Weighing up store lamb options

Damian Costello and Dr Frank Campion write on the options available to farmers finishing store lambs this autumn, focusing on the important aspects of budgeting and feeding.

With 2024 being a challenging year for lamb performance, many farms that run a breeding ewe flock are assessing their options for the remaining lambs on the farm.

In particular, with a reasonable store lamb trade, many will be asking themselves the question whether to sell stores or finish their remaining lambs.

Factors to take into account include: the number and weight of remaining lambs; estimated time to finish; availability of grass; availability of suitable housing if needed to finish indoors; as well as cash flow / credit situation.

On the purchasing side, farms that run a store lamb finishing enterprise are figuring out what they can afford to pay for stores and still allow for a decent margin on their investment. The two main factors that determine the profit margin in finishing lambs at this time of year and into the winter are:

• Current price of store lambs vs expected price for lamb carcass when lambs are due to finish
• Cost efficiency of carcass gain during finishing period.

Prepare a budget

Whether finishing homebred lambs or buying in lowland or hill lambs to finish, the first important step is to have a plan in place. While the price received is largely outside of the producer’s control, the cost of getting the lamb to the point of sale can be controlled.

A useful tool to estimate the cost of finishing store lambs on a grassland-only farm is the Teagasc Store Lamb calculator. It will also give a good estimate of when lambs will be fit for market. This excel programme allows you to input figures such as weight and price of lambs, concentrate price per tonne, as well as standard costs for veterinary, transport etc. The estimated finish date along with total concentrate required will be calculated with slaughter value of lamb being based on historic prices paid in previous years on the estimated slaughter date.

The Teagasc Store Lamb Calculator has recently been updated and is available here, or from your local Teagasc advisor.

When calculating a budget, it is important to accurately assess what lambs are left on the farm by weighing remaining lambs (or at least a representative proportion) and dividing it up into weight categories, i.e. <30kg, 30-35kg, >35kg. By dividing up the lamb crop like this, it will allow you to accurately assess how much time and feed it is going to take to finish the lambs.

Equally when purchasing lambs, it is important to consider that with lighter lambs vs heavier lambs you will have to adjust the number purchased to allow different residency periods on the farm.

Dietary options

There are a number of different options for finishing lambs during the autumn/winter months and each will give different levels of lamb performance. The main options are grazed grass, ad-lid concentrates and forage crops.

No one option will suit every farm/system and sometimes a combination of some or all the options will work best. Listed below are some of the key considerations for each of the three main diet options of ad-lib concentrates, forage brassicas and grazed grass.

1). Grazed grass

It is important to consider the implications of keeping store lambs will have on overall grass demand into the autumn. During the autumn and winter months in a lamb finishing systems, grass should be targeted at delivering cheap weight gain. If we assume grass availability is not an issue, the most economic system involves achieving as much gain as possible from top quality grazed grass followed by a period of meal supplementation - either indoors or at grass to finish lambs. The aim should be to regularly offer lambs fresh grass going in to covers of 1,500-2,000kg DM/ha (grass height of 8-10cm). Several studies have shown a positive impact on performance from moving on lambs when grass height reaches 6cm, thus not forcing lambs to fully graze out swards.

The use of temporary fencing optimises utilisation and allows fresh grass to be offered to lambs every 3 to 4 days. It is also important that any flock health issues such as parasite burden, lameness etc. are properly addressed and are not negatively impacting lamb performance at grass.

Table 1. Typical performance of lowland terminal sired lambs on good quality pasture

As outlined in Table 1 with excellent management, there is potential for lambs to gain 1kg per week live weight during this period on a grass only diet. For example, light lambs weighing 25-30kg in August should be approaching 40kg after 12 to 14 weeks of good grass and ready to start the finishing period.

2). Ad-lib concentrates

The biggest cost in any lamb finishing system is concentrate supplementation. Aim for high quality ingredients and ensure the feed is specifically intended for intensive finishing of lambs. It should be balanced for minerals and include 0.5% ammonium chloride to help avoid issues with urinary calculi. Most finishers will look for a good value for money commercial ration in pelleted form. The pelleted feed is less attractive to birds and avoids lambs sorting and selectively leaving behind certain ingredients as can potentially happen with a coarse ration. There is an opportunity for significant savings per tonne where buying in bulk is an option.

Where lambs are on ad-lib concentrates, it is important that they are gradually built up to ad-lib feeding levels. Increase the amount offered by 200g/day every 3 days until lambs are ad-lib feeding. It is also important where housed indoors that you ensure that the sheep house is well ventilated and adequately bedded with straw in the case of straw bedded sheds.

Performance will vary by breed and sex but on average lambs will be growing in excess of 200g/head/day or putting on 1.5-1.8kg live weight per week. Regular weighing is important to ensure lambs are drafted at the correct weight and assessed for muscle and fat cover prior to being drafted for sale.

3). Forage crops

Lambs grazing on forage crops, such as forage rape and hybrid brassica, won’t perform as well as lambs housed indoors on ad-lib concentrates but can perform satisfactorily and finish off these crops where properly managed. Hill cross lambs will grow at approximately 140g/head/day once adapted onto the crop and kill out around 44-45%, depending on breed and sex of the lamb.

Grazing forage crops in the winter for lamb finishing requires careful management and lambs need to be weighed regularly once approaching target weights. Fields need to be divided in blocks to allow lambs access to fresh forage every 2-4 days. Care should be taken to ensure lambs are not forced to overgraze the stalks of the crops, as this will reduce animal performance. Also check the correct guidelines for grazing these crops in terms of lie back space and buffer margins for compliance purposes. Where lambs are grazing forage brassica crops, the following guidelines are essential to maximise performance:

• Introduce lambs slowly to brassica crops to avoid digestive upsets over 7-10 days. Lambs will take 3-4 weeks for gut fill changes to take place fully.
• Measure crop yield and allocate grazing area accordingly, average utilisation will be approx. 60%, but will vary with weather and pre-grazing yield
• If running short on forage, consider feeding concentrates with the crop to boost performance.

Estimated finish date

The aim is to reach the maximum carcass weight that meat processors are paying on at the time of slaughter. On the other hand, regular drafting as lambs come fit is essential to ensure the target carcass weight is not being exceeded. This is particularly important where high levels of concentrates are being fed in the finishing period.

In terms of adding value through a carcass price rise, late February to April has been a good time to slaughter hoggets in recent years. For lighter stores, this is a good period to aim for in terms of finishing hoggets before spring lamb comes on the market. Some producer groups have arrangements with factories to finish smaller framed hill breeds at lighter carcass weights.

An information booklet on Store Lamb Finishing is available here.

The above article first appeared in the September/October edition of Today's Farm. For more information and to access the latest issue of Today's Farm, click here.