Absorption and bioavailability of DL-methionine hydroxy analog compared to DL-methionine

Intestinal absorption of crystalline DL-methionine (DL-MET) and DL-methionine hydroxy analog calcium (DL-HMA) were determined in a true-digestibility-balance assay using cecectomized (CEC) and sham-operated conventional (CONV) cockerels. The treatments consisted of fasted birds and birds crop-intubated (CI) with 30 g of a corn-soybean meal basal diet (16% CP) supplemented with 0, .2, or .4% of DL-MET or equimolar levels of DL-HMA. There was no detectable free D-MET or L-MET or HMA in the excreta of fasted birds or of those fed the unsupplemented basal diet. The intestinal absorption of DL-HMA was 95.9 +/- .8% (means +/- SE) for CEC and 98.8 +/- .8% for the CONV cockerels. The absorption of DL-MET was approximately 99.7 +/- .2% for the CEC and the CONV cockerels. In a second experiment procedures were developed for a bioavailability assessment by comparing the growth responses to CI and intraperitoneal-injected (IP) DL-MET or DL-HMA in chicks fed a crystalline-amino-acid diet deficient in methionine. Graded increments of pH-adjusted DL-MET or DL-HMA (in water solutions) were administered twice daily in a 7-day growth assay. Slope-ratio analysis indicated that bioavailability (+/- SE) of CI DL-HMA was 91.3 +/- 11.8% relative to the CI DL-MET on an equimolar basis. The bioavailability of CI DL-HMA was similar to that of IP DL-HMA, indicating that the intestinal absorption of DL-HMA was highly efficient.(ABSTRACT TRUNCATED AT 250 WORDS)