Determination of Zn–, Cu– and Mn–glycinate complexes in feed samples and in-vitro and in-vivo assays to assess their bioaccessibility in feed samples

A method was developed for the quantification of Zn–, Cu– and Mn–glycinates in supplemented feed samples. The coupling of capillary electrophoresis (CE) with ICP MS detection after purification of the extract by ultrafiltration was shown to be efficient for the quantitative recovery of glycinates. The method developed was then applied to evaluate the bioaccessibility of glycinates using a sequential enzymolysis approach. The data obtained indicated a strong bioaccessibility of each element (79–94%). A new complex was also found to be formed during the digestion process. Bioavailability was then evaluated by analyzing plasma samples of horses supplemented with glycinates-rich feed. Intact glycinates could not be detected in plasma samples but a Cu-containing molecule was found more abundant after CuGly treatment.