Farm Ireland

Saturday 20 January 2018

Lamb output per ewe

A well thought-out policy is the key to improving performance and profitability rules on replacements

Michael McHugh

On average, 20pc of the ewe flock is replaced annually. In the 2009 eProfit Monitor flocks (see table 1, below right), the average replacement cost was €17/ewe. However, there is a huge variation between farms.

The annual replacement cost will be influenced by the option used for flock replacements. Table 2 (below left) shows that putting replacements in-lamb in their first year will result in lower replacement costs. However, extra management costs, such as labour, medicines and mortality, may be associated with mating ewe lambs.

A well thought-out replacement policy, combined with flock management, is the key to improving the performance and profitability of sheep flocks.

The breeding of replacements will influence the productivity of the flock. Having ewes in the correct condition at mating will maximise the litter size of a particular breed. Most breeds will be capable of producing 1.4-1.5 lambs weaned per ewe to the ram with good management. However, higher weaning rates can only be achieved with the selection of prolific replacements.

Table 3 (below right) shows the relative difference between breeds. Some farms will have management systems that produce lower litter sizes than below, but others will exceed this performance. Hill flock crosses (eg, Mule/Greyface, Belclare, Suffolk-cross Cheviot) have traditionally been a source of replacements for lowland flocks. These types will give a uniform sheep flock and are capable of producing high numbers of quality lambs when crossed to terminal sires. This option of buying in replacements suits smaller flocks (less than 150 ewes) where it is not as practical to breed replacements.

Hill flocks are estimated to make up around 25pc of the national ewe flock. A high proportion of hill ewes are now mated to terminal sire rams -- eg, Suffolk, Texel and Charollais -- and this limits the potential of hill flocks to produce prolific female replacement crosses for lowland flocks. In fact, it is probably less than 10pc of the annual demand.

Results from the Hill BETTER Farm Sheep Programme are showing that hill flocks can improve output and returns through using maternal sires for producing lowland replacements on the proportion of the ewe flock that is not required to breed hill flock replacements.

Breeding own replacements

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This gives complete control on the type of ewe and minimises the risk of introducing disease into the flock. However, breeding own replacements is best suited to the larger flocks. There are basically two options:

•The flock is divided into two, a small replacement flock that is mated to a maternal ram (eg, Belclare, Leicester and Lleyn) and a main flock to a terminal sire for producing finished lambs. Here's a 200-ewe flock example: Sixty ewes are mated to replacement rams that will produce about 40 ewe lambs. The remaining 140 ewes will require about 30 replacements each year -- these can be selected from the 40 ewe lambs. To maintain the flock of 60, around 12-15 ewes will need to be purchased each year. Buying hill cross ewes will introduce traits such as good mothering ability and hardiness associated with hill ewes into the main flock (see table 4, bottom right).

•Crossbreeding -- Here, two breeds are continuously back crossed to produce replacements. This will produce ewes that have a 75pc/25pc mix of the two breeds (see table 5, bottom left). This option is more suitable for larger flocks with more than 200 ewes.

Ram selection

While there are breed differences for traits such as growth rate and carcass quality, there is a greater variation within breeds. Performance recording is a useful tool for assessing the true potential of a ram.

The Sheep €uroStar index for sheep that participated in the LambPlus Sheep Breeding Scheme reflects how much profit a sheep farmer can achieve from selecting a particular ram.

Indo Farming