High energy and nutrient content are crucial in order to gain the maximum from the basic ration. Only by producing forage which is rich in energy and nutrients will you be able to reduce the quantity of concentrates that have to be used. To achieve this, some natural principles and basic characteristics of different forage species must first be taken into account.
Crop development and cutting time
During their development, the composition of forage plants changes. With grass, for example, the stage of maturity has a big influence on the repartition of cell contents (protein, lipids, sugars and minerals) and cell walls (hemicellulose, cellulose and lignin), as the share of the latter increases steadily during growth.
As a result, the grass nutrient content, especially protein and minerals, declines whereas the crude fiber content rises. Moreover, an increasing percentage of crude fiber reduces the energy content as well as lowering the digestibility and feed intake by the animals.
Influence of crude fibre and energy content of grass covers of different ages on the milk performance
Source: Jeroch et. al., 2008
It becomes more obvious now, why the right cutting time plays such an important role: not cutting at the right time can have a negative impact on dry matter intake and milk performance of the cows. Whilst the crude fiber increases, the energy content declines rapidly during the days after the ideal harvest date. The table below clearly illustrates the huge impact on milk performance, if the grass is cut too late. Losses of up to 35 % of the potential milk yield if the harvest is postponed by just eight days!
The role of plant population
Another factor influencing the energy and nutrient content is the crop composition. The percentage of grasses, legumes and herbs define its characteristics and each of the three components have a different impact upon forage quality.
While grasses are important for good yields and provide sugar for fermentation, legumes and herbs contribute towards a higher mineral content in the forage. These enhance not only the feed value but also its
Additionally, a high share of both legumes and herbs allows flexibility concerning the cutting time, as their crude fiber content doesn´t rise as quickly as those found in grasses. This reduces the risk of losing too much energy per hectare, should the weather delay cutting.
The high protein content of legumes also increases the overall protein content of the forage. An aspect of growing importance as current debates promote the production of more protein from grassland in order to reduce soya imports.