After years of variable performance, store lamb finishing systems have returned a margin for most in the last two years.

As reported in the sheep trade price overview on page 8 of this week’s Focus supplement, demand for store lambs intensified earlier this year with higher competition levels. While prices have eased back in recent weeks, the trade can still be described as solid.

Mart managers report many new faces at sales, including beef farmers who have surplus grass and view the system as safer than competing for more cattle.

Whatever enterprise you are operating, the decision on purchasing store lambs should not be solely dictated by having a surplus of grass. Economics need to be taken into account and the best way of doing this is to complete a finishing budget.

Variables will differ between farms, but one aspect that should remain constant is using realistic costs and levels of animal performance.

Purchase weight and price

Weight, price and quality of lambs should all be taken into consideration together. The first factor to determine is what type of lamb suits your system best. If grass supplies are limited, then you should be in the market for a short-keep store lamb weighing 38kg to 40kg upwards.

The mistake is often made of having a figure in your head of what you are willing to spend, with weight and quality of lambs compromised to achieve a target purchase price.

Allowing this to happen can be the costliest mistake, as purchasing a lighter lamb than suits your system, or what grass supplies cater for, can lead to high levels of supplementary feeding being introduced to finish lambs, with costs soaring quickly.

As a rough guide, a sward with grass height of 8cm to 9cm should provide grazing for 10 lambs per hectare (four/acre) for 10 weeks, while a lower sward height of 6cm to 7cm will provide grazing for seven lambs/ha (about three lambs/acre) for 10 weeks. This is based on a good-quality sward where there is not a butt of poor quality or high proportion of stem at the base of the sward and reasonable levels of grass utilisation (70% to 80%) are achieved.

While many don’t factor a grass cost into finishing budgets, a ballpark figure of 7c to 10c per day can be used to calculate grass costs. This may also be available in the case of a short-term or temporary grazing agreement, which should also be considered when developing budgets.

Realistic performance

Performance will be greatly influenced by sward quality and potential of the lambs you purchase. A good performance target for lambs on good-quality grass at this stage of the year is 180g to 200g/head/day.

Depending on previous management, lambs short of flesh may achieve compensatory growth for a period, while on the flip side lambs that have been very poorly managed with their growth stunted will take a few weeks to start performing.

Where selecting lambs to purchase, avoid competing for lambs where there is a wide range in weight, as while the purchase price may look appealing, it will be the lighter lambs that will end up running into higher costs than expected.

The exception to this is where there is scope to carry lambs longer-term and it is seen as feasible to draft those coming fit for slaughter regularly.

Performance reduces as the season progresses in line with a drop in nutritional quality of grass and often diminishing levels of grass utilisation.

Performance targets on a grass-only diet should be eased back to 150g/day to 170g/day as you progress into September, with performance dropping to 100g/day into late October and November, as daily liveweight gain is tested most in periods of poor weather. Thereafter, performance can be highly variable.

Unless you have a good run of dry ground or access to forage crops, it is realistic to factor some level of concentrate supplementation for lambs that will not be finished this side of Christmas. This is especially the case for lighter mountain or hill lambs.

These finishing systems will be covered in much greater detail in the coming weeks using the good work being completed on hill lamb finishing systems in Teagasc Athenry.

Table 1 looks at the costs accumulating from varying concentrate supplementation levels based on purchasing a simple barley-based three- or four-way ration with minerals, costing €250/t loose or in half tonne bags. Costs will increase significantly where purchasing concentrates in 25kg bags.

The table looks at supplementing for 10 and 12 weeks to show what costs can run to, but if supplementation is required at higher levels for this length, letting lambs develop a frame at grass and indoor ad-lib finishing systems may be more economical.

Miscellaneous costs

While concentrate costs can increase quickly, so too can miscellaneous costs. A reasonable figure to factor into account is €7 to €8/head.

This includes a cost for mortality, veterinary, transport and other costs, such as purchase and sale costs, which can range from €1.80 to €3 depending on final destination of the sheep. Shearing will add another 70c to €1 to costs when the value of wool is factored into consideration.

Where lambs will be retained longer-term and could be finished on forage crops, crutching will help in keeping them clean and in optimum condition for slaughter.

The important health costs that should be factored into the budget are clostridial disease vaccine, worm and possibly fluke treatment, dipping or treatment for external parasites and foot-bathing.

As is the case when bringing any animals on to the farm, it is important to operate a quarantine procedure, with treatment to guard against worm resistance critical.

Teagasc advice recommends using a combination product such as the recently released wormer Startect or a moxidectin injection and the monepantel drench Zolvix with animals retained off pasture for 24 to 48 hours.