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Effect of microbial phytase on the standardized total tract digestibility and in vitro release of phosphorus in corn, soybean meal, and rice bran fed to growing pigs
Two experiments were conducted to determine the effect of microbial phytase on the standardized total tract digestibility (% STTD) of P in corn, soybean meal, and full fat rice bran when fed to growing pigs, and to determine if in vitro P release measured using procedures adapted from Liu et al. (1997) may be used to predict STTD of P. Each raw material was used as the sole source of P in semi-purified diets (without or with microbial phytase, 500 units/kg of Optiphos 2000, Enzyvia, Sheridan, IN) that also contained sucrose, vitamins and minerals except P. In experiment 1, 36 barrows (PIC L337 × C24, initial BW = 22.3 ± 1.4 kg) were fed semi-purified diets for 10 d, with a 5 d adaptation period and 5 d for collection of feces. Each pig was housed in metabolism cages that allowed for total collection of feces. Basal endogenous P loss (EPL) was assumed to be 200mg/kg DMI. Addition of phytase increased (P < 0.05) the STTD of P in corn from 53.38 to 73.35%, in SBM from 46.12 to 73.05%, and in rice bran from 49.76 to 64.43%. In experiment 2, 1.0 g of each diet was incubated with 3000 units of pepsin at pH 2.5 for 75 min. The pepsin digesta was then mixed with 2.4 mg of pancreatin and then incubated at pH 6.0 for 240 minutes. The in vitro release of P was highly correlated (r = 0.94) with the in vivo P digestibility. In conclusion, microbial phytase improved the STTD of P in corn, SBM, and full fat rice bran, and the in vitro procedure may be used to predict the STTD of P in corn, SBM, and full fat rice bran fed to growing pigs.
Table 1. Effect of phytase on apparent total tract digestibility (ATTD), and standardized total tract digestibility (STTD) of P in corn, soybean meal (SBM), and full fat rice bran. |
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Ingredient: |
Corn |
SBM |
Full fat rice bran |
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Phytase, FTU/kg |
Phytase, FTU/kg |
Phytase, FTU/kg |
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Item |
0 |
500 |
SEM |
P-value |
0 |
500 |
SEM |
P-value |
0 |
500 |
SEM |
P-value |
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ATTD of P, % |
47 |
66 |
4 |
0.005 |
38 |
68 |
8 |
0.018 |
47 |
62 |
4 |
0.012 |
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Basal EPL, mg/d |
136 |
147 |
10 |
0.478 |
149 |
134 |
4 |
0.030 |
159 |
159 |
9 |
0.994 |
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STTD of P, % |
53 |
73 |
4 |
0.004 |
46 |
73 |
8 |
0.035 |
50 |
64 |
4 |
0.015 |
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Keywords: Phosphorus digestibility, Rice bran, Pigs