Winter forage crops or brassicas are a low-cost option for farmers when it comes to providing a high-energy feed during the winter period.

These crops can take the pressure off housing space, they are fast-growing and animals tend to perform well on them.

Depending on the crop, they are suitable for feeding sheep, beef cattle or dairy cows (small amounts in milking cows).

There are a range of different options for winter forage crops and the right one will depend on the farmer’s personal preference and the time of sowing.

As we are now at the beginning of August, the options are really limited to kales, rapes and hybrids.

Forage kale

By now most farms who plan to sow kale will have it in the ground. Late June, early July is the latest kale crops are advised to be sown in order for them to be well enough grown by early November.

Kale crops can be grazed anywhere from early September up to the middle of March and are generally considered a very hardy winter crop. Germinal’s Claire Bailey-Archibald said on a recent forage crop webinar, that kale requires roughly 20 weeks from the time of sowing to the day of grazing, in order to achieve a good yield.

The yield is typically anywhere from 7t DM/ha up to 12t DM/ha, with a protein content between 16% and 18%. Animals will utilise up to 90% of the dry matter as the plant has a high leaf to stem ratio.

Forage rape

This crop is an option for those farms who are thinking of sowing, but haven’t yet done so. The crop is fast to establish and therefore can still be sown up until mid- to late August.

When sowing these crops, soil moisture is needed.

With the current weather situation, don’t sow until rain is forecast.

The yield of forage rape is lower than that of kale at somewhere between 4t DM/ha and 6t DM/ha and the crop is not as hardy as kale.

Protein content of the feed is higher however, at over 18% and like kale, rape has a high utilisation rate due to the high leaf to stem ratio.

Hybrid brassicas

The third option when it comes to winter forage crops is a hybrid brassica. The hybrid crop is a mix of both kale and rape.

This crop has the advantages of both crops and can be sown anytime up to late August.

The yield of the crop is in the region of 6t DM/ha to 8t DM/ha, with a protein content of 18% to 20% and a high utilisation rate.

Speaking on hybrids, Claire Bailey-Archibald said “the crop will mature in roughly 90 days and is extremely hardy”.

Feeding

These crops are an excellent option for farms over the winter months, but they do take managing and there are a couple of key considerations to take into account before sowing.

Firstly, animals must have a lie-back. The minimum requirement is 30% of the total area. If the crop is across 1ha, for example, the lie-back needs to be 0.3ha. It can be either grass or stubble, but the ground can’t be severely poached and needs to be accessible at all times.

These forage crops aren’t suited to heavy land and areas of the country with high over-winter rainfall, as poaching becomes too much of an issue and utilisation rates of the crops drop off.

The most important consideration when feeding these crops is a fibre source. Forage crops are notoriously low in fibre and animals need to be offered silage or hay alongside the crop. At least 30% of the diet should be a fibre source

As the crops are very high energy, animals need to be introduced to them gradually, so they don’t suffer from bloat or toxicity poisoning. Claire Bailey-Archibald recommends introducing animals to the crops over seven to 10 days.

Using a strip wire, the farmer can allocate just a couple of kilos to begin with and build up gradually each day. The fence should be moved every day, as allocating a couple of days’ worth of feed will cause digestive issues. When setting up the strip fence, it’s good practice to have a second wire a couple of metres behind, in case the first one is broken through.

The most important consideration when feeding these crops is a fibre source. Forage crops are notoriously low in fibre and animals need to be offered silage or hay alongside the crop. At least 30% of the diet should be a fibre source.

As forage crops are low in key minerals, these need to be provided through a bolus, water or powdered mineral source.

The costs of growing a forage crop is somewhere around 15c/kg of utilised dry matter. This cost includes all growing expenses except for a land charge.

This is roughly half the cost of pit silage per kilo of utilised dry matter. Winter forage crops are therefore a great option for a farm looking to reduce pressure on housing and reduce the costs of winter feed.