Many sheep producers will be thinking about how best to finish any remaining lambs off forage at this time of year. Grass is the predominant feed for most UK lamb producers and, if managed well, is generally the most cost-effective way of finishing lambs. Increasingly though, a range of other forage crops can be used to extend the grazing season and improve lamb growth rates.
Finishing lambs off grass
Once lambs reach 12 weeks of age good quality grass in decent growing years should be able to meet almost all of their requirements. Grassland should be well managed though to maximise its potential otherwise much of it can be wasted.
The overall nutritional quality of the grass dictates lamb growth rates. Lambs will have the highest growth rates (150g-200g/day) on short leafy swards with intake characteristics, whilst performance on mature, stemmy swards can be as low as 50-60g/day.
Managing sward height through the year can be very challenging. Keeping available grass short and leafy is the key to high digestibility and good lamb growth rates. Aim for 4-6cm sward height early in the season, but after weaning lambs will perform better if sward heights are 6-8cm. Sward heights above 8cm are too high and will lead to a build up of dead material and inefficient utilisation.
Supplementing lambs at grass
Supplementary feeding may be necessary under certain conditions and on some farms. Provided any outlay on creep feeds can be offset by improved returns (e.g. when targeting higher early season finished lamb prices), then it can make economic sense to supplement what grass is available.
Finishing lambs off alternative forages
Red and white clover, and chicory, can all be utilised within grass swards or as standalone crops, to help finish lambs. Multi-species leys combining these nitrogen-fixing and nitrogen-lifting pasture plants offer significant benefits, particularly in low input systems.
However, it only makes sense to use proven varieties to be sure of good and consistent results, with grasses and clovers selected from the current Recommended List being a good basis for reliability. The concept of combining plants in a sward with complementary characteristics is now quite well understood, with some of the benefits having been demonstrated in widespread European studies.
For example, including nitrogen-fixing species such as clovers alongside ryegrasses, has been shown to result in comparable or higher animal performance than is achieved from ryegrass-only swards with higher nitrogen fertiliser inputs.
There is also evidence showing that plants with different – but complementary – root structures can lead to more effective use of soil nutrients, giving an overall advantage compared to monoculture swards. Using deep rooting species such as perennial chicory or plantain, for example, means nutrients are being taken up from a different part of the soil profile than is the case with shallower rooting ryegrasses. Having a range of different species will also mean multiple sources of protein, energy and minerals, presenting a more complete nutritional profile.
These benefits can certainly translate into improved lamb performance, and help reduce reliance on bought-in feeds and fertilisers, but the effects will be compromised if sub-standard varieties are used.
Wherever possible it is advisable for at least half the seeds mixture to be a high ranking perennial ryegrass, with all other components to be either selected from the latest Recommended List for Grass and Clover or to be from a known and reputable source.
With thanks to Hybu Cig Cymru and forage experts Germinal
as information sources for this blog on finishing lambs.