The productivity gap between genomically-tested and non-tested herds is widening. This alone easily justifies and offsets the cost of using this breeding technology, which has seen a surge in use across UK herds.
TEXT KAREN WRIGHT
The number of genomically-tested heifers in UK dairy herds is increasing by at least 50% year-on-year, following the trend seen in the US where genomic testing is becoming part of routine herd management.
And, as the benefits become more transparent, the gap in herd productivity and efficiency is widening between those testing and those not. This increase in genomic testing of females comes as no surprise to NMR’s genomic services manager Richard Miller.
“So far in 2022, uptake of genomic testing is increasing faster than ever,” he says. “Around 12% of all eligible dairy heifers are now genomically tested. In February 2022, AHDB evaluated 8,000 female genomic tests compared with 3,652 in February 2021.”
This trend reflects that seen in US-based herds where 33% of all replacements are now genomically tested. “Testing started slowly in the US then ‘took off’ about three years ago. In 2021, almost one million dairy females were genotyped. I think we’ll see the same trend here,” Mr Miller says.
Key traits
The increase seen in NMR’s genomic testing has been spurred on by the company’s investment in its own UK-based DNA testing laboratory. “The introduction of key industry traits by AHDB, such as Feed Advantage and EnviroCow, will drive more herds to adopt genomic testing,” says Mr Miller.
“These important new efficiency indices are only available for genomically-tested dairy animals. They will be important tools in steering us towards breeding more efficient, sustainable and profitable cows that are better converters of feed into milk.”
Using parent averages to measure and rank heifers – plus some visual assessment on farm – will never match the accuracy of a genomic test result for a heifer calf. “For many years, we’ve relied on parent averages to give the best estimate of a heifer’s potential,” he adds. “But her DNA is a far more accurate measure for all key traits and also provides a measure of her genetic potential in a whole wealth of additional management areas such as health, milking ease, temperament and TB advantage.”
The reliability of data based on parent average is 30% compared with that based on genomic data of at least 60%. “And ongoing work at AHDB is likely to demonstrate the reliability figure for genomic proofs is actually much higher than this,” says Mr Miller.
Accurate ranking
“Those producers using genomic-test results can rank heifers more accurately and be confident that they are breeding replacements from the best females. It adds another level of precision to herd management.”
NMR has demonstrated the gap between using parent-average and visual assessment with genomic tests to rank heifers in its ‘You be the judge’ competition. From more than 500 entrants, none correctly matched the order of highest to lowest genomic PLI using parent average data and a photograph of the animal.
“This shows how difficult it is to read a young heifer’s potential based on parent data and her appearance,” stresses Mr Miller. “As animals get older and have their own production data, we are seeing the close alliance with their genomic proof that reflects reliability.” AHDB’s head of genetics Marco Winters says this shouldn’t be a surprise as the calculation for heifers is the same as for young bulls. “We already know from previous work on young sires that early genomic predictions are good forecasts of ultimate progeny performance.
“Growing acceptance of the reliability of genomics is reflected in AHDB data, which shows that around 70% of all dairy inseminations are now by young, genomically-tested sires. This confidence is extending into heifer genomic testing,” says Mr Winters.
NMR has analysed cow records of animals born from 2016 to 2020 in more than 2,000 herds and compared the genetic potential of those with 75% or more genotyped animals against those with none.
“We found a £86 difference in PLI at the outset in 2016, but by the end of 2019 this difference was £151 PLI, reflecting the widening gap between tested and non-tested herds,” says Mr Miller.
The early adopters of genomic testing were already showing better genetic potential than the rest, so were ahead at the start. But the gap widened as they continued on the programme.
This increased rate of gain in PLI is reflected in profitability. Recent work by AHDB and Promar indicates that each additional point of PLI is worth, on average, £1.58 of extra profit per lactation. “So in this case the extra £151 PLI adds up to an additional £238 of profit per lactation.”
Increased rates of improvement in production potential were also seen among the tested herds. “The fertility index, which reflects a reduction in calving interval and better non-return rates, also increased at a faster rate in tested herds,” adds Mr Miller. “This shows herds are successfully combining improved fertility with better production, which has long been one of the biggest issues facing the industry.”
At the beginning the difference in predicted fertility index was 0.89 points and this increased to 1.64 by 2019.
Accelerated progress
“Overall, the data shows the accelerated progress being made in genomically-tested herds versus those not tested. Herds exploiting their full potential in key areas will make better gains in efficiency and sustainability,” he says.
Overriding the traditional reliance on parent average and visual assessment of heifers and cows with genomic testing is a big step forward. “But it is a necessary step if producers want to make the most of the genetic opportunities present within every herd.
“Over time we can expect significant differences in efficiency, production and profitability where a genomic programme is in place, while those herds not recording or testing stand to be left even further behind,” says Mr Miller.
The premium cost of sexed semen and the benefit of reducing the number of dairy bull calves born, combined with the added value of beef-cross calves, makes more accurate breeding planning even more important for maximising herd efficiency and profitability.
“Rearing costs of dairy heifers is the same regardless of potential, but the outcomes are not,” Mr Miller stresses. “The gap, which is widening at an increasing rate, can easily offset the cost of genomic testing.”
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