The researchers studied how different types of roughage, protein levels, and energy levels affect methane production and fermentation in the rumen. They found that high-energy diets with paddy straw as roughage produced more gas and methane. Low-energy diets with wheat straw reduced methane production. Enzyme activities were lower with sugarcane bagasse. High-energy diets increased certain types of protozoa. Overall, energy levels had a bigger impact on methane production and protozoa populations than protein levels in the diet. Manipulating diet could potentially reduce methane production in the rumen.