Genetics and Genomics - Frequently asked questions

What is genetics?

Genetics is the science of heredity and variation in living organisms.

What is genomics?
Genomics is the study of the genomes , ie. the full set of genes or chromosomes, of organisms.

What is a gene?
A gene is the most basic unit of heredity. It consists of a relatively short sequence (several thousand nucleotides) of DNA at a specific location on a chromosome that determines a particular characteristic in an organism through the production of a specific protein end-product.

What is heredity and how does it work?
Heredity is the passing of traits to offspring (from its parent or ancestors). This is the process by which an offspring acquires the characteristics of its parents.

What is a phenotype?
A phenotype is any observable characteristic or trait of an organism: such as its morphology, development, biochemical or physiological properties, or behavior. Phenotypes result from the expression of an organism's genes as well as the influence of environmental factors and possible interactions between the two.

What is a genotype?
The genotype of an organism is the inherited instructions it carries within its genetic code.

What is DNA?
DNA, or deoxyribonucleic acid, is the building block of the genetic code. A DNA molecule is composed of two strands of nucleotides wrapped around one another and connected at the bases to form a double helix. DNA is present in all nucleated cells in an animal, with cattle having approximately 2.7 billion nucleotides in the code. DNA is organized into 30 pairs of chromosomes in cattle. We refer to the complete DNA makeup of an animal as its genome.

What is a DNA marker?
A DNA marker is a variation in the DNA code, mapped to a specific location in the genome. DNA markers can be genotyped and may be associated with one or more physical characteristics.

Are all DNA markers alike?
Markers can differ in mode of inheritance, physical size (number of base pairs), functionality and how they are applied in genetic improvement. The prevailing type of marker now being used in DNA testing for traits is known as a single nucleotide polymorphism (SNP). SNP markers vary at a single base location in the genome, creating two different alleles (or forms) of the marker.

How does a DNA marker relate to a gene?
A DNA marker can actually be located directly within the gene sequence that causes a change in the trait of interest. More commonly, DNA markers are linked to (inherited with) a nearby gene that causes a change in the trait of interest.

Do we know the full code (i.e., sequence) of DNA for cattle and other livestock?
The full code set for an animal’s genome is comprised of about 2.7 billion connected bases. The genome of a number of species has been sequenced including humans, cattle, chickens, horses, and the platypus! Additional commercially important species such as sheep and swine are currently being sequenced.

How is an animal’s makeup (i.e., genotype) for a DNA marker determined?
An individual’s genotype is fixed at birth with the inheritance of one chromosomal copy from each of its parents. The animal’s genotype for the marker is determined by analyzing the DNA sequence variation at the marker location in the genome using high throughput DNA genotyping technologies that are routinely used around the world for a variety of applications.

Will an animal’s marker genotype change during its lifetime?
No, an individual’s genotype is unique and fixed not long after fertilization of an egg by a sperm, and remains fixed throughout its lifetime.

Does a DNA marker only relate to one trait?
Many traits are genetically correlated to one another due to the fact that genes can impact multiple traits. Likewise, DNA markers that are either within these genes or linked to them are likely to have effects on multiple traits. It is also possible for a marker to have a positive effect for one trait and a negative effect for another.

What is an economically relevant trait?
A trait is an observable or measurable characteristic of an individual. An economically relevant trait is one that directly affects profitability through an association with a specific cost of production or income stream. Examples of economically relevant traits include reproduction, lean meat yield and feed efficiency.

Are all economically relevant traits heritable?
Economically relevant traits vary in level of heritability, measured as the percentage of observed variation that is due to underlying gene effects that can be transmitted from one generation to another. While heritability may differ between populations, in general, traits such as fertility tend to be more lowly heritable than traits such as growth rate and tenderness, which exhibit moderate to high degrees of heritability.

If a trait is lowly heritable, does that mean that it cannot be improved genetically?
Traits with a low degree of heritability can still be improved genetically, though not as rapidly as more highly heritable traits. The rate of genetic progress is not controlled by heritability alone; the amount of observable (phenotypic) variation and the accuracy with which the variation can be identified are also key factors.

How many genes are responsible for the expression of economically relevant traits?
We do not yet know exactly how many genes impact economically relevant traits, but research indicates that many genes are likely to have small- to moderate-sized effects on performance for any given trait.

Are the effects of DNA markers the same for different breed sub-populations around the world?
Often they are similar, although the more divergent or distant a population is from another, the greater chance there is for the effect of markers to vary.


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Sheep DNA Testing Information

News Releases

Faster sheep DNA testing with new Australian GeneSeek lab
Sheep breeders using DNA testing to improve their genetic selections can look forward to faster turnaround times for test results thanks to Neogen Corporation’s decision to establish a genomic testing laboratory within Australia. GeneSeek Australasia, a wholly owned subsidiary of United States-based parent company Neogen, has acquired the assets of the Animal Genetics Laboratory (AGL), based at the Gatton campus of the... Click Here To Read Full Article » https://www.sheepcrc.org.au/information/news/faster-sheep-dna-testing-with-new-australian-geneseek-lab-04-09-2017.php
Dramatic increase in early season searches on RamSelect
Inquiry for rams through RamSelect has never been stronger with a dramatic increase in the number of buyers searching the site so far this season compared to last year. More than 1129 ram searches were conducted on RamSelect during July, compared to just 154 at the same time last year. Click Here To Read Full Article » https://www.sheepcrc.org.au/information/news/dramatic-increase-in-early-season-searches-on-ramselect-22-08-2017.php
DNA testing to drive new era of ewe competitions
The traditional ewe competition is set to enter the innovation era with the inclusion of DNA Flock Profile tests as part of next year’s Doug Bicket Memorial Ewe trial in Parkes, NSW. The Cooperative Research Centre for Sheep Industry Innovation (Sheep CRC) will provide DNA profiling for all flocks entering the 2018 competition, currently valued at $800 plus GST per flock, as a means of supporting improved genetic selection... Click Here To Read Full Article » https://www.sheepcrc.org.au/information/news/dna-testing-to-drive-new-era-of-ewe-competitions-18-07-2017.php
The predictive power of ASKBILL immortalised in song
An off-the-cuff comment and a spur of the moment decision to “have a go” have resulted in the sheep industry’s new predictive app, ASKBILL, being brought to life in song by Uralla musician Rhonda Brooks. Performed in a bush ballad style by Coffs Harbour musician Mal Winckle, the track is proving a popular addition to the ASKBILL website, helping to capture producers’ imagination as to the possibilities on offer... Click Here To Read Full Article » https://www.sheepcrc.org.au/information/news/the-predictive-power-of-askbill-immortalised-in-song-10-07-2017.php
RamSelect moves towards commercial business model
The popular RamSelect app will move to a commercial funding model ahead of this season’s ram sales, as a first step towards ensuring the genetic selection tool’s financial viability and availability to producers in the long-term. RamSelect Plus is an easy to use web-based application, www.ramselect.com.au, which allows ram buyers to find and rank rams based on Australian Sheep Breeding Values (ASBVs) that match their own... Click Here To Read Full Article » https://www.sheepcrc.org.au/information/news/ramselect-moves-towards-commercial-business-model-03-07-2017.php
Faster, more accurate DNA Parentage and Poll test to be released in July
Sheep breeders will have access to a faster, more accurate DNA test for parentage and poll/horn status from July, which also includes new features to detect a range of genetic defects. First launched in 2012 by the Cooperative Research Centre for Sheep Industry Innovation (Sheep CRC), the DNA Parentage and Poll test has proven very popular with sheep breeders seeking to improve their genetic selections through more precise... Click Here To Read Full Article » https://www.sheepcrc.org.au/information/news/faster-more-accurate-dna-parentage-and-poll-test-to-be-released-in-july-26-06-2017.php
‘Eye opening’ DNA Flock Profile delivers new breeding insights at Beechworth
DNA testing to obtain a genetic flock profile has changed the way Victorian Merino breeder Stuart Warner not only looks at his flock, but how he will approach his genetic selection decisions in the future. As a registered deliverer of Bred Well Fed Well and RamSelect workshops, Mr Warner has a close understanding of the power of Australian Sheep Breeding Values (ASBVs) as an objective genetic selection tool. Click Here To Read Full Article » https://www.sheepcrc.org.au/information/news/eye-opening-dna-flock-profile-delivers-new-breeding-insights-at-beechworth-05-06-2017.php
The power of prediction now in sheep producers’ hands – just ASKBILL
A new app launched today will give sheep producers the power to see their stock’s future, all from the palm of their hand. The app, available at www.askbill.com.au, was made live to the public today, marking the start of a limited offering of the ASKBILL platform as part of a pre-release user feedback program – a vital step in putting the finishing touches to the product prior to ASKBILL’s full commercial release later... Click Here To Read Full Article » https://www.sheepcrc.org.au/information/news/the-power-of-prediction-now-in-sheep-producers-hands-just-askbill-22-05-2017.php
To see your livestock’s future, just ASKBILL – new app live from Monday
Sheep producers and farm advisers are set to be wowed by the predictive power of the Sheep CRC’s latest flock-management app, ASKBILL, which will be released to industry on Monday. The web-based app, www.askbill.com.au, has been designed to draw on information generated by biophysical models that use daily downloads of climate data and forecasts to provide estimates for individual farms of the risk of flystrike and... Click Here To Read Full Article » https://www.sheepcrc.org.au/information/news/to-see-your-livestocks-future-just-askbill-new-app-live-from-monday-16-05-2017.php
DNA Parentage raises the bar for ASBV accuracies
DNA Parentage testing of progeny from multiple sire mating groups significantly improves the accuracy of breeding values associated with their bloodlines, a new trial has found. A genomic validation trial conducted in conjunction with Australian Wool Innovation, Sally Martin Consulting, Moses & Son, and Bluechip Livestock, used Sheep CRC DNA tests to identify parentage of the progeny of 300 ewes that had been joined in a... Click Here To Read Full Article » https://www.sheepcrc.org.au/information/news/dna-parentage-raises-the-bar-for-asbv-accuracies-27-03-2017.php
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