Sheep: Index score not the only criteria used to select replacements
Published 23/09/2015 | 02:30
Grass growth has recovered well on the sheep grazing block at Lyons and is now running at 35kg/ha of drymatter (DM) per day.
In addition demand is continuing to decline from the lamb flock as these animals are slaughtered.
Almost 80pc of all lambs on the mixed species study have now been drafted for slaughter at an average liveweight of 46kg.
The mixed species swards continue to outperform the perennial rye grass only swards but as always it's important to remember that this is just the first year of the study and we need to look at the persistency of these swards before any conclusions can be drawn.
Lamb growth rate remains strong at just under 200g per day and, as we are down to the poorer 20pc of lambs within the flock, this is quite acceptable.
The Ag Science students arrived back in UCD two weeks ago and on their first day back the fourth year animal and crop production students and animal science students visited Lyons for practical classes.
The focus of the sheep class was lamb selection for slaughter and flock preparation for the breeding season.
Ewes had their most recent body condition score (BCS) check in late August. The flock average was three and we will target over 3.5 at mating.
This gives us approximately six weeks for the ewes to gain just over half a BCS (6-7kg live weight), which given the current grass supply and quality is more than adequate.
Our plan is to mate 100 ewe lambs again this year. We use a number of methods to select our ewe lambs.
As we are members of the Sheep Ireland Central Progeny Test (CPT) scheme we have star ratings for all our main crop lambs.
We look at the replacement index ratings when selecting our ewe lambs and target five stars.
We do not rely solely on the star ratings as occasionally a highly rated lamb will not reach our target live weight (at least 45kg) at mating, or may have some other functional issue that we do not want in the flock, so visual assessment is also crucial.
Our ideal ewe lamb is one that will be prolific, a good mother with minimal lambing difficulty and produce plenty of milk.
In the absence of star ratings (which encompasses this information) how do we select these lambs?
We look for the heaviest lambs at weaning (or ideally eight weeks of age but very few farmers will have this information) coming from twin and triplet litters whose mothers did not give problems at lambing time. This is our objective, but each farmer must decide what they want to achieve from their flock and select accordingly.
Our ewe lamb selection is ongoing since the first draft of lambs for slaughter. Any females that meet our criteria for replacements are separated from the main flock once they reach 45kg and run as a separate group.
These animals are the future of the flock and merit additional attention. These lambs will hopefully reach 52/53kg liveweight at mating.
The forage rape, which was sown in early August, has established well and will carry the ewes during late November and early December. Preparation for sowing involved discing the stubble, following which the seed was broadcast and rolled in. CAN was applied at 46 units per acre.
Dr Tommy Boland lectures in sheep production at Lyons Research Farm, UCD. Email: firstname.lastname@example.org
Ewes and ewe lambs will be sponged on October 5 and sponges removed on October 17 for AI on October 19. The ewe lambs will be bred using natural service rather than AI.
We will begin closing paddocks for spring grazing in mid-October also. Our ewes will be turned out to the silage ground in mid-March and then moved to the hill in mid-April.
As the hill has a late start to the grass growing season that too will begin to be closed in mid-October.
Ewes and ewe lambs will receive their trace elements in the coming weeks in preparation for mating also.
Foot care is also a priority as we want to have any lameness addressed prior to mating. This year has proved to be a good one from a lameness point of view, but this is due to constant attention from Stephen Lott.
Any lameness should be sorted prior to mating as we don't want to disturb ewes in the first month after breeding.