Effect of crude fiber and total dietary fiber on the calculated nitrogen-free extract and metabolizable energy content of various dog foods fed to client-owned dogs with osteoarthritis.

OBJECTIVE: To compare measurements of crude fiber (CF) and total dietary fiber (TDF) for various dog foods and their effect on the calculated nitrogen-free extract and metabolizable energy (ME) content, and to compare label-guaranteed and laboratory-analyzed macronutrient values. SAMPLES: 51 dog foods fed to client-owned dogs with osteoarthritis. PROCEDURES: Foods were analyzed for dry matter, ash, crude protein, acid-hydrolyzed fat, CF, and TDF. Metabolizable energy was calculated by use of a formula with modified Atwater factors and formulas recommended by the National Research Council that included both CF and TDF values. Linear regression analysis was performed to determine the correlation between CF and TDF values. RESULTS: Only a few foods failed to conform to the guaranteed analysis for all macronutrients except for CF, in which approximately 40% of the foods exceeded the guaranteed maximum values. The CF and TDF values were moderately correlated (r = 0.843). Correlations among CF- and TDF-based ME estimations were moderate with use of the modified Atwater formula and strong with use of the National Research Council formulas (r = 0.86 and r = 0.91, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Values for CF were the most variable of the macronutrients of the evaluated dog foods and results suggested that CF is an incomplete and inaccurate measurement of dietary fiber content and, thus, its inaccuracy may lead to inaccurate and variable ME values.

Ancient grains as novel dietary carbohydrate sources in canine diets.

Ancient grains are becoming an increasingly abundant carbohydrate source in the pet food market as a result of their popularity and novelty in the human market. Thus, it is imperative to evaluate the characteristics of these ingredients in vivo. Ten adult intact female beagles were used in a replicated 5 × 5 Latin square design. Five dietary treatments were evaluated containing either: rice (CON), amaranth (AM), white proso millet (WPM), quinoa (QU), or oat groats (OG). All diets were formulated to include 40% of the test grain and to be isonitrogenous, isocaloric, and nutritionally complete and balanced for adult dogs at maintenance. The objectives were 1) to evaluate the effects of the novel carbohydrate sources on total apparent total tract digestibility (ATTD), fecal microbiota, and fermentative end-product concentrations and 2) to evaluate the effects of novel carbohydrate sources on the postprandial glycemic and insulinemic responses in healthy adult dogs. All diets were well accepted by the dogs and fecal scores remained within the ideal range for all treatments. In terms of ATTD, all diets were well digested by the dogs; WPM had the highest digestibility of dry and organic matter in contrast with dogs fed the other treatments (P < 0.05). Additionally, ATTD of total dietary fiber was highest for WPM (72.6%) in contrast with QU (63.5%) and CON (50.8%) but did not differ from AM (65.7%) and OG (66.6%). Dogs fed AM or OG had greater (P < 0.05) fecal concentrations of total short-chain fatty acids, as well as propionate and butyrate concentrations, than CON. Ancient grain inclusion appears to beneficially shift fecal microbial populations, with increases in relative abundances of butyrogenic bacteria (i.e., members of the Lachnospiraceae family) observed for OG and reductions in Fusobacteriaceae for both AM and OG when compared with CON. Postprandial glycemic and insulinemic responses did not differ among treatments. Together, these data suggest that ancient grains can be included up to 40% of the diet while eliciting beneficial effects on the overall host health without detrimentally affecting nutrient digestibility.

Chemical composition and in vitro fermentation characteristics of legumes using canine fecal inoculum.

Legumes are a popular grain-free alternative carbohydrate source in canine diets, however, information on their fermentative characteristics have not been established. Thus, the objectives of the present study were to 1) quantify the chemical compositions and 2) fermentative profile of select legumes using canine fecal inoculum. Five legume varieties, whole yellow peas (WYP), green lentils (GL), black bean grits (BBG), navy bean powder (NBP), and garbanzo beans, were analyzed and compared to a positive control, beet pulp (BP). Substrates were analyzed for gross energy (GE), dry and organic matter, crude protein (CP), acid hydrolyzed fat, and total dietary fiber (TDF) fractions, beta-glucans, starch-free, and hydrolyzed sugars, as well as fermentative characteristics: pH, short-chain fatty acids (SCFA), branched-chain fatty acids (BCFA), total gas, hydrogen, and methane. Substrates then underwent a two-stage in vitro digestion and subsequent fermentation using canine fecal inoculum for 0, 3, 6, 9, and 12 h. All test substrates contained approximately 8% to 9% moisture and 4.5 kcal/g GE. The highest CP content was observed in GL (27%). Analyzed TDF content of test substrates was greatest for WYP (32%) and GL (36%). Total starch content was greatest for GL (58%) and WYP (56%). Sucrose and stachyose were the most predominant free sugars and glucose was the most predominant hydrolyzed sugar among test substrates. After 3 and 6 h of fermentation, a net negative change in pH was observed among most substrates with a net negative change in all substrates after 9 and 12 h. Values for SCFA did not differ among substrates after 3 or 6 h of fermentation with BP and WYP among the greatest acetate (1,656 and 1,765 umol/g, respectively) and propionate production values (157.7 and 126.1, respectively) after 9 h. All substrates produced greater total gas volumes than WYP after 3 h, with no differences observed after any other time points. However, BP hydrogen production values were greater after 9 and 12 h (P < 0.0001; 726,042 and 394,675 ng/g, respectively) with greater methane production values after 12 h (P < 0.0001; 54,291 ng/g) than all test substrates. These data suggest that legumes offer a diverse macronutrient profile and appear to be a source of slowly fermentable fiber, which may have beneficial implications on the ratios of saccharolytic to proteolytic fermentation toward the distal colon.

Chemical composition and in vitro fermentation characteristics of ancient grains using canine fecal inoculum.

Human interest in ancient grains replacing traditional carbohydrate sources has reached the pet food market; however, chemical composition of these grains and their digestive properties in the canine model, specifically the fermentative characteristics, have not been established. Five ancient grain varieties were analyzed: amaranth (AM), white proso millet (WPM), oat groats (OG), quinoa (QU), and red millet (RM). Cellulose (CEL) was used as a negative control, and beet pulp (BP) was used as a positive control. Substrates were analyzed for macronutrient composition as well as free and hydrolyzed sugar profiles in addition to their in vitro fermentative characteristics. Substrates were allocated into 2 sets to allow for quantification of pH, short-chain fatty acids, and branched-chain fatty acids, as well as gas volume and composition. Samples were digested for 6 and 18 h with pepsin and pancreatin, respectively, prior to inoculation with fecal bacteria for 0, 3, 6, 9, or 12 h. Detectable levels of cereal ß-glucans were observed solely in OG (3.5%), with all other substrate containing <0.35% cereal ß-glucans. All test substrates had fairly similar macronutrient and starch profiles with the exception of RM that contained the highest resistant starch content (2.4%), with all other test substrates containing <0.5% resistant starch. However, the analyzed pseudocereals, AM and QU, had the highest concentrations of free glucose while the minor cereal grains, WPM, OG, and RM, contained the highest concentrations of hydrolyzed glucose. All test substrates had propionate production values similar or greater than BP after 3, 6, 9, and 12 h of fermentation, and similar or greater butyrate production values than BP after 6, 9, and 12 h. All substrates had greater (P < 0.05) changes in pH than CEL after 6, 9, and 12 h, with AM, WPM, OG, and RM having greater (P < 0.05) changes in pH than BP after 9 and 12 h. These data suggest select ancient grains have similar fermentation characteristics as BP, a moderately fermentable fiber considered the gold standard in terms of fiber sources in the pet food market today, and that OG and AM may be more fermentable during longer fermentation periods.