Tips for monitoring silage

In times like these, when milk prices are volatile, the quality of the basic feed becomes crucially important. “Every farmer should know the exact nutritional value of the silage they use and the kind of feed it is suitable for,” is the advice given by Dr Sabine Rahn, AGRAVIS Raiffeisen AG’s expert on ensiling and preservation ensiling and preservation. This knowledge has to be derived both from the chemical analysis of the correct ingredients and regular sensory checks as well.

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There are various parameters that affect silage quality. Nutrient and energy density are important factors, as are fermentation quality and hygiene status of the silage. “All these characteristics determine the feed intake and the health of the animal and as such play a part in the quality of the animal,” says Dr Rahn. To achieve a proper balance in the nutritional intake all the elements have to be put together in the correct ratio. The silage should be stored for six to eight weeks before the first sample is taken. “Then it’s normal to test the raw nutrient contents using the NIR method. This analysis produces the data from which the rations are then calculated. No other parameters are usually tested.

Importance of fermentation quality and hygiene status

However, to be able to correctly evaluate the suitability of the silage for use as feed it is necessary to specify the fermentation quality for each grass silage and the hygiene status for each maize silage. “The fermentation quality tells us about more than the palatability of the silage: it also shows to what extent the energy density revealed in the analysis needs to be adjusted,” explains our expert. Maize generally lends itself well to ensiling, albeit with a greater tendency to heating up, so it is also advisable to carry out an hygiene status check for maize silage. The germ density of the yeast found provides information about the potential risk of the silage heating up.

Regular monitoring

Many farmers rely too heavily on the analytical data they have on paper. Sometimes they only test the entire store once or twice during the feeding period. It is not possible to be sure that the data from the analysis really tells the whole story: “Only regular visual checks when removing the silage will provide a clear picture, because the quality of the feed is variable across the silo,” Rahn explains. Both the composition of the grasses and the wilting process in the field can be inconsistent. And the lactic acid fermentation process itself is also subject to certain variations.

No more blind feeding!

It is clear, then, that the data analysis from the test sample can only reveal a snapshot of the actual condition of the silage. Farmers who do not keep an eye on their silage are feeding blind, so to speak. Even a minor misjudgement can have commercial ramifications and cost money. For this reason it is always advisable to conduct regular sensory checks on your silage. With a little practice and experience this kind of testing by smell, structure and colour will become a dependable early warning system. Inspections should also include looking for impurities, signs of heat or mould, and watching as the feed is consumed in the sheds. “If these sensory checks throw up any discrepancies or abnormalities another chemical test should be carried out,” advises Dr Rahn.

By keeping tabs on their silage through chemical and sensory checks farmers can respond more quickly and adjust their feed management as required. When it comes to the next round of silage making they will be particularly well placed to apply any measures needed to safeguard the quality of their silage. One important quality assurance measure is the targeted use of the silage agents Siloferm and BioCool.

More information about this topic is available from Dr Sabine Rahn, tel. +0049 251 682-2289, or go to