Phytase improves apparent total tract digestibility of phosphorus and calcium in piglets fed diets with adequate or reduced phosphorus content.

The effect of a thermotolerant 6-phytase produced by Trichoderma reesei on performance and apparent total tract digestibility (ATTD) of P and Ca was evaluated in 192 weaned piglets (randomized block design; 16 replicates; 2 piglets each). Diets based on wheat (Triticum aestivum), barley (Hordeum vulgare), oat (Avena sativa), soybean (Glycine max) meal, and whey protein with adequate [positive control (PC)] or reduced [negative control (NC)] Ca and P levels were fed for 46 d after weaning. The PC and NC diets contained 8.0 and 6.4 g/kg Ca and 2.9 and 1.9 g/kg digestible P, respectively. Pelleted diets contained 0, 500, or 1000 phytase units (FTU)/kg. Growth performance and G:F were measured during starter (25 d) and weaner pig (21 d) periods. The ATTD of Ca and P was determined by spot sampling at the end of the weaner pig period (8 pens per treatment over 5 consecutive d). Data were analyzed using a mixed model with random block effect and fixed effect of dietary P and phytase level and their interaction. Dietary P level did not affect ADG or G:F of piglets over the entire feeding period (P > 0.10) whereas phytase increased G:F (P < 0.05). During the starter period, phytase linearly enhanced (P < 0.05) ADG (258, 266, and 292 g) and G:F (639, 677, and 664 g gain/kg feed DM) without further increase in the weaner pig period (P > 0.10). A P × phytase interaction (P < 0.05) was observed for ATTD of P, more so for NC (48, 61, and 68%, respectively) than PC diets (52, 62, and 61%). The ATTD of Ca was higher (P < 0.05) for PC than NC diets (68 vs. 58%) and increased quadratically by phytase (61, 65, and 63%). In conclusion, the phytase tested enhanced piglet performance during the postweaning period and increased ATTD of P and Ca.