) of frozen raw, freeze-dried raw, fresh, and extruded dog foods and assess their effects on fecal characteristics, and fecal metabolites of healthy adult dogs. Ten healthy adult spayed female dogs were used in a replicated 5x5 Latin square study to test the following diets: Chicken and Barley Recipe [extruded diet; Hill’s Science Diet (EXT)], Chicken and White Rice Recipe [fresh diet; Just Food for Dogs (FRSH)], Chicken Formula [raw frozen diet; Primal (FRZN)], Chicken and Sorghum Hybrid Freeze-dried Formula [hybrid freeze-dried raw diet; Primal (HFD)], and Chicken Dinner Patties [raw freeze-dried diet; Stella &amp; Chewy (FD)]. The experiment was composed of five 35-day periods. Total feces excreted during a 5-day total collection phase was frozen until analyses and ATTD calculations. On the first day of fecal collections, one fresh fecal sample was collected for measurement of pH, dry matter (DM) content, and bile acid (BA) and fermentative metabolite concentrations. Data were analyzed statistically by Mixed Models using SAS 9.4, with P &amp;lt; 0.05 being significant. Widespread differences were noted among diets. Wet and DM fecal output was greater for EXT than other diets, and wet fecal output was greater for FRSH than FRZN, HFD, and FD. Protein ATTD was greater for FRZN and FD than other diets, and greater for HFD than FRSH and EXT. Fat ATTD was greater for HFD than FRZN and EXT, and less for EXT than other diets. Fecal pH was less in EXT and FRSH than other diets. Fecal scores were greater (looser) in EXT and FRSH than FRZN and FRZDR. Fecal DM% was greater in FD than other diets, and greater in FRZN and HFD than EXT and FRSH. In general, fecal short-chain fatty acids were highest in EXT, intermediate in FRSH and HFD, and least in FRZN and FD. Fecal branched-chain fatty acids were greatest in FDF, intermediate in EXT, FRZN, and FD, and least for FRSH. Fecal phenols and indoles were greatest in HYB and least in FRSH, with others being intermediate. Fecal primary BA were greater in FRSH than other diets, while fecal secondary BA were greater in FRZN than HFD, FRSH, and EXT, greater in FD than FRSH and EXT, and greater in HFD than FRSH. In summary, the diets tested were very different in regard to nutrient digestibility, fecal characteristics, and fecal metabolites. More research is necessary to distinguish how ingredient source, diet processing, macronutrient composition, and other factors may contribute to these differences.

199 Effects of Dietary Fiber and Biotic Supplementation on Apparent Total Tract Macronutrient Digestibility, Fecal Characteristics, and Fecal Metabolites of Healthy Adult Dogs

Abstract Synbiotics, or mixtures of live microorganisms and substrates selectively utilized by host microorganisms, may confer complementary or synergistic health benefits to the host. Although synbiotics have demonstrated the potential to modulate the gut microbiome and improve gastrointestinal health in many host species, research trials in companion animal diets are limited. Therefore, this study was conducted to determine the apparent total tract macronutrient digestibility (ATTD) of diets supplemented with fibers or biotics and to evaluate their effects on the fecal characteristics, metabolites, microbiota, and immunoglobulin (Ig) A concentrations of dogs consuming them. Healthy adult female beagles (n = 12; age= 6.2 ± 1.6 yr; BW = 9.5 ± 1.1 kg) were used in a replicated 3 x 3 Latin square design to test three dietary treatments: 1) basal diet based on rice, chicken meal, tapioca starch, and cellulose and without probiotics or prebiotics + a placebo treat (control, CT); 2) diet based on rice, chicken meal, garbanzo beans, and cellulose + placebo treat (GB); 3) diet based on rice, chicken meal, and garbanzo beans, and functional fiber/prebiotic blend (mannanoligosaccharides; fructooligosaccharides, inulin, pea fiber, alfalfa meal, Saccharomyces cerevisiae fermentation product) + probiotic-containing treat (synbiotic treatment, SYN). The probiotic treat contained Bacillus subtilus and Bacillus amyloliquefaciens (2 x 109 CFU/d). In each 28-day period, a 22-day diet adaptation was followed by a 5-day fecal collection phase for measurement of ATTD and fecal characteristics, metabolites, microbiota, and IgA concentrations. Fasted blood samples were collected on day 28 for serum chemistry and complete blood count. All data were analyzed using the Mixed Models procedure of SAS 9.4, with P &amp;lt; 0.05 being significant. ATTD of dry matter (DM), organic matter, and energy were less and DM fecal output was greater in dogs fed SYN than those fed CT or GB, whereas ATTD of crude protein was greater in dogs fed CT and SYN than those fed GB. ATTD of fat was higher and wet fecal output was less in dogs fed CT than those fed GB or SYN. Fecal DM% was greater in dogs fed CT than those fed SYN or GB, and greater in dogs fed SYN than those fed GB. Fecal short-chain fatty acids (SCFA; acetate, propionate, total SCFA) were higher in dogs fed GB than those fed CT or SYN, and higher in dogs fed GB than those fed SYN. Fecal IgA concentrations were greater in dogs fed GB than those fed CT. Serum triglycerides were less in dogs fed GB than those fed SYN or CT. Our results demonstrate that legume-based dietary fibers, with or without prebiotics and probiotics, slightly reduce nutrient digestibility, increase stool output, beneficially shift fecal metabolites, and reduce blood lipids of adult dogs.

Effects of commercial and traditional kefir supplementation on apparent total tract macronutrient digestibility and the fecal characteristics, metabolites, and microbiota of healthy adult dogs.

Kefir is a fermented dairy beverage that has been consumed by humans for centuries, but poorly studied in pets. The objective of this study was to determine the effects of commercial or traditional kefir supplementation on apparent total tract macronutrient digestibility (ATTD) and fecal characteristics, microbiota populations, and metabolite and immunoglobulin (Ig) A concentrations of healthy adult dogs. Twelve healthy adult dogs (5.67 ± 1.72 yr, 7.27 ± 1.15 kg) were used in a replicated 3 × 3 Latin square design (n = 12/group). All dogs were fed a commercial diet and allotted to 1 of 3 treatments (60 mL/d): 2% reduced-fat milk treated with lactase [CNTL; 4.57E + 03 lactic acid bacteria (LAB) colony-forming units (CFU)/mL], commercial kefir (C-Kefir; 6.95E + 04 LAB CFU/mL), or traditional kefir brewed daily from 2% reduced-fat milk and kefir grains (T-Kefir; 1.79E + 09 LAB CFU/mL). The experiment was composed of three 28-d periods, with each consisting of a 22-d transition phase, a 5-d fecal collection phase, and 1 d for blood collection. Fecal samples were collected for determination of ATTD and fecal pH, dry matter, microbiota, and metabolite, and IgA concentrations. Data were analyzed using the Mixed Models procedure of SAS 9.4. The main effects of treatment were tested, with significance set at P ≤ 0.05 and trends set at P ≤ 0.10. Kefir products differed in microbial density and profile, but fecal microbiota populations were weakly impacted. Bacterial alpha diversity tended to be greater (P = 0.10) in dogs fed T-Kefir than those fed CNTL. Bacterial beta diversity analysis identified a difference (P < 0.0004) between dogs-fed CNTL and those fed C-Kefir. Dogs-fed C-Kefir tended to have a greater (P = 0.06) relative abundance of Fusobacteriota than those fed CNTL or T-Kefir. Dogs-fed T-Kefir had a greater (P < 0.0001) relative abundance of Lactococcus than those fed CNTL or C-Kefir. Dogs-fed T-Kefir also tended to have a lower (P = 0.09) relative abundance of Escherichia Shigella and greater (P = 0.09) relative abundance of Candidatus stoquefichus than dogs-fed CNTL or C-Kefir. Dogs-fed C-Kefir tended to have lower (P = 0.08) fecal valerate concentrations than those fed CNTL or T-Kefir. All other measures were unaffected by kefir treatments. Our results suggest that kefir supplementation had minor effects on the fecal microbiota populations and fecal metabolite concentrations of healthy adult dogs without impacting ATTD, fecal characteristics, or fecal IgA concentrations.

Apparent total tract macronutrient digestibility of mildly cooked human-grade vegan dog foods and their effects on the blood metabolites and fecal characteristics, microbiota, and metabolites of adult dogs.

Vegan, mildly cooked, and human-grade dog foods are becoming more popular, as beliefs and views of pet owners change. To our knowledge, however, dog studies have not examined the digestibility of commercial vegan diets. Therefore, the objective of this study was to determine the apparent total tract digestibility (ATTD) of mildly cooked human-grade vegan dog foods and their effects on blood metabolites and fecal microbiota, characteristics, and metabolites of adult dogs consuming them. Three commercial dog foods were tested. Two were mildly cooked human-grade vegan dog diets, while the third was a chicken-based extruded dog diet. Twelve healthy adult female beagles (7.81 ± 0.65 kg; 7.73 ± 1.65 yr) were used in a replicated 3 × 3 Latin Square design. The study consisted of three experimental periods, with each composed of a 7 d diet adaptation phase, 15 d of consuming 100% of the diet, a 5 d phase for fecal collection for ATTD measurement, and 1 d for blood collection for serum chemistry and hematology. During the fecal collection period, a fresh sample was collected for fecal scoring and dry matter, pH, metabolite, and microbiota measurements. All data were analyzed using the Mixed Models procedure of SAS (version 9.4). All three diets were shown to be highly digestible, with all macronutrients having digestibility values above 80%. The vegan diets had higher (P < 0.001) ATTD of fat, but lower (P < 0.05) ATTD of organic matter than the extruded diet. Dogs consuming the vegan diets had lower circulating cholesterol (P < 0.001), triglyceride (P < 0.001), and platelet (P < 0.009) concentrations and lower (P < 0.010) blood neutrophil percentages than dogs consuming the extruded diet. Dogs consuming vegan diets had lower (P < 0.001) fecal dry matter percentages, lower (P < 0.001) fecal phenol and indole concentrations, and higher (P = 0.05) fecal short-chain fatty acid concentrations than those consuming the extruded diet. Fecal bacterial alpha and beta diversities were not different (P > 0.05) among diets, but dogs consuming vegan diets had altered (P < 0.05) relative abundances of nearly 20 bacterial genera when compared with those consuming the extruded diet. In conclusion, the mildly cooked human-grade vegan dog foods tested in this study performed well, resulting in desirable fecal characteristics, ATTD, and serum chemistries. The vegan diets tested also led to positive changes to serum lipids and fecal metabolites, and interesting changes to the fecal microbial community.

Palatability and apparent total tract macronutrient digestibility of retorted black soldier fly larvae-containing diets and their effects on the fecal characteristics of cats consuming them.

There is a growing interest in using black soldier fly larvae (BSFL) due to its supposed sustainability and nutritional qualities. Because little research has been conducted to evaluate the use of BSFL in cats, our objective was to determine the palatability and apparent total tract macronutrient digestibility (ATTD) of BSFL-containing canned diets and the fecal characteristics of healthy adult cats consuming them. First, three palatability tests were conducted to compare the following diets: 1) diet with poultry byproduct meal (PBPM) and chicken serving as the primary protein sources (control) vs. diet with BSFL meal replacing PBPM (BSFL meal); 2) control vs. diet with whole BSFL replacing some PBPM and poultry fat (BSFL whole); and 3) control vs. diet with BSFL oil replacing poultry fat (BSFL oil). All diets were formulated to meet Association of American Feed Control Officials nutrient profiles for adult cats and were produced using a still retort. A paired t-test was conducted to analyze data from each palatability test, with a higher (P < 0.05) consumption ratio being observed for BSFL meal (1.93:1), BSFL whole (2.03:1), and BSFL oil (1.57:1). Second, 32 adult cats (20 females and 12 males; BW: 4.19±0.55kg; age: 3.3±0.38 yr) were used in a completely randomized design study composed of a 21-d baseline period and a 70-d experimental period. Cats consumed the control diet during the baseline and were then allotted to one of four experimental diets (n = 8 per group): 1) control, 2) BSFL meal, 3) whole BSFL, and 4) BSFL oil. Fecal samples were collected after baseline and experimental periods for ATTD and fecal characteristic analysis. Fecal output was higher (P < 0.05) and fecal dry matter percentage was lower (P < 0.05) in cats fed BSFL meal than those fed BSFL oil. Organic matter, crude protein (CP), and energy ATTD were lower (P < 0.05) in cats fed BSFL meal than those fed BSFL oil or control. CP and energy ATTD were lower (P < 0.05) in cats fed BSFL whole than those fed BSFL oil. A few serum metabolites were affected by diet (P < 0.05) but remained within reference ranges. Hematology was not affected by diet (P > 0.05). Overall, our results suggest that BSFL-containing diets are palatable and do not negatively affect fecal characteristics or serum chemistry but may have slightly lower nutrient digestibilities in adult cats.

Dietary supplementation with fiber, "biotics," and spray-dried plasma affects apparent total tract macronutrient digestibility and the fecal characteristics, fecal microbiota, and immune function of adult dogs.

A variety of functional ingredients, including fibers, prebiotics, probiotics, and postbiotics may be added to pet foods to support gastrointestinal and immune health. While many of these ingredients have been tested individually, commercial foods often include blends that also require testing. This study was conducted to evaluate the effects of diets containing blends of fibers, "biotics," and/or spray-dried plasma on apparent total tract digestibility (ATTD), stool quality, fecal microbiota and metabolites, and immune health outcomes of adult dogs. A total of 12 healthy adult intact English pointer dogs (6 M, 6 F; age = 6.4±2.0 yr; BW = 25.8±2.6kg) were used in a replicated 3×3 Latin square design to test diets formulated to: 1) contain a low concentration of fermentative substances (control diet, CT); 2) be enriched with a fiber-prebiotic-probiotic blend (FPPB); and 3) be enriched with a fiber-prebiotic-probiotic blend + immune-modulating ingredients (iFFPB). In each 28-d period, 22 d of diet adaptation was followed by a 5-d fecal collection phase and 1 d for blood sample collection. All data were analyzed using SAS 9.4, with significance being P < 0.05 and trends being P < 0.10. FPPB and iFPPB diets led to shifts in numerous outcome measures. Dry matter (DM), organic matter, fat, fiber, and energy ATTD were lower (P < 0.01), fecal scores were lower (P < 0.01; firmer stools), and fecal DM% was higher (P < 0.0001) in dogs fed FPPB or iFPPB than those fed CT. Serum triglycerides and cholesterol were lower (P < 0.01) in dogs fed FPPB or iFPPB than those fed CT. Fecal protein catabolites (isobutyrate, isovalerate, indole, and ammonia) and butyrate were lower (P < 0.05), while fecal immunoglobulin A (IgA) was higher (P < 0.01) in dogs fed FPPB and iFPPB than those fed CT. Fecal microbiota populations were affected by diet, with alpha-diversity being lower (P < 0.05) in dogs fed iFPPB and the relative abundance of 20 bacterial genera being altered in dogs fed FPPB or iFPPB compared with CT. The circulating helper T cell:cytotoxic T cell ratio was higher (P < 0.05) in dogs fed iFPPB than those fed CT. Circulating B cells were lower (P < 0.05) in dogs fed FPPB than those fed iFPPB, and lower (P < 0.05) in dogs fed iFPPB than those fed CT. Our results demonstrate that feeding a fiber-prebiotic-probiotic blend may provide many benefits to canine health, including improved stool quality, beneficial shifts to fecal microbiota and metabolite profiles, reduced blood lipids, and increased fecal IgA.

The influence of food processing methods on serum parameters, apparent total-tract macronutrient digestibility, fecal microbiota and SCFA content in adult beagles.

Food processing methods may influence the health of dogs. However, previous studies have mostly been based on a comparison of several commercial dog foods with different ingredients. In this study, eighteen adult beagles of the same age and health status (assessed by routine blood tests) were used in the experiments. This study analyzed the effects of the following different processing methods: raw, pasteurized, and high temperature sterilization (HTS) made with the same ingredients and nutrients (based on dry matter) on serum parameters, apparent total-tract macronutrient digestibility, fecal microbiota and short-chain fatty acid (SCFA) content in beagle dogs. The data showed, after a test lasting 56-days, the apparent digestibility (ATTD) of protein and fat in HTS food was 91.9%, which was significantly higher (P< 0.05) than that in dry food (89.2%, P < 0.05). The serum content of triglyceride increased in beagles fed HTS food (P < 0.05), and the number of neutrophils in beagles fed raw food and pasteurized food increased significantly (P < 0.05), and the platelet count in beagles fed raw food showed an increasing trend compared with the beagles fed HTS food. Different processing methods had an impact on the intestinal microbiota and SCFA of beagles; at least 14 genera were significantly affected by the food produced using different processing methods. In particular, the abundance of Allprevotella, Escherichia-Shigella and Turicibacter, and the total acid content were lower in beagles fed the raw diet, whereas Streptococcus, Collinsella, Bacteroides and Ruminococcus gnavus were more abundant following the HTS diet, and Lactococcus showed the highest abundance in beagles fed the pasteurized diet. This study showed that dog food produced by different processing methods affected the health of adult beagles.

Effects of dietary macronutrient profile on apparent total tract macronutrient digestibility and fecal microbiota, fermentative metabolites, and bile acids of female dogs after spay surgery

Obesity and estrogen reduction are known to affect the gut microbiota and gut microbial-derived metabolites in some species, but limited information is available in dogs. The aim of this study was to determine the effects of dietary macronutrient profile on apparent total tract macronutrient digestibility, fecal microbiota, and fecal metabolites of adult female dogs after spay surgery. Twenty-eight adult intact female beagles (age: 3.02 ± 0.71 yr, BW: 10.28 ± 0.77 kg; BCS: 4.98 ± 0.57) were used. After a 5-wk baseline phase (week 0), 24 dogs were spayed and randomly allotted to one of three experimental diets (n = 8 per group): 1) control (CO) containing moderate protein and fiber (COSP), 2) high-protein, high-fiber (HPHF), or 3) high-protein, high-fiber plus omega-3 and medium-chain fatty acids (HPHFO). Four dogs were sham-operated and fed CO (COSH). All dogs were fed to maintain BW for 12 wk after spay and then allowed to consume twice that amount for 12 wk. Fecal samples were collected at weeks 0, 12, and 24 for digestibility, microbiota, and metabolite analysis. All data were analyzed using repeated measures and linear mixed models procedure of SAS 9.4, with results reported as a change from baseline. Apparent organic matter and energy digestibilities had greater decreases in HPHF and HPHFO than COSH and COSP. Increases in fecal acetate, total short-chain fatty acids, and secondary bile acids were greater and decreases in primary bile acids were greater in HPHF and HPHFO. Principal coordinates analysis of weighted UniFrac distances revealed that HPHF and HPHFO clustered together and separated from COSH and COSP at weeks 12 and 24, with relative abundances of Faecalibacterium, Romboutsia, and Fusobacterium increasing to a greater extent and Catenibacterium, Bifidobacterium, Prevotella 9, Eubacterium, and Megamonas decreasing to a greater extent in HPHF or HPHFO. Our results suggest that high-protein, high-fiber diets alter nutrient and energy digestibilities, fecal metabolite concentrations, and fecal gut microbiota, but spay surgery had minor effects. Future research is needed to investigate how food intake, nutrient profile, and changes in hormone production influence gut microbiota and metabolites of dogs individually and how this knowledge may be used to manage spayed pets.

White and Red Sorghum as Primary Carbohydrate Sources in Extruded Diets of Felines.

The research objectives were to evaluate the effect of dietary supplementation of white (WSH) and red (RSH) sorghum grains on gastrointestinal health of felines through the determination of apparent total tract macronutrient digestibility (ATTD), fecal characteristics, fermentative end-products, and microbiota, compared with a traditional corn-based diet. We hypothesize that inclusion of RSH and WSH, respectively, would be well-accepted by cats, and the RSH and WSH diets would be comparable to corn when added as the main carbohydrate source in extruded diets. Three diets containing 30% corn, 30% WSH, or 30% RSH were formulated to meet or exceed the AAFCO (2018) nutrient profiles for cats during growth. Nine male cats (0.8 ± 0.00 yr) were randomly assigned to one of the three dietary treatments using a triplicated 3 × 3 Latin square design. Experimental periods consisted of 14 d (10 d of diet adaption and 4 d of total and fresh fecal collections). The ATTD of dry matter (DM) did not differ amongst treatments, organic matter was greatest (P < 0.05) for both sorghum diets (86.4%) and lowest for the corn diet (84.2%), crude protein was comparable among diets ranging from 84.5 to 86.6%, acid hydrolyzed fat was high among diets varying between 91.4 and 92.8%, and total dietary fiber was greatest (P < 0.05) for the WSH diet (56.0%) with the corn diet being lowest (44.7%). Digestible energy was greatest (P < 0.05) for the WSH diet (4.66 kcal/g) and lowest for the corn diet (4.54 kcal/g), with the RSH diet being intermediate (4.64; P > 0.05). Fecal pH (6.3–6.5) and most fecal metabolites did not differ among diets except for phenol/indole concentrations that were significantly lower (P < 0.05) in cats fed the RSH diet (1.5 μmole/g DM) than for cats fed the corn diet (2.1 μmole/g DM). Bacteroidetes, Firmicutes, Fusobacteria, and Proteobacteria were the major phyla observed in the microbiota of feces of cats fed the three experimental diets, with no differences seen amongst all treatments. Data indicate that dietary supplementation of these varieties of WSH and RSH as carbohydrate sources were well-tolerated by the cat.

Evaluation of a novel animal milk oligosaccharide biosimilar: macronutrient digestibility and gastrointestinal tolerance, fecal metabolites, and fecal microbiota of healthy adult dogs and in vitro genotoxicity assays.

Milk oligosaccharides (MO) are bioactive compounds in mammalian milk that provide health benefits to neonates beyond essential nutrients. GNU100, a novel animal MO biosimilar, was recently tested in vitro, with results showing beneficial shifts in microbiota and increased short-chain fatty acid (SCFA) production, but other effects of GNU100 were unknown. Three studies were conducted to evaluate the safety, palatability, and gastrointestinal (GI) tolerance of GNU100. In study 1, the mutagenic potential of GNU100 was tested using a bacterial reverse mutation assay and a mammalian cell micronucleus test. In study 2, palatability was assessed by comparing diets containing 0% vs. 1% GNU100 in 20 adult dogs. In study 3, 32 adult dogs were used in a completely randomized design to assess the safety and GI tolerance of GNU100 and explore utility. Following a 2-wk baseline, dogs were assigned to one of four treatments and fed for 26 wk: 0%, 0.5%, 1%, and 1.5% GNU100. On weeks 2, 4, and 26, fresh fecal samples were collected to measure stool quality, immunoglobulin A, and calprotectin, and blood samples were collected to measure serum chemistry, inflammatory markers, and hematology. On weeks 2 and 4, fresh fecal samples were collected to measure metabolites and microbiota. On week 4, total feces were collected to assess apparent total tract macronutrient digestibility. Although revertant numbers were greater compared with the solvent control in tester strain WP2uvrA(pKM101) in the presence of metabolic activation (S9) in the initial experiment, they remained below the threshold for a positive mutagenic response in follow-up confirmatory tests, supporting that GNU100 is not mutagenic. Similarly, no cytotoxicity or chromosome damage was observed in the cell micronucleus test. The palatability test showed that 1% GNU100 was strongly preferred (P < 0.05; 3.6:1 consumption ratio) over the control. In study 3, all dogs were healthy and had no signs of GI intolerance or illness. All diets were well accepted, and food intake, fecal characteristics, metabolite concentrations, and macronutrient digestibilities were not altered. GNU100 modulated fecal microbiota, increasing evenness and Catenibacterium, Megamonas, and Prevotella (SCFA producers) and reducing Collinsella. Overall, the results suggest that GNU100 is palatable and well-tolerated, causes no genotoxicity or adverse effects on health, and beneficially shifts the fecal microbiota, supporting the safety of GNU100 for the inclusion in canine diets.

Graded dietary resistant starch concentrations on apparent total tract macronutrient digestibility and fecal fermentative end products and microbial populations of healthy adult dogs.

Resistant starch (RS) is fermentable by gut microbiota and effectively modulates fecal short-chain fatty acid concentrations in pigs, mice, and humans. RS may have similar beneficial effects on the canine gut but has not been well studied. The objective of this study was to evaluate the effects of 0%, 1%, 2%, 3%, and 4% dietary RS (Hi-maize 260) on apparent total tract macronutrient digestibility, fecal characteristics, fermentative end-product concentrations, and microbiota of healthy adult dogs. An incomplete 5 × 5 Latin square design with seven dogs and five experimental periods was used, with each treatment period lasting 21 d (days 0 to 17 adaptation; days 18 to 21 fresh and total fecal collection) and each dog serving as its own control. Seven dogs (mean age = 5.3 yr; mean body weight = 20 kg) were randomly allotted to one of five treatments formulated to be iso-energetic and consisting of graded amounts of 100% amylopectin cornstarch, RS, and cellulose and fed as a top dressing on the food each day. All dogs were fed the same amount of a basal diet throughout the study, and fresh water was offered ad libitum. The basal diet contained 6.25% RS (dry matter [DM] basis), contributing approximately 18.3 g of RS/d based on their daily food intake (292.5 g DM/d). Data were evaluated for linear and quadratic effects using SAS. The treatments included 0%, 1%, 2%, 3%, and 4% of an additional RS source. Because Hi-maize 260 is approximately 40% digestible and 60% indigestible starch, the dogs received the following amounts of RS daily: 0% = 18.3 g (18.3 + 0 g), 1% = 20.1 g (18.3 + 1.8 g), 2% = 21.9 g (18.3 + 3.6 g), 3% = 23.7 g (18.3 + 5.4 g), and 4% = 25.5 g (18.3 + 7.2 g). Apparent total tract DM, organic matter, crude protein, fat, and gross energy digestibilities and fecal pH were linearly decreased (P < 0.05) with increased RS consumption. Fecal output was linearly increased (P < 0.05) with increased RS consumption. Fecal scores and fecal fermentative end-product concentrations were not affected by RS consumption. Although most of the fecal microbial taxa were not altered, Faecalibacterium were increased (P < 0.05) with increased RS consumption. The decrease in fecal pH and increase in fecal Faecalibacterium would be viewed as being beneficial to gastrointestinal health. Although our results seem to indicate that RS is poorly and/or slowly fermentable in dogs, the lack of observed change may have been due to the rather high level of RS contained in the basal diet.

Effect of a novel animal milk oligosaccharide biosimilar on macronutrient digestibility and gastrointestinal tolerance, fecal metabolites, and fecal microbiota of healthy adult cats.

GNU100 is a novel animal milk oligosaccharide (AMO) biosimilar. In a recent in vitro fermentation study, GNU100 was shown to be fermentable by feline gastrointestinal microbiota and lead to increased short-chain fatty acid production. Our objectives herein were to evaluate the palatability, safety, and gastrointestinal tolerance of GNU100 in healthy adult cats. Exploratory end-points were measured to assess utility. In study 1, 20 adult cats were used to test the palatability of diets containing 0% or 1% GNU100. In study 2, 32 (mean age = 1.9 yr; mean body weight = 4.6 kg) male (n = 12) and female (n = 20) adult cats were used in a completely randomized design. After a 2-wk baseline, cats were assigned to one of the following treatment groups and fed for 26 wk: control (CT, no GNU100), low dose (LD, 0.5% GNU100), medium dose (MD, 1.0% GNU100), and high dose (HD, 1.5% GNU100). On weeks 2, 4, and 26, fresh fecal samples were collected for the measurement of stool quality and immune and inflammatory markers and on weeks 2 and 4 for microbiota and metabolites. On week 4, total feces were collected to measure apparent total tract macronutrient digestibility. On weeks 2, 4, and 26, blood samples were collected for serum chemistry, hematology, and inflammatory marker measurement. The palatability test showed that 1% GNU100 was strongly preferred (P < 0.05), with GNU100 having a 17.6:1 consumption ratio compared with control. In the long-term study, all cats remained healthy, without any signs of gastrointestinal intolerance or illness. All diets were well accepted, resulting in similar (P > 0.05) food intake, fecal characteristics, immunoglobulin A, and calprotectin, and dry matter, organic matter, fat, and crude protein digestibilities. Fecal butyrate was greater (P = 0.02) in cats fed HD than cats fed LD or MD. Fecal indole was lower (P = 0.02) in cats fed HD than cats fed LD. Cats fed CT had a higher (P = 0.003) relative abundance of Actinobacteria than cats fed LD. The relative abundance of Peptococcus was impacted by diet and time. At 4 wk, Campylobacter was lower in fecal samples of cats fed HD. Overall, the data suggest that dietary GNU100 supplementation was highly palatable, well tolerated, did not cause detrimental effects on fecal quality or nutrient digestibility, increased fecal butyrate concentrations, and reduced fecal indole concentrations, supporting the safety of GNU100 for inclusion in feline diets and suggesting potential benefits on gastrointestinal health of cats.

PSIII-17 The effects of a yeast product on apparent total tract macronutrient digestibility, fecal characteristics, fecal fermentative end products, fecal microbiota, and immune responses of adult dogs

Abstract Research in various animal species has demonstrated the effectiveness of yeast products to improve health and performance. However, little research on yeast products are available for dogs. The objective of this study was to investigate the effects of a yeast product on apparent total tract macronutrient digestibility (ATTD), fecal characteristics, fecal microbiota, and immune responses of adult dogs. Twelve adult female beagles (age: 4.8±0.9 yr; BW: 13.3±0.7 kg) were fed the same diet, but supplemented with a yeast product (165 mg/d) or a placebo (125 mg cellulose/d) via gelatin capsules in a crossover design. In each period, a 21-d adaptation phase was followed by 5 d of total fecal collection for ATTD measurement. Fresh fecal samples (within 15 min defecation) were collected on d 22 for fecal dry matter, pH, fermentative end-products, and fecal microbiota measurements. Blood samples were collected on d 27 and peripheral blood mononuclear cells were isolated for evaluations of immune cell populations and immune cell responsiveness. Except for microbiota data, data were analyzed using Mixed Models procedure of SAS 9.4. Microbial sequence data were analyzed using QIIME 1.9.1. and STAMP 2.1.3. ATTD, fecal characteristics and fermentative end-products were not altered by treatment (P &amp;gt; 0.05). Microbial alpha- and beta-diversity and specific microbial taxa were not affected by treatment (P &amp;gt; 0.05). Immune cell populations and immune cell responsiveness of toll-like receptors were not altered by treatment (P &amp;gt; 0.05). However, the strong period effect reported for all parameters may have mitigated the yeast product expected benefits. In conclusion, the yeast product tested in this study did not significantly alter the outcomes measured in healthy adult dogs. Future studies testing higher yeast product dosages, studying dogs undergoing stress, antibiotic administration or immune challenge, or studying dogs most susceptible to gastrointestinal distress (weanling; geriatric), may be of interest.

PSIII-35 Effects of dietary macronutrient profile on apparent total tract macronutrient digestibility and fecal metabolites of female dogs after spay surgery

Abstract Obesity reduces the quality and length of life of companion animals. Spaying increases risk, but dietary modification may attenuate obesity and related co-morbidities. The objective of this study was to determine the effects of specially formulated diets on apparent total tract macronutrient digestibility (ATTD) and fecal metabolites of female dogs after spay surgery. All procedures were approved by the University of Illinois Institutional Animal Care and Use Committee prior to experimentation. Twenty-four dogs were spayed and randomly allotted to three experimental diets: 1) moderate-protein, moderate-fiber diet (control; COSP), 2) high-protein, high-fiber diet (HP-HF), or 3) high-protein, high-fiber diet plus omega-3 fats (HP-HF-O). Four dogs were sham-operated and fed the control diet (COSH). Dogs were fed to maintain BW for 12 weeks after spay, then allowed to consume twice that amount for another 12 weeks. Change from baseline data were analyzed statistically, with P &amp;lt; 0.05 being significantly different. Food intake in dogs fed HP-HF or HP-HF-O was greater than COSH dogs, but COSP dogs were intermediate. Fat and organic matter digestibilities were lower in dogs fed HP-HF or HP-HF-O compared with COSH and COSP dogs. Fecal dry matter percentage and volume increases were greater in HP-HF and HP-HF-O dogs than COSH and COSP dogs. HP-HF and HP-HF-O dogs had higher fecal acetate than COSH or COSP dogs. Fecal butyrate tended to be greater (P = 0.08) in HP-HF dogs than COSH dogs. COSH and HP-HF-O dogs had lower fecal valerate than COSP dogs, while fecal ammonia tended to be higher (P = 0.05) in HP-HF-O than COSP and HP-HF dogs. Fecal total short-chain fatty acid (SCFA) increases in HP-HF-O dogs were higher than COSH dogs. Our results indicate that a high-protein, high-fiber diet can reduce energy content by reducing fat digestibility without affecting protein digestibility, modulate fecal SCFA concentrations, and decrease fecal branched-chain fatty acid.

244 White and red sorghum as primary carbohydrate sources in extruded diets of felines

Abstract The human interest of ancient grains replacing modern carbohydrate sources has reached the pet food market, and there has been increased focus on corn- and wheat-free diets in pet foods. The objectives of this research were to evaluate the effect of dietary supplementation of white and red sorghum grains on the gastrointestinal health of felines through the determination of apparent total tract macronutrient digestibility (ATTD), fecal characteristics, fermentative end-products, microbiota, and how the sorghum grains compared against a traditionally corn-based diet. Three diets containing 30% corn (CO), 30% white sorghum (WS), or 30% red sorghum (RS) were formulated to meet or exceed the AAFCO (2017) nutritional requirements for felines. Nine male cats were randomly assigned to one of the 3 dietary treatments using a replicated 3x3 Latin square design. Experiment periods consisted of 14 days (10 days of diet adaption + 4 days of total, fresh collection). All diets were highly digested by cats, however, ATTD of dry matter was highest (P &amp;lt; 0.05) for RS (81.13%) and lowest for CO (78.28%), organic matter was greatest (P &amp;lt; 0.05) for RS (86.40%) and lowest for CO (84.15%), crude protein was similar amongst diets with a range of 84.52%-86.57%, acid hydrolyzed fat was similar amongst diets with a range of 91.36%–92.79%, and total dietary fiber was greatest (P &amp;lt; 0.05) in WS (55.96%) with CO being lowest (44.66%). Fecal pH (6.28–6.54) and most metabolites did not differ among diets (P &amp;gt; 0.05), except for phenol/indole concentrations that were significantly lower (P &amp;lt; 0.05) in cats fed RS (178.88 ug/g) compared to CO (240.34 ug/g). Overall, the data gathered suggest that dietary supplementation of WS and RS as carbohydrate sources were well tolerated by the cats. Thus, sorghum is an acceptable alternative to corn in extruded diets of felines.

Extruded feline diets formulated with high inclusion of soybean hulls: effects on apparent total tract macronutrient digestibility, and fecal quality and metabolites.

Dietary fibers have gained renewed interest in companion animal nutrition as a means to manage pet obesity and improve gut and host health. Soybean hulls (SBH), a coproduct of the soybean oil extraction process, is an accessible and economical fiber source. However, limited research is available on the use of SBH in feline nutrition. Thus, the aim of this study was to determine the effects of a high SBH inclusion level on daily food intake, apparent total tract (ATT) macronutrient digestibility, fecal quality, and fecal fermentative end products in diets of adult cats. Four diets were formulated with either SBH, beet pulp (BP), or cellulose (CL) as the main source of dietary fiber, with the control diet formulated with no added fiber (NF). The fiber treatments were formulated to achieve approximately 15% total dietary fiber (TDF). Eight adult male cats (mean age = 10.5 yr ± 0.1; mean BW = 6.1 ± 0.8 kg) were used in a replicated 4 × 4 Latin square design. Each period consisted of 14 d, with 10 d of diet adaptation followed by 4 d of total fecal and urine collections. Food was offered twice daily and cats were fed to maintain BW. Food intake on a DM basis (DMB) was lower (P < 0.05) in cats fed BP (55.2 g/d) when compared with SBH (70.8 g/d). As-is fecal output did not differ in cats fed BP or SBH, and when expressed on a DMB, fecal output did not differ among fiber treatments. The ATT digestibility of DM, OM, and GE was greater (P < 0.05) in cats fed NF when compared with those fed BP, CL, or SBH. Cats fed CL had the greatest (P < 0.05) ATT CP digestibility (88.5%), followed by cats fed NF (84.9) and SBH (81.7%) with the lowest values (77%) noted for cats fed BP. Acid-hydrolyzed fat (AHF) digestibility was greater for cats fed CL (92.9%) than for cats fed BP (86.9%) and SBH (88.6%). The TDF ATT digestibility was lowest for cats fed NF and CL (8.5% and 15.1%, respectively), followed by SBH (18.0%), with BP having the highest digestibility (33.7%). Total short-chain fatty acid concentration was greatest (P < 0.05) in cats fed BP (699.7 μmole/g) when compared with the other 3 treatments, whereas phenol and indole concentrations did not differ among treatments. In conclusion, a high inclusion level (15% TDF) of SBH appears acceptable in diets for adult cats, resulting in no negative effects on daily food intake, fecal scores, and similar ATT digestibility for most macronutrients when compared with BP and CL.

PSXIII-28 Inclusion of Soybean Hulls in Extruded Diets for Adult Cats: Effects on Apparent Total Tract Macronutrient Digestibility, Fecal Quality, and Fermentative End-Product Concentrations.

PSXIII-28 Inclusion of Soybean Hulls in Extruded Diets for Adult Cats: Effects on Apparent Total Tract Macronutrient Digestibility, Fecal Quality, and Fermentative End-Product Concentrations.

374 The effects of a yeast fermentation product on diet palatability, apparent total tract macronutrient digestibility and fecal characteristics of adult dogs.

374 The effects of a yeast fermentation product on diet palatability, apparent total tract macronutrient digestibility and fecal characteristics of adult dogs.

Apparent total-tract macronutrient digestibility, serum chemistry, urinalysis, and fecal characteristics, metabolites and microbiota of adult dogs fed extruded, mildly cooked, and raw diets1.

Despite their popularity, little research has been performed on lightly cooked and raw diet formats for pets. Therefore, the objective of this study was to determine the apparent total-tract macronutrient digestibility (ATTD); fecal characteristics, metabolites, and microbiota; serum chemistry metabolites; urinalysis; and voluntary physical activity levels of adult dogs fed commercial diets differing in processing type. The diets included: 1) extruded dry kibble (EXT) diet; 2) high-moisture roasted refrigerated (RR) diet; 3) high-moisture grain-free roasted refrigerated (GFRR) diet; and 4) raw (RAW) diet. Eight dogs (mean age = 3.6; mean BW = 13.0 kg) were used in a replicated 4 × 4 Latin square design. Each period consisted of 28 d, with a 14-d adaptation phase followed by a 7-d phase for measuring voluntary physical activity, 1-d adaptation phase to metabolic cages, 5-d phase for fecal and urine collection, and 1 d for blood collection. Except for microbiota, all data were analyzed statistically by mixed models using SAS. Microbiota data were analyzed using Quantitative Insights Into Microbial Ecology (QIIME) and Statistical Analyses of Metagenomic Profiles (STAMP) software. Many differences in digestibility were observed, including greater (P < 0.05) ATTD of CP and fat in dogs fed GFRR and RR than dogs fed EXT. Dogs fed RAW had the lowest fecal pH and DM %, but fecal scores were not affected. Dogs fed RR had higher (P < 0.05) fecal indole and total phenol and indole concentrations than dogs fed the other diets. Dogs fed RAW had a higher (P < 0.05) fecal ammonia concentration than dogs fed the other diets. Fecal microbial diversity was altered by diet, with dogs fed GFRR and RAW having reduced species richness than dogs fed EXT. Dogs fed RR, GFRR, or RAW had lower (P < 0.05) Actinobacteria and higher (P < 0.05) Fusobacteria than dogs fed EXT. Dogs fed RAW or GFRR had higher (P < 0.05) Proteobacteria than dogs fed EXT or RR. Dogs fed RAW had higher (P < 0.05) Bacteroidetes and lower (P < 0.05) Firmicutes than dogs fed EXT. Serum triglycerides were within reference ranges, but greater (P < 0.05) in dogs fed EXT than dogs fed GFRR and RAW. All diets were well tolerated and dogs remained healthy throughout the study. In conclusion, the lightly cooked and raw diets tested were highly palatable, highly digestible, reduced blood triglycerides, maintained fecal quality and serum chemistry, and modified the fecal microbial community of healthy adult dogs.