After such a wet winter, where little field work was possible, the risk of silage becoming contaminated from soil and slurry when it’s made will be greatly increased.

Uneven, rutted field surfaces, left by machines travelling on wet land, increase the risk of soil and soil bacteria, such as clostridia, contaminating silage.

Clostridia feed on grass sugars and proteins. They can also feed on the good silage acid, lactic acid, wasting as much as 50% of the dry matter (DM) and a fifth of the energy that they consume. They also produce compounds that make silage less palatable, compromising intakes.

Meanwhile, late slurry applications mean less time for slurry bacteria to decline before first cut. Slurry bacteria such as enterobacteria waste about 40% of the DM and 16% of the energy in the grass sugar they ferment.

Ten weeks

Ideally, about 10 weeks should elapse between applying slurry and making grass silage, but this is rarely possible. For those cutting on 15 May, slurry should have been applied by 6 March. But few farmers achieved this.

If grass crops were fairly light when slurry was applied, this might help to reduce contamination because the grass might have been able to grow through the slurry layer. But with heavy grass crops, there’s less chance of this.

For more details, you can reach out to Peter Smith at Volac. He can be contacted at 07920 721955 or via email at peter.smith@volac.com. Feel free to get in touch with any inquiries or questions you may have!