The study looked at how different sizes of paddy straw in buffalo calf diets affect nutrient use and methane emissions. Calves fed with smaller or longer chopped straw ate more than those fed unchopped straw. Calves fed with longer chopped straw had better digestion of dry matter, organic matter, and acid detergent fiber. Calves fed with smaller chopped straw had better digestion of neutral detergent fiber. Methane production was lower in calves fed with chopped straw compared to unchopped straw. Including medium-sized chopped paddy straw in calf diets improved feed intake and reduced methane emissions.