Differences in chemical composition and fibre digestion of rice straw with, and without, anhydrous ammonia from 53 rice varieties

The chemical composition and fibre digestion of straw from 53 rice varieties with, and without, ammonia treatment were determined. Four varieties were classified as tropical japonica, 41 as temperate japonica, six as indica, and two as intermediate. The results show a wide range of chemical composition among straws. Neutral-detergent fibre (NDF) ranged from 56.6% for Basmati-370 to 68.6% for M-204 with a mean value of 62.7%. Acid-detergent fibre ranged from 33.6% for Basmati-370 to 43.2% for Italica Livorno with an average of 37.7%. Lignin averaged about 4% and nitrogen ranged from 0.44% for M-201 to 0.86% for Basmati-370. The mean ash content was 18.6% with a fairly constant contribution of 72% silica. Treating the rice straw with anhydrous ammonia increased the nitrogen content (p < 0.0001) on the average by 0.53% and increased the NDF digestion on an average by 24% (p < 0.0001). Composition differences did not reflect the parentage of the varieties and cannot be used directly in breeding programs.