Why genetics may play a bigger role in breeding lameness

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Good husbandry, environment and nutrition all play a role in the fight against lameness in dairy cows. However, new research has revealed that genetics play a bigger role than previously thought.

Research from the University of Liverpool, Scotland’s Rural College (SRUC) and the Royal Veterinary College also shows that the UK Genetic Index for Lameness – AHDB’s Lameness Advantage (LA) – can have a significant impact on eradicating the disease.

See also: How leg sensors helped manage lameness in dairy herds

This is achieved by reducing the propensity of cows to have the various causes of lameness, particularly sole ulcers and sole bleeding or bruising.

“Many existing studies have shown that the heritability of lameness is between 1% and 20%,” says Georgios Oikonomou, Professor of Cattle Health and Welfare at the University of Liverpool.

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

Georgios Oikonomou © Matthew Barden

These low estimates — sometimes expressed as 0.01-0.20 — have cast doubt on how quickly and efficiently farmers could achieve lameness improvements through breeding.

But research showed a much higher heritability for lameness, particularly sole ulcers, at 0.35 (or 35%) and sole bleeding at 0.29 (or 29%).

This equates lameness with most conformation traits, which are generally easier to measure.

In addition, by having AHDB calculate a genomic index for LA for each animal involved in the study, the researchers showed that LA has a strong association with lameness later in life.

Genetic Selection

In fact, the likelihood that a cow had sole ulcers decreased by 32% for each point at which LA increased in the participating animals.

“To put this in perspective, a recent study reported a 20 percent reduction in the likelihood of sole ulcers in cows that had preventive foot trimming prior to drying off,” said Prof.

“For this reason, we would advise manufacturers to use LA as a genetic selection tool in the prevention of ulcers and bleeding alone,” he said.

“The cost of selecting high LA bulls is negligible compared to other interventions, which often include redesigning the barn or increasing hoof trimming frequency.

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

High quality data

The researchers included more than 2,000 dairy cows in their study and self-recorded their lesions, using the same trained veterinarian for each cow.

This allowed for a better and more consistent measure of the cows’ phenotype (their actual appearance or performance) and removed much of the so-called “noise” caused by other factors, including inconsistent scoring.

This enabled the researchers to create a higher quality data set than was previously possible.

Records in foot trimming

The study demonstrated the potential for reliable lameness records that can be used for genetic selection to reduce claw horn lesions, sole ulcers and sole bleeding.

“For genetic selection to work, we need big data,” says Prof. Oikonomou. “The AHDB is currently using health data collected through the milk record in their calculation of LA and it’s working really well.

“However, these data may be incomplete or skewed towards the more serious causes of lameness. We can further improve the dataset by using foot trimming records.”

This is why the team in Liverpool, along with the AHDB, have partnered with hoof trimmers through the National Association of Cattle Foot Trimmers and the Cattle Hoof Care Standards Board.

They also work with commercial software companies, including All4Feet, VetImpress and Hooftec, with the goal of making foot care data easier to access.

Their aim is to create a national database bringing together the records of various UK podiatrists to be used for genetic assessment of foot lesion resistance.

“If we can get hoof trimming data from thousands of farms instead of hundreds, it will improve data quality and LA’s effectiveness,” he says.

However, the challenge has been getting formal consent to share data, and he urges farmers to ask their podiatrist or veterinarian how to give consent.

“We need to get better with lameness because it’s a matter of welfare and financial issues,” he says.

“It needs to be addressed through better management, housing and nutrition, but if we can breed a more resilient cow that gives us a head start.”

Targeted lameness

The lameness benefit score was developed by the AHDB in 2018 using records collected in farming software and through milk logging.

It was included in the UK national breeding goal, the Profitable Lifetime Index (PLI), in 2019.

Marco Winters, head of animal genetics at AHDB, says selecting bulls based on PLI will already help farmers reduce lameness in their cows.

“However, if producers want to specifically target lameness, they should go through the PLI components and make sure they choose a bull with a positive lameness advantage [LA] score,” he says.

“The Liverpool study showed that for every two points reduction in the lameness benefit, the risk of having a sole ulcer doubled,” he says. “It shows how effective breeding for LA can be.”

“However, the study also shows the benefits of more data and more consistency of data, meaning that records from podiatrists are used.

“We urge farmers to consent to the use of their data as it makes the LA-Score more effective and allows them to breed natural resistance to lameness in their cows more quickly.”

Sole ulcers and sole bleeding

sole ulcers

A plantar ulcer is an area of ​​damaged plantar horn that has lost all horny tissue down to the dermis (the tissue that produces new plantar horn).

It occurs when the structures that support the pedal bone in the hoof weaken.

The bone can then move and sag, damaging the horn. As the sole wears, the area of ​​the damaged horn becomes exposed, leading to the development of an ulcer.

Bleeding alone

Sole bleeding or sole bruises are characterized by red and sometimes yellow spots or areas on the sole and can occur where the sole is particularly thin.

It is caused by pressure on the dermis, causing damage to cells and blood vessels.

Flammable chemicals can cause permanent changes to the pedal bone and possibly the finger pad, leading to further bruising.

Sole bleeding is the usual precursor to sole ulcers.

Source: AHDB

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