Phosphorus Fractions in Manure from Growing Pigs Receiving Diets Containing Micronized Peas and Supplemental Enzymes

Abstract

Different livestock feeds manipulations have been reported to reduce the total P concentration in manure. Information on the influence of these dietary manipulation strategies on the forms of P in manure is, however, limited. This study was, therefore, conducted to investigate the effect of diet manipulation through feed micronization and enzyme supplementation on the forms of P in swine manure. Eight growing pigs were fed four diets: barley–raw pea (BRP), barley–micronized pea (BMP), barley–raw pea with enzyme (BRPE), and barley–micronized pea with enzyme (BMPE) in a 4 × 4 Latin square design. Because we are interested in the effect of enzyme cocktail and pea micronization on manure P, we did not reduce the non‐phytate P with enzyme addition in this study. The fecal material and urine were collected and analyzed for total P. Fecal material was fractionated to determine the total P in H 2 O‐, NaHCO 3 –, NaOH‐, and HCl‐extractable fractions. The total P in the residual fractions was also determined. About 98% of the total P excreted by the pigs was found in the fecal material. Inclusion of micronized pea in pig diet did not have any significant effect ( p > 0.1) on either the total P or the different P fractions in the manure. The labile P (the sum of H 2 O‐P and NaHCO 3 –P) was significantly reduced ( p < 0.05) by the addition of enzyme to swine diets. Pigs fed the BRPE and BMPE had 14 and 18% lower labile P, respectively, compared with pigs fed the BRP. Enzyme addition to pig diets reduced not only the total P in manure, but also the labile P fraction, which is of great environmental concern. Thus, the potential of P loss to runoff and the subsequent eutrophication can be reduced by enzyme addition to pig diets.