Effects of corn-expressed phytase on growth performance and gut health of nursery pigs

Abstract Text: This study was conducted to determine the super dosing effects of phytase from corn-expressed phytase (CEP, Agrivida, Inc., Medford, MA) on growth performance and gut health of nursery pigs. Pigs (16 barrows and 16 gilts; 21 d of age and 6.19 ± 0.71 kg BW) were individually housed and allotted to one of 4 dietary treatments based on a randomized complete block design with the initial BW and sex as blocks. Pigs were fed a basal diet supplemented with ground CEP to provide phytase activity at 0, 500, 1,500, or 3,000 FTU/kg during 2 phases (Phase 1: 10 d and Phase 2: 20 d) for a total period of 30 d. Dietary Ca and P were not reduced, with 0.83% Ca and 0.44% STTD P or 0.74% Ca and 0.36% STTD P during Phase 1 and 2, respectively. Feed intake and BW were recorded every 10 d. Plasma samples were collected on d 25 postweaning to measure cytokine tumor necrosis factor-a (TNF-a) and malondialdehyde (MDA). Pigs were euthanized on d 30 to collect tissues from duodenum and jejunum for the evaluation of morphology, TNF- α, and MDA. Digesta were collected from proximal jejunum to measure viscosity. Data were analyzed using polynomial contrasts in the MIXED procedure of SAS version 9.3 (SAS Inc., Cary, NC, USA). Increasing the levels of phytase increased (linear, P < 0.05) BW on d 20 (10.2 to 12.1 kg) and on d 30 (16.1 to 18.6 kg), increased (linear, P < 0.05) ADG from d 10 to 20 (0.32 to 0.49 kg/d), and tended to increase (linear, P = 0.052) overall ADG (0.33 to 0.41 kg/d). Increasing supplemental levels of phytase increased (linear, P < 0.05) villus height in the duodenum (420 to 559 μm) and jejunum (426 to 491 μm), and the villus height-crypt depth ratio (1.5 to 2.1) in the duodenum. Increasing levels of phytase tended to decrease (Con vs. T₁ + T₂ +T₃, P = 0.089) TNF- α (6.53 to 5.36 pg/mg) in duodenum and tended to decrease (linear, P = 0.080) MDA (0.5 to 0.34 umol/g protein) in jejunum. Viscosity of jejunal digesta tended to decrease (quadratic, P= 0.078) from 2.55 to 2.15 cP (at 1,500 FTU/kg). In conclusion, super dosing corn-expressed phytase up to 3,000 FTU/kg enhanced growth performance of nursery pigs with improved villus developments, reduced inflammatory cytokine levels, and oxidative stress products.

Keywords: corn-expressed phytase, growth performance, gut health, nursery pigs