Livestock News

  • Written by: Farmers Guide
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A closer look at genomic testing

Rachael Porter explores how an innovative genomic test from Zoetis can boost dairy herd health and profitability, and speaks to two farmers who have both used genomic testing, with completely different results and views.

Genomic testing of heifers could allow dairy producers to take herd breeding programmes to the next level – significantly improving the efficiency, productivity and sustainability of their business. Zoetis’ Clarifide Plus test is the first dairy genetic evaluation available in the UK that specifically includes proven cow and calf health and wellness traits in Holstein and Jersey cattle. And it is the only genomic test to incorporate these traits with the production traits, which are delivered by standard testing.

“This evaluation tool allows producers to genomically select heifers, and cows, for breeding based on their risk of developing any of six key production diseases, including: mastitis, lameness, metritis, retained placenta, displaced abomasum, and ketosis,” explains Zoetis vet Dave Armstrong. The test also offers information on the likelihood of heifers’ calves developing scours or respiratory disease, or calf mortality.

The test comprises an Allflex tissue sampling kit, which takes an ear notch from the animal. This is then sent off to the lab for analysis. Hair follicle samples can also be sent off for testing. The test and results reveal a Dairy Wellness Profit Index (DWP) for each animal. DWP is based on lifetime productivity and health, giving an overall view as to how profitable a cow is likely to be. Results are accessible via an online analysis tool, called SearchPoint. This allows producers to determine which animals will be most profitable on their farm.

Standard genomic testing allows for a prediction on an animal’s potential, but this test gives a prediction on the animal’s ability to remain healthy and fulfil its potential. “DWP incorporates production, reproduction, health, type and wellness making it ideal to base your cow selections on,” says Mr Armstrong.

Potential cost savings

On UK farms, the difference in lifetime profitability between the top and bottom 10 per cent of animals ranked by DWP is around £1,029. When the top third of cows are compared with the bottom third for individual wellness traits there is: 38 per cent less incidence of retained placenta; 76 per cent less incidence of metritis; 49 per cent less incidence of lameness; and 49 per cent less incidence of mastitis.

“Cows selected using the test results are 106 per cent more profitable during their lifetime, compared to selecting by parent average. And those in the top 25 per cent are, on average, more than twice as likely to stay healthy as cows in the bottom 25 per cent,” he adds.

He advises producers to begin by testing all heifers under 12 months old: “Breeding decisions have already been made for in-calf heifers and cows in the milking herd. Testing at birth means that it can quickly become part of the management routine and, more importantly, it can help producers make decisions about heifer rearing and breeding. For example, they can accurately select the best heifers to rear as replacements and pick out the ones to sell as calves.

“If producers choose to rear all their heifer calves then, to give another example, the test will highlight which ones should be used for rearing replacements with sexed semen, while the lower-end heifers could be put to a beef sire.”

It costs around £2.30 a day, typically £1,800 in total, to rear a dairy heifer replacement, with the payback on this investment taking until the middle of her second lactation. “So, by predicting a heifer’s ability and health earlier, producers can decide which heifers to ‘invest’ in. If they choose, for example, to sell the bottom 15 per cent of heifers as calves – say 15 calves out of 100 – then they’d save £27,000. And that’s just the start.

“The heifers that they do keep and rear to calve at 24 months will be healthier and remain in the milking herd for longer, which will not only increase efficiency and sustainability, but will also significantly increase the herd’s overall rate of genetic gain.”

Mr Armstrong says that solely looking at genetic return on investment ratio is typically 6:1. “But it can, and often is, much higher. Include reduced heifer rearing costs, vet and med and labour costs, because cattle are healthier, and the improved production and efficiency that goes hand-in-hand with that, and you’re looking at a close to a six-figure sum return on a test that costs around £39 per head.

“When I go through the potential cost savings and benefits with producers they say often say ‘no way’. This technology really can have a significant impact on dairy breeding and, ultimately, business profitability and sustainability.”

Uptake on dairy farms

So far around three per cent of the UK herds test heifers – some test all females – to aid breeding decisions and sire selection.

“We’re seeing a steady uptake as producers begin to see and understand the huge benefits on offer for what is actually a small one-off investment,” says Mr Armstrong. “That said, around 25 per cent of producers still rely solely on parent averages when making breeding decisions. But this method has a reliability of around 25 per cent, compared to 68 per cent for genomic testing. And the other 72 per cent of producers still go by eye, which has a reliability of less than one per cent, when it comes to breeding decisions.”

One US producer, Tom Oesch, told Mr Armstrong that he wouldn’t be able to make breeding decisions, or farm efficiently, without Clarifide Plus. Genomic testing has nearly halved the vet and med bill on his unit – where he milks 2,200 Holsteins – from £180 to £100 per cow per year.

Tom recently visited the UK, to share the improvements to his herd’s health and productivity during a series of roadshows. Since he began using the test on all females in the herd in 2012, he says he’s seen fewer herd health issues and believes this is the result of genetic improvements and management changes. By highlighting cows more prone to metritis, the herd has seen a 77 per cent reduction in prevalence from the worst group to the best group. Genomic testing has also highlighted a difference in milk yield of 2,864 litres between animals in the top and bottom 25 per cent.

“Cows and heifers performed exactly as the genomic test predicted, despite the same management conditions,” Tom says. “The animals that showed increased health issues were the ones that the test also identified as being potentially problematic.”

Meanwhile, Northamptonshire-based producer Haydn James used another genomic test through his semen company on all heifers back in 2016, for just one season. He runs the 175-cow Chalkhill herd of pedigree Holsteins, plus 140 followers, near Wellingborough. He says it cost around £29 per animal – a fraction of the cost of rearing a heifer – but for him, it was very much a one-off investment.

“We didn’t repeat it the following year with the next crop of heifers. I think it served its purpose, for us, by confirming that we were already breeding from our best stock. Genomic testing didn’t highlight any ‘outliers’ that we may have overlooked. There were no surprises and I’m happy with the cows and heifers that I have now – and the breeding decisions that we’re making.”

He explains that black-and-white sexed semen is used, to breed replacements, on the top 50 per cent of the herd. Beef sires are used on the remaining 50 per cent. “And that’s the approach that we’ve taken for the past five years.

The herd’s average yield is 10,400 litres, at 4.04 per cent butterfat and 3.35 per cent protein, on twice-a-day milking.

“Using genomic testing technology confirmed that we’d been making good decisions based on our own judgements, but we may re-evaluate this in the future. It’s important to keep an open mind.”

Zoetis says work is ongoing to add more information to the test. The Jersey test already includes an additional health trait – milk fever, as this is a particular problem in Jerseys and impacts on profitability.

Zoetis receiving the Product Innovation Award at AgriScot in November 2019.

  • Written by: Farmers Guide
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