Farm Ireland

Sunday 17 December 2017

Why creep grazing can lift lamb performance and cut weaning stresses

The move to a grass diet for lambs presents several challenges
The move to a grass diet for lambs presents several challenges
Tommy Boland

Tommy Boland

Lambing is complete at Lyons farm with the last ewe lambing last week.

The first born lambs, which represent about 75-80pc of all lambs born, will be on average seven weeks of age this week.

This is an important juncture in the life of the lamb, because at this stage the lamb is starting to become more dependent on grass intake to support its energy needs and daily live weight gain.

Up to about six weeks of age the lamb is largely dependent on the milk supply of the ewe.

This move to a more grass based diet for the lamb presents a number of challenges for the lamb and the farmer.

Firstly grass is less energy dense than milk, so we must ensure that the grass available to our lambs is of the highest possible quality.

This year on many farms there is an adequate supply of grass so rather than grass being in deficit, achieving the correct post grazing sward height, which will influence grass quality in second and subsequent rotations is proving to be more of an issue than in many years. As the lamb becomes more grass dependent it is crucial to maintain grass quality.

At high stocking rates, high litter size, or where it is a struggle to hit target residuals, creep grazing may offer benefits for lamb performance.

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There is evidence to show it may also reduce the weaning stresses as lambs are more accustomed to be separated from the ewes. However it does require suitable infrastructure to carry out

Secondly when the lamb is grazing they are exposed to a wider range of intestinal parasites, with Nematodirus battus causing particular issue for young lambs.

One of the most challenging aspects of dealing with this parasite is the faecal egg count (FEC) test does not provide us with much information as to when we should treat.

The reason is the immature parasite causes significant damage to the animal before they begin to produce the eggs which are measured in the FEC test.

This means by the time we see the eggs in the faeces, much of the damage is done.

To counteract this dosing is performed either on a timed basis (ie five to six weeks of age) or in response to the DAFM parasite forecast. The lambs at Lyons were dosed last week with a white drench to deal with this issue.

While the white drenches have a lot of resistant issues for other classes of intestinal parasites, they are still largely effective in the treatment of nematodirus.

Michelle McManus is focusing her studies on the milk yield of the ewe at the moment.

This involved a rather intensive set of measurements on some of our flock, including intake, milk production, heart rate, blood pressure, infrared thermography (IRT to measure heat production) weight change and BCS change.

This type of intensive measurement allows us to become very familiar with each ewe and her lambs.

It really is stark to see the different levels of lamb performance, when they are being suckled by ewes that on first appearance, appear to be a relatively similar group.

Lamb growth rate from birth to four weeks of age averaged 345 grams per lamb per day.

There are ewes which are good at maintaining their own body condition but their lambs have poor growth rates.

We have ewes which are mobilising a lot of body condition, but their lambs are growing really well, there is a third group who are a mixture of the above traits (holding condition reasonably well and doing a good job on the lambs) and then the final few who are doing neither.

The objective of this research is to identify these more efficient ewes, to develop easily measurable markers to identify these efficient ewes and ultimately to breed a more efficient flock.

Grass growth at Lyons is ranging between 50 and 60kg DM per ha per day over the two weeks up to April 24, but the unseasonably cold weather of last week has reduced this.

Supply is still ahead of demand and there are no current deficit issues.

The major tasks for the coming weeks focus on maintaining pasture quality ahead of the sheep, silage making and hosting a workshop to present the results of the SMARTGRASS project (which examined alternative grazing mixtures and multispecies swards) for sheep production.

Assoc Prof Tommy Boland; Lecturer in Sheep Production, Lyons Farm, University College Dublin. @Pallastb

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