A single-shot vaccine to sterilise female cattle and boost productivity in northern breeding herds is being developed using ground-breaking biotechnologies.
Led by The University of Queensland (UQ), the research is part of a three-year project supported by Meat & Livestock Australia (MLA) that if successful, could produce a cattle contraceptive vaccine that is effective for at least 12 months.
The project is one of 12 new on-farm research, development and adoption (RD&A) projects to receive MLA investment in 2017-18, instigated through MLA’s regional consultation process. The process enables producers to have input into the direction of RD&A funding most relevant to them.
MLA Animal Health, Welfare and Biosecurity Program Manager, Dr Jim Rothwell, said a potential vaccine would eliminate the need for surgical sterilisation of female cattle that involves removal of ovaries, or oviducts (commonly called ‘spaying’ or ‘webbing’).
Dr Rothwell said spaying of cull cows and surplus heifers was a practice used in extensively-managed beef operations to prevent pregnancy and to allow them to achieve a saleable body weight and ultimately boost herd productivity.
“MLA and the wider red meat industry are investigating alternatives to replace spaying with an effective, easy to use and welfare-friendly vaccine – predicted to cost less than $20 per shot,” Dr Rothwell said.
Professor Michael Holland, of the UQ School of Veterinary Science, is leading the new project with fellow UQ researcher Professor Michael McGowan. Professor Holland has worked on immune responses and vaccines that can induce temporary contraception in a range of pest and domesticated livestock species since the early 1990s.
His team has tested several naturally-occurring and synthetic proteins that are showing promise for use in a slow-release vaccine specifically for female cattle.
These proteins target the outermost layer of the female egg, called the zona pellucida (ZP), provoking an immune response and preventing egg fertilisation.
Professor Holland said this type of vaccine would save time for beef producers in treating stock once annually at the time of regular mustering, reduce cattle stress, cut potential losses from surgical spaying and address some animal welfare concerns associated with current sterilisation procedures.
He said initial trials using a set of proteins derived from pig ovaries, called Porcine Zona Pellucide (PZP), were showing promise for use in a cattle vaccine.
“In Brahman female cattle, we achieved 46 weeks of infertility in 89% of animals treated,” Professor Holland said.
“But this required three injections – one in young heifers, a booster at one month and another at six months. Whereas, our aim is to have a single shot injection that can be applied as early as post-weaning and persist for at least 12 months.
“If we can achieve that, it will meet the management needs of rangelands producers because if they don’t want to sell treated females at 12 months, they can do a second injection to prolong infertility into a second year – or even let them breed.
“It is about providing herd management flexibility that can’t be achieved with a surgical option which, by its nature, is irreversible.”
The next step for the UQ researchers, in conjunction with colleagues in engineering and others at the Melbourne-based Swinburne University of Technology, is to investigate slow release systems.
Professor Holland said these systems would allow the agent provoking the immune response to be inserted and the agent to be slowly released over time, resulting in at least 12 months infertility.
“In addition, we are working to use biotechnologies to produce a refined or synthetic vaccine product to replace the PZP,” Professor Holland said.
“We are making progress, but the proteins we are trialling do not yet have the persistence achieved with the native pig ovary material.
“Through the MLA project, we will be looking at options to make a product that more closely resembles the natural material, or see if we can chemically synthesise parts of the PZPs.”
Professor Holland said this was rapidly evolving biotechnology, but – if successful – would be the cheapest form of a vaccine for producers.
“We are not just seeking a scientific solution, but want to make a product that is cost-effective and economic – with a goal to have a zero failure rate in female cattle,” he said.
Professor Holland said a single-shot vaccine for inducing cattle infertility could also have application in Australia’s dairy and southern beef herds and in countries such as Brazil and South Africa, where cattle are grazed extensively.
He said similar vaccines had been found to work in pest species across the globe and it was just a case of finding the right protein for the task.
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