'God's plant' the saving grace

For Murray and Fraser McKnight, feeding lucerne to grow out lambs and ewes is a “no-brainer”.

11-08-2010 | Lynda Gray

Lucerne has huge potential in Central Otago.

That's the short and sharp verdict of Fraser and Murray McKnight who are part of Lucerne for Lambs, a Sustainable Farming Fund project looking at the use and management of lucerne beyond hay and silage.

One goal of the project is to investigate the potential of lucerne for earlier finishing of lambs. It is drawing on practical advice from Lincoln University plant scientist Derrick Moot.

He calls the legume crop "God's Plant" in dryland environments such as Central Otago because of its ability to access water and use it more efficiently than a nitrogen-deficient grass.

Although the project has been running since only late last year the initial results from a grazing trial on the McKnights' Ida Valley property have convinced them that feeding lucerne to grow out lambs and ewes is a "no-brainer".

This year their average weaning weight until January 3 was 33kg.

"That's the best ever and it was due to the lucerne," Fraser says.

"It's just a pity that the drought slowed growth (from then on)."

For the trial the McKnights rotationally grazed 40ha of lucerne with two mobs of lambs and ewes (260 twin-bearing and
235 single-bearing) from early in October.

At the beginning, the lucerne was producing around 1800kg/DM/ha. The ewes and lambs were grazed around hot-wired blocks at 10su/ha and moved every seven to 10 days for 45 days.

The first draft of 261 lambs, including some twins, left the property on December 17 and achieved a 17.1kg carcaseweight (CW) average.

"As a rule we don't get a draft away before Christmas."

The ewes' condition score improved 1.5 on the lucerne with average weights of around 90kg.

After the first rotation the lucerne was left until flowering kicked in then grazed again by mobs of weaned lambs.

"We had to because we had nothing else," Murray says.

They had concerns about the possibility of lamb deaths from grazing the high-quality crop but, apart from a couple of losses, they had no animal-health issues.

"One ewe and lamb died right at the start but we were told that was because we didn't have enough fibre for them to graze," Murray says.

The lucerne was managed according to Moot's "bend test", grazing it to the point where the stalk breaks when bent.

"It means they're getting the high-value feed but if they graze below that point they're into the lower value, woody stalk stuff."

Lambs were drafted off the lucerne until mid-April.

The 2009-10 average carcaseweight of 16.9kg was about half a kilo short of last year but pleasing considering the drier-than-dry season.

More significant was that the McKnights got more lambs away sooner.

"It lightened the load and that's what Derek hoped this trial would prove," Fraser says.

Using lucerne as a finishing crop has required a change of mindset and management but it has been worth it.

"It's worth so much more than just for winter feeding," Murray says.

Initially they considered growing lucerne on everything below the water race but now think they'll expand it further to the hard to irrigate parts of the property which could total around 120ha.

"We don't know where the ideal balance is. We're told it's around 30%."

Their immediate plan is to simplify grazing management of the lucerne by subdividing into 6ha blocks.

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