Genomics provides producers with an opportunity to accelerate genetic progress with confidence.
North Yorkshire-based vet Neil Eastham undertook a Nuffield Scholarship to explore how UK dairy farmers can benefit from the use of genomic testing.
Below, Mr Eastham shares some of the practical ways to make better use of genomics, based on the findings from his study tour.
1. Determine your breeding objectives
Before you think about how you could use genetics and genomic testing, you must have a clear understanding of what you want to achieve.
This should be based on your needs now, as well as what they will be in the future. These will vary depending on a number of factors including the type of system you run, what kind of milk contract you are on, any herd health challenges, and where your herd is now in terms of performance and genetic base.
2. Think about your management
Genetics alone is not the whole answer – to complement enhanced breeding it is essential good herd health management is practised.
An important part of determining if your herd will benefit from female genomic testing is to assess the response you are achieving from selection.
Are high genetic merit cows outperforming their lower genetic merit counterparts?
If not, it may be that investment and effort should be directed towards improving management before spending on female genomic testing.
3. Take a structured approach to breeding
Selection should focus on traits where an improvement through breeding will help achieve your breeding objectives.
Use a selection index aligned with your system – for example, Profitable Lifetime Index for all-year-round calving herds. AHDB has done a great job in ensuring that in a single step you make progress across a number of important traits.
Be sure to capitalise on the superior genetic merit of genomic-proven bulls versus their older daughter-proven counterparts.
More farms are now changing up their approach and using a sexed semen/beef only strategy, but whatever your future approach is, it is really important to work with your vet to ensure your plans will not be to the detriment of performance.
4. Consider female genomic testing
Female genomic testing has its place, but it will not be relevant to every dairy herd.
For most producers embarking on genomic testing, the motivation to test should be to find the bottom end. There must be scope to deselect these animals if a return on investment is to be realised. If you are going to genomic test and do nothing with the results, it is an expensive waste of time.
Tested females should be ranked according to their suitability for the farm and its breeding objectives. They should then be aligned to a defined breeding strategy, and this must be deployed with ruthless precision, by ensuring you deselect or sell the lesser animals in the herd, for example.
The use of sexed dairy and conventional beef semen, together with the sale of surplus low genetic merit heifers, is likely to yield the greatest short- and long-term financial returns.
5. Weigh up the practicalities and benefits of other strategies
When it comes to selecting strategies to maximise your rate of genetic gain, as a minimum use sexed semen alongside targeted use of beef semen.
If possible, generating a small surplus (10-15%) of heifers and selling the worst animals after testing can help speed up progress.
At the other end of the spectrum, there is also the opportunity to work with your best animals to replicate their genetics, and some farms are now choosing to use in vitro embryo production (IVP) as a strategy to expedite their gains.
One 2,000-cow herd I visited in the US was generating more than 100 IVP-derived pregnancies a month, and by increasing selection intensity and reducing the generation interval through this method, genetic gain per year was much higher.
This farm believed that in future there would be a growing interest in “off the shelf” embryos (where other producers can simply buy a ready-made embryo that encompasses the exact traits they are looking for) and so this approach meant that they had a surplus of embryos for sale.
6. Work with your vet to add value to your strategy
Genetics play a fundamental role in herd health. As vets, it is imperative we understand the genetic potential of the herds that we are working with. This is vital when looking to set realistic targets and recognise when failures to harness genetic potential are occurring.
On-farm observations and data analysis provide vets with an appreciation of the challenges that can be, at least in part, addressed through breeding. With an understanding of the statistical nature of breeding and the science behind genomics, vets are well-placed to provide advice.
Case study: Walmsley Fold farm, Preston
- Walmsley Fold farm, Preston
- 370 pedigree Holstein cows
- Housed all year round
- All-year-round calving
- Milk sold (cow/year) = 10,507 kgs (2 x milking)
- Quality indicators: Fat = 4.29%, protein = 3.24%, SCC = 16
- Calving interval = 384 days
- Youngstock in top 1% of UK national herd for £PLI
- 100% of Holstein inseminations to genomic-proven bulls, sourced from five different breeding companies
With a long-standing interest in genetics, Neil Eastham has been trialling the benefits of genomic testing on his home farm in Preston.
The herd comprises 370 pedigree Holsteins, and the farm has been carrying out genomic testing since 2016 – with more than 650 animals tested to date.
“Prior to this, we selected replacement heifers based on the traditional parent average transmitting abilities, as well as looking at dam milk records and classification data.
“However, we wanted to bring our breeding programme more in line with our system objectives and targets. We run an all-year-round calving, high input-high output herd and so we wanted to be able to select specifically for production, obviously, but also health, fertility and moderate stature, as well as good feet, legs and udder.”
The Easthams use the testing results to rank heifers and align them against different strands of the breeding strategy, he explains. “For example, of those to be retained, the bottom 20% of heifers are bred to beef, and the top 80% are bred to sexed dairy semen.
“The aim of this is to always have a 10% surplus which are then sold on.”
Such is the rate of genetic gain on farm, the genetic merit of the animals sold still places them in the top 40% of the national population for Profitable Lifetime Index (£PLI).
According to Mr Eastham, the main benefit of this strategy is the earlier insight into the genetic merit of their animals: “This means we have more confidence in terms of which animals to use sexed semen on, and this has resulted in optimising our breeding strategy to drive calf sale revenue through the generation of more beef calves and fewer Holstein bull calves.
“For us, female genomic testing is now a tried and tested strategy. Completed first lactation performance from over 200 tested heifers shows those in the top quartile ranked on their genomic PTA for milk produced more than 1,300 litres more in their first lactation compared to those ranked in the bottom quartile.
“Similarly, those ranked in the top quartile – based on their fertility index had a calving to conception figure some 16 days shorter than those ranked in the bottom quartile.”
- 12% Percentage of eligible heifers genomic tested in the US
- 7% Percentage of eligible heifers genomic tested in Canada
- 2% Percentage of eligible heifers genomic tested in the UK