What is genetics?
Genetics is the use of actual measurement of an individual and relatives to assess and predict the potential genetic merit of that individual’s progeny.
What is genomics?
Sheep genomics is about the direct assessment of the genetic makeup of sheep and ways it can be used to improve rate of genetic gain. Each sheep has 27 pairs of chromosomes each with tens of thousands of production related genes. Some of these key genes or groups of genes can be identified and used to improve productivity.
How are the key genes identified?
Genes are made up of varying numbers of base pairs of four different nucleotides and differences between animals in these are the basis of SNPs (single nucleotide polymorphisms – pronounced ‘snips’). By identifying varying numbers of SNPs and relating these to phenotypic production measurements in individual sheep, researchers can relate them to production traits of interest.
In practice how can this be used?
The SNP chips can be purchased for individual animals – rams and ewes – and used for early predictions of ‘genomic breeding values’ which can be combined with existing Australian Sheep Breeding Values (ASBVs) for improved rates of genetic gain. SNP predictions can also be used where there have been no direct measurements and for hard to measure traits such as reproduction, disease resistance and meat or wool quality.
What is an RBV?
A Research Breeding Value (RBV) does not meet the stringent requirements of a full ASBV value and its use by industry should reflect its preliminary ‘research’ status. The key difference lies in the accuracy levels of the RBVs, which in some cases are lower than would normally be released by Sheep Genetics. RBVs are derived from a combination of the animal’s genomic information from a 50k SNP Chip analysis, and measurements from other animals in the Sheep CRC Information Nucleus Flock.
In the context of genetic assessment, ‘accuracy’ means the accuracy of predicting or estimating a true breeding value i.e. the true genetic merit for a trait. It is not the accuracy of measuring a physical parameter i.e. a phenotypic measurement. For instance, in terms of genetics, an accuracy of 50% (or 0.5 on a scale from 0 to 1), means we are half-way to perfection (which is an accuracy of 100%, or 1 on a 0 to 1 scale). It does not mean there is a 50:50 chance of picking the right or wrong animal. As more direct measurements from the Information Nucleus flock are analysed, accuracy will improve over time.
Why should I as a breeder get involved with this new technology?
Some of the advantages you as a sheep breeder can experience include:
What is it going to mean to my bottom line?
It is hard yet to quantify the dollar value benefits. Genetic improvement will be enhanced by around 20% through a shortened generation interval for some traits and availability of other new traits. It is expected that many of producers will seek rams that show use of this new genetic technology.
How widely available is genomic information?
At this stage use of genomic information is only available for the major breeds since there is sufficient data, for these breeds, to achieve accurate predictions. It is also unlikely that, in the foreseeable future, we will be able to develop accurate prediction of breeding values for minor breeds based on genomic data.
When will genomic (DNA) tests become commercially available in Australia?
It is expected that the genomic tests being developed by the Sheep CRC will become commercially available during 2012.
How much will they cost?
At this stage it is too early to speculate on the price of the genomics tests, but the price will reflect the declining costs of the SNP chip technologies.
Where can I find out more about genomics?
Click here to find more information about terms relating to genomics.
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.
During LambEx 2012 the Sheep CRC hosted a genomics breakfast workshop - download the papers from the workshop below.