Effect of Increased Heat Processing and Particle Size on Phosphorus Bioavailability in Corn Distillers Dried Grains with Solubles
2007
Martinez Amezcua, C. | Parsons, C.M.
Previous studies have reported that increased heat processing and feeding larger particle size ingredients may increase the bioavailability of phytate P in some feedstuffs. Therefore, one chick experiment was conducted to determine the effect of various increased heat processing treatments on bioavailability of P in corn distillers dried grains with solubles (DDGS), and 2 chick experiments were conducted to determine the effect of particle size on bioavailability of P in DDGS. In addition, one precision-fed cecectomized rooster assay was conducted to evaluate the effects of increased heating on amino acid digestibility. For the chick experiments, a P-deficient cornstarch-dextrose-soybean meal basal diet containing 0.10% nonphytate P was supplemented with 0.0, 0.05, or 0.10% P from KH2PO4 or 1 of 2 levels of DDGS. Diets were fed from 8 to 22 d of age, and P bioavailability relative to the P in KH2PO4 was estimated using the standard curve or slope-ratio methods with tibia ash as the response variable. Increased heating of DDGS by autoclaving at 124 kPa and 121 degrees C for 60 to 80 min or by heating in a drying oven at 121 degrees C for 60 min significantly increased relative P bioavailability in DDGS (from 70 to as high as 91%) in several treatments. Amino acid digestibility, however, was greatly reduced by increased heating in most cases, particularly for Lys. Relative bioavailability of P was not significantly affected by DDGS particle sizes ranging from 542 to 837 micrometer. Our results indicated that increased heating of DDGS increased bioavailability of P but decreased digestibility of amino acids, particularly Lys, and that bioavailability of P was not affected by particle size.
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