The perfect crop, the best cutting time, the highest yields - factors that only work if the forage also retains its quality by the time it ends up at the farm. Until then, dirt ingress is another key factor. Soil is often the cause of inferior quality basic ration. The negative effects are often underestimated.
Crude ash as a parameter for forage contamination
A frequently used parameter for forage contamination is the crude ash content. It should be noted, however, that crude ash does not equal "dirt" . Each plant contains minerals and trace elements that contribute to the crude ash content. These amount to a good 70 g/kg DM, depending on the plant species and the stage of development. In addition to these minerals, dirt ingress in the form of sand and clay is also counted as crude ash.
The guideline value for a clean forage crop is a crude ash content of less than 100 g/kg DM.
Lower forage value
Lower forage intake by the livestock
The increase in crude ash content inevitably results in diluting the nutrients. In terms of energy content, with 10 g of crude ash, about 0.1 MJ NEL / kg dry matter is lost due to dirt ingress.1 The crude protein content decreases by about 1.6 g/kg DM.2
In addition, contaminated forage is consumed by ruminants in smaller quantities. The reason for this is because it tastes different, it is not as digestible, and the forage has a lower energy content.
As a rule of thumb: 1% of dirt contamination results in 200 kg less milk from the basic ration per cow and lactation.3
1 Resch. R (2009): Qualitätsbewertung von österreichischen Grassilagen und Silomais aus Praxisbetrieben. Abschlussbericht Silageprojekt, 29.
2 Resch, R.; Frank, P.; Stögmüller, G.; Tiefenthaller, F.; Peratoner, G.; Adler, A.; Gasteiner, J. und Pötsch, E. M. (2014): Futterverschmutzung mit Erde - Ursachen, Erkennung und Auswirkungen. Landwirt Sonderbeilage.
3 Resch, R. (2012): Qualität der Silagen – Theorie und Praxis. 3. Burgenländisch-Steirische Bauerntage. 9.2.12.