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Ram performance trial compares New Zealand and UK genetics

Livestock | 9 May, 2008

SUFFOLK sheep breeders from across the UK visited a West Wales coastal farm to hear the initial findings from a ram performance trial comparing New Zealand and UK genetics.

The large-scale trial, which is still on-going, was set up to find if there was anything to be gained from using Suffolk rams with New Zealand genetics, and supposedly carrying easier care attributes, in UK commercial crossbred flocks – but so far little variation between the two has been found.

The comparison trial is being carried out at the Institute of Biological, Environmental and Rural Sciences’ Morfa Mawr Farm, Aberaeron, funded by HCC, Innovis and the Suffolk Sheep Society.

Dr Janet Roden

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Dr Janet Roden, Aberystwyth University researcher, who runs the project.

Progeny from the 506 mixed age Welsh Mule ewes (ran as a commercial enterprise finishing lambs off grass without concentrates) are being compared not only on growth and carcase quality but also the level of shepherding required.

In all, 10 rams have been used – four New Zealand Suffolks, three high index UK Suffolks and three ‘traditional’ UK type Suffolks – on three identically matched groups of ewes inseminated on-farm in September.

On average the ewes scanned at 1.93 lambs per ewe inseminated and, at lambing in February, the ease of lambing, lamb vigour, ability to suck unaided, birth weights and losses were recorded for all the 702 lambs born. Ewes and lambs were turned out 24 hours after lambing and no creep has been provided.

The biggest different found so far (see panel) is that lambs sired by the New Zealand Suffolks had slightly lower birth weights and consequently required less assistance at birth than those sired by the high index UK sires.

“The lambing results have revealed some variation in the easy care attributes of lambs sired by different rams,” said Dr Janet Roden, the Aberystwyth University researcher running the project.

Further information will become available over the coming months on the general ease of management and slaughter data.

Full carcase analysis will also be carried out on all the lambs and a final report bringing together all aspects of the trial published later in the year.

“The lambing and pre-weaning results so far show there are some slight differences between the different types of Suffolk,” said Dr Roden.

“Perhaps most importantly there is a great deal of variation within all the populations – confirming the importance to commercial producers of always using the best information available to choose the best ram.”

Initial data from the trial

• Around 99 per cent of all lambs were born alive with only 2.3 per cent lost within the first 48 hours of life.

• New Zealand lambs tended to be lighter at birth and, therefore, had the highest percentage of easy lambing.

• Incorrect lamb presentation at birth gave rise to 80 per cent of the lambing assistance required.

• Some 97 per cent of singles and twin lambs overall sucked without assistance with those that did mainly being triplets.

• The variation between individual sires for vigour – judged on the ability to stand up – and to suckle was far greater than the variation between groups of sires.

• Average birth weights were 6.1kg for singles and 5kg for twins. At eight weeks singles were up to 26kg while twins were 21kg.

• There was little difference in the averages between the groups with the UK high index-sired lambs being marginally higher at 21.6kg. The UK traditional Suffolks were 20.7kg and the New Zealand Suffolks were 20.6kg.

• At eight weeks of age the lambs sired by both UK Suffolk groups were slightly heavier than lambs sired by New Zealand Suffolks.

• Lambs sired by the New Zealand Suffolks were slightly less daggy (15 per cent compared to 20-25 per cent for the UK-sired lambs) with one of the traditional Suffolk rams ranking second overall on cleanliness.