Relationship between in vivo digestibility and in situ degradability of grass silage

In 1997 and 1998 silage from a pasture composed by Lolium. perenne and Trifolium pratense was harvested at different maturity stages[jointing (26th March), stark of spiking (10 April and spiking 2 April] preserved with 3.5 l of formic acid/tonne of fresh pasture and ensiled in clamp silos. Silages were offered to three non lactating cows placed in a metabolic chamber for in vivo apparent digestibility of dry matter (DMD), organic matter (OMD), neutral detergent fiber (DNDF), nitrogen (DN) and effective in situ degradability (MDd, MOd, FNDd y Nd) following a latin square design. In situ degradability was a good predictor of in vivo digestibility.