Most of our advice around worm management in deer is extrapolated from what is known about sheep and cattle. However, throughout the history of deer farming in NZ, we have found examples of where these lessons don't apply - the starkest being the extreme vulnerability of deer to lungworm in comparison to other species.
Most worm control decisions in deer centre on the need to prevent deaths from lungworm, which is perfectly valid. However this has tended to lead to a heavy reliance on using long-acting endectocide pour-on drenches, a practice which is highly exposed to the development of drench resistance, plus a relative lack of attention to other management practices that could give effective worm control.
A major limitation of our advice is the scarcity of valid data and information about worms in deer.
Thankfully however, Massey University and AgResearch Invermay are currently doing some really good basic work to better define the way worms behave in deer, which will be really useful in providing better advice.
The Massey group is finding that ‘comparatively low' doses of gut worms cause immediate and major reductions in appetite and liveweight gain in young deer.
Fawns develop quite high faecal egg counts within a few weeks of birth if they and their mums are grazing contaminated pastures. Thus these young fawns have the potential to be major sources of contamination themselves.
It also appears that the phenomenon of the rise in faecal egg output that can occur in ewes around the lambing period does not occur in red hinds - meaning that the level of worm larval challenge faced by these young fawns is mainly set by the previous grazing history.
In summary:
- Young deer are probably just as susceptible as young lambs to appetite suppression and reduced weight gain from daily intakes of worm larvae
- Fawns/weaners are the major sources of pasture contamination, even when supposedly still getting much of their dietary intake from milk
- This effect is likely to be greater where lactating hinds are already grazing heavily contaminated areas
- There is no evidence that red hinds show a rise in egg counts around the birth period the way that ewes can
So what does this mean for me?
There is opportunity to improve growth rates of fawns on lactating hinds by making an effort to provide ‘cleaner' pasture for fawning.
Depending on the area in deer fencing and the balance of deer versus other stock classes, there may be scope for grazing fawning paddocks with a different stock class for a few months before fawning. Grazing the area only with adult deer rather than weaners could also help.
Weaning fawns onto a different area to where they were grazed with mum would help break the cycle of contamination that builds up over the autumn. Obviously selling fawns at weaning will do this really nicely!
All of these messages apply equally to reducing the challenge from lungworm and possibly Johne's disease as well.
So now is the perfect time to start thinking about how to apply this information in your own system at fawning this year. Feel free to give your friendly deer vet a call at the Feilding branch of Totally Vets if you would like any further help with managing worms in your deer.
