Why genetics can play bigger role in breeding out lameness

Good husbandry, environment and nutrition all play a part in the fight against dairy cow lameness. But new research has found genetics has a bigger role than was previously thought.

The research, by the University of Liverpool, Scotland’s Rural College (SRUC) and the Royal Veterinary College, also shows that the UK’s genetic index for lameness – AHDB’s lameness advantage (LA) – can have a significant effect on eradicating the condition.

See also: How leg sensors helped get on top of lameness in dairy herd

It does this by reducing the tendency of cows to have the various causes of lameness, particularly sole ulcers and sole haemorrhage or bruising.

“Many existing studies have shown the heritability of lameness to be between 1% and 20%,” says University of Liverpool professor of cattle health and welfare Georgios Oikonomou.

Mr Oikonomou was a co-supervisor of this Biotechnology and Biological Sciences Research Council (BBSRC) initiative.

Georgios Oikonomou © Matthew Barden

These low estimates – also sometimes expressed as 0.01-0.20 – have raised doubts about how quickly and efficiently farmers could make improvements in lameness through breeding.

But the research demonstrated a far higher heritability for lameness, particularly for sole ulcers, at 0.35 (or 35%), and sole haemorrhage at 0.29 (or 29%).

This puts lameness on a par with most conformation traits, which are generally more easily measured.

Furthermore, by having a genomic index for LA calculated by AHDB for every animal involved in the trial, the researchers demonstrated that LA has a strong association with lameness later in life.

Genetic selection

In fact, the odds of a cow having sole ulcers declined by 32% for every point increase in LA in the animals taking part.

“To put this in context, a recent study reported a 20% reduction in the odds of a sole ulcer in cows that had been preventively foot-trimmed before drying-off,” said Prof Oikonomou, adding that foot-trimming was considered key in sole ulcer prevention.

“For this reason, we would advise producers to use LA as a genetic selection tool as part of sole ulcer and sole haemorrhage prevention,” he said.

“The cost of selecting high-LA sires is negligible in comparison with other interventions, which often include redesigning housing or increasing foot-trimming frequency.

“And the magnitude of the potential reduction in sole ulcer incidence that could be achieved through genetic selection would result in a substantial improvement in both animal welfare and farm efficiency.”

High-quality data

The researchers involved more than 2,000 dairy cows in their study, and recorded their lesions themselves, using the same trained vet for every cow.

This gave a better and more consistent measure of the cows’ phenotype (her actual physical looks or performance), and removed much of the so-called “noise”, which is created by other factors, including inconsistent scoring.

As a result, the researchers were able to create a higher-quality dataset than had previously been achieved.

Foot-trimming records

The trial showed the potential for reliable lameness records to be used for genetic selection to reduce the claw horn lesions, sole ulcers and sole haemorrhage.

“For genetic selection to work, we need big data,” says Prof Oikonomou. “The AHDB currently uses health data collected through milk recording in its calculation of LA, and that’s working really well.

“But this data can be incomplete or skewed towards the more severe causes of lameness. We can make the dataset even better by using foot-trimming records.”

For this reason, the team at Liverpool, together with the AHDB, have partnered with foot-trimmers through the National Association of Cattle Foot Trimmers and the Cattle Hoof Care Standards Board.

They are also collaborating with commercial software companies, including All4Feet, VetImpress and Hooftec, with the aim of facilitating access to foot-trimming data.

Their aim is to create one national database, merging different UK foot-trimmers’ records that will be used for the genetic evaluation of resistance to foot lesions.

“If we can get foot-trimming data from thousands of farms rather than hundreds, it will improve the quality of data and the effectiveness of LA,” he says.

However, the challenge has been to obtain formal consent for data-sharing, and he urges farmers to ask their foot trimmers or vets how they can give their consent.

“We have to get better with lameness as it’s a welfare and financial concern,” he says.

“It has to be tackled through better management, housing and diet, but if we can breed a more resistant cow, that gives us a head start.”