The correlation between growth rate and adult weight is ~0.8 one of the stronger correlations.High mature weight means a longer growth curve , not nessesarily high growth rates , we have rams here that grow well to 50kg then slow quickly but not stopping giving a fast long weight finish
Fat is laid down as growth slows its why ewe lambs are easier to finish , you can have good growth rates without excessive fat
spot on
neils assumption on high fat , high muscle is pretty near the mark assuming the right weight regard the best rams to use imo , and they wont be those hulking great showstoppers either .
its pretty much what we have found , and i think signets early purge on fat may have lost some very good genetics (can you go back ? )
What does the accuracy value mean in real terms?
For instance, if a sheep's EBV's have a 50% accuracy value, does it mean that it's performance (all things being equal) might lie 50% either side of the "estimate", whilst the variation of one with 90% accuracy might be 10% either side? If not, is there not a better way of estimating the estimate?
This was meant to the one that no one appears to have an answer for, but this muppet clicked on the wrong reply link
Different set of statistical laws.In statistical terms 90% accuracy is considered low. Statisticians prefer 3% or even 1% margin for error. A young ram when you buy it will never, ever, get anywhere near that.
Accuracy in ebvs is a measure of the possible change in ebvs up or down
How is that different from margin for error?
Isn't 75% accuracy is +/- 25% on the variance from mean?
So if a ram has an EBV of +2 for eye muscle but an accuracy of 50% he could add 1-3mm of muscle depth, but a ram with +1.5 but 99% accuracy will add 1.485-1.515mm (on the assumption that the lambs' dams are exactly average and all of the lambs from both sites are treated exactly the same)
Not at all, remember buying one animal means the ebv may change. But if you buy two rams per year, the chance of one going up is equal to the chance of one going down, its important to remember that on average ebvs are accurate.Thank you. That was very interesting.
Only 67% confidence in one standard deviation (only 96% confidence in two standard deviations!) and needing lots of linkages and/or hundreds of progeny to get to 99% accuracy.
To be frank, on that basis, if your buying by untested animals you may as well ignore EBVs altogether. It sort of proves the point that until everybody records it's a bit of a waste of time.
Too small? There is an over supply of bulls in almost every breed.
And so it goes on.
Now then, if a ram with an index of say 300, which comprises the genetics of sire with, say 340, and a dam of 240, even with 90% accuracy, it's genetics is made up from so many variables with 16 great, great grandsires/dams, can there be any chance of estimating it's likely performance.
The only guarantee would be line bred animals perhaps.
I don't disagree. Did anyone suggest an under supply?
,
nearly all our main line sires are homebred and have been for 25 years , we use purchased new genetics on the sh ewes , and the best recorded sons used over the main flock within family groups ,for the next 4/5 years , its the only way you can magnify the best of your own genetics , and limit the influence of any problems the new ram WILL bring in , new sires are then sold within a few years unless they contribute nearly all good genes and very few poor ones .
So it's a self fulfilling prophesy.
And so it goes on.
Now then, if a ram with an index of say 300, which comprises the genetics of sire with, say 340, and a dam of 240, even with 90% accuracy, it's genetics is made up from so many variables with 16 great, great grandsires/dams, can there be any chance of estimating it's likely performance.
The only guarantee would be line bred animals perhaps.