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Effects of increasing dietary levels of Aspergillus oryzae-derived phytase (Ronozyme) on the growth performance of nursery pigs fed an adequate phosphorous diet
Pigs (PIC 29 × 380, n = 270) were blocked by initial BW (6.89±0.29 kg) at weaning (21±3 d) and allotted to 1 of 5 pens within each of 9 blocks. Pens within blocks were randomly assigned to 1 of 5 dietary treatments: HiP0 (devoid of phytase with aP = 0.55, 0.40, and 0.33 % for phase 1, 2 and 3), HiP1, HiP2, HiP3 (HiP0 + 0.015%, 0.037% and 0.059% of Ronozyme HiPhos 2700 GT), and HInP (HiP0 + monocalcium-phosphate to meet the estimated-aP-level in HiP3). Nutrients in all diets were formulated to meet or exceed the NRC 2012 requirement throughout the 3-diet-phases fed during the 37 d experiment. For phase 1 (d 0 to 9); ADG and ADFI were improved (P < 0.03) for HiP1-, 2-, and 3-fed-pigs compared to those fed HiP0. HiP3- and HInP-fed-pigs had similar (P > 0.70) ADG, ADFI, and G:F. During phase 2 (d 9 to 23); HiP1-, 2-, and 3-fed-pigs had greater ADG (Cubic, P < 0.03), ADFI (Quadratic, P < 0.05), and G:F (Cubic, P < 0.04) compared to those fed HiP0. HiP3-fed-pigs had similar ADG (P = 0.09) and ADFI (P = 0.66), but improved G:F (P < 0.05), compared to those fed HInP. In phase 3 (d 23 to 37); ADG was improved (Cubic, P < 0.05) in HiP2-fed-pigs compared to those fed HiP0, and HiP2- and 3-fed-pigs had increased (P < 0.03) ADG compared to those HInP-fed. Overall, ADG (Quadratic, P < 0.05), and G:F (linear, P < 0.01)of HiP1-, 2-, and 3-fed-pigs were higher than those fed HiP0, but ADFI was similar (P = 0.23). HiP3-fed-pigs had greater (P < 0.01) ADG, and a tendency (P = 0.07) for higher G:F than those fed HInP. The results of this study demonstrate that adding phytase to nursery diets believed-to-be P adequate improved ADG, and G:F; which indicates that the P requirement may be underestimated or that phytase provides benefits beyond releasing P.
|
HiP0 |
HiP1 |
HiP2 |
HiP3 |
HInP |
SE |
P-value |
ADG, kg |
Treatment |
||||||
Phase 2 |
0.43a |
0.51b |
0.50b |
0.54b |
0.51b |
0.01 |
<0.01 |
Phase 3 |
0.64c |
0.59ab |
0.68d |
0.62bc |
0.57a |
0.02 |
<0.01 |
Overall |
0.43a |
0.44a |
0.48b |
0.47b |
0.43a |
0.01 |
<0.01 |
ADFI, kg |
|||||||
Phase 2 |
0.56a |
0.62b |
0.62b |
0.63b |
0.62b |
0.02 |
<0.03 |
Feed Efficiency |
|||||||
Phase 2 |
0.77a |
0.82b |
0.81ab |
0.87c |
0.82b |
0.02 |
<0.01 |
Overall |
0.68a |
0.69ab |
0.72bc |
0.73c |
0.70abc |
0.01 |
<0.03 |
a.b.c. Means within row with different superscript differ (P < 0.05)
Keywords: phytase, adequate P, nursery pigs