Lamb growth rate is holding up well
Published 29/07/2015 | 02:30
Despite the recent rainfall, grass growth is still hovering around 40kg dry matter per hectare per day on the sheep grazing ground at Lyons. This is probably partly linked to the slightly lower than average air and soil temperatures for this time of the year.
Lamb growth rate is holding up well however. In the first two weeks after weaning we saw a drop in lamb growth rate to 190g per day.
These growth rates have recovered to 225g per day. This is quite positive considering the fastest growing lambs from these groups have been slaughtered.
Looking at growth rate figures over two week periods can be sometimes misleading, so when we look at growth rate from birth to 18 weeks of age we see a figure of 265g per day.
The most recent group of lambs to be slaughtered were sent to the factory on Friday July 15.
These had an average live weigh of 45.5kg and killed out at 44pc to give a carcase of just over 20kg.
Ewes were treated with pour-on to prevent fly strike on July 15 and lambs were treated with a short withdrawal product on July 20.
As we are currently running eight separate groups of sheep in the experimental farmlets of four groups of lambs and four groups of ewes the workload with gathering the sheep is greatly increased.
All sheep were foot-bathed last week also, but this is more of a preventative action at the moment as lameness is well under control within the flock.
Lambs continue to be dosed in response to faecal egg count (FEC) results. On the multispecies grazing study, all lambs are being assessed for parasite burden using FEC's every two weeks.
This is a very laborious process and takes about 10 days for our team to complete, along with all their other tasks on this study.
We have selected at random 12 Sentinel lambs within each group which are assessed immediately post collection and use this information to make our dosing decisions.
All groups were dosed pre-weaning at 10 weeks of age for nematodirus control.
Two of the four groups have received one additional dose, when FEC's exceeded 400 eggs per gram, and the other two groups have not yet received a further dose, with FEC's at 18 weeks of 210 eggs per gram.
These are the two mixed species swards and this finding would tally with work conducted in New Zealand. It is very early stages in this study and the full picture will require a lot more data collection.
We are now turning our attention to identifying ewes for culling from the flock and the retention of replacement ewes lambs is underway since lambs began to be drafted for slaughter.
Reasons for culling include, mastitis, persistent lameness, poor teeth, prolapse and poor mothering ability and poor lamb performance. The latter three are facilitated by using the Psion handheld device and electronic identification (EID) of our ewes.
This is very useful as it allows an accurate record of problems that may have occurred four months ago to flash up as the ewe is scanned.
Poor lamb performance to weaning is a good indicator of ewe milk yield and milk yield is highly repeatable from one year to the next.
When selecting ewe lamb replacements we select fast growing twins and triplets in an effort to select for prolificacy and milk yield.
By selecting on growth rate to weaning alone you run the risk of selecting a lot of singles, potentially reducing litter size.
Dr Tommy Boland lectures in sheep production at UCD's Lyons Farm