Cut costs of wintering cattle using forage brassicas

For some farmers, the poor spring conditions may have had a negative impact on silage yields and they may wish to look at forage brassicas as an alternative way of increasing the amount of winter fodder on farm. Growing forage brassicas such as Kale or Rape allows cows to be held outdoors longer over winter, or provide an opportunity to get cows and calves out early in spring and reduce costs.

Grazing cows on kale in winter supplemented with some big bale silage can cost between 50-70p/day  A 650kg cow calved  indoors in February on first cut silage at £25/ton fresh (£100/ton DM) costs around £1.20/day for silage only. Both kale and rape are high in protein and require some minerals to be fed but no meal. Cows are also fitter grazing, resulting in fewer calving difficulties. The crop can be fed to dry cows, weanlings, store cattle and spring calved cows.

If properly grown and well fenced, it is less labour intensive than feeding housed cattle. Moving one electric fence will take less time than feeding silage using a block cutter or feeder wagon.

Whilst it will not be applicable on the majority of farms throughout N Ireland, those who farm drier, flatter fields, then growing brassicas could be a viable option.

Before growing, consider when you want to feed the crop – brassicas can be grazed from June to March. Once the plant flowers in the late spring/early summer, it can no longer be grazed as it is poisonous to livestock.

Typical sowing dates and grazing dates are outlined below:

Choose a dry, relatively flat field with some form of shelter to facilitate grazing in mid winter. It may be an advantage to have the field close to the yard as during very wet weather cattle may need to be housed. It will also be more convenient when checking stock.

In order to meet the requirements of Cross Compliance a dry field must be chosen.  Brassica fodder crops should not be grown on steeply sloping fields with a high risk of soil erosion.  Leaving an uncultivated grass buffer strip adjacent to watercourses and ditches, and temporarily fencing them off or grazing towards them will help to reduce the risk of soil run-off.

It is best to rotate the growing of brassica crops. If it has to be grown for a second year in the same field, club root is an issue. Caledonian Kale is resistant, while Bittern has some resistance. Kale is more frost resistant, winter hardy and has a yield approximately double that of rape.  Swift is a hybrid of both kale and rape.

Providing a run back area is advised, or leave the head-rigs in grass. This will provide cattle with a lying area, reducing the level of poaching.

Get a soil test to determine its fertility, both kale and rape grow best at soil pH 6 – 6.5 and P & K index 2. At this fertility level apply about 50 kg/ha (40 units/acre) of Phosphate & Potash to the seedbed and 85-110 kg/ha (70 – 90 units/acre) nitrogen. The seed can be drilled at 6-7.5kg/ha (2.5 – 3kg/acre), or broadcast at slightly higher rates and roll afterwards. Controlling weeds can be difficult if they get established, so use glyphosate pre sowing to make sure that grass and weeds are well burned off prior to sowing.  

Due to the low fibre content of the crop, livestock should receive at least 25% of their intake as roughage from straw, hay or baled silage to avoid rumen problems. Bales should be placed in the field when dry (October time) to minimise the risk of tracking, compaction and soil run-off.

Strip grazing is required to make best use of the crop. The electric fence should be moved up to the face of the crop every day to allow the cattle to graze under it and being careful to ensure the crop does not earth the fence. Match the group size to the feeding area of the field and gradually introduce stock to the crop to allow rumen adjustment. Minerals will be required as brassicas are low in magnesium, copper & iodine.

Typical feed values and yields are outlined below:

(Establishment costs include ploughing, tillage, seed and fertiliser)

For length of grazing period as a rule of thumb

Growing 3-4 acres of brassicas can greatly reduce winter feeding costs. As cattle are outdoors, the amount of slurry storage and slurry spreading required is reduced saving time and money later in the year. If part of a reseeding rotation, the fertiliser required for a spring reseed will be reduced. Whilst it is not an option for every farm, it does have a definite role on drier farms as an aid to cut cattle winter feed cost.

Cows grazing brassica

Advisers and farmers discussing the option of brassicas