A comparison of organic matter digestibility (OMd) determined in vivo and in vitro was conducted with samples of grass, grass silage, hay, and maize silage (n = 20 per feed) from the Agroscope Posieux collection. The in vitro method was carried out with the Ankom «DaisyII» Incubator (Ankom Technology Corp., Fairport, NY, USA). The coefficients of determination (R2) were 0.660, 0.929 and 0.863 for grass, grass silage and hay, respectively. For maize silage a R2 of OMd of 0.413 was obtained. The overall R2, exclusing the samples before 1990, went from 0.723 to 0.730. Differences between the in vitro and in vivo OMd ranged from –2.5 to –3.0 %-points for hay, grass and maize silage, and stood at +4.0 %-points for grass silage. The tested in vitro method offers good prospects for predicting the organic matter digestibility of fresh and conserved herbage, especiallly for setting up a database for OMd prediction models by near-infrared spectroscopy.
In vivo and in vitro organic matter digestibility determined with the Ankom DaisyII Incubator