title: Performance and phosphorus balance of pigs fed diets formulated on the basis of values for standardized total tract digestibility of phosphorus.
abstract: Three experiments were conducted to test the hypotheses that pigs fed diets that are equal in digestible P will perform equally regardless of the concentration of total P in the diets, and that the addition of microbial phytase, distillers dried grains with solubles (DDGS), or a combination of phytase and DDGS will result in a reduction in P excretion. In Exp. 1, a P-free diet and 6 diets containing corn, soybean meal (SBM), or DDGS without or with microbial phytase (500 phytase units per kg) were formulated. Diets were fed for 12 d to 42 pigs (initial BW = 13.5 +/- 3.9 kg) housed in metabolism cages that allowed for total collections of feces. Basal endogenous P losses were determined to be 199 mg/kg of DMI for pigs fed the P-free diet. Addition of phytase increased (P < 0.01) the standardized total tract digestibility (STTD) of P in corn (64.4 vs. 26.4%) and SBM (74.9 vs. 48.3%), but there was no effect (P > 0.10) of the addition of phytase on the STTD of P in DDGS (75.5 vs. 72.9%). In Exp. 2, a total of 160 pigs (initial BW = 11.25 +/- 1.95 kg; 4 pigs/pen) were allotted to 4 corn- and SBM-based diets with 2 amounts of phytase (0 or 500 phytase units per kg) and 2 amounts of DDGS (0 or 20%) in a 2 x 2 factorial arrangement of treatments. All diets were formulated to contain 0.32% STTD of P according to the STTD values determined in Exp. 1. Diets were fed for 21 d and results indicated that inclusion of phytase in the diet containing no DDGS tended (P < 0.10) to decrease G:F, but inclusion of 20% DDGS in the diets tended (P < 0.10) to increase ADG, ADFI, and final BW. In Exp. 3, the diets used in Exp. 2 were fed to 24 pigs (initial BW = 14.6 +/- 1.4 kg) that were placed in metabolism cages individually. Feces and urine were collected for 5 d. Phytase and DDGS increased (P < 0.01) the apparent total tract digestibility of P in the diets. Absorption of P was greater (P < 0.05) in pigs fed corn-SBM-DDGS diets than pigs fed corn-SBM diets, and phytase, DDGS, or the combination of phytase and DDGS reduced (P < 0.01) P excretion. In conclusion, the addition of phytase increased the STTD of P in corn and SBM, but had no effect on the STTD of P in DDGS. Diets may be formulated based on STTD values without compromising pig performance, and dietary phytase, DDGS, or the combination of phytase and DDGS will reduce P excretion by growing pigs.
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana, IL 61801, USA. hstein@uiuc.edu
authors.forename: F N
authors.initials: FN
authors.lastname: Almeida
authors.forename: H H
authors.initials: HH
authors.lastname: Stein
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002118:Calcium; D004032:Diet / Q000662:veterinary*; D004063:Digestion / Q000502:physiology; D005260:Female; D041981:Gastrointestinal Tract / Q000502:physiology*; D008297:Male; D010758:Phosphorus / Q000378:metabolism*; D013552:Swine / Q000254:growth & development*
chemical_list: D010758:Phosphorus; D002118:Calcium