Maximise Returns from Finishing Lambs This Winter
Grass is the cheapest resource of feed on a farm, as the year progresses the quality and quantity of grass diminishes. The expected liveweight gain for growing lambs on short leafy swards is 150-200 grams/day, compare this to mature stemmy swards, where the expected liveweight gain is far less at 50-60 grams/day. It is vitally important that the finishing lambs, do not impact on resources of forage for the breeding ewes, as this will have implications for the next years lamb crop.
As the season progresses lambs may require supplementary feed to aid their nutrition and maximise returns. The best response is when grass falls below 4cm in height. This would aid in maintaining growth rate, as well as adding fat to leaner lambs for marketing. Good flock management is essential to maximise lamb performance e.g. transition on to brassicas or concentrate, parasite control, prevent lameness, etc.
Lambs should be weighed frequently, to understand if the finishing system is working. Ideally with weighing lambs, you should know what weight they need to gain and match the feed available to the different groups. Batching lambs allows for tailored nutrition for the performance required.
After weaning, lambs have a food conversion of 6:1 – 10:1, meaning for every 6-10kg of feed eaten, they are expected to gain 1kg. An example of this would be 37kg lamb converting at 8:1, would need to eat 40kg of feed to gain 5kg of liveweight. If the feed was £250/t this would cost £10, with a liveweight price of £3/kg this would add £15 of liveweight.
It should also be mineralised with an inclusion of 0.5% (5000 mg/kg) ammonium chloride and low magnesium to reduce the risk of urinary calculi in castrated males.
Home mixing of feed may be a popular option this year, with stocks of feed barley on farms. If home mixing, ensure the ration is well mixed and balanced with adequate protein and energy for the lambs’ requirements. Barley should not be over processed for lambs. An intensive lamb mineral should be mixed into the feed, at the manufacturers recommended inclusion rate.
Feeding Rules of Thumb
When introducing feed, start with trough feeding twice daily at a low rate e.g. 0.25kg/hd/day, ensuring all animals are eating, before introducing the hoppers. This will help prevent upsets to the rumen. Ensure fresh water is supplied and never let the hoppers run empty.
Minimum space allowances for growing lambs are 30cm/lamb for a ration fed at a trough, whereas an ad lib concentrate space is 10-15cm/head.
Expected Daily Live Weight
Once lambs are safely feeding from hoppers, they can eat up to 1kg+/head per day depending on forage availability and bodyweight.
The daily liveweight gain that can be expected from concentrate fed lambs would be 150-350g/day. Lambs on brassica and roots would be expected in the region of 150-250g/day.
Brassica and Root Crops
Lambs can be finished on brassica and root crops such as swedes, forage rape, stubble turnips. This does require careful management of the stock during transition to the crop, ensuring that all animals are eating the new forage they are being offered.
To enhance utilisation of the crop, lambs should be grazed behind an electric wire. This could be moved every two to three days, once the forage has been eaten. Shelter, water and an area of run back are essential. Concentrates may be offered to the lambs while grazing brassicas if additional energy and protein is required. Long forage (hay/silage) should always be offered when feeding a brassica or root crop.
Five Top Tips
- Lambs should be batched by weight and offered the correct available feed for the growth rate required.
- Transition from a grass diet to a concentrate or brassica diet gradually to prevent rumen upset.
- Feed should be made of good quality ingredients and 14-16% protein and 12.5 MJ/ME DM metabolise energy.
- Ensure there is adequate feeding space for the lambs.
- Ensure feed is mineralised to ensure there is 0.5% ammonium chloride to prevent urinary calculi in castrated males.
Kirsten Williams, Senior Sheep and Beef Specialist, Kirsten.Williams@sac.co.uk
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Posted by Unearthed News on 12/11/2025
