Voluntary intake and in vivo digestibility of forages from semi-natural grasslands in dairy cows

Abstract

To study in vivo digestibility of forages from semi-natural grasslands two experiments were carried out. In the first experiment lactating dairy cows were offered three different silage-based diets. Silage originated from intensively managed grassland (IM), extensively managed species-poor grassland (SPP), or extensively managed species-rich grassland (SPR). In the second experiment lactating dairy cows were offered IM or a diet in which part of the IM had been replaced by 20% SPP (20SPP), 60% SPP (60SPP) or 60% SPR (60SPR). Intake was significantly lowest on diets with SPP, but intake on diets with SPR was not significantly lower than intake on IM. In both experiments gross energy and in vivo digestibility of organic matter, crude protein and neutral detergent fibre were highest for IM. In the first experiment SPP had a significantly higher digestibility than SPR, but in the second experiment differences in digestibility between 60SPP and 60SPR were not statistically significant. In both experiments in vivo digestibility was almost similar to in vitro digestibility, but no suitable equation could be found to estimate in vitro or in vivo digestibility from the chemical composition. Although digestibility and crude protein content were significantly lower for SPR than for SPP, intake of digestible organic matter appeared to be higher. It was concluded that there appears to be more scope for silage from extensively managed species-rich than for silage from extensively managed species-poor grassland