Extruded diet macronutrient digestibility: plant-based (vegan) vs. animal-based diets in client-owned healthy adult dogs and the impact of guardian compliance during in-home trials

Abstract

IntroductionPlant-based (vegan) diets for dogs are commercially available, however, research investigating long-term nutritional adequacy of these diets is scarce. Use of client-owned animals has become increasingly popular for apparent total-tract nutrient digestibility (ATTD) studies, yet low guardian compliance with the study protocol, such as providing daily dietary intake information, is a challenge. However, the impact of low diet reporting compliance on the overall ATTD results is unknown.MethodsSixty-one, client-owned healthy adult dogs completed a randomized, double-blinded longitudinal study. Dogs were randomly assigned into two groups that were fed either a commercial extruded meat-based diet (MEAT, n=30) or an experimental extruded vegan diet (PLANT, n=31) for 12 weeks. At the end of the study, pet guardians performed a 72-hour total fecal collection for ATTD assessment. Pet guardians were asked to complete a food diary for the duration of the trial, however only a subset of guardians (n=35) provided this food diary at the end of the study.ResultsNo evidence of an association between pet guardians providing a food diary and apparent digestibility coefficients (ADC) of crude protein (CP) (p=0.14), crude fat (EE) (p=0.72), and dry matter (DM) (p=0.68) was found. Apparent digestibility coefficients for CP (p=0.52), EE (p=0.78), and DM (p=0.43) did not differ between PLANT and MEAT. Body weight and age were found to be associated with CP (p=0.03) and DM (p=0.01) digestibility, but no association with EE (p=0.07) digestibility was present.DiscussionThese results indicate that vegan- and animal-based diets with similar nutrient profiles can have comparable nutrient digestibility. Moreover, presence or absence of a guardian-reported food diary had no effect on the overall results of the ATTD study. Further studies investigating guardian compliance for ATTD trials are needed to develop a standardized protocol and reduce current challenges and limitations related to pet guardian’s participation in digestibility trials.

Comparison of the fecal microbiota of adult healthy dogs fed a plant-based (vegan) or an animal-based diet

“…Recruitment of trial participants was conducted through an eSurvey designed on the Qualtrics (Provo, UT, USA) platform to collect data regarding suitability for study enrollment. Details regarding this recruitment survey were published previously ( Dodd et al, 2023 ; Liversidge et al, 2023 ). The survey was advertised locally around the University of Guelph campus and surrounding community, as well as shared virtually on social media to local dog-related groups.…”

“…Proximate analysis and mineral analysis were performed on both diets post-manufacturing at a commercial laboratory (Bureau Veritas, Mississauga, ON, Canada). Details regarding the diets used were published previously ( Dodd et al, 2023 ; Liversidge et al, 2023 ). Pet guardians and researchers were blinded to the identity of the diets being fed to study participants throughout the duration of the testing period and remained blinded until after all data were analyzed.…”

“…These concerns are based on lower concentrations of nutrients and poor bioavailability of nutrients in plant-based ingredients used in vegan diet formulations ( Dodd et al, 2021 ). Digestibility studies however, on individual plant ingredients, mildly cooked human-grade, and whole plant-based diets have demonstrated that plant-based ingredients if processed correctly have the potential to demonstrate similar nutrient digestibility when compared to conventional animal-based ingredients ( Kendall and Holme, 1982 ; Bednar et al, 2000 ; Liversidge et al, 2023 ). This is likely due to coevolution of dogs and humans which has led to dogs becoming closer related biologically to humans rather than to their wolf ancestors ( Buff et al, 2014 ).…”