Groundbreaking work being undertaken by the Texel Sheep Society on the genetics behind mastitis and footrot in sheep will provide crucial support for the industry as it drives to reduce its reliance on antibiotics in future.
The Society’s landmark genomic research project, which is being undertaken in conjunction with SRUC, is aiming to identify the genetic variations responsible for resistance to both these key economic diseases, explained Texel Sheep Society chief executive John Yates.
“The economic and welfare impacts of both these diseases cannot be overstated, with estimates suggesting each case of footrot costing more than £8/ewe, with further lost productivity costs amounting to up to £3/ewe.
“Additionally, it is believed that the industry loses 7-12% of breeding ewes a year due to intramammary infections.”
Both of these conditions can also cause significant welfare issue for affected sheep, something every farmer wants to avoid, added Mr Yates.
“Crucially, most current treatment regimes for both footrot and mastitis rely heavily on antibiotics to eliminate infections. But with continuing pressure on farming to reduce its reliance on antibiotics in light of fears of antibiotic resistance the industry has to look at other control strategies.”
As with all diseases prevention is far better than cure, but due to the environmentally infective nature of both these diseases, prevention can be difficult, particularly in the case of mastitis, he said.
“Using genomics, and furthering pioneering research work undertaken in footrot by the Society and SAC nearly a decade ago, we aim to introduce genomic breeding values (GBVs) for both conditions to help both Texel breeders and the wider sheep industry by breeding sheep with inherent resistance to both mastitis and footrot.”
SRUC geneticist Joanne Conington says research done by the Texel Sheep Society and SRUC between 2005 and 2008 identified a number of gene variants responsible for resistance to footrot.
“We know there is a genetic basis to footrot, with a heritability of 20% and we also know how it is linked to a number of traits of economic importance. The challenge now is to expand our knowledge of the link between resistance to footrot with that for mastitis and their interactions with other traits to develop a genomic breeding value for the breed,” she explained.
“Collecting phenotypes across genetically well-connected flocks to fuel these genomic evaluations will enhance the accuracy of genomic breeding values,” she added. “Combining footrot and mastitis makes the Texel Society work unique and pioneering at an international level.”
Dr Conington recently published a study based on records collected in the Society’s previous footrot research, which showed there are many gene variants linked to footrot susceptibility, with no big ‘major genes’ playing a pivotal role.
“This is different to, for example scrapie resistance, and means that, for footrot, the use of genomic selection, where footrot records are combined with whole-genome data is likely to be the most effective method to breed sheep that have more resistant to the disease.”
As the UK sheep industry is heavily reliant on purchased breeding stock, most commercial farmers depend on sheep breeders undertaking genetic improvement on their behalf, she added. “The inclusion of ‘breeding for resistance’ into breeding programmes leads to a win-win situation for both better welfare as well higher economic return. This is as a result of having sheep more resistant to the disease, as well as lower contamination levels on the farm as a source of infection.
“The pressure to reduce antibiotic use in farming will only increase and the sheep industry has to be ready to farm without reliance on antibiotics at some point in future. Already in New Zealand animals are being screened for antibiotic residues prior to slaughter, so the pressure is increasing on a worldwide level,” said Dr Conington.
By developing GBVs within the Texel breed, it is hoped that farmers will be able to breed stock with greater genetic resistance to both footrot and mastitis and deliver a triplefold benefit across the industry, added Mr Yates.
“Breeding stock with greater resistance to these key diseases will improve animal welfare, boost farmer returns and reduce reliance on antibiotics, cutting the chances of antibiotic resistance developing.
“This is a major benefit to everyone involved in the UK sheep industry and once again the Texel Sheep Society is putting itself at the forefront of supporting industry and developing the breed to the benefit of commercial producers.”