New protein ingredients are used to support pet food market growth and the development of new products while maintaining animal dietary needs. However, novel protein sources (e.g., spray-dried chicken, and (or) rice, pea, and potato protein concentrates) have limited data available regarding their protein quality. The objective of this study was to evaluate protein ingredients used in the pet food industry by laboratory analysis and a chick growth assay as a model. Following analysis for proximate and amino acid composition, chicks (six birds per pen with four pens per treatment) were fed experimental diets for 10 d. Diets contained 10% crude protein from each of the experimental protein sources (spray-dried egg—SDEG; spray-dried egg white—SDEW, spray-dried inedible whole egg—SDIE, chicken by-product meal—CBPM, chicken meal—CKML, low-temperature fluid bed air-dried chicken—LTCK, low-temperature and pressure fluid bed dried chicken—LTPC, spray-dried chicken—SDCK, whey protein concentrate—WPCT, corn gluten meal—CGML, corn protein concentrate—CPCT, potato protein isolate—PPIS, rice protein concentrate—RPCT, pea protein isolate—PEPI, soy protein isolate—SPIS, and soybean meal—SBML) along with an N-free diet (negative control). Chicks fed SDEG, SDIE, and LTPC had the highest protein efficiency ratio (PER; P < 0.0001; 5.18, 5.37, and 5.33, respectively), LTCK and SDCK were intermediate (4.54 and 4.79), and the CBPM and CKML were the lowest among the poultry proteins for EAA:NEAA, PER, and Lys availability. Among the vegetable proteins, PPIS and SBML had the highest PER values (3.60 and 3.48, P < 0.0001). In general, the chick PER method ranked the quality of animal protein sources higher than vegetable proteins, and these results were consistent with the EAA:NEAA ratio and Lys availability.

Dogs can benefit from dietary fibers. Traditionally, cellulose (CE) and beet pulp (BP) have been used by pet food companies as insoluble and soluble fiber sources. Miscanthus grass (MG) is a novel fiber ingredient made from Miscanthus giganteus, a C4 grass produced for its fiber content, but it has not been evaluated for dogs. The objectives of this study were to determine the effects of different fiber sources on nutrient utilization and stool consistency by dogs. Twelve Beagle dogs were fed 3 dietary treatments varying in their fiber sources (BP, CE, MG). Diets were fed for a 14-d period (9 d adaptation), fecal samples were collected (5 d total fecal collection) and scored. Nutrient digestibility was estimated using total fecal collection (TFC). Dogs fed BP diet had softer stools than dogs fed CE and MG (3.15 vs. 3.68 and 3.64, respectively). Wet fecal output was higher for dogs fed CE compared to MG, with dogs fed BP having the lowest values (254.3 g vs. 241.6 g vs. 208.5 g, respectively). Dogs fed CE and MG had lower DM digestibility than dogs fed BP (P < 0.05), dogs fed BP had lower CP digestibility compared with dogs fed MG and CE (81.4% vs. 85.5% and 85.8%, respectively). In conclusion, MG could be used as an alternative fiber source to CE.

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Grain-free diets tend to have greater inclusions of pulses in contrast to grain-based diets. In 2018 the Food and Drug Administration (FDA) released a statement that grain-free diets may be related to the development of canine dilated cardiomyopathy (DCM). However, all dog foods met regulatory minimums for nutrient inclusion recommended by the Association of American Feed Controls Official (AAFCO). In some FDA case reports, but not all, dogs diagnosed with DCM also had low concentrations of plasma or whole blood taurine, as such we hypothesized that feeding these diets will result in reduced taurine status from baseline measures. The objective of this study was to determine the effects of feeding a grain-free diet to large breed dogs on taurine status and overall health. Eight Labrador Retrievers (4 males, 4 females; Four Rivers Kennel, MO) were individually housed and fed a commercial complete and balanced grain-free diet (Acana Pork and Squash formula; APS) for 26 wk. Fasted blood samples were collected prior to the start of the trial (baseline; wk 0), at wk 13 and wk 26 for analyses of blood chemistry, hematology, plasma amino acids (AA), and whole blood taurine. Urine was collected by free catch at wk 0 and 26 for taurine and creatinine analyses. Fresh fecal samples were collected at wk 0 and 26 for bile acid analyses. Data were analyzed using the GLIMMIX procedure with repeated measures in SAS (v. 9.4). Plasma His, Met, Trp, and taurine and whole blood taurine concentrations increased over the course of the study (P &lt; 0.05). Urinary taurine to creatinine ratio was not affected by diet (P&gt;0.05). Fecal bile acid excretion increased after 26 wk of feeding APS to dogs. Despite the higher fecal excretion of bile acids, plasma and whole blood taurine increased over the 26-wk feeding study. These data suggest the feeding APS, a grain-free diet, over a 26-wk period improved taurine status in Labrador Retrievers and is not the basis for incidence of DCM for dogs fed APS. Other factors that may contribute to the etiology of DCM should be explored.

Dietary fibers can influence a dog’s overall health, but high concentrations of soluble dietary fibers can cause soft stools. An in vitro model could be useful to predict the rate fibers are fermented once they reach the colon. Pet food companies are constantly searching for new ingredients to differentiate their products from competitors. Miscanthus grass (MG), pea fiber (PF), and sorghum bran (SB) are novel fiber sources that could be alternatives to standards like cellulose (CE) and beet pulp (BP). The objectives of the study were to determine the effects of fiber source on organic matter disappearance (OMD), estimated organic matter disappearance (EOMD), and fermentation end-product concentrations using an in vitro fermentation procedure and dog fecal inoculum. Total dietary fiber (TDF) residues from MG, CE, BP, PF, and SB were fermented in vitro with buffered dog feces. Fecal samples were collected and maintained in anaerobic conditions until the dilution and inoculation. Test tubes containing the fibrous substrates were incubated for 4, 8, and 12 h at 39 °C. Short-chain fatty acids (SCFA), branched-chain fatty acids (BCFA), OMD, and EOMD were determined for each fiber source and time point. Beet pulp had the highest OMD, EOMD, and SCFA production of all tested fiber sources (38.6% OMD, 26.2% EOMD, 2.72 mmol SCFA/g of substrate). Sorghum bran led to greater concentrations of BCFA (59.86 µmol/g of substrate) and intermediate OMD and EOMD compared to the other tested fibers. Cellulose and MG were poorly fermented with the lowest OMD, EOMD, SCFA, and BCFA compared to other fibers. In conclusion, MG could be used as an insoluble minimally fermentable replacement fiber for CE in dog foods.