In order to achieve high feed intake, organic matter digestibility of pure grass should be between 78 and 81%.
If there is between 30 and 50% clover in the clovergrass mixture, we need "only" 76-80% digestibility of the organic matter as clover passes more rapidly through the rumen. For this reason you will be able to reach a much higher level of forage quality just by adding clover into your grass mixture.
If we want to understand what affects organic digestibility of grass, we must go to the cellular level and see how the grass plant cells are built.
A plant cell may be divided into cell content and cell wall:
The content of the cell consists mainly of protein, crude fat, starch and sugars, all of which have a constant and high digestibility close to 100%, see table below.
This means that the cell content in general has a constant and high digestibility.
In the cell wall, which consists of β-glucanes, pectines, cellulose, hemicellulose and lignin, it is quite different.
Pectines and β-glucanes have a high digestibility (100%), while the digestibility of lignin is 0%. The digestibility of cellulose and hemicellulose varies, which means that the digestibility of these components in practice are determent for the overall digestibility of grass.
Hemicellulose and cellulose together with lignin is what we often refer to as the cell wall (Neutral detergent fiber). Summed up, a high digestibility of NDF is synonym with a high digestibility of organic matter. The content of NDF can be determined by lab analysis which is important as digestibility of NDF is calculated from the content of NDF.
The digestibility of cellulose and hemicellulose depends, among other factors, on cutting time, weather and fertilisation, but we have also seen a difference between grass varieties, when they are compared under the same growing conditions.
We test all varieties for feeding quality, and those showing to be high above average concerning digestibility of NDF are marked with our cell wall logo.
Photo: Erik Nissen