Dear Dr. Atul Deshmukh,

first of all, I apologize for the delayed feedback!

Betaine, having three methyl groups and the so-called zwitterionic structure (being positively and negatively charged), is acting as a methyl group donor and as an organic osmolyte.

As a methyl group donor, betaine can replace other potential sources of methyl groups: choline, partially methionine and folic acid. Methyl groups are not equally available for use in methylation reactions. Having betaine in the diet, the dietary methionine will be available predominantly for protein synthesis and choline, also as native choline, will be available for cell membranes and neurotransmission as acetylcholine.
Betaine is the most efficient methyl group donor for the remethylation (conversion of homocysteine into methionine) because no metabolic conversion steps are required, as in case of choline.

Therefore we can replace by betaine the added choline from cholinechloride in animal feed, partially methionine (in good conditions), but no lysine, or threonine. Indirectly, is betaine also a source of glycine, relevant when formulating diets with low crude protein levels.

In conclusion, we can not replace lysine and/ or threonine by betaine.

All best and kind regards,
Ana Gavrau