Sheep grazing forage crops

Eamonn Dempsey, Teagasc Advisor, discusses the utilisation of forage crops for feeding sheep during the winter months. He highlights suitable crops, grazing management practices and considerations for maximising crop utilisation.

Forage crops are available for feeding mainly from October to February, replacing grass which is either closed off or in short supply. For finishing lambs post weaning, rapid growing crops such as Tyfon or Rape are most suitable, with the added advantage that where they are leniently grazed they will re-grow for further grazing every five to eight weeks. Other crops destined for finishing store lambs in the late autumn/winter include swedes, hybrid brassica and kale.

In general, brassicas destined for out-wintering stock should be completely grazed by early March as they tend to flower after the winter. This may lead to health issues for stock grazing flowering plants/seeds. Crop utilisation of around 70% needs to be factored in when calculating grazing days and is dependent on the crop type, yield, grazing management, weather conditions and soil type. From the expected yields, you will be able to work out intakes and carrying capacity, which will give an idea of how long the crop will last, then decide how to graze the crop to get maximum utilisation. Lowland lambs weighing 35 – 40 kg intake 1.25 kg of dry matter, hill lambs have a lower intake and as a result a lower performance on forage crops, whereas mature ewes utilise forage crops the best with an intake of 1.6 kg of dry matter.

Forage crops are most suited to lighter animals, a runback area allows for a greater number of lambs to be finished off any given crop. Where ewes are grazing brassicas with young lambs a runback area and shelter are required. Care must be taken not to force animals too hard to consume unpalatable parts of the crop i.e. roots, stem and soiled leaves. To get the maximum from the crop choose to graze the longest side of the paddock so animals get fresh feed and trampling is kept to a minimum. Move the fence to crop face frequently, every 2 to 3 days in good conditions and daily in poor conditions. In frozen weather conditions don’t feed frozen crops, allow time to thaw by moving fences in the afternoon.

Sheep need time to adjust to the use of a 3 strand electric fence, so train beforehand in a small area with maximum power so the fence will be respected in the forage crop. Sheep on forage crops need a fibre source of hay/silage making up about 30% of the diet. As a general guide lowland store lambs can be expected to increase live-weight by between 100 to 150g per day while grazing forages in autumn. Forage crops are generally low in trace elements such as selenium, iodine, copper and cobalt so access to high quality minerals or boluses are necessary to avoid any potential problems.

Adapt sheep gradually to crops over at least one week and don’t graze older ewes on roots as it may damage their teeth. Check your flock for lameness and remove lame sheep for treatment before the introduction to the forage crop. If finishing lambs on forage crops they may need to be removed off the crop for the last few weeks before marketing to comply with the clean livestock policy for sheep.