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Genomics
What is it, Why should I care?
Genomics gives us information on the genetic potential of an individual. By analysing the DNA of an animal, we gain insight into its genetic ability to perform in certain areas when under pressure such as environmental stress. Genomics is proven and widely used in the dairy industry but currently underutilised in the beef industy. We hope to change that.
For example: In a good season, most animals will get in calf within a 4 month period after calving. In a tough season, the animals with a higher genetic potential to get back in calf in the above timeframe are more likely to preg test in calf than animals with a lower genetic potential in this area. By selecting animals with a higher genetic potential in certain areas means we can increase the fertility of the entire herd over time, essentially finding our better adapted cattle prior to the tough season and therefore lessening the economic impact of sub-optimal conditions and increasing the fertility of the herd under pressure.
Valera Vale has used naturally occuring environmental conditions to apply heavy selection pressure to our herd over many years following our strict “One Calf Every Year No Exceptions No Excuses” policy. We see genomic analysis as an essential and exciting way to fast track our progress toward a more fertile, adaptable herd by being able to select superior animals as replacement heifers and sires, prior to external selection pressure being applied.
To quote Ben Hayes, the co-inventor of genomic selection in cattle, we can expect a 2% improvement in the herd every year by incorporating genomic data into our selection criteria. This improvement is cumulative, so in 10 years time, the herd wil be 20% better for the selected traits than it is today.
Polled Genetics
A lot of things have been wrongly implied to be caused by the poll gene in cattle. Including: Preputial Prolapse (Busted Pizzle Bulls), Premature Spiral Deviation of the Penis (PSDP), and reduced serving capacity. Support for this notion has often been garnered by a research paper published almost 40 years ago, pre-dating both genetic testing and increased animal welfare standards, public perception of animal welfare and the pressure of the media. It is worth noting that this study only compared polled and horned populations of different breeds, not horned and polled individuals within the same breed and was heavier on opinion than data.
A systemic literature review by Dr Scott Norman et al (2009) largely debunked these claims using collated data from several cattle veterinarians and beef cattle researchers. They found that PSDP did have a heritable component, but this was unrelated to the polled gene. In fact there were familial lines of horned bulls that had equally high prevalence of PSDP.
In regard to preputial prolapse, the report concluded that factors unrelated to the polled gene, such as sheath structure, have a far greater influence on the likelihood of occurrence than any impact of the polled gene. There was no link found between the polled gene or polled cattle and reduced serving capacity. One fact the report did touch on was that the population of polled cattle had a higher incidence of preputial eversion (where the inner skin of the prepuce remains visible). We arent denying it! In fact, we are actively indentifying it in our herd, and selecting against it, and have been for generations. However, this is not caused by the polled gene.
All these points perfectly highlight the need for a strict, multifaceted approach to selection criteria.
At Valera Vale we brand approximately 1200 bull calves a year. ALL of these are single or double polled. Less than 10% of these are catalogued for our sale. Sheath structure, bull structure, semen morphology, growth, temperament, genomic DNA analysis are all heavily selected for when we are reviewing which bulls make the sale.
When the poll gene was first selected for in cattle, it was from a population that had, as with any population, other faults. Because there was insufficient selection against these other faults, they have been inadvertently selected for in other populations of cattle and have been wrongly attributed to polledness. The polled gene is responsible for polledness, nothing else.
The problem comes with selecting on single genes and losing sight of the big picture. For example: A bull may be polled, and have a bad sheath. If you ignore the sheath on that bull, and use him because he is polled, he will pass on the gene for poll and also the genes for bad sheath. But if you select a polled bull that has a good sheath, he will pass on the polled gene and also the genes for good sheaths. . By selecting cattle with good sheaths we are able to keep the poll - without the problem.
One positive of the polled gene is lower mortality, as the Cash Cow project identified at 2% higher in dehorned cattle in the 12 months after branding.
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