The purpose of this doctoral thesis was to explore the effects of whole grains of wheat, oats and rye on the dog's metabolism, intestinal microbiota and the amount of short-chain fatty acids (SCFA).
When the dog was domesticated from the wolf, its digestive system was adapted to a diet of starch, which in today's dog food can make up a large part of the content. For humans, a diet containing whole grains, instead of refined flour, may have metabolic health benefits, possibly linked in part to the microbiota and the short-chain fatty acids (SCFA) that some bacteria, e.g. Prevotella, forms during fermentation of dietary fiber.
The aim of this doctoral thesis was to explore the effects of whole grains of wheat, oats and rye on the dog's metabolism, intestinal microbiota and SCFA. Rye is an unusual ingredient in dog food. In a first study, with six beagles, the appropriate level of inclusion of whole grain rye was therefore evaluated and effects on microbiota were compared against refined wheat. In the next substudy, 18 privately owned dogs were fed in a cross-over design with three different diets, containing whole grains of wheat, oats or rye. Effects on microbiota, SCFA and the postprandial metabolism were studied.
Feed with a 25% admixture of whole grain rye was accepted by the dogs and had acceptable digestibility. When the admixture level of rye was 50%, changes were seen in the general microbiota composition with increased relative abundance of Prevotella. No differences in general microbiota composition were seen between diets with wheat, oats or rye in substudy two, but diversity was higher after wheat than after rye. The occurrence of Bacteroides was lowest after rye and negatively correlated to the occurrence of Prevotella. The acetate and propionate concentration in the faeces was higher after rye than after oats. The oat feed produced higher postprandial blood concentration of glucose, glucagon-like peptide 1 (GLP-1) and triacylglycerol compared to wheat. The fasting level of insulin was highest after rye. Insulin release per glucose and GLP-1 tended to be highest after wheat.
Overall, the results indicate that whole grain rye can affect the dog's microbiota and its function in a health-promoting direction. Further studies are needed regarding the metabolic effects of whole grains in dog food.
Hanna Palmqvist defended her doctoral thesis on October 19.