A decade of research in livestock health:
technology, microbes and uncooperative animals
Dr Katharina Watson
Senior Lecturer in Animal Science at the Royal Agricultural University.
There were three components to this talk:
- Livestock disease
- Antimicrobial resistance
- Agritech
The goal of all three is animal welfare improvement although there also are economic consequences.
Livestock disease
There are huge economic costs associated with livestock disease, as well as welfare and food security issues. There are also mental health impacts in the farming sector and potentially the consequences of zoonoses.
We can discriminate between epidemics such as foot and mouth with their obvious impacts on farmer welfare, and endemic disease such as TB for which we now know badger culls are not the best approach. We also can identify zoonotic diseases such as swine, flu, cryptosporidiosis and avian flu, some of which are notifiable.
Disease control for all of these could consist of:
- Vaccination.
- Medication such as antibiotics.
- Animal management.
- Herd health plans
- Biosecurity
- Government action plans.
Turning first to endemic disease: examples might be sheep scab, mastitis in cows, campylobactor in hens, zoontic pneumonia in pigs. It can be a struggle to control or eliminate such endemic diseases in the UK.
Moving to specific studies that Kat has undertaken, the first that she discussed, her PhD research, was endemic lameness in sheep. 70 to 80 % of this is foot rot. The pathogen responsible is dichelobacter nodosus. This penetrates hoof horn and then the bacteria moves into the foot tissue. The bacterium spreads from sheet to sheep via pasture.
This research involved taking a lot of samples from animals and from the environment, and also recording climatic parameters. DNA analysis of samples was used to look for dichelobacter and to attempt strain typing. The idea was to see how different strains move through flocks. One major finding was that the primary longer-term reservoir is diseased sheep feet.
Kat has undertaken similar new work on enterococcus cecorum on chicken broiler farms. Broiler chicken rearing is very rapid; only 5 to 6 weeks from hatching to plate. There are known issues with campylobacter and salmonella, but enterococcus is a more recent problem. It’s a common gut bacterium gone bad.
The team sampled chicken houses before the birds arrived from the hatchery, samples of birds post mortem that had died of other causes, and installed SMART cameras to monitor bird activity and distribution; the analysis was similar to the sheep situation and they looked at both virulence and transmissibility genes.
- There were no severe outbreaks during the study, but bacteria were found to be endemic in the environment and on all incoming chick boxes. The agent can survive on concrete for at least three weeks.
- The camera showed unexpected drops in activity at around 8 days; this was subsequently found to be due to bacterial infection (not enterococcus) showing that the smart camera approach works.
Antimicrobial resistance
One of the World Health Organisation’s top 10 global public health threats is antimicrobial resistance. It claims 700,000 lives a year and there have been no new licensed antibiotics since the 1980s. The main reason for this is over-use and misuse globally. In some countries there are restrictions on livestock farmers attending medical facilities and there is an increasing focus on reduction of antibiotic use, and particularly stopping prophylactic use.
Kat looked at antibiotic use in dairy farming with a focus on mastitis, particularly as caused by staphylococcus aureus and E coli.
Farmers commonly monitor white blood cell count in the udder; if it is too high milk can’t be sold. The team used a laser spectral technique to assess bacterial load post treatment. This uses the time of flight of laser-induced particle emission to identify which bacteria are present and even for strain and analysis using machine learning.
The project looked at antibacterial resistance, with high accuracy; it also looked at samples in milk but this was inconclusive, and it looked at farming practices such as slurry management and bedding.
This project introduced another topic that Kat discussed: the use of new technologies in agriculture. This is sometimes known as Agritech or precision livestock farming. Some familiar examples are milking robots to give cows autonomy over the time that they are milked, and automated feeding systems, which can even allow animal-specific feeding regimes. Farmers are increasingly using animal mounted sensors to assess lameness and for example fertility: the farmer needs to know when carving is imminent Kat’s team used smart collars to assess when cattle were in heat in conjunction with GPS trackers and tail sensors incorporating accelerometers. Tail raising is linked to both health and imminent calving. The sensors proved a valuable indicator of imminent birth but a lot of them were lost in use, particularly with beef cattle.
Kat finished her talk with an introduction to some of the other new technologies being used in agriculture. One of these is far ultraviolet irradiation for disinfection, operating in the range 222 to 230 nanometres. This is very effective against bacteria and has been used in buildings, and also for treating wellington boots in poultry lobbies.
There followed a lively question session which covered in more detail the safety implications of far UV radiation and concluded overall that the increased diseases across all the topics Kat has studied are linked to more intensive agriculture and to pathogen evolution in those environments.
Phil Chadwick
