Disease and Parasite Resistance in Deer

An update on recent deer industry research at AgResearch Invermay, which includes the impact of the Deer Progeny Test project – a project which offers improved productivity and profitability in the farmed deer herd.

The DPT (Deer Progeny Test) is a project that was funded by DEEResearch, a joint venture partnership between AgResearch and Deer Industry NZ, along with Landcorp Farming Ltd and Alliance Group. The idea was to better describe the genetics of performance and profitability of deer. That required a significant trait measurement and breeding values system.

The project tested industry sires across commercial hinds on three farmed herds including Invermay as well as herds at Whiterock Station (Rangitata) and Haldon Station (McKenzie Basin).

The project had five aims:

improve sire linkage between recorded herds on DEERSelect (national deer genetics database),
offer a platform to evaluate breeding values across breeds,
evaluate new traits for optimisation of selection goals,
offer a starting point for evaluating maternal traits,
establish a population for future genomic tools.
The study covered three breeding seasons with the DPT’s final AI programme taking place in April 2013 and assessments were completed in December 2014. Most progeny across the three years were slaughtered for assessment of carcass traits.

As the DPT project progressed, it met its first objective of improving sire linkage between stud herds involved in the project. As a result of the project, farmers are now able to compare the traits of an animal with those in other herds and do so with a reasonable degree of confidence.

The flow on effects will be improved genetic gain, meat quality and sensory traits as well as measurements for temperament.

AgResearch scientist Geoff Asher says some of the immediate benefits from the Deer Progeny testing were increases in growth, reproduction and meat yield traits.

Following the three-year Deer Progeny Test programme, Geoff says the next step was using the database for assessment of heritability of novel industry-relevant phenotypes. He says the parasite challenge is the “sleeping giant” of the deer industry and that drench resistance is a big factor looming on the horizon. One option was to select for host resistance to parasites but that required a tool to measure the appropriate phenotype. He says that tools like faecal egg/larval counts were ”highly unreliable” in deer.

During the DPT project, CarLA (carbohydrate larval antigen), a salivary antibody, was identified as possibly being a good measure of increasing resistance to worm challenge.

The DPT study showed that the CarLA response in deer is heritable, offering the opportunity to select for resistance and reduce reliance on drenching over time.

The progeny in the DPT study were give a routine drench to minimize parasitism, and although they showed a CarLA response to ingesting worms, they were prevented from showing the effects of clinical parasitism. That means further studies in young deer need to be carried out to understand the effects of CarLa on actual parasitism when drench use is minimised.

Geoff says if he asked 30 deer farmers how important temperament was, 30 would say very important, but ask them what they would select for and he would get 30 different answers.

What the actual traits are that need to be measured and defined, such as around reducing aggression, nervousness or flightiness is something they are continuing to work on.

Various in-yard scoring systems had been developed that are being routinely applied to DPT progeny and their dams.

Geoff says heritability of those traits was generally quite low – the environment has a big effect on deer behaviour. However, some progress could be made over time by selecting for or against such traits as nervousness and agitation. Even with low heritability for these traits, there was still value in recording temperament and culling individuals that cause problems during yarding.

Professor Frank Griffin has had a lengthy career in animal science at Otago University. He was part of a university based research team devoted to solving animal health problems in the deer industry including the two major bacterial diseases – TB and Johnes.

Since his ‘retirement’ from the university based research team he’s continued his work at Disease Research Ltd (DRL) which is based at Ag Research’s Invermay centre. DRL is continuing the work on Johne’s as well as looking at areas such as general disease resistance and parasite prevention. The work on Johne’s includes a study on a group of immune markers (biomarkers) for resistance .

While the DPT has started opening up new horizons around carcass, parasite resistance and temperament traits, the opportunity to select for a much wider range of commercially relevant traits is something the deer industry is pursuing.

Future projects include selecting for novel traits of high performing red deer and developing a selection tool for specific traits.

Geoff Asher says the field of genetics never stands still and new technologies would open up new opportunities to accurately measure phenotypes of productive importance, such as disease resistance.

The ”genomic revolution” might one day provide the technological platforms to identify specific genes of importance.