Metabolic effects of various carbohydrates and fibre in dog food

Sammanfattning: The lack of scientific studies regarding dog nutrition highlights the need for future studies, especially when we know the importance of food in relation to health. The variety of ingredients in commercial dog food is huge. However, a common denominator in dry dog food is often the high amount of cereals, consisting usually 30–60% grains of the energy source in dry matter. There is an interest to study how different types of grains might impact the different types of metabolic pathways since the content of dietary fibres and bioactive compounds differ between grains. Dietary fibres have many beneficial health effects such as maintaining healthy gut microbiota and have shown a protective effect against diseases, mainly in human studies. Now we need metabolomic studies to provide wider knowledge about which different metabolites and metabolic pathways the different types of grains can stimulate in dogs. In this study, the metabolic response was analysed in 17 dogs after four weeks of feeding with three experimental feeds composed of different grain sources; whole grain wheat, peeled oats, and whole grain rye. Fasting and postprandial urine samples were used to generate metabolic profiles by Nuclear Magnetic Resonance spectroscopy (NMR). The multivariate analyses showed a significant differentiation in metabolic profiles between the diet with whole grain wheat and whole grain rye. A total of ten metabolites could be linked to this differentiation. The concentration of the ten metabolites was calculated in both fasting and postprandial samples to analyse if a difference could be found between the three experimental feeds. The metabolite methylguanidine showed a significant difference in concentration between the feed with whole grain wheat and peeled oat in postprandial urine. Additionally, the metabolite tyramine differed significantly postprandial between the feed with whole grain wheat and whole grain rye. The concentration of some identified metabolites differed between fasting and postprandial samples and most of these metabolites were linked to a significant shift in concentration after feed intake for the diet of whole grain wheat. In this study, only healthy dogs were included and no specific metabolic pathways or risk factors for metabolic diseases could be proven in connection to the differentiation between grains. However, the result showed variety in metabolic profiles after feed intake of different grains and now further studies are needed to look deeper into the relationship between metabolic differentiation of the grains and the activation of metabolic pathways.