NMR-based metabonomics reveals distinct metabolic profiles of plasma from sows after consumption of diets with contrasting dietary fibre levels and composition

Proton (1H) nuclear magnetic resonance (NMR) spectra of biofluids such as plasma or urine provide specific information of the metabolite profile of these samples. In the current investigation NMR-based metabonomics was applied to arterial and portal vein blood samples obtained from the absorptive and post-absorptive phases of sows fed diets varying in dietary fibre (DF) levels and composition. A total of six sows were fed 3 experimental diets - low-DF, high-DF soluble, and high-DF insoluble in a repeated 3 × 3 Latin square design. The NMR profiles demonstrated differences between the arterial and portal blood, which could be identified as dietary-introduced changes in glucose, fatty acids, lactate, betaine, creatine and specific amino acids. In addition, our approach of subtracting spectra from simultaneously collected arterial and portal blood samples showed the uptake of nutrients at different absorption phases and between diets could be explored. In this way betaine was seen to have a much higher concentration in the blood of the low-DF than the high-DF fed sows but the net-absorption of betaine was only slightly higher in low-DF fed sows.