Laboratory feed analysis

Feed analysis is an important step in the silage making process. The results will allow you to determine the best time to feed your silage and may also help you identify ways to improve silage quality next season.

Silage should be sampled when it is fully fermented. This is normally one to four weeks after ensiling depending on silage drymatter and inoculant use. To collect a representative silage sample:

  • Use a silage corer or collect handfuls from at least five different places in the stack. If you are sampling baled silage, take a core sample from at least five bales.
  • Mix the samples together thoroughly and take a 1 kg subsample.
  • Place the 1 kg subsample into a laboratory sample bag, or a clean plastic bag. Squeeze the air out of the bag and seal it.
  • Send the sample immediately by courier or FASTPOST to the laboratory (do not send samples on a Friday unless you are sure they will reach the laboratory before the weekend).
  • Samples that cannot be submitted immediately should be stored in the refrigerator overnight, or frozen.

If you have sampled a closed stack or bales that you do not plan to feed immediately, fill the sample holes with salt and reseal the cover using silage tape.

The important things to get analysed are drymatter, crude protein and an estimate of the metabolisable energy content. The pH and ammonia nitrogen percentage will tell you about the success of the silage preservation process. The amounts of volatile fatty acids (lactic, acetic and butyric) are also useful.