Phosphorus digestibility and phytate degradation in pigs fed wheat-based diets with different intrinsic phytase activity and added microbial phytase
Creators: name: Klein, Nicolas
name: Papp, Marius
name: Rosenfelder-Kuon, Pia
name: Schroedter, Annika
name: Avenhaus, Ulrike
name: Rodehutscord, Markus
Publisher: name: Taylor & Francis
Year: 2021
Subjects: subject: Biochemistry
subject: Microbiology
subject: FOS: Biological sciences
subject: Molecular Biology
subject: Pharmacology
subject: Biotechnology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: Ecology
subject: Developmental Biology
subject: Plant Biology

description: The objective of this study was to investigate the effect of variation in wheat-derived phytase activity on <i>myo</i>-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP<sub>6</sub>) degradation, inositol phosphate (InsP) isomer concentration and phosphorus (P) digestibility in pigs fed wheat-based diets. Additional effects of a microbial phytase supplementation were also studied. Three wheat genotypes (W1-W3) with an analysed phytase activity between 2760 and 3700 FTU/kg were used to formulate four experimental diets that included soybean meal and rapeseed meal but did not contain a mineral P supplement. DietW1-DietW3 only differed in the included wheat genotypes (W1-W3) at an inclusion level of 400 g/kg. DietW3+ contained W3 and a commercial 6-phytase supplementation at 500 FTU/kg diet. Eight barrows with an initial body weight of 27 kg were fitted with a simple T-cannula at the distal ileum and assigned to the four dietary treatments in a completely randomised row column design. The experiment included four periods of 12 d each. The first 5 d of each period were for diet adaptation, followed by collection of faeces (4 d), ileal digesta (2 d), and blood (last day). In DietW1-DietW3, the mean precaecal (pc) InsP<sub>6</sub> disappearance was 48% and the mean pc P digestibility was 37% without a significant effect of the wheat genotype. The InsP<sub>6</sub> disappearance measured in the faeces was close to complete in all treatments, and faecal P digestibility was not significantly affected by the wheat genotype (36% overall). The addition of microbial phytase caused a significant increase in pc InsP<sub>6</sub> degradation (to 79%) and pc and total tract P digestibility (to 53% and 52%, respectively). The concentration of InsP<sub>6</sub> degradation products in ileal digesta was not significantly affected by the wheat genotype, except for that of Ins(1,2,3,4,6)P<sub>5</sub> and <i>myo</i>-inositol, which were higher in DietW3 than in DietW1 and DietW2. The added microbial phytase significantly reduced the concentration of InsP<sub>5</sub> isomers in the ileal digesta and increased the concentrations of lower InsP isomers and <i>myo</i>-inositol. There were no significant effects of the added microbial phytase on pc amino acid digestibility; however, the wheat genotype exerted significant effects on the pc digestibility of Cys, Gly and Val. It was concluded that an increase in the intrinsic phytase activity of wheat achieved by crossbreeding was not reflected in InsP<sub>6</sub> degradation and P digestibility in pigs fed wheat-based diets.