There are many studies on adding betaine to broiler diet at high temperature, mainly focusing on feed intake, feed conversion rate, meat quality and other production indicators.There are few researches for betaine effect on immune levels of broilers .The betaine contains three methyl groups and can provide methyl instead of methionine,it also can promote protein synthesis, reduce fat deposition, effectively prevent fatty liver, maintain osmotic pressure balance, improve intestinal environment, good palatability, promote broiler feeding.  

Betaine tastes good as an additives,it can increase the palatability of feed, improve the appetite of animals and promote the feeding of poultry.The Vogt study found that adding 200mg/kg betaine to chicken could make increase the weight of broiler and feed conversion rate by 4% and 2%. If adding 1000mg/kg betaine in the feed can significantly improve feed intake and digestion and absorption efficiency of broilers under high temperature environment.The effect of high concentration betaine on feed intake was better than low concentration betaine, and 2000 mg/kg betaine had the most obvious effect. 

Just as importantly, betaine acts as an osmolyte,helping maintain the bird’s cellular water balance to protect cells and tissues from dehydration and osmotic inactivation.Water cannot be directly bound or held by the cell.It will move according to the prevailing concentration gradient of salts and solutes between the inside and outside of the cell.Therefore,when the concentration is greater outside the cell,water will be pulled out of the cell in an effort to balance the concentration gradient.The cell shrinks in volume,and the concentration of ions and solutes increases inside the cell.If left uncorrected the cell will eventually die.