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.

This research article explores a method to measure the quantity of Zn-, Cu-, and Mn-glycinates in animal feed samples and tests their level of accessibility in the body through a series of in-vitro and in-vivo tests. The method created tests the effectiveness of coupling capillary electrophoresis—an analytical technique used to separate ions based on their size and charge—with inductively coupled plasma mass spectrometry (ICP MS) for glycinate recovery. The results showed a high level of glycinate absorption in the body, and also discovered a new complex that forms during digestion.

Method Development

• The research focused on developing a novel technique to analyze and quantify the amounts of zinc (Zn), copper (Cu,) and manganese (Mn) glycinates in supplemented animal feed. Glycinates are used in the feed supplements for their high level of bioavailability which contributes to the animal health.
• The technique combined capillary electrophoresis (CE), a method used to separate ions based on their size and charge, and inductively coupled plasma mass spectrometry (ICP MS), a type of mass spectrometry that is highly sensitive and capable of detecting metals and several non-metals at concentrations as low as one part in 1015.
• To ensure the method was effective, the extract was purified by ultrafiltration, a process in which fluids are forced through a semipermeable membrane to separate the small and large molecules.

Bioaccessibility of Glycinates

• The developed method was used to evaluate the bioaccessibility of glycinates in the body, using a sequential enzymolysis approach. This approach uses enzymes to break down substances in order to analyze their basic components.
• The research found that these elements were highly bioaccessible, with each element showing between 79% to 94% accessibility. This means a large majority of these elements could potentially be absorbed by the body after digestion.
• Interestingly, the research also found that a new complex is formed during the digestion process. However, the article does not elaborate further on the nature or potential impacts of this newly discovered complex.

Bioavailability Evaluation

• The bioavailability of these elements was further evaluated by analyzing plasma samples of horses that had been fed glycinates-rich feed.
• Although intact glycinates were not found in the plasma samples, indicating they likely break down during digestion, a Cu-containing molecule was found in greater abundance after the horses had consumed CuGly— a chelated form of copper often used in animal feed supplements.