A simplified in vitro test tube (TT) method was developed to estimate the percentage of available P in feed ingredients for swine. The entire digestion procedure with the TT method consists of three consecutive enzymatic digestions carried out in a 50-mL conical test tube: (1) Pre-digestion with endo-xylanase and beta-glucanase for 1 h, (2) peptic digestion for 2 h, and (3) pancreatic digestion for 2 or 4 h. The TT method is simpler and much easier to perform compared to the dialysis tubing (DT) method, because dialysis tubing is not used. Reducing sample size from 1.0 to 0.25 g for the TT method improved results. In conclusion, the accuracy and validity of the TT method is equal to that of our more complicated DT method (r = 0.97, P < 0.001), designed to mimic the digestive system of swine, for estimating the availability of P in plant-origin feed ingredients.

This study summarizes the levels of the mycotoxins aflatoxin B 1 , deoxynivalenol, zearalenone, ochratoxin A, and fumonisin B 1 in domestic feed produced in Japan. We collected samples of Japanese domestic feed used in livestock farming establishments or by small farmers from April 2012 to March 2014, and measured mycotoxin concentrations in each sample. Regarding corn, deoxynivalenol had the highest detection rate (84%), maximum value (2370 µg/kg), and mean value (400 µg/kg). These results suggest that deoxynivalenol is a major mycotoxin contaminant in Japanese-produced domestic feed. Zearalenone and fumonisin B 1 presented the second highest detection rates. The maximum concentration of zearalenone was 1200 µg/kg in grass samples, but its median was under 25 µg/kg, and, overall, it occurred at low concentrations. The detection rate of fumonisin B 1 was about 30%, but its maximum concentration in corn was 2400 μg/kg, slightly higher than deoxynivalenol. Overall, mycotoxin concentrations were lower in grass than in corn. Although deoxynivalenol was detected in samples collected from all regions, concentrations in samples from Hokkaido were particularly high. Fumonisin B 1 was mainly distributed in Kanto and the southern regions. Concentrations of ochratoxin A and aflatoxin B 1 were low; however, the maximum concentration of aflatoxin B 1 was 22 μg/kg in corn. Although aflatoxin B 1 and ochratoxin A were rarely detected, they occasionally presented high levels, therefore requiring attention. Overall, mycotoxins produced by Fusarium sp. fungi require attention in Japanese-produced domestic feed.

The validity of a simplified in vitro test tube (TT) method was compared with a more complicated dialysis tubing (DT) method to estimate the percentage of available phosphorus (P) in 41 plant origin and five animal origin feed ingredients for swine. The TT method using 1.0 or 0.25 g samples was compared with the DT method using 1.0 g samples at two pancreatic incubation times (2 vs 4 h) in a 3 x 2 factorial arrangement of treatments. Each DT and TT method treatment was replicated three and six times, respectively. Both methods utilize three enzymatic digestions: (i) predigestion with endoxylanase and beta-glucanase for 1 h, (ii) pepsin digestion for 2 h, and (iii) pancreatin digestion for 2 or 4 h. For the TT method, the entire procedure was conducted in a 50 mL conical centrifuge tube and replicated six times. For the DT method, the first two digestions were conducted in a 10 mL plastic syringe before the contents were quantitatively transferred into a segment of DT for the pancreatic digestion. The percentages of hydrolyzed P for plant origin ingredients measured by the DT method using 1.0 g samples and the TT method using 0.25 g samples were highly correlated (r = 0.94-0.97, P < 0.001) with each other and with published in vivo available P values for swine. Repeatabilities for these two methods ranged from 99.64 to 99.86%. The TT method using 1.0 g samples, however, did not provide valid estimates of P availability for all ingredients. For animal origin ingredients, neither method was significantly correlated (r = 0.1-0.6, P >or = 0.4) with published in vivo available P values. In conclusion, the accuracy and validity of the TT method using 0.25 g samples with a 2 h pancreatic digestion time was equal to or superior to the DT method using 1.0 g samples with a 4 h pancreatic digestion time for estimating P availability in plant origin feed ingredients.

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