Evaluation of nutrient digestibility and fecal characteristics of exotic felids fed horse- or beef-based diets: use of the domestic cat as a model for exotic felids

The objective of this study was to determine the effects of feeding commercially available beef- and horse-based diets on nutrient digestibility and fecal characteristics of large captive exotic felids and domestic cats. Four species of large exotic felids including cheetahs, Malayan tigers, jaguars, and Amur tigers, and domestic cats were utilized in a crossover design. Raw meat diets included a beef-based diet (57% protein; 28% fat) and a horse-based diet (51% protein; 30% fat). All cats were acclimated to the diet for 16 days followed by a 4 day collection period, where total feces, including one fresh sample, were collected. All feces were scored on collection. Intake did not differ due to diet, but fecal output was greater when cats consumed the horse-based diet. Total tract apparent dry matter (DM) digestibility was higher (P<0.05) and organic matter (OM) and crude protein (CP) digestibilities were lower (P<0.05) when cats were fed the beef-based diet compared with the horse-based diet. CP digestibility was similar in domestic cats and cheetahs, and greater (P<0.05) than Amur tigers. Fecal scores were lower and fecal DM was greater (P<0.05) when cats consumed the horse-based diet compared with the beef-based diet. Domestic cats had lower (P<0.05) fecal ammonia concentrations compared with all other species. Fecal ammonia concentrations were lowest (P<0.05) when cats were fed the horse-based diet. Fecal total short-chain fatty acid (SCFA), branched-chain fatty acid (BCFA), and butyrate concentrations were higher (P<0.05) when cats consumed the beef-based diet. Our results suggest that the domestic cat serves as an appropriate model for large exotic felid species, but differences among the species exist. Decreased nutrient digestibility by tigers and jaguars should be considered when developing feeding recommendations for these species based on domestic cat data.

Food intake and ingredient profile affect viscosity of ileal digesta of dogs

Two experiments were conducted to determine dietary factors affecting digesta viscosity. In experiment 1, six ileal-cannulated dogs were either full (607.1 kJ/BW0.67) or restricted (303.5 kJ/BW0.67) fed. In experiment 2, four dog foods were surveyed for effects on digesta viscosity based on protein source [animal protein (AP) or plant protein (PP)] or dietary fibre source [soluble dietary fibre (SDF) or insoluble dietary fibre (IDF)]. Dry matter (DM) intake was higher (p<0.05) when dogs were full (11.4 g/kg) compared with restricted fed (5.98 g/kg). Ileal digesta viscosity tended to be higher (p=0.07) for full fed [10,251 centipoise (cP)] compared with restricted-fed dogs (6677 cP). Ileal digesta viscosities were 6561, 11,074, 13,830 and 15,967 cP for dogs consuming IDF, SDF, AP and PP treatments respectively. Ileal DM concentrations were 11.4%, 13.6%, 14.8% and 14.8% for SDF, IDF, AP and PP treatments respectively. DM digestibility coefficients were lowest (71.2%) for the PP treatment and highest (88.7%) for the IDF treatment. Organic matter digestibilities followed a similar pattern. Ileal digesta viscosity of dogs appears to increase with increased diet intake, and increased ileal DM concentration. More digestible diets result in less ileal DM and lower viscosity constants.

Diet type affects viscosity of ileal digesta of dogs and simulated gastric and small intestinal digesta

Two experiments were conducted to determine effects of diet type on viscosity of ileal digesta of dogs and simulated gastric and small intestinal digesta. In experiment 1, three canned and three dry dog foods were surveyed for effects on ileal digesta viscosity. Experiment 2 evaluated the same six diets for effects on simulated gastric and small intestinal digesta. Canned diets and dry diets contained an average 22.7% and 89.9% dry matter (DM) respectively. Concentrations of total dietary fibre (TDF) in the diets ranged from 1.8% to 26.5%. Ileal digesta viscosities ranged from 1326 to 46,641 and 7748 to 10,208 cP for canned and dry treatments respectively. Ileal DM concentrations ranged from 8.2% to 16.2% and 15.4% to 15.8% for canned and dry treatments respectively. Dry matter intake ranged from 224 to 290 and 295 to 325 g/day for canned and dry treatments respectively. During gastric digestion simulation, viscosity peaked at 2 and 4 h for all three canned diets and dry diets respectively. During small intestinal digestion simulation, viscosity peaked between 6 and 12 h for most diets except one canned diet and one dry diet, which contained high concentrations of TDF (25.1% and 26.5% respectively). Viscosity of these solutions peaked between 12 and 18 h. Viscosity of ileal digesta and simulated gastric and small intestinal digesta was the lowest after consumption of canned diets with the exception of the canned diet containing very high concentrations of dietary fibre (25.1% TDF). Ileal digesta viscosity of dogs appears to be responsive to the diet type characteristics.

Viscosity as Related to Dietary Fiber: A Review

Viscosity is a physicochemical property associated with dietary fibers, particularly soluble dietary fibers. Viscous dietary fibers thicken when mixed with fluids and include polysaccharides such as gums, pectins, psyllium, and beta-glucans. Although insoluble fiber particles may affect viscosity measurement, viscosity is not an issue regards insoluble dietary fibers. Viscous fibers have been credited for beneficial physiological responses in human, animal, and animal-alternative in vitro models. The following article provides a review of viscosity as related to dietary fiber including definitions and instrumentation, factors affecting viscosity of solutions, and effects of viscous polysaccharides on glycemic response, blood lipid attenuation, intestinal enzymatic activity, digestibility, and laxation.

Dietary fibers affect viscosity of solutions and simulated human gastric and small intestinal digesta

Two experiments were conducted to determine the viscosities of both soluble and insoluble dietary fibers. In Expt. 1, corn bran, defatted rice bran, guar gum, gum xanthan, oat bran, psyllium, soy hulls, stabilized rice bran, wheat bran, wood cellulose, and 2 methylcellulose controls (Ticacel 42, Ticacel 43) were hydrated in water overnight at 0.5, 1, 1.5, or 2% concentrations. In Expt. 2, guar gum, oat bran, psyllium, rice bran, wheat bran, and wood cellulose were subjected to a 2-stage in vitro gastric and small intestinal digestion simulation model. Viscosity was measured every 2 and 3 h during gastric and small intestinal simulation, respectively. Viscosities in both experiments were measured at multiple shear rates. Viscosities of all fiber solutions were concentration- and shear rate-dependent. Rice brans, soy hulls, and wood cellulose had the lowest viscosities, whereas guar gum, psyllium, and xanthan gum had the highest viscosities, regardless of concentration. During gastric simulation, viscosity was higher (P < 0.05) at 4 h than at 0 h for guar gum, psyllium, rice bran, and wheat bran. During small intestinal simulation, viscosities were higher (P < 0.05) between 3 and 9 h compared with 18 h for guar gum, oat bran, and rice bran. Guar gum, psyllium, and oat bran exhibited viscous characteristics throughout small intestinal simulation, indicating potential for these fibers to elicit blood glucose and lipid attenuation. Wheat and rice brans and wood cellulose did not exhibit viscous characteristics throughout small intestinal digestion; thus, they may be beneficial for laxation.

Effects of stage of maturity and cooking on the chemical composition of select mushroom varieties

Select mushrooms were analyzed for proximate constituents and carbohydrate profiles either raw or cooked and at different stages of maturity. White button mushrooms (Agaricus biporus) contained high concentrations of ash (12.5 and 11.9% for immature and mature mushrooms, respectively). Starch and total dietary fiber (TDF) concentrations were higher in maitake (Grifola frondosa) and shiitake (Lentinus edodes) mushrooms. Crude protein (CP) and acid-hydrolyzed fat (AHF) were highest in crimini (Agaricus bisporus) and white button and maitake mushrooms, respectively. Chitin concentrations were highest in portabella (Agaricus bisporus) and enoki (Flammulina velutipes) mushrooms (8.0 and 7.7%, respectively). Oligosaccharides were found in low concentrations in some mushrooms. CP and TDF accounted for 86.4 and 49.3% of mushroom organic matter. Cooking increased starch, TDF, and AHF but decreased CP and chitin concentrations. The chitin concentration increased with mushroom maturity. These results detail the complete carbohydrate profile of several important mushroom varieties.

Carbohydrate composition of selected plum/prune preparations

Eighteen plum/prune preparations and byproducts were analyzed for proximate constituents and carbohydrate profiles. Plum puree and prune juice contained the highest concentrations of ash (13.0 and 13.8%, respectively). Crude protein (CP), acid-hydrolyzed fat (AHF), and total dietary fiber (TDF) concentrations were higher in byproducts (waste cake and dried plum pits) compared with the other fractions. Several classes of oligosaccharides were found in low concentrations in many of the substrates and were associated with the fruit rather than the pit. Maltooligosaccharides were found in very high concentrations in three of the preparations as a result of the addition of maltodextrin during processing. Monosaccharides, sugar alcohols, and oligosaccharides were found in higher concentrations in the fruit than in the pit and accounted for 2.9-84.7% of substrate organic matter. These results indicate that carbohydrates of various types constitute a significant proportion of plum/prune preparations and byproducts.