In situ ruminal phosphorus degradation of selected three classes of feedstuffs in goats

Three 4-month-old growing wether goats were used to determine the ruminal P degradability of three classes of feedstuffs with in situ nylon bag technique. Three classes of feedstuffs were cereal (maize, wheat, barley, buckwheat, rice, millet, and sorghum), legume (horsebean, soybean, pea, mungbean, and jequirity) and tuber (potato, sweat potato, and cassava). The experiment consisted of 15 periods. During each period, the ruminal P disappearance of each one of these feedstuffs was measured at 0, 2, 4, 8, 12, 24 and 36 h, respectively. The exponential model of Ørskov and McDonald was employed to estimate degradation kinetics. Results showed that the degradability of feed P ranged from 805 to 986 g/kg P. Effective degradability of P generally exceeded 830 g/kg P, except for rice and millet. This updates the feed database of in situ P degradability in China, which would play an important role in improving biological P efficiency for modern ruminant production system.