Ensiling Potatoes with Silage to Add Feed Value to the Pit

High input prices have prompted us to closely look at the cost of feed supply for next winter and one way to bulk up silage and add energy is to ensile it with stockfeed potatoes if there are potatoes available to do so and the price is favourable.

Ensiling potatoes and grass is a well tried, tested and common procedure that works extremely well adding additional energy to the silage crop. There are some rules to play by however to ensure a good fermentation in the silage and good ‘cooking’ of the potatoes:-

1. The potatoes should be cleaned of soil as much as possible as dirt and soil will cause spoilage in the silage.
2. Either mix in the potatoes or put in alternate layers; about 0.6 m of grass followed by 0.15 m of potatoes.  The usual recommended ratio of grass to potatoes is 5:1 but some authorities have suggested that a ratio as low as 3:1 is acceptable.
3. Always have a layer of grass on the bottom of the pit prior to putting potatoes in.
4. Too many potatoes in one layer can lead to air pockets and spoilage which can be harmful to stock.
5. The potatoes will cook with the heat of the ensiling process and need shallow layers or mixed in to achieve this successfully.
6. Watch out for green and sprouted potatoes as they contain chemicals called glycoalkaloids which are toxic to animals.  Exposure to light and sprouting results in a large increase in the concentration of these toxins, with the sprouts containing up to 30 times as much as green tubers.  The ensiling process does destroy 30-40% of the toxins so including slightly greened potatoes with grass silage should be safe, however ensiling badly greened or sprouted potatoes is not without risk and every effort should be made to knock off the sprouts before ensiling.

Also consider the logistics required to pit potatoes; haulage required for hundreds of tonnes may not be easy to achieve in a short time frame and will need planning. Adding potatoes, in the correct way, will enhance the nutritional value of the silage pit however, it may not be suitable for all farms, for instance if the pit is for dry suckler cows not requiring additional energy.

Karen Stewart, karen.stewart@sac.co.uk