Dogs choose 23% of their calories as protein which is associated with body composition and circulating metabolites

As in other mammals, domestic dogs have specific taste preferences that can be influenced by macronutrient composition and physical characteristics of food as well as the presence or absence of specific taste imparting compounds (palatability enhancers). This study investigated the relationship of body composition and food choice and that choice on subsequent metabolomic shifts. Experimental foods were prepared with similar palatability for a population (as evaluated by the ratio of the test food to the total daily food consumed [grams test/(grams test+grams control)] through manipulations of factors independent of macronutrients. These foods with similar palatability preference for the population as a whole were then investigated for intake choice with 20 dogs with varying body fat (mean 3.9 kg, Std. Dev. 0.9) as well as subsequent effect of food choice on serum metabolites. Four completely balanced foods were available to the dogs at all times. The four foods had: a) 33% of calories from protein, b) 54% calories from fat, c) 56% calories from carbohydrate and d) intermediate level of calories from protein, fat and carbohydrate. Dogs chose to consume 23.0% calories from protein (Std. Dev. 1.5%, min 20% max 26%). Body composition influenced the choice of percent calories as protein; There was a positive relationship between body fat and percent calories as protein (r=0.56 p=0.02) while there was no relationship between body lean and percent calories as protein (r=0.06; p=0.82). Overall, dogs with high body fat showed the highest preference for dietary calories from protein. There was a positive association between the percent of calories as protein and ornithine and homocitrulline suggesting increased urea cycle metabolism. Increasing calories from protein were also negatively associated with specific metabolites in the TCA cycle (citrate, alpha ketoglutarate). There was an association with increased protein intake and decreasing endocannobionods (N‐oleoyltaurine, palmitoyl ethanolamide N‐palmitoyltaurine). In summary, when given the opportunity to choose between foods which had similar palatability dogs chose to consume 23.0% of their calories as protein and had an increased preference for protein as adiposity increased. These intake preferences were associated with metabolic changes reflecting metabolic shifts. Support or Funding Information Hill's Pet Nutrition, Inc.