Malcolm Stewart

A concerted effort to lower production costs by lambing outdoors has driven a pedigree Borders flock towards breeding lambs resilient to the cold.

Outside lambing has taken place for two years now at Brotherstone Farm, Melrose, where Suffolk and Lleyn breeder Malcolm Stewart is using a “cold weather test” to assist him in lowering two major costs.

He says labour and feed requirements are significantly reduced by lambing outside, but to ensure success the right preparation is required and he has called on the services of Lincoln University in New Zealand to help him.

See also: Fine-tuning ewe diets lifts lamb liveweights

Mr Stewart believes the future of sheep farming revolves around lambing outdoors and is working on a breeding plan for a range of specific traits, with the latest being cold weather tolerance.

“Lambing outside has been a solution to some things but it has brought new challenges for the flock,” admits Mr Stewart, who tested 26 tups for the “resilience gene” in 2015.

“We will look at breeding for worm and foot-rot resistance in the future but you can only breed for so much at once. Lamb mortality is economically important and we started with cold-weather tolerance because if they’re dead you can’t go any further.”

Cold weather tolerance test

Blood tests were taken on the top five sires from each of the five Suffolk families of Brotherstone’s Sandyknowe flock last year to assess how likely each sire was to produce lambs with the ability to mobilise brown fat, broadly categorised as A, B or C.

Studies conducted at Lincoln University’s laboratory designated the alleles of Malcolm’s sires as “A”, the best score.

The test, which cost Mr Stewart £920, categorises the beta3 andrenergic receptor (ADRB3 gene) and Malcolm was “pleasantly surprised” by the outcome and able to further select 10 sires to breed with his Suffolks and Lleyns.

A key element of lamb survival, the ability to mobilise brown fat is part of a range of thermogenesis traits which act as a heat source for the lamb within its own body and can be critical in early life to assist in standing and sucking.

This in turn helps realise the weight-gain potential of the Sandyknowe progeny, capable of achieving 500g daily liveweight gain on grass for the first three to four months.

“This means lambs can be marketed in the middle of August if they are born in April,” says Mr Stewart. “But unless they get good amounts of quality colostrum in the first five to six hours of life they will never thrive and realise that potential.”


Lambing all sheep outside took place for the first time in the fiercely cold spring of 2013.

Both Suffolk and Lleyn ewes are fed the same ration and are outwintered on rough grazing and more productive grass leys, with 200g/day of wheat grains supplemented, if needed, to maintain body condition through to lambing.

What is the brown fat test?

Jon Hickford, Lincoln University, New Zealand, says young mammals have a metabolic pathway allowing them to burn fat by producing heat from non-shivering thermogenesis, which is unfortunately lost as mammals age.

“Many of our NZ outdoor lambed Romney-cross sheep are AA on testing (this includes the Perendale and Comport breeds).

However Bs creep in with new breeds and Cs when any Merino or crosses thereof are typed.

Terminal sire breeds often have Bs too, reflecting I suspect a lack of selection for survival in these breeds.

A, B and C scores represent different forms of the gene, of which we know of at least 15 variants.

Sheep get two scores because their genetic material is duplicated, but they only pass half of it on to their progeny.

For example, an AC sheep passes on an A to 50% of their progeny and a C to 50% on average.

“The test makes farmers focus a lot more on lamb survival overall. I tell farmers that, gene test or not, they have to lift their game such that they all get down to the 5% or fewer lamb deaths we see in our NZ Romney work.”

“If it snows we put silage in for them,” adds Mr Stewart, who saw protein levels drop in silage this year, a trend for the region in general. “Normally, we aim for silage at 13ME and 12ME for protein, balancing it up accordingly.”

Lambing percentages of 130-140% are targeted this spring, with the focus on lambing fewer singles, more doubles and as few triplets as possible. Prior seasons have seen Lleyns lamb at 165% and Suffolks at 155%, weaning about 20% less.

“Hopefully the nutrition the flock receives will achieve the 130-140% level ruling out too many triplets, which you obviously don’t want if you are lambing outside.”

Cobalt has long been an issue on the farm, leading to a B12 injection, costing £12 a ewe, being administered for the first time in October 2015.

This is a long-term issue on the sandy loam soil at Brotherstone which locks up cobalt reducing B12 in the grass.

“The little cobalt on the farm has a major impact on vitamin B12, which has a knock-on effect on lambs getting up to suck,” says Mr Stewart.

The New Zealand produced injection is expensive but Mr Stewart is already seeing body condition improve in his ewes after administering the injection five to six weeks before tupping, which falls in early October at Brotherstone.

Veterinary advice recommends assessing cobalt levels in the animal as levels in a grass diet are affected by pH, grass type, clover content, grazing pressure, sheep age, genetics and stage of life (growing, pregnant or lactating).

The injection, available through Mr Stewart’s vet, is used in conjunction with a selenium, copper and cobalt bolus.

“Alarm bells started to ring about the mineral imbalance on my farm when it became glaringly apparent that more and more of my customers had lambs consistently outperforming my own,” says Mr Stewart, who sells sires to farms from the south of England right up to the Isle of Skye and Shetland.

“It was then that we thought about ways to address the deficiency, which at the moment sees us trying the B12 injection.”

Genetic progress

Maternal ability also plays a key role in lamb survival and since 1999, Mr Stewart has undergone a culling policy of both Suffolks and Lleyns to select for maternal genetics capable of meeting commercial requirements, namely to produce two lambs that can get up and suckle.

Driving this change was a very simple yellow record card for every ewe, he explains.

“We noted down date of birth, lamb gender and a comment on how each ewe lambed, with an additional comment on the back of the card on how the lambs looked at weaning time.

A “two strikes and out” policy was operated on the Suffolks to assess whether sheep produced viable lambs that got up to suck. Lleyns only had one strike and were out.

Then, from 2002 to 2004, New Zealand genetics were introduced, seeing 30 ewes AI’d each year to increase hybrid vigour. Mr Stewart is now considering “opening up blood lines” again with another New Zealand sire.

Borders flock

Farm sale

A breeding ethos of driving a pedigree sheep flock for commercial purposes eventually took Mr Stewart away from public sales, to focus on marketing stock privately, including an on-farm September sale held for the second time in 2015.

Mr Stewart admits the economics of feeding rams for public sales did not make sense and his “natural looking” tups appear out of place at events such as the Kelso sale, at which Mr Stewart was a major vendor for many years.

Following general auction sale rules, the Sandyknowe sale typically sees about 50 Suffolks and 10 Lleyns go under the hammer on the second Thursday of September, with Mr Stewart quick to stress the differences to a typical ram sale.

“If you show and sell your sires they need to be very well presented in a public arena,” explains Mr Stewart.

“People criticise breeders for producing big tups but that is what many people want to buy.

“We are trying to breed sheep that perform on grass, mimicking a commercial system with a pedigree flock as much as possible.”