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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2008-1219v1 87/4/1518    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Hill, B. E. Articles by Richert, B. T. Search for Related Content PubMed PubMed Citation Articles by Hill, B. E. Articles by Richert, B. T.

Effects of low-phytic acid corn, low-phytic acid soybean meal, and phytase on nutrient digestibility and excretion in growing pigs¹

Department of Animal Sciences, Purdue University, West Lafayette, IN 47907

³ Corresponding author: brichert{at}purdue.edu

Forty-eight grower pigs were used to evaluate the effects of feeding low phytic acid (LPA) corn, LPA soybean meal, normal corn (NC), normal soybean meal (NSBM), and phytase on nutrient digestibility and excretion. Barrows were blocked by BW (initial BW = 45.3 ± 1.6 kg) and randomly assigned to 1 of 8 dietary treatments in a 2 x 2 x 2 factorial arrangement (6 pigs/treatment). Pigs were fed twice daily (0700 and 1700 h) at 3 times the ME requirement for maintenance. Phytase was added to the diet at 510 phytase units/kg of feed (where 1 phytase unit is the quantity of enzyme that liberates 1 µmol of inorganic P/min from 0.005 mol/L of sodium phytate at pH 5.5 and 37°C), at the expense of corn starch, and all diets were formulated to provide 0.39% total P, 0.50% Ca, and 1.0% lysine with no supplemental inorganic P. Pigs were adapted to metabolism crates and dietary treatments for 7 d, followed by a 3-d total collection of urine and feces. Total fecal DM excreted, percentage of DM of feces, and percentage of DM digested were not different (P > 0.53) among treatments. Fecal P excretion was reduced for pigs fed LPA corn vs. NC (2.85 vs. 3.24 ± 0.119 g/d; P = 0.024), for pigs fed LPA soybean meal vs. NSBM (2.79 vs. 3.30 ± 0.119 g/d; P = 0.007), for pigs fed phytase vs. nonphytase diets (2.80 vs. 3.29 ± 0.119 g/d; P = 0.009), and for pigs fed LPA corn, LPA soybean meal, and phytase vs. NC and NSBM without phytase (2.16 vs. 3.70 ± 0.237 g/d; P < 0.001). Phosphorus digestibility was increased for pigs fed diets containing LPA corn vs. NC (48.4 vs. 39.9 ± 2.27%; P = 0.012), for pigs fed phytase vs. nonphytase diets (48.4 vs. 39.9 ± 2.27%; P = 0.019), and for pigs fed the LPA corn, LPA soybean meal, and phytase diet vs. the NC and soybean meal diet (60.1 vs. 34.1 ± 4.5%; P < 0.001) and tended to be increased for pigs fed LPA soybean meal vs. NSBM (47.2 vs. 41.1 ± 2.27%; P = 0.075). Corn type and soybean meal type had no effect (P > 0.11) on water-soluble P excretion. However, pigs fed diets containing phytase tended to excrete less total water-soluble P than those without phytase inclusion (1.99 vs. 2.27 ± 0.099 g/d; P < 0.066). This study demonstrates that feeding any combination of LPA corn, LPA soybean meal, and phytase was additive, significantly improving P digestibility and dramatically decreasing P excretion to reduce the potential impacts of P from pig manure on the environment.

Key Words: nutrient balance • phosphorus • phytase • phytic acid • pig manure