Experiments and experience have shown that adding betaine to mammalian foods, such as broilers, turkeys and ducks, increases nutrient digestibility, promotes growth and improves feed conversion. Additionally, adding betaine to poultry feed may reduce carcass fat and increase breast meat. Of course, the exact effect of the above functions is highly variable. Furthermore, the relative bioavailability of betaine to methionine is 60% under real conditions. In other words, 1 kg of betaine anhydrous can replace the addition of 0.6 kg of methionine. As for choline, it is estimated that betaine can replace about 50% of choline in broiler feed and 100% of choline in laying hen feed.

In most cases, animals are able to synthesize betaine to meet their own body's needs. The way betaine is synthesized is known as the oxidation of vitamin choline. Adding pure betaine to feed has been shown to save expensive choline. As a methyl donor, betaine can also replace the expensive methionine. Therefore, adding betaine to feed can reduce the need for methionine and choline. The assumption is, of course, that the cost of using betaine under commercial conditions would yield savings that would make it practical.

Betaine can also be used as an anti-fatty liver agent. In some studies, carcass fat deposition in growing pigs was reduced by 15% by adding only 0.125% betaine to the feed. Finally, betaine has been shown to improve the digestibility of nutrients because it provides osmoprotection to gut bacteria, resulting in a more stable gastrointestinal environment. Of course, the most important role of betaine is to prevent cell dehydration, but this is often taken for granted and overlooked.