Giraldo et al., 2006. Livest. Res. Rural Dev., 18 (6)

The production technique of gas in vitro has generated great interest in the last years, thanks to the potential to simulate rumen kinetics and the extension of the ruminal fermentation and to predict the degradability of the feed. This research aimed to establish the equation that correlates the pressure (P) and the volume (V) from experimental data in order to facilitate the introduction of the semi-automatic in vitro gas production technique in Colombia. Six tropical forages: Angleton (Dichantium aristatum), kikuyo (Pennisetum clandestinum), braquiaria (Brachiaria humidícola), the tree legume black acacia (Acacia decurrens), the herbaceous legume (Arachis pintoi) and the shrub legume cratylia (Cratylia argentea), 15 intervals of fermentation: 2, 4, 6, 8, 10, 12, 15, 19, 24, 30, 36, 48, 72, 96 and 120 h and three replicates of each forage, were used to generate the equation that relates (P) and (V). The equation was: V (ml) = 0.208 (± 0.092) + 5.045 P (± 0.091) + 0.015 P2 (± 0.021) [R2=0.98]. Later the equation was applied to a group of five tropical forages to verify its usefulness to predict several parameters of the ruminal fermentation in vitro.