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There have been a few queries following this week’s management notes on how silage and concentrate supplementation compares with finishing lambs on an ad-lib concentrate diet.
There has been quite a bit of research carried out in this area, with Teagasc researchers Tim Keady and Seamus Hanrahan leading a trial to investigate the merits of finishing lambs on grass silage, maize silage and ad-lib concentrates, the results of which were published in 2010.
Silage quality
In recent years, Philip Creighton has finished lambs in the Athenry research demonstration flocks on a diet of silage and concentrate supplementation.
The main factor influencing if lambs can be successfully finished on a silage diet is the quality of silage present.
Silage needs to be good quality, with a dry matter digestibility value of 70DMD upwards and ideally in the mid-70s.
Figure 1 details the results of the trial published in 2010.
The DMD of the silage classified as having a low feed value was 70DMD, while the DMD of the silage classified as high feed value silage was 75DMD.
The average liveweight gain achieved on the 70DMD silage ranged from just 50g/day where lambs were supplemented with 0.2kg concentrate, rising to about 150g per day where lambs were supplemented with 0.8kg concentrate.
Similar level
A similar level of liveweight was achieved from lambs grazing 75DMD grass silage and supplemented with 0.2kg concentrates and clearly shows the increased performance attainable by feeding high-quality silage.
Performance increased to in the region of 200g daily where lambs were offered 0.8kg concentrate and high-quality silage ad-lib, with a substitution effect reducing the volume of silage consumed.
The results of this clearly show that finishing lambs on silage and concentrates is only really a runner where high-quality silage is available.
Best option
Figure 1 also shows the level of performance attainable from feeding an ad lib concentrate diet.
For farmers with access to lower-quality grass silage or where high-quality grass silage is in tight supply and better utilised for feeding other animals, then the best option is finishing lambs on a high-concentrate diet.
SHARING OPTIONS: