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Title:Composition and digestibility of different sources of feed phosphates by growing pigs
Author(s):Lopez Diaz, Diego Andres
Advisor(s):Stein, Hans H.
Contributor(s):Murphy, Michael R.; Parsons, Carl M.
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
feed phosphates, impurities, phytase, pigs, volcanic
Abstract:Three experiments were conducted to determine the composition and digestibility of different sources of feed phosphates. In Exp 1, the hypothesis was that the process of production of feed phosphates removes most impurities including those potentially harmful for growing pigs. Seven sources of monocalcium phosphate (MCP), 4 of dicalcium phosphate (DCP), 2 of monosodium phosphate (MSP), and 1 magnesium phosphate (MgP) were used. Each feed phosphate was analyzed for minerals and then the P and Ca bound to impurities was calculated. Results indicated that the concentration of macro minerals were not different within each source of feed phosphate; whereas, micro minerals were more variable. For the potentially harmful minerals, the feed phosphates had variable concentrations but lower than the level of tolerance of the animal for all feed phosphates. In conclusion, the process to produce feed phosphates appears to be effective in generating a product with a specified concentration of P and low concentrations of potentially harmful minerals. In Exp. 2, the hypothesis was that P in feed phosphates from volcanic (igneous) sources have a greater digestibility than feed phosphates from sedimentary deposits when fed to growing pigs. A source of MCP and MSP from volcanic deposits and from non-volcanic (sedimentary) deposits were procured. Four diets were formulated to contain each source of phosphate as the sole source of P. A P-free diet was also formulated to estimate the endogenous P loss from pigs. Forty pigs were allotted to the 5 diets and housed individually in metabolism crates. Collection of feces took place 4 d after a period of adaptation of 5 d. Results indicate that the apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of P were not different between MCP and MSP from volcanic deposits and MCP and MSP from non-volcanic deposits. Values of digestibility were in agreement with previous data for STTD of P in MCP and MSP. In conclusion, the hypothesis was rejected because no differences were found between the volcanic and non-volcanic feed phosphates. In Exp. 3, the hypothesis was that the ATTD and STTD of P in feed phosphates was increased by the use of microbial phytase when fed to growing pigs. A source of MCP, one source of MSP, and one source of MgP were procured. Three corn-soybean based diets were formulated to included 0, 500, or 4,000 units of microbial phytase (FTU) per kg but with no inclusion of feed phosphates. Nine additional diets were formulated by adding each of the 3 feed phosphates to the 3 basal diets. A P-free diet was formulated to estimate basal endogenous loss of P. A total of 13 diets were used in the experiment. One-hundred and seventeen pigs were allotted to the 13 diets for a total of 9 replicate pigs per diet. Each pig was housed individually in metabolism crates that allow the total collection of feces. A period of 5 d was given to the pigs for adaptation to the diet, prior to a 4 d collection period. Results indicated that the ATTD and STTD of P increased in all diets with the inclusion of phytase. However, the ATTD and STTD of P in the feed phosphates were not affected by the inclusion of phytase. This implies that the increase in the ATTD and STTD of P observed in the mixed diets was due to the release of P from phytate in corn and soybean meal but not from an increase in digestibility of P in feed phosphates. Results also indicated that MgP had a lower (P < 0.05) ATTD and STTD of P than MCP and MSP. In conclusion, the inclusion of microbial phytase did not increase the digestibility of P in feed phosphates.
Issue Date:2020-06-18
Rights Information:Copyright 2020 Diego A. Lopez
Date Available in IDEALS:2020-10-07
Date Deposited:2020-08

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