Ensuring there will be sufficient grass for your ewes to graze on is an important consideration to bear in mind when aiming to finish lambs.
The head of the sheep knowledge transfer programme at Teagasc, Michael Gottstein, has discussed the challenges sheep farmers face due to difficult weather, impacting lamb performance, grass growth, and the need for strategic lamb drafting and sales to ensure sufficient resources for ewes.
Gottstein said it has been an “unusual and difficult year” for sheep farmers as the spring weather resulted in “most farms seeing lamb performance being hit”.
He added it is likely that on many farms lamb weaning weight will be back across the board.
In addition to a reduction in animal performance, Gottstein said that grass growth has also been challenging on most farms.
Depending on stocking rate, grass growth rate and the quantity of fodder available on the farm, he said “it is prudent to put in place a plan for lamb drafting.
“In years where lamb performance is compromised the biggest challenge is to get lambs off the farm in a manner that ensures there is sufficient grass available for the ewe flock.
“There is little point in feeding lambs into the back end of the year on grass that will be required to maintain the ewes,” Gottstein added.
Assess weight categories of lambs
Gottstein recommends to weigh lambs and identify what proportion of them should fall into the following weight categories:
Less than 25kg
These are very light lambs that will not be finished in this calendar year. Feeding high levels of concentrates to them is likely to be uneconomical.
The best option for these lighter ones is to allow them to grow on grass/forage until they reach 35kg.
Once over 35kg, they can be placed onto concentrate based diets and finished economically.
25 – 30kg
These are light lambs that again need to be given a chance to grow before being put on a finishing diet that contains significant levels of concentrates.
Depending on forage availability on farm, these lambs are also a cohort that could be considered for selling as stores.
30 – 35kg
This cohort of lambs are the faster growing and better performing ones on the farm. All going well, the last of these should be drafted by the end of October.
This group will be feeding lambs into the finishing group as they exceed 35kg liveweight.
35kg+
This is the finishing group and represent the faster growing lambs on the farm.
With good grass, a focus on flock health and some concentrate supplementation they should finish quickly (1.5kg – 2kg liveweight gain/week).
Optimum supplementation rates for this cohort of lambs is between 500g and 750g/day depending on grass supply and quality.
By targeting concentrates at the finishing lambs it reduces the amount of meal being fed when compared to feeding all the lambs.
Gottstein said the finishing group allows for consistent lamb drafting and as lambs in the lower groups increase in weight they can be moved up into the finishing groups.
It is also important to keep on top of health issues. Lameness, parasites and mineral deficiencies (in particular cobalt) can have a significant impact on lamb performance.
There is little point in feeding expensive concentrate feed to lambs that are lame, mineral deficient or have a belly full of worms, Gottstein added.