The 7/15 index is custom designed to move our commercial flock as quickly as possible to a flock that will cut 7 kgs of 15 microns. The following chart demonstrates the weighting of the relevant traits that comprise the index.
We identified our major profit driving traits and have decided to increase genetic progress in these traits as rapidly as possible by building an index around them. These traits in order of importance in the medium term for our flock are:
1. Clean Fleece Weight 2. Fibre Diameter 3. Body Weight 4. Staple Strength
Market indicators suggest that in the medium term micron premiums for superfine wool will not widen significantly. Hence, this is why fleece weight has overtaken micron as our premier trait of importance.
The default indexes that the industry are offering have some traits in them that we believed were dispensable compared to the importance of improving the major economic traits.
For example, one of the indexes has curvature in it. We believe that this is an arbitrary trait that may or may not increase the price of wool received. The latest research has shown that there is little difference in the processing qualities of high frequency crimping wool to low frequency crimping wool. In fact, if anything the bolder wool processed better.
CV is the other trait that makes up a significant proportion of the default indexes. Due to the strong correlations with Staple Strength we decided to leave CV out of the index. CV will also be controlled through sire selection and we will monitor the affect the index has on flock CV yearly. Overall on balance it was decided to leave CV out to gain more fleece weight and fibre reduction.
Net Lambs Weaned is the other trait that makes an appearance in the default indexes. This is basically a fertility trait that is directly extrapolated from body weight information. By incorporating body weight into our index we are directly increasing fertility.
The key message to understand is that the more traits that you apply to an index, the slower the genetic progress will be in each of these traits! This is why we have concentrated on what we believe are the major profit drivers.
Trait || Predicted Response in Yalgoo Flock in 10 yrs.
YWT || 1.4 kg
AWT || 0.8kg
YCFW || 10.5 %
ACFW || 11.4%
YFD || -0.7 microns
YCV || 0.15%
ACV || 0.30%
YSS || 1.74 newtons
ASS || 0.78 newtons
Our commercial wool clip in 2012 averaged 15.6 microns. Our adult commercial ewes (BW:50 kg) are cutting 4.8 kg of 16 microns. Our 2009 (BW:60 kg) drop wethers cut 5.5 kgs of 15.9 micron wool. This is the base from which the Yalgoo index has been worked out from. The predicted genetic response in ten years are displayed below:
IMPORTANT NOTE: These genetic responses are conservative because they take out any other flock management strategies you might be implementing to reach flock goals. For example, you may be indexing your commercial ewe base as well as your ram breeding core. Therefore, more selection pressure is being applied and genetic progress increases.
Other factors that may increase genetic progress are the amount of data being collected and the flock linkage.
Q: Why is 15 micron used as a flock goal?
A: We have used 15 microns as a flock goal for a few reasons.
1. Research shows there aren't a great deal of processing advantages for buyers using wool under 15 microns. i.e. 15 micron wool and 13 micron wool have similar processing capabilities. Therefore, premiums should logically be most pronounced at around 15 microns.
2. By only having to decrease flock micron by 0.8 we can put more emphasis on increasing fleece weight.
Q: Why are there no carcase or WEC traits included in the index?
A: Once again the more traits that you apply to an index, the slower the genetic progress will be in each of these traits.
The carcase value of a Merino ewe in a wool growing enterprise as a percentage of its lifetime income is only around 15%. This income is also 100% derived from body weight. No wool enterprise that I know, is being paid on a grid for the carcase characteristics of their ewes or wethers. Therefore, by using the Y-7/15 index we are still increasing carcase value because we are increasing body weight through its inclusion in the index and because of BW's high correlation to CFW.
To move WEC negatively enough to have a significant economic bearing in terms of reduced drenching costs, the index would have to primarily made up of WEC. Leaving no room for the important traits that are making you money. WEC is being controlled through sire selection and ensuring only proven resistant rams are infused into the flock.
Q: What will happen to my flock if it doesn't mirror Yalgoo's starting base flock?
A: If your flock is considerably stronger and you start selecting Yalgoo rams on the Y-7/15 index you will still experience a rapid reduction in micron. This is because our base micron is still extremely low and the rams being sold will still be genetically fine.
Also the fact that this index is heavily based on fibre diameter reduction means that the high indexing rams are generally the finer sheep. They will just have higher GFW.
Simply speaking, if you select Yalgoo rams on the Y-7/15 index your flock will end up with a flock somewhere between our current flock and your current flock.
If you wish to be more aggressive on micron at the expense of other traits, then you should consider the SGA FP+ index.
If you need any help deciding which index may be best for your flock, please feel free to contact us and we would be happy to assist you in any way we can.