catch crop

Making the most of brassicas

Forage Crop:  Brassicas

Forage crops are ideal grazing crops for growing and finishing lambs and in-lamb ewes. They can be very economical, allowing farmers to take the pressure off grass fields and increase farm output.

Before stock are turned onto forage crops, ensure they are covered by a clostridial vaccine as Pasteurella can be an issue.


It’s also essential sheep have access to the correct minerals. Forage and root crops are generally low in minerals, trace elements and vitamins, partly due to their short growth period. This means they are not in the ground long enough to take up any significant levels of these essential nutrients.

Brassicas, and especially root crops, contain glucosinolates which block the uptake of iodine from the diet. They are also low in iodine which affects the thyroid gland and the hormone it produces. This plays an important role in maintaining bodily functions and immunity. It is also very important for the development of the unborn lamb. Signs of deficiency include stillborn or very weak lambs.


Dry Matter Intakes

It is also a good idea to work out the required dry matter requirements for stock so decisions can be made on the diet and appropriate stocking rates.  

It is also important to have a transition period when moving stock onto forage crops. Introduce stock gradually and with full stomachs. Start with one to two hours per day initially and build this to unrestricted access in seven to ten days.

The forage crop inclusion rate should be between 35-50% of the dry matter intake. Allow access to a fibrous forage like hay or straw at all times and have an area of grassland for stock to run back on.

Bloat can be an issue as brassicas can be rapidly degraded in the rumen. This increases the need for them to have access to fibre. Animals should also have a transition period when moving off forage crops. This can help prevent prolapses in ewes.

Ideally, ewes should be moved off forage crops four weeks before lambing to ensure their full nutritional requirements are met, particularly when it comes to protein.


The Mole Valley Feed Solutions team can provide advice on grazing brassicas. For more information, please call the Feed Line on 01278 444829 or email [email protected]