Farmers in this field lab set out to investigate grazing their sheep on lucerne, a legume that is widely used as forage for sheep in New Zealand and valued for its high yield, drought tolerance, protein content, and digestible fibre.
With the effect of climate change on our farming systems becoming ever more acute, testing and demonstrating the potential of using lucerne as an alternative forage crop to grass has huge benefits to the farmers in this group (improved resilience, higher margins as better stock performance and soil fertility benefits for the arable system).
With increasing likelihood of drought in many parts of the UK, livestock farmers, particularly in the east of England, have been struggling with the effect low rainfall has on the available forage for their livestock. Some may have to give up livestock production if solutions are not found.
Lucerne (Medicago sativa), commonly known as alfalfa, is a legume and widely grown throughout the world. It is valued for its yield, protein content, digestible fibre and drought tolerance. Lucerne is used extensively in the “drylands” of New Zealand as a forage crop and much of the guidance and learning on using it for sheep comes from their experiences.
If successful, lucerne will make livestock farming more viable in drier areas previously dominated by input intensive arable production, enabling a return to mixed farming. The theory is that soil health will benefit from the nitrogen fixing qualities of lucerne as well as the reintroduction of livestock (and therefore manure) into arable farming rotations. As grazing lucerne can present a risk of bloat or red-gut in sheep, the research design includes careful monitoring of the sheep for such side effects.
The farmers established 6 hectares of lucerne and 6 hectares of a mixed sward containing ryegrass, white clover, chicory and plantain for comparison. Each field was split into paddocks for rotational grazing and stocked with twin-bearing ewe lambs. Part way through the field lab, the grass, herb & clover field needed further subdividing and five extra permanent pasture paddocks needed to be added to the rotation for the group of animals allocated to the control.
Ewe lambs on lucerne initially had access to fodder beet and a back run of grass to help their gut biology adapt to lucerne. Their lambs were weaned on lucerne only.
This year, all paddocks will be grazed by triplet bearing mixed aged ewes and twin bearing ewe lambs mixed together (last year, twin-bearing ewe lambs grazed on lucerne whilst mixed aged ewes grazed on the comparison grass, clover and plantain mix).
This year, another grazing option has been added so there are now three comparisons:
2) A legume and herb rich sward mix suitable for GS4 option for environmental schemes
3) Grass, clover & herb mix
As lucerne doesn't hold any salt but is high in protein, sheep have access to rock salt and hay to help prevent bloat.
The lucerne field has shown consistent growth and drought resilience. It grew well over a very dry 10 week period this spring/summer, whilst other grass fields browned off, even though the sheep stocking rate is 50% higher for lucerne than for the grass.
For ewe lambs (young lambs which now have their own lambs in litters of two), typically one lamb is taken away and hand-reared whilst the other stays with the ewe lamb, to reduce the strain on the mother. In the lucerne field, both lambs are able to remain because lucerne has 4 times more protein than the other grasses and grows freely, making grazing to get the nutrition required for the day quicker and easier. "The ewe lambs are in the best condition that they've been in". The new lambs will grow up feeding only on lucerne. A hay rack is also set up in the field to be eaten by the sheep try to counteract the richness and bloating effects of lucerne.
This field lab was featured in BBC 4's Farming Today programme on 29th July.
The pregnancy scanning results of the sheep revealed higher fertility rates for the sheep fed on lucerne, linked to better weight gain and body condition scores.
Around an acre of the lucerne was affected by winter flooding and was under water for 2 weeks. It appears to be recovering but growth has been hampered compared to the rest of the lucerne.
Open session took place where farmers learnt from the experiences and research of Prof. Derrick Moot, who has years of experience researching lucerne grazing in dryland systems in New Zealand. He discussed how to design a grazing system to make the most of lucerne's excellent spring growth.
· Key learnings on establishment and growth:
Key messages on livestock grazing preferences, health and management:
Nitrate poisoning can very easily kill. Be careful about flushes after sudden rainfall. Heavy rainfall after drought causes a sudden uptake of nitrate in the plant. If conditions are dull (no sun), there is not sufficient energy to convert nitrates into proteins. It is important to wait until the sun comes out, then graze.
One of the farmers' observations so far: "We have just started lambing on the lucerne seems to be no problems so fair with lambs popping out and to their feet as normal, also no visible signs of any adverse affects on the ewes and plenty of milk about... so all is well (finger crossed). The ewes have done a nice job of taking out most of the annual weeds and the cover is still building". Further measurements to come...
Blood samples have been taken from sheep fed on lucerne and those in the control group (no lucerne). The samples will provide data on energy, protein and trace elements - cobalt and selenium.
18th March 2020
31st July 2020
3rd March 2021
Liz loves working with progressive farmers who want to challenge their sheep and beef systems - particularly those introducing livestock into an arable business. She has a technical background in sheep and beef fertility and breeding and grass and forage management. Since visiting New Zealand in 2008, she developed tools and techniques to help UK beef and sheep farmers to improve their knowledge of grass and forage management. She is a partner in her family farm with arable, sheep and beef enterprises in south Lincolnshire.