Present study was conducted to see the effect of different levels (0, 50, 75 and 100 ppm of concentrate) of choline chloride on in vitro fermentation process with rations of different energy content. Two rations were prepared having different energy levels ( Mcal/kg NEL and Mcal/kg NEL) and both these rations were supplemented with different levels (0, 50, 75 and 100 ppm of concentrate) of choline chloride to see the effect of choline No significant effect of either choline supplementation at different levels was found on any in vitro parameter as compared to control diets with either low or high energy content of ration. On comparison of in vitro results obtained by supplementation of choline chloride irrespective of the level of supplemented choline chloride with low and high energy diets, significant differences in various parameters were obtained at 5% level of significance. | Effect of Choline chloride on in vitro rumen fermentation of oat hay based TMR’s varying in energy levels