Choosing a ram just got a lot easier

Saturday 30th September 2017

Choosing a ram just got a lot easier

This article appeared in Country-Wide Sheep magazine 2017

B+LNZ Genetics general manager Graham Alder says the recent upgrade of the SIL genetic engine and introduction of the New Zealand Genetic Evaluation (NZGE) changed the game. “SIL’s computing power is now such that it allows us to generate a single ‘index’ figure for every ram sold by a SIL breeder. It’s one number that’s comparable across all rams, regardless of breed. The higher the number, the better the ram.”

Terminal rams have lower scores than maternal rams, because their figure is calculated from a smaller number of traits. (See table.)

Maternal Worth (NZMW) or Terminal Worth (NZTW)?

Mr Alder says those breeding both replacement and finishing stock should look at rams with a high NZMW figure. “If you’re only breeding terminal stock, then look for rams with a high NZTW figure.”

The range of the indexes

While the single number concept is easy, Mr Alder says commercial farmers will need a period to “get their eye in” – to understand what is an especially good figure and what may sound ok, but probably isn’t.

“With regard to NZMW, the average is 1600, so that’s a good figure to lock in to your memory. Any ram with a figure of 2150 or higher is in the top 20% for New Zealand. A figure of 2600 is an exceptionally good ram. At the other end of the scale, anything below 1090 falls into the bottom 20% for NZMW.

 

NZTW figures are lower – because they are drawn from only three traits, not six – but the same principles apply. “The average figure is 1150, with any figure above 1440 being in the top 20% and any figure below 860 being in the bottom 20%.

Health traits

The index also extends to specific traits, like FE tolerance or resistance against internal parasites? 
“For instance, if you’re looking for facial eczema tolerance, identify breeders who prioritise FE, then ask them for NZMW + X, X representing the FE trait. 

“Or, if you’re looking for resistance to internal parasites, identify breeders who prioritise this trait, then ask them for NZMW + FEC.

“The same rule of thumb applies. The higher the number, the better the ram.”

Bottom line message

When you enquire about rams this year, ask your breeder for NZMW and/or NZTW figures:

NZMW – if you breed your own replacements.
NZTW – if you need a terminal sire.

The higher the figure, the better the ram. For more, visit ramindex.co.nz
 



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