Effects of high-fat and high-carbohydrate diets on fat and carbohydrate oxidation and plasma metabolites in healthy cats.

High-fat (HF) or high-carbohydrate (HC) diets (30% fat, 18.9% carbohydrate; HF and 10% fat, 46.3% carbohydrate; HC) and lengths of adaptation were investigated in cats (Felis catus; 10 ± 2 months, 3.6 ± 0.3 kg). Cats randomly received each treatment for 14 days in a crossover design with a 14-day washout period between each diet. Three 22-h indirect calorimetry studies were conducted after acute (day 0), semichronic (day 4) and chronic (day 13) dietary exposure. Blood samples were collected after a 24-h fast on days 1, 5 and 14. When cats consumed the HC and HF diet, oxidation of the restricted nutrient exceeded intake while oxidation of the nutrient in excess matched intake. Mean max energy expenditure (EE) of cats consuming the HF and HC diet were 107 and 102 kcal/kg(0.67)/day and occurred at a mean of 4 and 12 h post-feeding respectively. Maximal fat (0.90 g/h) and carbohydrate (carbohydrate; 1.42 g/h) oxidation were attained at 26 min and 10.4 h post-feeding respectively. The changes observed in macronutrient oxidation and EE suggest that cats adapt whole-body nutrient metabolism in response to changes in dietary macronutrient content, but may require longer than 14 day to adapt to a macronutrient that is present at a lower concentration in the diet.

Measuring body composition in dogs using multifrequency bioelectrical impedance analysis and dual energy X-ray absorptiometry.

Thirty-five healthy, neutered, mixed breed dogs were used to determine the ability of multifrequency bioelectrical impedance analysis (MFBIA) to predict accurately fat-free mass (FFM) in dogs using dual energy X-ray absorptiometry (DXA)-measured FFM as reference. A second aim was to compare MFBIA predictions with morphometric predictions. MFBIA-based predictors provided an accurate measure of FFM, within 1.5% when compared to DXA-derived FFM, in normal weight dogs. FFM estimates were most highly correlated with DXA-measured FFM when the prediction equation included resistance quotient, bodyweight, and body condition score. At the population level, the inclusion of impedance as a predictor variable did not add substantially to the predictive power achieved with morphometric variables alone; in individual dogs, impedance predictors were more valuable than morphometric predictors. These results indicate that, following further validation, MFBIA could provide a useful tool in clinical practice to objectively measure FFM in canine patients and help improve compliance with prevention and treatment programs for obesity in dogs.

Dietary galactooligosaccharides affect ileal and total-tract nutrient digestibility, ileal and fecal bacterial concentrations, and ileal fermentative characteristics of growing pigs.

The objective of this study was to evaluate dietary galactooligosaccharide (Gal OS) addition on swine nutrient digestibility, ileal and fecal bacterial populations, and ileal short-chain fatty acid (SCFA) production, and to determine their impact on ileal fermentative characteristics in vitro. Twelve T-cannulated pigs (BW = 25 kg) were fed a diet free of Gal OS for 21 d. On d 22, ileal digesta samples were collected for an in vitro fermentation experiment (Exp. 1). Substrates included: raffinose/stachyose combination (R + S), soy solubles (SS), and transgalactooligosaccharides (TOS). Also included were the non-OS components of SS and TOS. Nine pigs (three donors per treatment) served as ileal effluent donors. Each substrate was fermented in vitro for 6 h, and pH and SCFA and gas production were determined. Pigs then were allotted to three treatments: a Gal OS-free control diet and the control diet with either 3.5% added Gal OS from SS or TOS. Diets, feces, and digesta samples collected weekly for 6 wk on d 6 (feces) and 7 (digesta) were analyzed for DM, OM, CP, and chromic oxide concentrations. Feces and ileal digesta were analyzed for bifidobacteria and lactobacilli populations. Ileal digesta samples were analyzed for SCFA. On d 64, a second in vitro fermentation experiment (Exp. 2) was conducted using ileal effluent from three pigs per treatment and the same substrates used in Exp. 1. In vivo results showed that ileal and total tract DM and OM digestion were decreased (P < 0.05) by addition of both SS and TOS to the diet. Ileal and total-tract N digestibilities were decreased (P < 0.05) by dietary addition of SS. Fecal bifidobacteria and lactobacilli were increased (P < 0.05) by addition of SS and TOS to the diet. Ileal propionate and butyrate concentrations were greater (P < 0.05) for pigs fed diets containing both sources of Gal OS. In vitro results showed that fermentation data were not affected by donor animal adaptation to treatment. For both in vitro experiments, gas and SCFA production were higher (P < 0.05) for R + S than for SS or TOS. Fermentation of R + S resulted in a higher pH (P < 0.05) than did SS or TOS. Fermentation of non-OS components of SS and TOS resulted in more (P < 0.05) gas and SCFA production, and pH values that did not differ (P > 0.05) compared to SS and TOS. The Gal OS used in this study were prebiotics, increasing beneficial bacteria in vivo and SCFA concentrations both in vivo and in vitro.

Selected lignosulfonate fractions affect growth performance, digestibility, and cecal and colonic properties in rats.

We determined the effects of lignosulfonate (LS) on nutrient digestibility and on hindgut fermentation characteristics using 80 adult male Sprague-Dawley rats fed a control diet or a diet containing 3% (dry matter basis) of seven selected LS fractions. Lignosulfonate fractions were divided into three categories: two fractionated whole calcium spent sulfite liquors (CaSSL) and one low-molecular-weight permeate of CaSSL designated as WholeLS 1, 2, and 3, respectively; two extracted sodium LS (NaLS) fractions denoted as HighLS 1 and 2 (high percentage of NaLS); and two concentrated sugar solutions designated as LowLS 1 and 2 (low percentage of NaLS). All diets containing LS were less digestible (P < .001) than the control diet. Lignosulfonate treatment had a variable effect on short-chain fatty acid concentration except for LowLS 1, which tended to enhance butyrate concentration. Cecal organ weights were greater (P < .001) for LS treatments, but there was no difference in colonic organ weights. All cecal and colonic pH values, except the cecal pH for HighLS 2, were lower (P < .001) for LS treatment groups. Colonic Bifidobacterium increased (P < .005) with WholeLS 1 and 3 and HighLS 2 treatments. Cecal Lactobacillus levels were increased (P < .001) by WholeLS 1 and 2, LowLS 2, and HighLS 2. Results show that ingestion of selected LS fractions can modify digestive physiology and gastrointestinal tract characteristics of rats.

A dose-response experiment evaluating the effects of oligofructose and inulin on nutrient digestibility, stool quality, and fecal protein catabolites in healthy adult dogs.

In this experiment, three concentrations (0.3, 0.6, and 0.9% of diet, as-fed basis) of two fructans, oligofructose (OF) and inulin, were tested against a 0% supplemental fructan control. Seven ileal-cannulated adult female dogs were fed a meat-based, kibbled diet and assigned to treatments in a 7 x 7 Latin square design. Dietary supplementation of fructans had no effect on nutrient intakes or ileal digestibilities. Total-tract digestibilities of DM, OM, and CP decreased (P < 0.05) as a result of dietary OF and inulin supplementation. Dogs fed the control diet had a DM total-tract digestibility of 83.0%. The percentages of fecal DM for dogs fed the control and 0.3, 0.6, and 0.9% OF were 36.6, 33.3, 32.8, and 31.7%, respectively. When compared with the control, OF (P < 0.01) and inulin (P < 0.01) supplementation increased fecal ammonia concentrations. Higher fecal short-chain fatty acid (SCFA; P < 0.10) and isovalerate concentrations (P < 0.01) were noted for dogs fed both fructans. Total fecal SCFA for dogs fed the control diet and 0.3, 0.6, and 0.9% OF were 406.4, 529.9, 538.3, and 568.8 micromol/g of feces (DM basis), respectively. Dogs fed 0.3, 0.6, and 0.9% inulin had total fecal SCFA of 472.2, 468.8, and 471.5 micromol/g of feces (DM basis), respectively. Linear increases were observed in putrescine (P < 0.11), cadaverine (P < 0.07), spermidine (P < 0.12), and total amines (P < 0.05) in feces of dogs fed OF. Lower fecal phenol (P < 0.08) and total phenol (P < 0.04) concentrations occurred in dogs fed inulin, along with a linear decrease (P < 0.08) in total phenols with OF supplementation. Total fecal phenols for dogs fed the control, 0.3, 0.6, and 0.9% inulin were 3.03, 1.86, 1.97, and 2.23 micromol/g of feces (DM basis), respectively. Low-level dietary inclusion of inulin and OF positively affected indices known to be associated with gut health of the dog without seriously compromising nutrient digestibility or stool quality. Overall, the 0.9% OF treatment resulted in the best responses, including no adverse effect on nutrient intakes, ileal digestibilities, or stool quality, as well as increased fecal SCFA and decreased fecal phenols. The biological responses due to inulin were more variable.

In vitro fermentation characteristics of native and processed cereal grains and potato starch using ileal chyme from dogs.

Two in vitro experiments were conducted to evaluate the ability of small intestinal bacteria of dogs to ferment native and extruded cereal grains and potato starch and cereal grain and potato flours. Substrates included barley, corn, potato, rice, sorghum, and wheat. In addition to testing native grains and flours, extruded substrates also were tested. Substrates were extruded at low temperatures (LT; 79 to 93 degrees C) and high temperatures (HT; 124 to 140 degrees C) using a Wenger extruder (model TX-52). Substrates varied widely in concentrations of rapidly digestible starch (RDS), slowly digestible starch (SDS), resistant starch (RS), and total starch (TS). Extrusion of most substrates at HT vs LT resulted in increased RDS and decreased RS concentrations. Organic matter disappearance (OMD) values attributed to microbial fermentation for a 5-h period were as high as 27% for native extruded substrates (LT potato starch) and 39% for potato flour. Average OMD was higher for cereal and potato flours than for native extruded substrates (29.9 vs 25.4%). Average molar percentages of short-chain fatty acids produced from all substrates fermented for 5 h were 73, 14, and 13% (acetate, propionate, and butyrate, respectively). Average lactate production for substrates ranked as follows: flours > native and extruded cereal grains and potato starch (0.33 and 0.18 mmol/g OM, respectively). In vitro microbial fermentation of starches by ileal bacteria can be substantial and is affected by differences in starch source, fraction, and processed form.

In vitro fermentation characteristics of selected oligosaccharides by swine fecal microflora.

The objective of this study was to quantify the fermentation characteristics of oligosaccharides present in feed ingredients or isolated for dietary supplementation. Substrates studied included short-chain fructooligosaccharides, medium-chain fructooligosaccharides, long-chain fructooligosaccharides, raffinose, stachyose, soy solubles, granular and liquid forms of transgalactooligosaccharides, glucooligosaccharides, mannanoligosaccharides, and xylooligosaccharides. Three healthy pigs that had never received antibiotics served as sources of fecal inoculum. Each substrate was fermented in vitro; samples were taken at 0, 2, 4, 8, and 12 h, and pH change and short-chain fatty acid (SCFA) and gas production determined. Gas production at 12 h did not differ (P > 0.05) among all fructooligosaccharides, transgalactooligosaccharides, soy solubles, and xylooligosaccharides. Raffinose, stachyose, and raffinose + stachyose fermentation resulted in the greatest (P < 0.05) gas production at 12 h of all substrates tested. The rate of gas production was greatest (P < 0.05) for stachyose and least (P < 0.05) for glucooligosaccharides and mannanoligosaccharides. Substrate did not affect (P > 0.05) time to attain maximal rate of gas production. The pH at 12 h for all fructooligosaccharides and xylooligosaccharides did not differ (P > 0.05). The pH values at 12 h for raffinose, stachyose, and raffinose + stachyose were highest (P < 0.05) compared with all other substrates. Total SCFA production at 12 h was similar for all fructooligosaccharides and transgalactooligosaccharides, glucooligosaccharides, and soy solubles. Total SCFA production was greatest (P < 0.05) for xylooligosaccharides, stachyose, and raffinose + stachyose, and least (P < 0.05) for mannanoligosaccharides and raffinose. Stachyose fermentation resulted in the greatest (P < 0.05) rate and earliest time to attain maximal rate of SCFA production. All oligosaccharides studied were readily fermentable but varied in amount and type of SCFA produced. Fermentation of the pure forms of oligosaccharides contained in soy solubles resulted in greater gas production and higher pH compared with soy solubles. The oligosaccharides in the soy solubles matrix seemed to behave differently than their pure counterparts. The high rates of fermentation of most oligosaccharides tested indicate that they may serve as fermentable carbohydrate sources in the terminal small intestine or large intestine of swine.

Nutrient digestibilities, microbial populations, and protein catabolites as affected by fructan supplementation of dog diets.

Fructans are fermentable carbohydrates and include short-chain fructooligosaccharides (scFOS), inulin, and hydrolyzed inulin (oligofructose, OF). Two studies with dogs were designed to examine the effects of low concentrations of fructans on nutrient digestibilities, fecal microbial populations, and endproducts of protein fermentation, and fecal characteristics. In Exp. 1, 11 adult male beagles were fed corn-based, kibbled diets supplemented with or without OF to provide 1.9 +/- 0.6 g/d. Dietary inclusion of OF decreased (P < 0.05) nutrient digestibilities, but did not affect fecal characteristics. Increasing OF concentration tended (P < 0.06) to linearly decrease fecal ammonia concentrations, but not those of branched-chain fatty acids (BCFA), amines, indole, or phenols. Fecal concentrations of total short-chain fatty acids (SCFA) and butyrate tended to be higher in OF-supplemented dogs (P < 0.10), as was the ratio of bifidobacteria to total anaerobes (P = 0.15). In Exp. 2, ileally cannulated adult female hounds were fed a meat-based kibbled diet and were assigned to four scFOS treatments (0, 1, 2, or 3 g/d) in a 4 x 4 Latin square design. Ileal nutrient digestibilities tended to increase (P < 0.15) with increasing concentrations of scFOS. On a DMI basis, fecal output tended to decrease linearly (P < 0.10) in response to increasing scFOS supplementation, whereas fecal score tended to exhibit a quadratic response (P = 0.12). In general, fecal concentrations of SCFA, BCFA, ammonia, phenols, and indoles were not altered by supplemental scFOS. Supplementation of scFOS increased fecal concentrations of total aerobes (P < 0.05) and decreased concentrations of Clostridium perfringens (P < 0.05). From these data, it seems that low levels of supplemental fructans have divergent effects on nutrient digestibility and fermentative endproducts, but do not adversely affect nutrient digestibility or fecal characteristics and may improve colonic microbial ecology in dogs.

Corn hybrid affects in vitro and in vivo measures of nutrient digestibility in dogs.

Corn is a commonly used ingredient in dry pet foods because there is a stable supply and it is a relatively inexpensive source of nutrients. Corn hybrids are available that are higher in CP and amylose and lower in phytate concentration than conventional hybrids. Approximately 500 mg of high-protein (HP), high-protein, low-phytate (HPLP), and high-amylose (HA) corn were compared with conventional (CONV) corn and amylomaize starch (AM) in triplicate and exposed to pepsin/hydrochloric acid and pancreatin to simulate hydrolytic digestion. Substrate remaining after this was used to determine in vitro colonic fermentation. Organic matter disappearances as a result of hydrolytic digestion were >80% for CONV, HP, and HPLP, whereas HA (60.7%) and AM (43.7%) were lower (P < 0.05). Total digestion (TD) values after hydrolytic digestion and 8 h of fermentation using canine fecal inoculum were greater (P < 0.05) for CONV, HP, and HPLP vs. HA and AM. The residue left after hydrolytic digestion of all substrates was poorly fermented. Five ileal-cannulated dogs were fed each corn hybrid at approximately 31% of the diet in a 5 x5 Latin square design. Dogs fed diets containing HP corn had higher (P < 0.05) ileal OM digestibility (70.3%) and tended (P < 0.10) to have higher DM digestibility (64.6%). Ileal starch digestibilities were lower (P < 0.05) for dogs fed HA (64.0%) and AM (63.0%). Ileal digestibilities of essential (71.2%), nonessential (67.4%), and total (69.0%) AA tended to be higher (P < 0.10) for HP diets compared with CONV (66.4, 62.4, and 64.0%, respectively). Total-tract DM, OM, CP, and GE digestibilities (77, 82, 77, and 84%, on average, respectively) were higher (P < 0.05) for dogs fed CONV, HP, and HPLP than for those fed AM (66.9, 71.6, 72.6, and 76.5%) and HA (60.6, 65.7, 69.7, and 71.5%). Total-tract fat digestibilities were lower (P < 0.05) for dogs fed HA diets (86.6%) than for all other treatments (91.0%, on average). Total-tract starch digestibilities were higher (P < 0.05) for dogs fed CONV, HP, and HPLP (98%, on average) compared with HA (72.8%) and AM (76.5%). No differences were detected among treatments in fecal bifidobacteria, lactobacilli, or Clostridium perfringens concentrations. The experiments demonstrated that HP and HPLP corn had hydrolytic digestion and fermentation characteristics similar to those of CONV corn, whereas HA resulted in similar responses to AM, a well-established resistant starch ingredient.

Pet food and feed applications of inulin, oligofructose and other oligosaccharides.

Prebiotics may be considered as functional food ingredients. They are attracting considerable interest from pet owners, pet food manufacturers, livestock producers and feed manufacturers. The most common forms of prebiotics are nondigestible oligosaccharides (NDO), including inulin, oligofructose mannanoligosaccharides, gluco-oligosaccharides, and galacto-oligosaccharides. These NDO are nondigestible by enzymes present in the mammalian small intestine, but are fermented by bacteria present in the hindgut of nonruminants. Inulin and oligofructose are present in measurable quantities in feed ingredients like wheat, wheat by-products, barley, and peanut hulls. Consumption of prebiotic oligosaccharides elicits several purported health benefits. In companion animals, prebiotics have been shown to improve gut microbial ecology and enhance stool quality. In production livestock and poultry, prebiotics are employed to control pathogenic bacteria, reduce faecal odour, and enhance growth performance. Research to date indicates positive effects of prebiotics on health status and performance of companion animals, livestock, and poultry.

Petfood applications of inulin and oligofructose.

Published data on intestinal microbiota of dogs and cats are limited but suggest the presence of a complex and diverse colonic bacterial population (34 genera including 129 species) the majority of which are anaerobes. During the colonic fermentation of endogenous and undigested amino acids, several putrefactive compounds (i.e., ammonia, aliphatic amines, indoles, phenols and volatile sulfur-containing compounds) are produced and are responsible for the malodor of dog and cat feces. These fecal odor components also have been implicated as causes of colorectal cancer; therefore, dietary manipulation of gut microbiota towards a potentially more remedial community (Bifidobacterium and Lactobacillus) is gaining more attention. The health benefits derived from dietary supplementation of prebiotics (e.g., oligofructose and inulin) have been documented in humans. However, little is known of a potentially similar role in companion animals. Feeding another prebiotic (i.e., lactosucrose) to dogs or cats is reported to increase the numbers of bifidobacteria and decrease the numbers of pathogens and the concentration of fecal odor components. In our laboratory, oligofructose supplementation numerically decreased the concentrations of ammonia and amines and increased the numbers of bifidobacteria in dog feces.

Selected animal and plant protein sources affect nutrient digestibility and fecal characteristics of ileally cannulated dogs.

The objective of this study was to compare ileal and total tract nutrient digestibilities and fecal characteristics of dogs fed selected animal and plant protein sources incorporated into grain-based diets. Four crude protein sources--soybean meal (SBM), poultry meal (PM), poultry by-product meal (PBPM), and beef and bone meal (BBM)--were fed to four ileal cannulated dogs in a 4 x 4 Latin square design. Intakes of dry matter, organic matter, crude protein, and fat by dogs were similar. Total dietary fiber (TDF) intake was highest for the SBM treatment compared to other treatments. Ileal digestibilities of DM, OM, CP, fat, and TDF were not affected by treatment. Total tract digestibility of DM was lower for the BBM and SBM diets, while OM digestibility was lower for the SBM treatment only. Total tract CP digestibility was similar for BBM, PBPM, and SBM treatments and was higher for the PM treatment. As-is fecal excretion [g/d] was greater when dogs received the SBM treatment. Fecal output on a DM basis was higher for the SBM treatment compared to the other treatments. All diets were well utilized by the dogs as assessed by ileal and total tract digestibility data and fecal characteristics.

Glucose-based oligosaccharides exhibit different in vitro fermentation patterns and affect in vivo apparent nutrient digestibility and microbial populations in dogs.

To evaluate the potential of indigestible oligosaccharides (OS) to serve as "dietary fiber-like" ingredients, it is necessary to determine their extent of indigestibility. In vitro fermentation characteristics of two novel OS, alpha-glucooligosaccharides (GOS) and a maltodextrin-like OS (MD), were compared to those of fructooligosaccharides (FOS), gum arabic (GA), guar gum (GG) and guar hydrolysate (GH). Total short-chain fatty acid (SCFA) production (micromol/g dry matter) as a result of MD fermentation was higher initially compared with GA (P<0.01), but GA was more extensively fermented at 24 h (P<0.01). Total SCFA production for GOS was similar to that for FOS, GG, GH and GA. In the second experiment, GOS and MD were added at 6% to an enteral formula control diet (Control) and fed to ileal-cannulated dogs in a 3x3 replicated Latin-square design. Ileal digestibility of glucose was lower (P<0.05) and carbohydrate (CHO) numerically lower (P = 0.08) for both GOS and MD compared with the Control. Total tract digestibility of CHO and glucose was lower only for MD (P<0.01) compared with the Control. Total fecal weights were higher (P<0.01) for both GOS and MD treatments. Fecal concentration of bifidobacteria was numerically increased by GOS and MD supplementation (P = 0.13 and 0.23, respectively). Thus, GOS and MD are indigestible yet fermentable OS, and may act as "dietary fiber-like" ingredients.