For harvesting, the timing related to the physiological age of the plant is a compromise between the best quantity and the best quality. As the volume increases, the concentration of valuable plant nutrients gradually decreases.
1 Hemicellulose
2 Lignin
3 Cellulose
4 Cell content: Sugar, Starch, Protein, Fats
Lignin and cellulose, as part of the plant cell wall, form the most important indicator of changes in forage value during the course of vegetation growth. The parameter used to measure this is the crude fibre content or the sum of the structural substances (NDF, ADF).
As the plant ages, the content of indigestible lignin increases and grows into the cavities of the cellulose structure. This makes the cellulose indigestible for the microbes in the rumen. At the same time, the valuable cell ingredients become difficult to access. The forage becomes "lignified". In addition, as the proportion of structural substances increases, they dilute all other nutrients.
In the case of grass silage, harvesting when the leading grasses reach the "panicle and seed head" stage of development is considered optimal, because high energy and protein contents can be achieved at the same time as yielding high volumes.
Especially for the valuable first cut, the optimal time window is limited to just a few days. Rapid growth in the spring makes the plants "age" very quickly. According to long-term maturity tests, the energy content drops by around 0.3-0.6 MJ NEL per week during the main growth phase, depending on the geographical location.1
This means that for the best yields, you need reliable and powerful harvesting equipment that enables you to reliably take advantage of the short harvesting windows.
1 Klocker, H.; Prünster, T.; Peratoner, G. und Matteazzi, A. (2018): Leitfaden Grundfutterqualität. Nr. 01/2018, 2. Auflage 2019. Berendonk, C. (2006): Schnittzeitpunkt bestimmt die Futterqualität. Landwirtschaftskammer Nordrhein-Westfahlen: Reifeprüfung 2019 (13.05.2019) Landesbetrieb Landwirtschaft Hessen: Siloreife 2021 (02.06.2021)