When selecting rams for a commercial enterprise the first step is to set your breeding objective. Spend a few minutes to write down precisely what you are aiming for, including the levels of performance and by when you want to achieve it. Find more information on setting a breeding objective.
Because the most effective way to select for a trait or characteristic is to directly measure or assess that characteristic, you should buy rams from a stud that objectively measures or collects scores (using a standardized system) for the traits you wish to improve.
For instance, staple strength can be selected with much higher accuracy if the stud directly measures staple strength on its rams, rather than just having the ASBV calculated from related measurements such as fibre diameter coefficient of variation.
However, the ram’s own performance is only part of the picture. What you see in the ram isn’t necessarily what you will get in the progeny because much of the ram’s performance is a result of the ‘environment’.
Nutritional differences between animals are a key environmental element and not only come from what they eat, but whether they were born or reared as a twin or their mother was a maiden ewe—giving them less nutrition during pregnancy and lactation than for a single lamb and/or from a mature ewe.
Also, climate, disease and management differences will affect how they perform.
If you know these environmental factors for each individual, and if you have been able to inspect all of the animal’s relatives and see their performance data, you’d be able to predict very accurately, how the progeny will look and perform.
However, this is not practical for you to do, so studs that provide you with Australian Sheep Breeding Values (ASBVs) already have this information taken into account. Pedigree information, management groups, data from relatives and relationships to rams used in the stud and elsewhere are all accounted for and very important when calculating Australian Sheep Breeding Values.
Importantly, you can accurately compare rams from different studs (whether at opposite sides of the country or having had quite different management) if they both provide ASBVs for the same trait.
Choosing your stud(s).
The last decade has seen great changes in the information some studs offer and ram buyers have become more discerning. Gone are the days of believing that a ram simply throws back to the average of the stud, as more detailed analysis has shown that there is considerable variation across rams within a stud.
Comparing rams from different studs is easy and accurate when they have ASBVs because the differences associated with nutrition and management have been removed.
Choosing individual rams
Visual selection is still an important part of selection—particularly for wool sheep—because there are still traits of importance that are not available for selection using ASBVs.
2. Shortlist the rams based on your criteria, so that you can then spend your time at the sale more thoroughly visually assessing these, instead of wasting time on poorer performing animals.
3. On sale day, follow your shortlist and visually assess only the selected individuals. Avoid viewing poorer performing animals, so you are not influenced by those that look good, despite their poor performance.
Selecting rams with no ASBV data
Studs that do not provide ASBVs can certainly have good individuals, however, accurately identifying them is more difficul:
Within stud selection
If some raw measurements or scores are provided, these can be useful if the following applies.
Firstly, the animals that have been measured/scored should have all received equal nutrition and management, in other words, they needed to have been run together until when their measurements were taken. If not, this data can only be used to compare any animals that were managed together.
Secondly, the traits measured need to be able to be passed onto their progeny. Traits with higher heritability, a larger range in their expression and which can be measured very accurately are those where selection will be most successful. Good progress can still be made if, for example, only one of these factors is high or two of them are moderate.
Using a raw fibre diameter result is suitable as it has a high heritability, it can be measured quite accurately and there can be a wide spread of measurements within a related drop of lambs. Conversely, using raw worm egg counts for individuals is not so suitable as the WEC measurement itself is reasonably inaccurate, although it is moderately heritable, and has a wide expression within a mob. For traits such as WEC, the data of relatives must be built in to provide an accurate figure for selection; this can only be done with ASBVs.
Thirdly, take account of the birth and rearing status of the individual (e.g. born a twin, raised a single) as well as the age of his dam (maiden versus mature ewe). If the stud does not provide this information then you will almost certainly favour the single born lambs reared by mature ewes. This will be at the expense of genetically bigger, finer and heavier fleece weight rams that happen to look smaller and broader and lighter in the fleece, because they were twins and/or were born to maiden ewes. The exception is that when selecting for less wrinkle, you’ll favour sheep that are twins, were born from maiden ewes or were born in a drought, because the lower nutrition results in fewer wrinkles.
Across stud selection
Without Australian Sheep Breeding Values, determining how individuals in one stud objectively compare to extremely difficult as management and nutrition differences account for such a large part of performance.
Choosing rams that have been shown is one way, but heavily reflects the ability of the studmaster to feed and prepare their animals. You can also use results from bloodline comparisons (wether trials).
Rams run and measured under conditions most similar to your own (i.e. unhoused, uncoated, pasture-fed) will provide the most selection accuracy.
In conclusion, Australian Sheep Breeding Values are now available on rams from many studs. ASBVs offer:
Choose from the tabs below to find more detailed information.
ASBVs stand for Australian Sheep Breeding Values. They are the national language for benchmarking sheep based on their genetic merit and are produced by Sheep Genetics. ASBVs describe a sheep’s breeding value for a trait, e.g. fleece weight or body weight, and express the relative breeding value of sheep across different breeding flocks of that breed (or across breeds in the case of Terminal breeds). They are equivalent to estimated breeding values (EBVs) used in other livestock industries e.g. BREEDPLAN in the beef cattle industry.
Several case studies are available on the use and benefits of ASBVs - download the individual case studies below.
This guide is provided to help you understand the complexities of breeding profitable yet functional sheep that are right for your business.
The Merino Sheep Breeding Trainer Guide has been developed by Sheep CRC and Meat & Livestock Australia to allow vocational and education trainers (primarily in the TAFE, Agricultural College and School systems) to deliver up to date knowledge and skills in the area of Merino breeding to their students. It is designed to be used in conjunction with three Power Point presentations, produced by the Sheep CRC on developing a breeding objective, selecting a stud and rams and selecting ewes.
Visually assessed traits are included in the breeding objective of all stud and commercial sheep breeders, regardless of their target market or environment.
Sheep Genetics provides you with practical information on the genetic potential of your sheep. Sheep are ranked according to various production characteristics using Australian Sheep Breeding Values (ASBVs) across flock or Flock Breeding Values (FBVs) within flock. See Sheep Genetics brochures available for download below. To download other publications click here.
Download the genetics publications below.
This Conference combined world class science with its practical application.
This Conference combined world class science with its practical application.
During LambEx 2012 the Sheep CRC hosted a genomics breakfast workshop - download the papers from the workshop below.
This article appears courtesy of Meat & Livestock Australia (www.mla.com.au)
These proceedings are from the showcase conference of the Australian Sheep Industry CRC 'Wool meets Meat - tools for a modern sheep enterprise' conference held in Orange (NSW) during 2006.