Epsilon Archive for Student Projects

Abstract

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.