High index rams extra value

17 September 1999

High index rams extra value

By Jessica Buss

A HIGH index ram bought at sales this autumn will be worth an extra £900 in its lifetime compared with a low index tup.

SACs head of animal breeding and genetics Geoff Simm says a high index makes it worth paying more for a ram, particularly when profits are under pressure.

He believes the price difference between high and low index rams does not reflect their value. "The technology of breeding using animal indexes is well proven. We know it can improve profits."

Yet only 16% of lambs sold come from rams proven through sire reference schemes, showing considerable scope for improvement.

"Commercial producers must realise what high index rams have to offer," says Prof Simm. "We know we have the tools to breed a faster growing, leaner lamb which can make a difference at industry level." The way forward could be for lamb buyers to offer a price premium to producers using a high index sire, he adds.

Prof Simm advises ram buyers to decide which index or Estimated Breeding Value is relevant for their flock. Then, identify the highest index rams they can afford and check they are functionally sound before bidding for them.

Sire referencing schemes are making rapid genetic progress at 1.75% a year, faster than that of dairy herds, which are achieving 1% a year. Progress has been made using ultrasonic scanning to measure carcass traits, but the rate of progress is likely to increase with the use of computer tomography scanning. Prof Simm hopes a commercial CT scanning service will be available to sire referencing scheme members next year.

Replacing ultrasound with CT scanning could increase the rate of genetic progress by 50%, but at a likely cost of £75 an animal, would prove expensive.

Prof Simm, therefore, suggests using ultrasound to identify the top 15% of rams and then putting as many of those through the CT scanner as possible. This should achieve most of the genetic progress of replacing ultrasound scanning, but at a much lower cost, he says.

SAC researcher Mark Young adds that CT scanning is more accurate than ultrasound because it allows fat, bone and muscle to be measured because they appear as dark grey, white and light grey on the scanner image. Fat can be measured with 96% accuracy and muscle with 99% accuracy.

"We can see layers of fat between muscle and measure it. CT scanning tells us the density of muscle so in fat animals we can detect marbling fat in muscle, which we want to identify as a measure of meat quality. Muscle shape is also visible, helping us identify the shape of the animal such as a muscular shoulder or narrow back end."

The CT scanner causes no harm. Sheep are given a low level sedative to ensure they are not stressed. It scans cross-sections of the sheep, forming computer images which can be assessed for the proportions of fat and muscle. Over 3000 sire reference scheme lambs have been scanned in the past three years. &#42


&#8226 Buy high index rams.

&#8226 Fast progress possible.

&#8226 Use CT scanning.

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