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The methodology and accuracy of Sheep Ireland star-rating system doesn't stand up - ICSA


Our experts differ on the merits of the Sheep Ireland star-rating system

Our experts differ on the merits of the Sheep Ireland star-rating system

Our experts differ on the merits of the Sheep Ireland star-rating system

The methodology and accuracy of the star-rating system doesn't stand up to objective analysis, argues John Brooks

Even in breeds such as the Belclare where all individual sheep have been recorded since the inception of Sheep Ireland, accuracy figures are as low as 30pc, with a majority falling in the region of 30pc-40pc.

If reliability figures were used, as is the case with cattle, a 30pc accuracy would convert to 9pc reliability and a 40pc accuracy would convert into 16pc reliability.

Could this be the reason that sheep star ratings are so low?

Is inaccurate data therefore the reason that sheep star ratings fluctuate so much in a relatively short period of time? We often see five-star rams going to one star and those with one star going to five stars and everything in between.

How many star ram buyers actually check the star ratings of their purchases after six months or a year?

The problem lies with a recording system that allows breeders to record inaccurate data on important traits such as birth weight, type of birth (single, twin, etc), lambing difficulty score, mortality, weight at 40 days, 80 days, 120 days, as well as type of rearing, etc.

By careful manipulation of this data, unscrupulous breeders can in fact ensure high star ratings for their sheep, thus adding significant monetary value to them.

Sheep Ireland claim that visiting a number of breeders to record weight and back fat, and to scan muscle depth when the lambs are approximately five months old will help verify data.

However, these visits are done at the request of the breeder, and the breeder is only obliged to present a small percentage of his/her lambs of their own choosing.

How can recording a lamb at five months ever verify date of birth, birth type, mortality rate, lambing difficulty, type of rearing and birth weights at various intervals?

Data quality

Sheep Ireland also claim that Data Quality Indices (DQIs) will help ensure accurate data.

This is untrue. DQI indices are merely a reward rating awarded to the breeder based on the timing and volume of data submitted. It has absolutely nothing to do with data accuracy.

ICSA also questions the role Teagasc has to play in actively promoting Sheep Ireland's star-rating system knowing that they accept unverified data.

Why aren't Teagasc carrying out continuous trials in a controlled environment on the effect of using different star-rated rams on the resulting progeny right through to slaughter?

This would include evaluations on carcase weight, grades and kill-out percentage and could give an independent assessment of the monetary value of each star rating.

Current trials using just weaning weights and ­predictive slaughter weights are of limited worth when it comes to carcase value - the bottom line for the sheep producer.

Sheep farming is a low-­income, high-labour enterprise and deserves accurate and reliable information.

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However, promoting low-accuracy indices with high fluctuation rates is very costly to the individual farmer in the short term, and in the long term could prove very costly to the whole sheep industry

The onus is on Sheep Ireland to devise a better system that would give accurate results. They collect a levy from all sheep farmers at the point of slaughter; we have the right to expect better.

John Brooks is chair of the ICSA sheep committee

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