Dose-dependent effects of supplemental phytase on ileal and total tract digestibility of nutrients and growth performance in growing pigs

Abstract

The objective of this study was to determine the dose-dependent effects of supplemental phytase on ileal and fecal digestibility and hindgut disappearance (HD) of nutrients and growth performance in pigs. In experiment 1, twelve barrows with an initial body weight of 29.2 kg (standard deviation = 2.2) were allotted to 6 diets in a replicated 6 × 4 incomplete Latin square design to obtain 8 observations per dietary treatment. The coefficient of apparent ileal digestibility (CAID) and apparent total tract digestibility (CATTD) of nutrients were determined. Additionally, the HD was calculated as the deviation between CAID and CATTD. A high-phosphorus (HP; 5.1 g/kg total phosphorus) diet was prepared based on corn and soybean meal with dicalcium phosphate to meet the phosphorus requirement. Five additional diets mainly consisted of corn and soybean meal were formulated to contain a low phosphorus (LP; 3.8 g/kg total phosphorus) concentration. The LP diet was supplemented with phytase at 0, 300, 600, 900, or 1500 unit/kg. All experimental diets contained 5.0 g/kg of chromic oxide as an indigestible index. In experiment 2, two hundred forty barrows with an initial body weight of 29.5 kg (standard deviation = 2.4) were allotted to 1 of 6 diets in a randomized complete block design with 10 replicate pens per dietary treatment and 4 barrows per pen. The same experimental diets as in experiment 1 were provided to the pigs for 28 days. In experiment 1, the CAID, CATTD, and HD of dry matter was not affected but CAID and CATTD of calcium increased linearly (P < 0.05) with increasing phytase supplementation. The CAID, CATTD, and coefficients of standardized ileal and total tract digestibility of phosphorus increased (P < 0.01) in a quadratic manner with increasing supplemental phytase. The standardized HD of phosphorus was greater (P = 0.049) in pigs fed the LP diet compared with that in pigs fed the HP diet. Supplemental phytase resulted in a quadratic increase (P < 0.05) in CAID of all indispensable amino acids except methionine and tryptophan. In experiment 2, the growth performance was decreased (P < 0.05) in pigs fed the LP diet compared with those fed the HP diet but increased (P < 0.05) in a quadratic manner by supplemental phytase. In conclusion, the digestibility of calcium, phosphorus, and amino acids, and the growth performance of pigs were improved by supplemental phytase.