Effects of microbial phytase on the standardized total tract digestibility of phosphorus in soybean meal, corn, and corn co-products

digestibility;endogenous losses;phosphorus;phytase;pig

Almeida, Ferdinando ; Stein ; Hans H.

关键词: digestibility;    endogenous losses;    phosphorus;    phytase;    pig;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/16136/1_Almeida_Ferdinando.pdf?sequence=2&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Six experiments were conducted to investigate the effects of microbial phytase on the standardized total tract digestibility (STTD) of P in soybean meal (SBM), corn, and corn co-products. The objective of Exp. 1 was to measure the STTD of P in SBM, corn, and distillers dried grains with solubles (DDGS) without and with the addition of microbial phytase (Optiphos 2000, Enzyvia, Sheridan, IN). Two SBM based diets, 2 corn based diets, and 2 DDGS based diets were formulated to contain microbial phytase at a level of 0 or 500 phytase units (FTU) per kg. Soybean meal, corn, and DDGS were the only sources of P in the diets. A P-free diet was also formulated to measure the basal endogenous P losses (EPL) from pigs. Addition of phytase improved (P < 0.01) the STTD of P in SBM and corn, but did not improve the STTD of P in DDGS. Values measured for the STTD of P in Exp. 1 were used to formulate diets that were used in Exp. 2 and 3. The objectives of Exp. 2 and 3 were to test the hypothesis that pigs fed diets that are equal in STTD of P will perform equally well regardless of the concentration of total P in the diets, and that the addition of microbial phytase, DDGS, or a combination of phytase and DDGS will result in a reduction in P excretion. Four corn-SBM based diets were formulated and used in a 2 × 2 factorial design with 2 levels of phytase (0 or 500 FTU/kg) and 2 levels of DDGS (0 or 20%). All diets contained 0.32% STTD P according to the STTD values that were measured in Exp. 1. Experiment 2 was a growth performance study. Results showed that inclusion of phytase to the diet containing no DDGS tended (P < 0.10) to decrease G:F, but inclusion of 20% DDGS to the diets tended (P < 0.10) to increase ADG, ADFI, and final BW. Experiment 3 was a P balance study in which the 4 diets from Exp. 2 were used. Phytase and DDGS increased (P < 0.01) the apparent total tract digestibility (ATTD) of P in the diets. Absorption of P was greater (P < 0.05) for pigs fed corn-SBM-DDGS diets than for pigs fed corn-SBM diets, and phytase, DDGS, or the combination of phytase and DDGS, reduced (P < 0.01) P excretion. In Exp. 4 and 5, the objectives were to test the effect of a novel bacterial 6-phytase expressed in a strain of Aspergillus oryzae (Ronozyme HiPhos, DSM Nutritional Products, Parsippany, NJ) on the ATTD of P in corn-SBM diets fed to weanling and growing pigs, and to estimate the minimum level of phytase needed to maximize the ATTD of P. For both experiments, 6 diets were formulated (positive control, negative control, and negative control + 4 levels of microbial phytase). Addition of phytase to the diets increased (linear and quadratic, P < 0.01) the ATTD of P in corn-SBM diets fed to both weanling and growing pigs. For weanling pigs the breakpoint for ATTD of P (68.4%) was reached at a phytase inclusion level of 1,016 FTU/kg, whereas for growing pigs the breakpoint for the ATTD of P (69.1%) was reached at a phytase inclusion level of 801 FTU/kg. In Exp. 6, the objectives were to measure the effects of graded levels of microbial phytase on the STTD of P in corn, DDGS, high protein distillers dried grains (HP-DDG), and corn germ, and to develop regression equations to predict the response of adding phytase to each of these ingredients. Four corn based diets, 4 DDGS based diets, 4 HP-DDG based diets, and 4 corn germ based diets were formulated to contain 0, 500, 1,000, or 1,500 FTU/kg (Optiphos 2000, Enzyvia, Sheridan, IN) within each ingredient. A P-free diet was also formulated to measure the basal endogenous P losses. Addition of phytase increased (linear, P < 0.01; quadratic, P < 0.05) the STTD of P in corn and HP-DDG, increased (linear and quadratic, P < 0.01) the STTD of P in corn germ, and tended to increase (linear, P =0.07) the STTD of P in DDGS. Regression equations for the effect of added microbial phytase on the STTD of P in corn, HP-DDG, and corn germ were developed, and these equations may be used to predict the STTD of P in each ingredient when phytase is supplemented to diets that contain these ingredients.