The flow of inositol phosphate esters and phytate phosphorus in the proximal and distal parts of the digestive tract of broilers receiving diets adequate in available phosphorus and supplemented with high levels of phytase
The aim of this study was to characterize the flow of inositol phosphate (iP) esters and disappearance of phytate phosphorus (PP) in the gizzard and ileum of broilers receiving diets adequate in available phosphorus (aP) and supplemented with high levels of phytase. One-hundred-and-sixty-eight Ross 308 broilers at 1 d of age were allocated to 3 treatments (0, 1500, and 3000 FTU/ kg phytase) in a randomized complete block design, where the pen was the experimental unit (6 birds per pen). Feed and water were provided ad libitum, and digesta from the gizzard and ileum were collected on d 21 and analysed for iPs and PP relative to TiO2, the indigestible marker used. In the gizzard, iP6 and iP5 levels were lower (P < 0.01) and inositol higher (P < 0.01) in the diet supplemented with 1500 or 3000 FTU/kg phytase compared with the control. In the ileum, supplementation with 1500 or 3000 FTU/kg reduced levels of iP6 (3115, 3552, nmol, for 1500, 3000 FTU/kg respectively, P < 0.01) and increased that of iP4 and inositol (3115, 3552, nmol for 1500, 3000 FTU/kg, respectively, P < 0.05) compared with broilers fed the control diet (482 iP6, 1650 inositol), except for iP5 which was greater (P < 0.01) in control and with 1500 FTU/kg phytase compared with 3000 FTU/kg. There were no phytase effects on IP3 flow. In the gizzard, PP disappearance was greater (P < 0.01) in diets supplemented with 1500 or 3000 FTU/kg compared with control diet. No differences were seen in ileal PP disappearance between the control and diet supplemented with 1500 FTU/kg, or between supplementation of 1500 and 3000 FTU/kg; however, PP disappearance was greater in (P < 0.01) diets with 3000 FTU/kg than control. Total tract PP disappearance was greater (P < 0.05) in diets supplemented with 1500 or 3000 FTU/kg (74.5, 85.5%, respectively) than in the control diet (60.3%). The results show that the phytase rapidly hydrolysed iP6 and iP5 in the gizzard, leading to an accumulation of inositol, and the hydrolysis continued in the distal gut. It is concluded that the phytase was effective in rapidly hydrolysing phytate, releasing free inositol even in the gizzard and that higher phytase doses may lead to further phytate phosphorus hydrolysis in the ileum.
Other Titles/Title of Conference
Joint Annual Meeting of American Society for Animal Science, Kansas City, USALinking animal science and animal agriculture: Meeting the global demands of 2050
Journal of Animal Science