Brassicas for out-wintering

With pressure mounting for many this year due to the rising input costs and difficult silage season, farmers are having to investigate different wintering strategies.

For many, brassica fodder crops have provided low-cost options to supplement winter feed. Especially for those short on silage or those who are concerned about straw supplied over the winter.

However, these crops do not fit into every system and site selection is crucial – especially when used for out-wintering. Brassicas including kale, grazing turnips, stubble turnips and rape/kale hybrids are suitable for feeding both beef and sheep. Swedes are more recommended for cattle with fully mature teeth and are not suitable for broken-mouthed sheep. Swedes would also be a suitable option for robust, in-calf heifers that are not near calving. Calves which are less than one year old would struggle to meet target growth rates and it could impact fertility in bulling heifers. Only healthy animals in good body condition should be considered for out-wintering, and a body condition score of three to 3.5 is advised. Any animals which are thin or lame should be managed separately or housed.

If planned and managed carefully, out-wintering is a cost-effective alternative to housing, with no detrimental effects on early lactation or animal condition. AHDB research has shown no negative effects of out-wintering on cattle health, fertility, milk yield or somatic cell count in first-lactation heifers.

Cattle should be gradually transitioned over the course of seven to ten days. It is advised to introduce them for an hour or two to begin with, then increase the level of forage crops in their diet by one kilo per day, or in one-hour allocations. It can then be increased until access is unrestricted. Because of the high levels of digestible carbohydrate content and low fibre content, a transition period is important for the rumen microbes to adapt and reduce the risk of bloat.

While brassicas can make an excellent winter fodder crop, roughage with good fibre levels should be provided to complement forage brassica crops. This is because the quality of brassicas can be very high, with a high leaf proportion meaning that they are very fermentable in the animal and can result in loose faeces. Roughage must form at least 35% of cattle’s daily dry matter intake and should be provided ad-lib. The research has shown growing cattle out-wintered on brassicas can achieve growth rates of 0.6–0.9 kg per day. However, these good growth rates depend on the quality of hay or silage with the brassicas.

Out-wintered cattle have a higher energy requirement than housed cattle. Between 10–20% more energy should be allocated depending on their body condition, ground conditions and how much shelter is provided. Mineral supplementation should be discussed with the farm vet and nutritionist, depending on the crop and forage choice as brassicas are low in phosphorus, magnesium, copper, iodine and selenium, so supplementation may be required especially for any in-calf heifers.

The key to successful feeding with brassicas is to strip graze, using an electric fence to maximise crop utilisation. The allocated area should be long and narrow but allow all the livestock to assess the crop at once. Ideally, the fence should be moved daily. For accurate feed planning, it is essential to measure the DM yield of the crop.

For more information on the management, performance and financial implications of including brassicas in your system visit Outwintering livestock on brassica and forage crops.

AHDB is also running a series of farm events where New Zealand fodder beet expert, Dr Jim Gibbs, and UK expert, Marc Jones, will be looking at grazing fodder beet for cattle and sheep and integration into a mixed farming system. To register for this event, visit ahdb.org.uk/events