Betaine (trimethyglycine) is typically used as an alternative methyl group donor to replace choline chloride. The possibility to reduce methionine is additionally discussed and betaine acts as a strong osmolyte to support intestinal osmoregulation. To understand the full potential of betaine, a closer look into the different levels of digestion and metabolism might help:

• On intestinal level, betaine supports enterocytes in their osmoregulation to save energy and ensure nutrient absorption as well as water and mineral balance in stress situations

• On metabolic level, betaine improves the availability of methyl groups to eliminate limitations in the transmethylation process and maximize the responsiveness of animals to any kind of stress

• On nutritional level, betaine increases the glycine supply to safeguard carcass quality and avoid growth restrictions caused by low protein diets limiting the glycine availability

Different sources and forms of betaine available on the market.

Betaine was first obtained in sugar beets and this source still plays an important role in the market. It is the only source of betaine allowed in organic feed production. Natural betaine opens a great opportunity to improve the nutritional value of organic feed, as many synthetic feed additives cannot be used. It is available as a liquid and as a crystalline product. Betaine, derived from sugar beets, has a lower risk of contamination compared to synthetic products. This makes its use interesting for all feed producers, especially considering its positive image as a natural product.

In all organisms, where betaine can be found, it is present as a bipolar molecule. In feedstuff, this form is labeled as betaine anhydrous. Besides the natural betaine, synthetic products are also available as betaine anhydrous. Synthetic production starts with a reaction of trimethylamine and chloroacetic acid. Therefore, synthetic betaine is additionally available as betaine hydrochloride (betaine-HCl). Betaine-HCl is often used in premixes as it is less hygroscopic and easier to handle than anhydrous powder products. The strong water attraction is a good indicator of the strong osmotic power of betaine anhydrous.

Betaine’s effects as an osmolyte on intestinal level.

After intestinal absorption, enterocytes can accumulate betaine and use its osmotic power to maintain their osmoregulation. This reduces the demand for energy-consuming ion pump activity and supports the cells to maintain their function during stress periods.

Stressors can be climate conditions (high temperature-humidity-index), where betaine anhydrous has a supportive effect on water and electrolyte balance. Consuming less energy for osmoregulation means avoiding additional metabolic heat production and the associated involuntary reduction of feed intake in that particular situation.

Betaine supports the cells to maintain their normal function during other challenges for the intestinal enterocytes, such as coccidiosis infections or diarrhea situations. This improves intestinal integrity and reduces the negative impact of these diseases on animal performance and well-being. All this support of intestinal osmoregulation is based on the presence and accumulation of betaine. Therefore, it is also available for metabolism with a slight delay.

Betaine’s effects as a methyl group donor on metabolic level.

Methyl groups are non-independent molecules. As a one-carbon group (CH3), they are always part of larger compounds. Transmethylation is a core process in the endogenous synthesis of vital substances. In the methylation pathway, methionine plays a central role as S-adenosyl methionine (SAM) donates the methyl groups and converts to homocysteine. It can be irreversibly transformed to cysteine or remethylated to methionine if a methyl group donor is available to avoid an accumulation of the cytotoxic homocysteine. Betaine delivers this methyl group via the enzyme BHMT (betaine-homocysteine-methyltransferase). A high level of betaine can directly increase transmethylation since this is the betaine's primary pathway in the metabolism. In contrast, choline has other basic functions and before acting as a methyl group donor, it has to undergo a two-step oxidation. For this reason, choline has a lower efficiency in increasing the availability of methyl groups.

Following processes require methyl groups:

• DNA/RNA synthesis and regulation of the gene activation by methylation

• Protein synthesis and tissue repair

• Detoxification- and immune functions

• Adrenaline, carnitine and creatine synthesis

• Phosphatidylcholine (lecithin) synthesis from phosphatidylethanolamine

The demand for transmethylation is variable and often underestimated. Poultry diets typically have a significant safety margin of methionine to avoid performance depression in case of an increased need for methyl groups. Betaine can take over this role and be a kind of buffer stock.

Betaine’s effects as a glycine precursor on nutritional level.

After delivering the first methyl group, dimethylglycine and monomethylglycine will transfer the other methyl groups into THF (tetrahydrofolate) cycle. Finally, betaine ends up as glycine and increases the glycine + serine availability. These amino acids are interchangeable and non-essential, but there is much evidence that they become limiting in high productive animals fed with low crude protein diets. Glycine is needed for the synthesis of bile acid, keratin, and uric acid. It is also part of the endogenous antioxidant glutathione. One of the serine functions is the involvement in transforming homocysteine to cysteine—a direct link to the methylation cycle.

Animals’ response to betaine supplementation.

The use of a high dosage of betaine, preferably in anhydrous form, can support animal productivity in different ways. Many satisfied customers and several farm trials give us confidence that betaine improves intestinal integrity and optimizes nutrient availability. Animals respond with higher performance, improved carcass quality and lower mortality. Positive effects are often also observed where it was not expected. This is an indicator that betaine compensates for imbalances and helps to maintain performance during stressful situations.