Genomic testing females offers huge scope to accelerate herd genetic gain and improve production efficiencies as part of a breeding strategy with sexed semen.
The ability to genomic test females to establish their genetic merit from around two months of age is a game-changer for British dairy farmers and provides the potential to make rapid gains in efficiencies on-farm.
For years, genetic gain on commercial farms has largely been biased towards males through the use of artificial insemination sires, while all heifers – whether good or bad – have been bred. This has ultimately restricted selection intensities on the female side.
However, the development of genomic testing means farmers now have the power to gain a better understanding of a heifer’s genetic status from a young age. This creates the opportunity to accurately select the best quality heifers, increase selection intensity, drive genetic gains and in turn increase profits.
David Kendall, director of genetic advancement for ST Genetics, explains: “You can tell by the time she’s six weeks old, the potential for her production and her ability to transmit to the next generation. And you can make a decision on whether she’s worthy to keep in production or breed from. It allows us to get a better understanding of the inheritance of the herd and make informed management decisions.”
He believes the real gains are to be had from using this type of technology, alongside sexed semen as part of a ‘sexed and beef’ strategy. In doing so, the best females are bred to sexed semen to produce replacements, with the lower end put to beef.
Considering it costs an approximate average of £1,800 to rear a heifer from birth to calving in, this will help lower costs and boost efficiencies by only carrying the exact amount of replacements needed, while receiving income from beef sales.
In addition, using both technologies can aid herd development. “By combining genomics with sexed semen, we can make even faster genetic gains,” Mr Kendall says.
For example, combining genomic testing with the use of sexed semen on your best heifers can lead to nearly a five-fold increase in genetic progress every generation, compared to serving all heifers to conventional semen. This is due to the fact less heifers are retained – which increases selection pressure – while those which are selected are done so with greater accuracy.
Mr Kendall says genomic testing is up to 70% reliable and predicting an animal’s genetic worth based on parent average is around 35% reliable. For example, nonidentical twin heifers might both have a parent average £PLI of £500, however when genomic tested, one may be £700 and the other £300. Without testing, such variation would go unnoticed.
The reliability of genomic testing is also being seen at farm level. A Cogent trial carried out on 200 milking cows at Grosvenor Farms, Cheshire, found those heifers which were ranked in the top quartile for milk production following genetic testing produced approximately 2,000 litres more milk in their first lactation, versus the bottom quartile.
Mr Kendall says genomic testing also provides a greater, more accurate understanding of an animal’s ancestry. “It allows us to make corrections in this generation and the parent generation, which is crucial to accurate genetic evaluations and controlling inbreeding,” he adds.
ANDREW HOLLIDAY, GENETIC PRODUCT MANAGER, COGENT
Andrew Holliday answers some questions about how genomic testing can be used on-farm.
Farmers can use Cogent’s ‘Precision DNA’ genomic testing service to assess the genetic merit of their heifers. Most pure-bred dairy cattle can be assessed, including Holsteins, Jerseys, Ayrshires and Guernseys. Genomic testing should be carried out before heifers are 10 months old so an informed decision can be made before breeding. It involves taking an ear tissue sample using a device with a TSU (tissue sampling unit) tube. It is like putting an eartag in. A tissue sample is punched out and put in the tube with a preservative. The tube number and heifer number are then recorded. The sample is then sent to Cogent which will send it to ‘Genetic Visions’ in the US for testing.
Specialists at ‘Genetic Visions’ extract the DNA from the ear tissue sample. The DNA is broken down into more than 70,000 pieces. This information is sent to AHDB Dairy which formulates the genomic evaluations in the UK by comparing an individual animal’s DNA to the UK SNP chip. This takes about six weeks.
The way we interpret the data is really key to our customers. It is important to be able to utilise and benchmark which animals are best and which animals hit that herd’s specific criteria. It’s important to breed an animal which is right for each herd. Where we’ve seen a lot of people go wrong is using the wrong genetics in their herds. With genomic information we can accurately see which animal will work best for that specific farm, based on that specific milk contract. That’s key. If the farmer is not taking into account if they’ve got a cheese or a milk contract, they are not breeding what they need to make money.
The cost has come down over the years as the technology has developed. On average, genomic testing through ‘Genetic Visions’ costs about £28 an animal, but can be cheaper depending on volume.
Many of our customers are moving to a ‘sexed and beef’ strategy. Genomic testing enables farmers to identify the best females in their herds, breed replacements from them and put high quality beef on the rest. It is about maximising the value of every pregnancy. The launch of SexedULTRA 4M means farmers can have more confidence to use sexed semen due to the fact each straw includes double the usual dose rate and offers the potential to achieve similar conception rates to conventional semen in both heifers and milking cows.