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Grass-finishing lambs without concentrates is still possible over the next six weeks, provided animals have access to high-quality swards, CAFRE sheep technologist Dr Eileen McCloskey told farmers at last week’s AgriSearch lamb-finishing roadshow at Swatragh Mart.
According to McCloskey, lambs grazing on good-quality ryegrass swards can gain 1kg to 1.2kg/week during autumn.
As a result, farmers looking to kill lambs off grass should weigh and select out animals within 5kg to 6kg of their target slaughter weight.
Once drafted, these animals should get priority over lighter lambs.
McClosley also advised farmers to carefully consider their options when it comes to finishing lighter lambs.
Where concentrates will be required, start with a high-energy ration fed at 300g/head/day.
Concentrates can be increased toward a maximum of 1kg/day as grass growth tails off in late autumn. At 1kg/day of concentrate, lambs will be eating very little grass.
When lambs are essentially on an all-concentrate diet, it takes approximately 8kg of ration to gain 1kg of liveweight, or 0.48kg of lamb carcase, said McCloskey.
At a concentrate price of £240/t, it costs £1.76 to put on 0.48kg of carcase.
At a lamb price of £3.70/kg, a carcase gain of 0.48kg/day is worth £1.78, so this barely covers the spend on concentrates, let alone labour, veterinary and fixed costs.
McCloskey concluded that where grass supplies are limited on sheep farms, farmers should prioritise grazing for breeding ewes this autumn, then for heavier lambs close to slaughter weight.
Careful thought should be given to selling lighter lambs as stores now, rather than these animals staying on the farm and competing for limited autumn grass.
Double grass yield by rotational grazing
The average sheep farm in NI grows around 5.4t of grass dry matter per hectare (DM/ha) annually, but there is potential to almost double this to 10t/ha where rotational grazing systems are used, Tara Meeke told farmers at the Lamb Finishing Roadshow.
Tara is an AFBI member and a PhD student at Queens University Belfast at the School of Biological Sciences, with a BSc in agricultural science.
The grazing research project, as part of Tara’s PhD studies, was based on two rotational grazing systems, both measuring 1.6ha in size.
Block one was split into four paddocks, with the second block split into eight.
Each block was stocked with 22 ewes and twin lambs, or 14 ewes/ha.
Lambs had an average date of birth of 8 March and were finished at 45kg liveweight on a grass-only system. There was no difference in liveweight gain from birth to 10 weeks old.
But from 10 to 14 weeks, daily liveweight gain was 60g/day higher in lambs grazing on the four-paddock block.
However, the eight-paddock system grew more grass across the season. Sward utilisation was 12% higher, with 84% of grass grown being grazed by livestock.
Alternatives to EUROP grading
In this presentation at the AgriSearch roadshow, AFBI’s David Farrell gave a brief overview on how technology can be used to assess carcase grade, as well as meat yield and eating quality.
Farrell suggested that the current EUROP system used in the UK is limited, and does not deliver for either farmers or consumers.
AFBI is involved in trials to assess the efficiency of alternative systems for grading sheep. Farrell added that meat eating quality should be incorporated into a carcase-grading system, as there is inconsistency in taste due to a range of finishing systems and breed types.
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