Forrage preservation – It’s all in the mix

Posted February 4, 2016

Forage preservation

The method of forage preservation is dependent on the amount of moisture present in the forage.

Wet forage preservation (silage) is achieved by the bacterial conversion of forage moisture and sugar into lactic and acetic acid. The lactic acid drops the pH of the silage, and, in combination with the air free environment achieved through the use of plastic wrapping, protects the silage from yeast and mould outgrowth.

Dry forage preservation (Hay) is achieved by removing the water from the forage and making the environment too dry for bacteria, yeast and mould to survive. Bacteria cannot grow when the hay is at 70% dry matter (30% moisture) but yeast and mould continue to actively grow to 85% dry matter (15% moisture). As bacteria cannot grow in the ‘Hay dry matter range’ they cannot produce the chemicals that will inhibit the yeast and mould.

Successful hay treatment is through the application of chemical treatments at a sufficiently high concentration and volume of chemical(s). Yeast and mould treatment is similar to treating an infection with antibiotics – the correct chemical has to be applied in order to kill the specific yeast and mould present. Similarly, a sufficiently high level of the chemical must be used. Hay treatment products with combinations of different chemicals will tend to be more effective than single chemicals.

Dry Matter


Moisture Content

Yeast and mould will be present on the forage when it is baled, and if sufficient moisture is present they will outgrow, generating heat as they grow. The chemical hay treatment will equilibriate through the bale as the hay cures, and, when it comes into contact with the yeast / mould will kill the spoilage organisms.

Gordon Marley
Sil‐All Global Product Manager