Farmers encouraged to test grass prior to cutting

Bio-Sil technical advisor Jeremy Nash is encouraging farmers across Northern Ireland to test grass prior to cutting swards for silage over the coming days.

He explained: “The recent spell of cold, dry weather means that many grass crops have not had the opportunity to utilise a significant proportion of the nitrogen fertiliser applied some weeks ago. As a result, high nitrate levels may well have built-up within these swards.”

Nash continued: “In the short term, luxuriant amounts of free nitrate within ensiled grass can lead to fermentation challenges. The buffering capacity of these forages is exceptionally high. As a result, it will require considerably high levels of acid to get the pH down to an acceptable level within the clamp.

“This will lead to an increase in the time required to stabilise freshly made silage. In addition, it is very difficult to predict the overall fermentation profile that will develop within a clamp containing high levels of free nitrate.”

The silage consultant went on to point out that nitrogen taken up by grass plants will, eventually, be turned into proteins. But in the interim it is still soluble within the crop.

High nitrate levels – above 1000 parts per million, or 0.1% - in grass fed to animals will reduce intakes, reduce milk yields with weight loss and diarrhoea.

Silages containing high nitrate levels can cause all of the above whilst also producing very poor fermentations.

This type of silage that’s low in sugar will take a long time to get to a stable pH. During this time proteins will be converted to ammonia by bacterial actions and nitric acid can also be produced.

The resultant silage will not only be mildly toxic to the livestock, but it will also have lost much of its feed value. At very high nitrate levels (6000 parts per million) this silage can even be fatal to humans, if toxic nitrogen dioxide gas is allowed to form.

Nash continued:“Given current circumstances, I would strongly advise farmers to test fresh grass prior to cutting. Strip testing kits can now be purchased, that will deliver a result in the field.  

“In the event of nitrate levels being extremely high, I would urge farmers to consider delaying their harvesting operations for a couple of days. This will allow a proportion of the nitrate to be converted to protein within the grass plants.”

According to Nash, sugar levels are extremely low in grasses across Northern Ireland at the present time.

He explained:“Again, this is a result of the very cold weather conditions that have characterised recent weeks. In such circumstances, it is critically important to treat freshly cut grass with an inoculant that will ensure the delivery of very large quantities of lactic acid producing bacteria.

“Depending on the bacteria on the grass to achieve this outcome is just too big a risk to take.”

Nash added:“Bio-Sil has been formulated to deliver extremely high numbers of lactic acid producing bacteria at time of ensiling.

“These will then act to control the fermentation processes that take place within the clamp. The end result will be the attainment of the desired lactic acid fermentation in tandem with a very fast pH drop.

“Silage stability is secured within 48 hours in a way that preserves as much as possible of the sugars that were in the fresh grass.”

For further information, contact Bio-Sil on 07841 954328.