Effects of chop lengths of ramie silage on ruminal fermentation, free amino acid content, and cellulase activity in goats

Twelve Liuyang black goats were selected and divided into three groups in a randomized design and they were provided one of the three treatment diets with different chop lengths of ramie silage [1 cm (RS1), 2 cm (RS2), and 3 cm (RS3)]. The length had no effect on pH or the content of acetic acid, butyric acid, and valeric acid. In contrast, NH3–N decreased (P = 0.024) and the ratio of acetate to propionate (P = 0.083) and total volatile fatty acid (TVFA) content (P = 0.087) tended to decrease, and the proportion of propionic acid tended to increase (P = 0.096) with an increase in the chop length of ramie. The increasing lengths of ramie silage decreased the content of total essential amino acids (AA) (P = 0.001), total non-essential AA (P = 0.003), and total AA (P = 0.001), and decreased the concentration of aspartic acid (P = 0.076) in the ruminal fluid. Ramie silage affected xylanase activity (P = 0.043), with greater activity in RS1 than in RS2 and RS3. The recommended chop length of ramie silage is 1 cm because of increasing TVFA, amino acid concentration, and xylanase activity in the ruminal fluid of goats.