Farm Ireland

Sunday 18 March 2018

Act fast if your ewes are short on condition


Tommy Boland

Tommy Boland

The UCD sheep flock consists of 350 midseason lambing ewes, and is an important teaching and research resource for undergraduate and post-graduate students studying Agricultural Science in UCD.

It also serves in providing information to the wider sheep industry. Animals not used in research are run on a commercial basis and the flock is one of the central progeny test flocks for Sheep Ireland.

Our most recent batch of 67 lambs was slaughtered on Friday, July 29. These lambs averaged €99 with a kill-out percentage of 46pc. This is down on 16 lambs slaughtered on July 21 which had a kill-out percentage of 48pc and left €103/head.

We would be reasonably happy with the kill-out percentages and you would often see lower values at this time of year.

Lambs are grazing the second rotation after silage at this stage and there is a good clover content in the swards. Grass growth in the week-ending August 5 was 57kg DM/ha/day, significantly up on the previous week.

Half the lambs received a cobalt drench every fortnight, while the remainder received a cobalt bolus at weaning. Lambs receive a worm drench on a monthly basis and we rotate products every other year.

We are weighing lambs again today and will draft them from 42-43kg liveweight. We monitor growth rates on a fortnightly basis. Weaning took place on June 16 and since then lambs have gained 210g/day or just under 1.5kg/week. Ewe lambs are growing 25g/day slower than the wethers. We plan to breed about 100 ewe lambs again this year, which have been selected at this stage.

We select the majority of our ewe lambs based on the Eurostar ratings, although an additional 15 ewe lambs will be selected from the mule, greyface and halfbred progeny on the farm.

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Any lambs failing to reach 45kg at mating will not be bred, with the exception of the crossbreds listed above, which we do not breed as lambs.

The ewe lambs will be bred along with the mature ewes with a target mean lambing date of March 12. This will mean the ewes and lambs will be mated on October 17.

The ewe lambs will only get one repeat service whereas the mature ewes will get two. We were happy with the performance of the ewe lambs last year which scanned 1.4 lambs/ewe mated. Their lambs were about 2kg lighter at weaning than the progeny of the mature ewes.

UCD's chief livestock supervisor, Stephen Lott, tells me these hoggets were in good shape at weaning and he will continue to manage them as part of the main flock.

For mid-March lambing, now is the time to start looking at the condition of the ewes. Having your ewes in the correct body condition score (BCS) is key to a successful mating and lambing performance. It is important to remember that it is not something that can be changed overnight.

The target BCS for a lowland ewe is 3-3.5 at mating -- hill ewes will be anywhere between 0.5 to 1 full condition score less than this. Getting this wrong will reduce the number of live lambs born, increase the number of barren ewes and increase the length of the lambing period.

Having ewes over or under-conditioned at mating can cause problems, but generally it is under-conditioned ewes which are the main concern. Data from Britain suggests that one in five ewes will have a BCS of less than 2, while only one in 25 will have a BCS of 4.5 or 5 at mating.

An excessive number of thin ewes in the flock usually results from delayed weaning, poor quality and/or quantity of grass or underlying health problems.

With good grass, a ewe will gain one condition score in about six weeks but with poorer quality grass this may be closer to 10 weeks.

Increasing a lowland ewe's BCS by one full point is roughly equivalent to a live weight gain of 6-7kg. Addressing this now will eliminate a lot of problems later in the year.

Dr Tommy Boland is a lecturer in sheep production and ruminant nutrition at Lyons Research Farm School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Newcastle, Co Dublin

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