Slaughter performance

There are regular reports of lambs drafted from a grass-only diet killing poorly. Reports indicate that kill-out percentages as low as 41% to 43% have been recorded in ram lambs with an average cover of flesh.

In the worst affected cases, lamb carcases have fallen below the minimum carcase weight of 17kg.

As such, it is important to assess lambs carefully and where necessary, increase the drafting weight accordingly.

The potential to draft lambs at lighter weights ranging from 42kg to 44kg will only be feasible where lambs are young, possessing a good flesh cover and have a good kill-out potential, i.e. are well-conformed lambs capable of delivering a high-quality carcase.

Typical kill-out percentages reported are averaging in the region of 44% to 46% for lambs finished on good-quality grass swards where there have been no issues with supplies.

Top-quality lambs and lambs with access to meal are achieving a kill-out 1% to 2% above this range, with lambs finished on ad lib concentrates from 46% to 49% depending on the type of lamb on hand.

Where strong ram lambs are present with an average-to-good cover of flesh, then drafting weights will typically need to be upwards of 45kg and closer to 48kg to 50kg where the aim is delivering a heavier carcase.

If it is your first draft and you are in doubt, then drafting a smaller number to assess slaughter performance may be the best option. If problems exist then consideration needs to be given to increasing the energy intake of the diet.

Weaning hill lambs

Last week we touched on options available for lowland flocks weaning lambs. Weaning is also taking place in some hill flocks and the recommendations are similar. Lambs should be assessed on weight – less than 25kg; 25kg to 30kg; 30kg to 35kg and greater than 35kg.

For farms with a high percentage of improved or green grazing and also utilising a percentage of crossbreeding, the aim should be to have upwards of 80% of lambs weighing in excess of 25kg.

On harder hills where ewes with a lower mature weight are running and herbage quality is much lower, there could typically be 30% to 40% of lambs weighing less than 25kg.

Lambs less than 25kg are a longer term prospect, and finishing decisions with such lambs also need to account for the growth potential that is present.

Where lambs have scope to feed in to heavier weights, the optimal finishing programme is to graze lambs and allow them to develop a frame before finishing. The other option is where there is a market outlet for lambs weighing between 12kg and 16kg carcase weight.

A similar scenario is applicable to lambs weighing 25kg to 30kg, with the difference here being more scope to start progressing with finishing diets.

The most options are available to heavier lambs, with these realising a higher sales value if sold live or representing a lower cost in finishing.

There is more scope to transfer lambs weighing 30kg to 35kg and upwards of 35kg on to a finishing diet, but exploiting the most from grass will also deliver significant benefits in achieving cheap weight gain.

The Teagasc store lamb finishing calculator which can be found at teagasc.ie/animals/sheep/financial-management is a good aid in making decisions.