Hazeldean Breeding Objective and Selection indexes

Index Selection
Rather than trying to weigh up fleece weight, fibre diameter, body weight and possibly many other traits in your head and then apportioning the correct value to each when selecting sheep, it is possible to combine all measured traits and present them as one figure. This figure is known as an index.

In addition to making the job of selecting much easier, it is possible to place more emphasis on one particular trait over another when calculating the index. This way you can push your flock in the direction you want it to go much more easily.This system ranks animals on their capacity to reach our breeding objective as quickly as we possibly can.  

Hazeldean Merinos breeding objective is to improve fibre performance, while reducing fibre diameter and at the same time increasing fleece weights. We want to reduce fibre diameter at a faster rate than we increase fleeceweight. We therefore place a 12% premium on the value of fibre diameter when we calculate our index. We also want to increase staple strength. As staple strength and CV are correlated traits we include in our index calculation an emphasis on lower CV.

We also select for fertility, worm resistance, growth rate and carcase value. The gains made by the Hazeldean program are quantifiable, permanent and compound over time.


Our focus is on increasing the potential of Hazeldean Merinos to generate more money for our clients.


We are achieving this goal - Hazeldean Merinos are proven to be the clear leader in dollar terms in on-farm bloodline comparison trials.

Every year Hazeldean undertakes a large AI program with it's best and most proven progeny tested sires thereby producing large lines of high performing rams sired by the most profitable rams in the industry.

Three different breeding objectives are:
 

. The 3% micron premium index gives a high priority to increasing fleece weights. It is valuable for those breeders who wish to maintain their fibre diameter and place maximum emphasis on increasing the fleece weight of their flock.
. The 12% micron premium index is useful for breeders who wish to place maximum emphasis on decreasing their flock fibre diameter, without losing fleece weight.
. The 6% micron premium index simultaneously increases fleece weight and decreases fibre diameter. It is a compromise between the other two.

Hazeldean has primarily been using the 12% micron premium index.


What is Micron Premium?
The micron premium tells you how much the price of wool increases if the fibre diameter decreases by one micron.

Genetic worth can be expressed in two different ways:

EBV's (Estimated Breeding Value) and ASBV's (Australia Sheep Breeding Values)
Both are an estimate of genetic worth for any particular trait.

What's the difference?
An ASBV is an estimate of the genetic worth of an animal for any measured trait. ASBV's can be thought of as a picture of the entire number of the animal's genes for any trait.

An ASBV is an estimate of the genetic influence an animal can have for any measured trait when used for breeding. ASBV's can be thought of as a picture of half of the animals genetic worth for any trait because in reality a ram (or ewe) will only contribute half of its genes to its progeny, the other half coming from the other parent.

So in effect ASBV's look at the worth of the total of an animals genes whereas ASBV's look only at the effect of those genes in the progeny. This is because the other parent has watered down by 1/2 the expression of the other parents genes.

Examples of using ASBV's

Comparing the two rams, Ram 1 has an ASBV for clean fleece weight of +8%. That is, the progeny of Ram 1 are expected to be 7% superior (8.0 minus 1.0) for clean fleece weight (or have 8% heavier fleeces than the average), than the progeny of Ram 2 with an ASBV of 1% (which will be expected to have fleeces only 1% heavier than the average).

Similarly, Ram 1 has an ASBV for Fibre Diameter of -1.2micron. Ram 2 has an ASBV for Fibre Diameter of +0.8micron. The progeny of Ram 1 are expected to be 2microns finer (-1.2 minus 0.8) than the progeny of Ram 2, (that is, the progeny of Ram 1 are expected to be 1.2 microns finer than the average, while the progeny of Ram 2 are expected to be 0.8 micron stronger than the average).
(reproduced with permission from the University of Melbourne's Mackinnon Project)

More about Austrailan Sheep Breeding Values and how they can help you....