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Wednesday 14 November 2018

Why the quality of first cut silage crop could pose big issues this winter

The difference in dry matter between silage made during the summer drought and recently made autumn silages, is as high as 40pc
The difference in dry matter between silage made during the summer drought and recently made autumn silages, is as high as 40pc

Gerry Giggins

The sight of mowers, balers and silage harvesters in full flight over the past two weeks was yet another indication as to what a unique year 2018 has been.

Thankfully, on many farms, fodder deficits have now been significantly reduced. With grazing conditions continuing to remain good, the fodder crisis can hopefully be less of an issue than was previously feared.

While the supply of fodder stocks has been rectified, there still remains issues surrounding feed quality, mineral status and contamination levels of many silages.

Last week I noted fellow nutritionist, Brian Reidy commenting on the forage quality that he has encountered, particularly in relation to secondary fermentation or overheating in dry silage pits.

The difference in dry matter between silage made during the summer drought and recently made autumn silages, is as high as 40pc.

This equates to a suckler cow requiring either 42kg/day of a wet silage or 15kg/day of a high dry matter silage. There are many variables to consider when feeding either of these silage types. High dry matter silage, which is obviously a lot more prevalent this year will have a higher pH, higher sugar content and quite often a high NDF level.

When stored in a pit, this type of silage can be very difficult to manage.

The effectiveness of a shear grab is lessened and heating at the pitface is common. Where heat is present, moulds are forming, both visible and invisible to the naked eye.

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These moulds can result in a mycotoxin challenge to animals, resulting in lower performance, reduced fertility and increasing the likelihood of lameness.

Dry silage, while made in excellent conditions, may have a higher level of soil/dust contamination.

Any soil contamination can lead to mineral lock-up and reduced availability of both natural and supplemented minerals.

As previously mentioned, recently made silages and short term grasses still to be ensiled have supplied a welcome boost to forage stocks but will pose some challenges at both storage and feeding time.

In contrast to high dry matter silage, they will likely contain low NDF levels, low sugar, high ammonia, low pH and have lower dry matters. If in a pit, effluent run off is a risk, while bale stacking may prove difficult. Last week I witnessed recently made bales with significant effluent run off.

Removing plastic, net wrap and twine from these bales can be an arduous task.

This type of silage is likely to have a high reading for protein content, in the form of non-protein nitrogen.

Twinned with a low NDF and low pH, it could result in animals having loose dung or scouring.

Maize

Where grass growth struggled in 2018, maize crops thrived. With the exception of some storm damaged crops, the harvest has been a dream for both growers and contractors. Early sampling that I have carried out is showing quality to be of an excellent standard.

As with dry grass silage, any storm damaged maize crops could pose issues as a result of their high dry matter and possible soil contamination.

These damaged crops were allowed to dry out in order to make harvesting possible, but some soil contamination was unavoidable.

Wholecrop silages are testing low on starch and energy contents, which is a reflection of the poor grain yields that were experienced during the harvest.

For farmers feeding whole-crop and wet grass silage in a TMR situation, mixing these feeds in the correct proportion will enhance the utilisation of both forages.

A 60:40 mix of grass silage to wholecrop is usually recommended in this situation.

Gerry Giggins is an animal nutritionist based in Co Louth

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