Genomic testing benefits evident in just two years

At Walmsley Fold Farm, Samlesbury, Preston, run by Richard Eastham and his father John, the decision to genomically test all heifers from their 350-cow herd came in 2016. The pair had been using young genomic bulls since 2012 when UK genomic evaluation figures were first launched by AHDB. They quickly acquired confidence in the technology, so decided to select their heifer replacements using the same power of prediction.

Working with vet Neil Eastham (from Bishopton Veterinary Group, North Yorkshire, who is trained to use the independent genomic testing service CLARIFIDE® from Zoetis) they drew up a set of breeding objectives.

The objectives were aligned with the requirements of the milk contract, an appraisal of the herd’s genetic merit (using AHDB’s Herd Genetic Report tool) and a review of herd health issues that could be in part improved through breeding.

The Easthams’ main breeding objectives included:

l Improve Profitable Lifetime Index (£PLI)

l Increase milk yield but not at the detriment of fat and protein percentage. Target fat and protein percentages are 4% and 3.2% respectively.

l Improve fertility. The whole herd is a fed a flat rate TMR (comprising of a meal, potatoes, brewers’ grains, protected fat and grass silage) so excellent fertility is paramount to avoid late lactation cows getting fat.

l Avoid extremes in stature.

Prior to using genomics, they were selecting replacement heifers based on traditional parent average predicted transmitting abilities (PTA’s) as well as looking at dam milk records, health performance and classification data.

How to use genomics

Since 2016 the entire heifer crop has been genomically tested. Heifers are tested in batches at 7-10 months of age. Test results are returned within 6-8 weeks, in time for the onset of breeding. Calves can be tested as soon as they are born, but since there are inevitable losses, the Easthams opt to test as close to breeding as possible. They often time the test with another management task such as vaccination or weighing. In the last two and a half years almost 400 heifers have been tested.

Testing with CLARIFIDE is simple, it involves taking a small tissue sample from the ear, which is then sent to the Zoetis lab for analysis. Genomic PTA’s are returned by AHDB across a wide range of traits including; £PLI, Production, Health and Fitness, Management and Type. Additional information on genetic conditions is also returned directly from Zoetis. The reliability of genomic PTA’s is far greater at around 70% when compared to traditional parent average PTA’s (15-35%).

Test results are accessible on a bespoke, intuitive on-line analysis tool called SearchPoint. SearchPoint allows vets to provide additional analysis to farmers in order to determine which animals will be most profitable. Using SearchPoint, Neil ranks the heifers based on their genomic PTA’s. A bespoke herd index made up of £PLI with extra emphasis on Fertility and Milk Yield is used to optimise the ranking against the farm’s breeding objectives.

The Easthams have been surprised about how much the heifers re-rank after testing. Neil said: “Five of the 43 animals in the last batch tested had a genomic £PLI £200 or more higher than their parent average £PLI (see figure 1). Without genomic testing we simply couldn’t have identified these individuals and they would have been incorrectly bred to beef semen.”

Once ranked, heifers are aligned against different breeding strategies. For example, of those to be retained the bottom 20% of heifers are bred to beef (Angus) and the top 80% are bred to sexed semen. The aim is to have 10-15% of surplus heifers which are sold freshly calved. Such is the rate of genetic gain on the farm the genetic merit of the animals sold still places them in in the top 50% of the national population for £PLI.

Because the Easthams have a better insight earlier in life of their animals’ genetic merit, they have greater confidence in determining which animals to use sexed semen on. This has resulted in them optimising their breeding strategy to drive calf sale revenue through the generation of more beef calves and fewer Holstein bull calves.

In the cows:

l 60% of the adult herd are bred to beef (British Blue) vs 40% prior to genomic testing

l 25% to sexed semen vs 10% prior to genomic testing

l 15% to conventional semen vs 50% prior to genomic testing

Richard said: “Because we are using more sexed semen in the cows we can breed more to beef. British Blue calves are selling for about £200 a head compared to £30 a head for a Holstein bull calf. Angus bulls from the heifers sell for £150-160 a head.” They are mainly sold privately for rearing at two-weeks-old and on the CO-OP calf scheme to Dunbia.

Since starting testing, 82 heifers have completed their first 305 day lactation. Analysis of their performance has demonstrated a close correlation between performance and their early genomic PTA figures.

Milk Yield benefits

When the 82 heifers were ranked according to their early genomic PTA for milk, the first lactation yield difference between the top 25% and the bottom 25% of heifers was expected to be 928kgs. However, the gap actually realised was a lot wider. Across their 305-day first lactation there was a difference of 1,482kg of milk per heifer between the top and bottom quartiles. At an average milk price of 30.69ppl (AHDB Dec18) this is a difference of £454.82 per heifer between the top and bottom 25%.

Fertility benefits

Selection for fertility through use of the Fertility Index is also paying off. The top 25% of animals spend on average 33 days less open compared to the bottom 25% ranked by their early genomic PTA for Fertility Index.

The bottom 25% took 114 days on average to conceive post calving compared to an average of 81 days across the top 25%. At a cost of £3.50 for every day a cow is not in calf above a 365 days interval (AHDB) that’s a difference of £115.50 on average per heifer.

Neil remarked: “The difference realised in terms of calving to conception performance is startling. Especially when you consider a large number of the first lactation heifers with high fertility index figures will have been bred to sexed semen whilst their low-ranking counterparts have been bred to straight to beef.”

When using genomic testing farmers have got to be ruthless, warns Richard.

“You can’t start selecting which heifers to test, you need to test them all. We had a show heifer with a good pedigree, when we tested her, she ranked as one of the worst for fertility index. It took her six services to conceive to beef as a maiden heifer and she took eight serves to get in calf as a milking heifer. Before genomic testing we would have bred her to Holstein. You have to have faith in the results and stick to the plan.”

Neil says having good management in place on the farm is important before starting to use genomic testing. “Genomic testing won’t solve your problems, it’s just part of the puzzle, the combination of high genetic merit and excellent management will yield the best results. We know that genetics play a fundamental role in herd health. The role that genomic testing can play in realising faster genetic progress should not be ignored when looking to improve productivity and resulting profitability.”

Farm facts

350 pedigree Holstein cows.

Housed all year round.

>10% adult herd ≥6 lactations

Milk sold cow/year = 10,223 kgs (2x milking)

4.03% Fat 3.2% Protein 118 SCC

Calving interval 380 days

Milking herd and youngstock in top 5% of UK national herd for £PLI.

100% of Holstein inseminations to young genomic bulls (6-8 at any given time), sourced from four different breeding companies.