Nutritive value of grassland plants: Digestibility

Digestibility of the organic matter of 10 main grassland species were compared for two years. Samples were collected in field trials during the first growth and during two to three regrowths at three locations at different altitudes. During the first growth cycle, the digestibility of the grass species and of red clover decreased, while white clover and dandelion kept their high digestibility from the beginning to the end. The correlation between the digestibility and the age of the plants as well as the stage of development was high for the first growth of grass and clover. During the regrowths, the digestibility decreased from 0.8 to 3.2 % per week depending on the species. At the beginning of each regrowth (three and five week old forage), the estimation of the digestibility was more accurate than at the end of the regrowths, when the range of variations in digestibility was much higher. Compared to our results, the official Swiss tables of nutritive value underestimate the digestibiity of grass species during the first growth cycle and overestimate the digestibility during regrowth. For the first growth, the digestibility of white and red clover is in correspondence with the tables, but the digestibility is overestimated by the tables for the regrowths.