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Animal Science

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Translational Animal Science





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Previous research indicates that “super-dosing” phytase may improve pig growth performance by improved nutrient use, although the benefits appear to be more consistent in nursery than in grow-out pigs. Therefore, two experiments were conducted to determine if performance could be improved by feeding phytase at super-dosed levels, and whether this response would be different if energy and amino acid (AA) were limiting. Experiment 1 involved 440 weaned pigs (6.27 ± 0.01 kg) in a factorial arrangement of treatments comparing the main effects of diet (positive control [PC] balanced for all nutrients vs. a negative control [NC]: 10% lower standardized ileal digestible (SID) lysine with relative reduction of all other essential AA and 1% reduced fat) and phytase levels (0 vs. 2,500 FTU Quantum Blue 5G phytase/kg). Pigs were assigned to pen according to a randomized complete block design based on body weight (BW). Feed and water were provided ad libitum across four dietary phases: 3 × 1 wk plus 1 × 2 wk. The average daily gain (ADG) and gain to feed ratio (G:F) were improved in the PC relative to the NC (P < 0.05) indicating success in formulating a diet limiting in energy and/or AA. Phytase improved ADG and G:F, regardless of diet composition (P < 0.05). Thus, super-dosing phytase improved nursery pig growth performance, irrespective of diet nutrient adequacy or deficit. Experiment 2 involved 2,200 growing pigs (36.6 ± 0.30 kg) allotted to five treatments: a balanced PC (250 FTU Quantum Blue 5G phytase/kg), an NC (PC with 15% less SID lysine and 1.5% lower net energy [NE]), and three super-dosing phytase treatments applied to the NC totaling 1,000, 1,750, and 2,500 FTU phytase/kg. Feed and water were available ad libitum. At trial completion (approximately 122 kg), the PC pigs were heavier and more efficient than the NC pigs (P < 0.05) indicating success in formulating an NC treatment. Super-dosing phytase had no effect on whole body ADG or average daily feed intake (P > 0.10) but tended to improve G:F and feed energy efficiency (P < 0.10). Super-dosing phytase improved carcass-based feed and feed energy efficiency (P < 0.05) and tended to improve ADG (P < 0.10). Supplying phytase at “super-dosed” levels—above that required to meet the phosphorus requirement—improved growth performance in nursery pigs (6 to 22 kg BW) and provided smaller benefits in grow-finish pigs (37 to 122 kg BW). The improvement during the nursery period was independent of energy and AA levels in the diet.


This article is published as Holloway, Cassie L., R. Dean Boyd, Dean Koehler, Stacie A. Gould, Qingyun Li, and John F. Patience. "The impact of “super-dosing” phytase in pig diets on growth performance during the nursery and grow-out periods." Translational Animal Science 3, no. 1 (2019): 419-428. doi:10.1093/tas/txy148.

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Creative Commons Attribution-NonCommercial 4.0 International License
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