Effects of Exogenous 6-Phytase (EC 3.1.3.26) Supplementation on Performance, Calcium and Phosphorous Digestibility, and Bone Mineralisation and Density in Weaned Piglets

SIMPLE SUMMARY: Supplementation with a low dose (up to 500 FTU/kg feed) of a new 6-phytase, obtained by assembling gene sequences of various phytase-producing bacteria, increases phosphorous and calcium availability in phosphorus-limiting piglet diets. Therefore, this phytase can be used to reduce the use of unsustainable sources of inorganic phosphorous without compromising piglets’ performance and bone mineralization and density, and the higher phosphorous utilization will also reduce its excretion to the environment. This study also demonstrates that the effects of phytase on bone density can be evaluated using computed tomography, which may be useful for studies with live animals. ABSTRACT: Phosphorus (P) is an essential mineral for growing piglets, which is poorly accessible in vegetable feedstuffs as it is stored as phytates. Thus, phytase supplementation is essential to increase P availability. Two experiments were conducted to evaluate a novel 6-phytase (EC 3.1.3.26) in weaned pigs fed low-P diets. In each experiment, one hundred and twenty piglets were fed a positive control (PC; adequate in Ca and P), a negative control (NC; limiting in Ca and P), or NC supplemented with 125, 250, or 500 FTU/kg of phytase (NC125, NC250, and NC500, respectively). P content was lower in diets of Experiment 1 than diets of Experiment 2. In Experiment 1, piglets offered PC or phytase diets had higher growth and efficiency compared with NC diets. In Experiment 2, similar effects were obtained, but the effects were less significant. In both experiments, P and Ca ATTD and bone density were significantly increased with phytase supplementation. Moreover, PC and NC500 had higher P concentrations and lower alkaline phosphatase activity in plasma than NC. To conclude, supplementation with the new 6-phytase at doses up to 500 FTU/kg enhanced P utilization, growth performance, and bone density in piglets fed P-limiting diets.