245 Safety, gastrointestinal tolerance, and digestibility of brewed chicken protein in healthy adult dogs.

As human and pet populations continue to increase globally, sustainable agricultural practices will be needed to meet the demands. In addition to efficiently increasing overall food supply, the production of high-quality proteins is extremely important. Producing sufficient amounts of traditional animal proteins is and will continue to be a challenge. Alternative protein sources may provide economic and ecological relief, but adequate testing is necessary to confirm safety and evaluate nutritional value. The objective of this study was to evaluate the safety, efficacy, gastrointestinal tolerance, and apparent total tract digestibility (ATTD) of brewed chicken protein (BCP; Saccharomyces cerevisiae expressing a chicken protein). Thirty-two healthy adult beagle dogs (20 spayed females; 12 neutered males; BW: 9.68±1.18 kg; age: 4.16±1.85 yr) were used in a completely randomized design (n=8/treatment). After a 2-wk acclimation phase, baseline measurements were collected and then dogs were allotted to the following treatments and fed for 26 wk: control diet based on chicken by-product meal and brewers rice (0% BCP; Control), 15% BCP (Low), 30% BCP (Medium), or 40% BCP (High). All data were analyzed using the Mixed Models procedure of SAS 9.4, with P< 0.05 being significant and trends accepted at P< 0.10. The consumption of BCP did not affect BW, body condition score, physical examination parameters, food intake, serum chemistry, hematology, and urinalysis parameters, with the majority of metabolites being within the reference ranges for adult dogs. The ATTD of dry matter, organic matter, and crude protein were greater (P < 0.05) for the High diet, while the ATTD of fat was greater (P < 0.05) for the Control diet than the Medium and High diets. Fecal output was lower (P < 0.0001) and fecal dry matter was lower (P < 0.001) for dogs fed the High diet. Fecal metabolites were altered by treatment, with acetate concentrations being lower (P < 0.05) and propionate concentrations tending to be higher (P=0.06) in dogs fed BCP. Fecal isobutyrate, isovalerate, indole, total phenol and indole, and ammonia concentrations were lower (P < 0.001) and fecal valerate concentrations were higher (P < 0.0001) in dogs fed BCP. Fecal bacterial alpha diversity was lower (P < 0.05) in dogs fed BCP. Fecal bacterial beta diversity was also affected by treatment, with those fed Control being different than those fed BCP. The relative abundance of over 20 fecal bacterial genera were affected by BCP consumption. Overall, these results indicate that the BCP ingredient tested is safe for use in adult dog foods at an inclusion level of up to 40%. While there were treatment differences noted, all data were within ranges expected in healthy adult dogs. No detrimental effects were observed, and interesting changes to nutrient digestibility and fecal characteristics, metabolites, and microbiota populations suggest potential benefits to gastrointestinal health.