The fight against dairy cow lameness includes good husbandry, environment and nutrition. But new research has found genetics has a bigger role than was previously thought.
The research, carried out by the University of Liverpool, Scotland's Rural College and the Royal Veterinary College, shows that the UK's genetic index for lameness – Agriculture and Horticulture Development Board (AHDB)'s lameness advantage – can have a significant effect on eradicating the condition (10.1002/vetr.1632).
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, a cosupervisor of this Biotechnology and Biological Sciences Research Council initiative.
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 lameness advantage calculated by AHDB for every animal involved in the trial, the researchers demonstrated that lameness advantage has a strong association with lameness later in life.
Genetic selection
The odds of a cow having sole ulcers declined by 32% for every point increase in lameness advantage 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 Professor Oikonomou, adding that foot-trimming was considered a key part of preventing the development of sole ulcers.
‘For this reason, we would advise using lameness advantage as a genetic selection tool as part of sole ulcer and sole haemorrhage prevention,’ he said.
‘The cost of selecting high-lameness advantage sires is negligible in comparison with other interventions, which often include redesigning housing or increasing the frequency of foot-trimming.
‘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 included more than 2000 Holstein cows from four predominantly housed dairy herds in the UK 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, and removed much of the so-called ‘noise’ created by other factors, including inconsistent scoring.
As a result, the researchers were able to work with 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 frequency of claw horn lesions, sole ulcers and sole haemorrhage.
‘For genetic selection to work, we need big data,’ says Professor Oikonomou. ‘The AHDB currently uses health data collected through milk recording in its calculation of lameness advantage, 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 with the aim of facilitating access to foot-trimming data.
Their aim is to create one national data-base, merging the records from different UK foot-trimmers, 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 lameness advantage,’ said Professor Oikonomou.
However, the challenge has been to obtain formal consent for data-sharing, and he urges vets to encourage farmers to 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.’