As the gate closes on Beef + Lamb New Zealand’s Future Farm Lanercost, a final field day was held to summarise what had been achieved over the farm’s five-year tenure. Part two of a three-part series will look at how the Lanercost management team dealt with parasites and drench resistance.
Parasites and Drench resistance
Double drench resistance was identified early in the lease on Lanercost and in 2020 farm performance and profit took a real hit from poorly managed parasites. To help manage the situation, the Lanercost management team sought advice from AgResearch’s Dr Dave Leathwick and local vet Ben Allott.
The decision was made not to drench any adult sheep and instead focus on monitoring and implementing management strategies to help manage parasite burdens.
This included rotating ewes and lambs behind cattle and not grazing pasture covers too hard with ewes and lambs. Cattle were used to clean up pasture residues over autumn and winter.
Most importantly, they made the decision to sell all male and female terminal sire lambs at weaning.
To maintain refugia, tail-end two-tooths were run with the replacement ewe lambs.
Speaking at the field day, Dr Leathwick explained how drench resistance was ubiquitous, with 15-30 percent of farmers having resistance to triple combination drenches on their farm.
“Farmers are getting into serious animal welfare and financial trouble due to triple drench resistance,” he says.
All cattle farmers will have some resistance on their properties.
He says there has been too much reliance on drenches to control internal parasites and this cannot continue.
“Farm systems are collapsing. Drench will not be the mainstay of parasite control into the future.”
Without drench, farmers will need to monitor parasite burdens using Faecal Egg Counts (FECs), but the challenge will be in interpretating the results.
Not all worms are the same and some are pathogenic while others are not. Different classes of stock will be carrying different worms at different times of the year.
Cooperia, for example, is very benign and huge burdens will be required to have an impact on production. Conversely, Haemonchus contortus (Barber’s Pole) which thrives in warm, wet conditions, can cause significant production losses in lambs.
It is impossible to determine different worm species from faecal egg counts but larval cultures performed by a lab will give more information. At Lanercost, Farm Manager Willy Pears sent faecal samples to the lab for larval cultures throughout the year to build a picture of what parasites were present and when. Through the testing, the management team did get an understanding of
the how the mix of worms and worm species such as trichostrongylus changed through spring and summer.
The testing gave the Lanercost team confidence in their decisions to reduce the amount of drench they were using and that the drench they did use was well targeted.
Dr Leathwick said a complete change of mindset was needed to manage parasites into the future and this includes looking at stocking policies.
“People get into strife by loading up their farms with lambs in autumn and then pushing burdens in-lamb ewes.
“The cause and effect can be much greater than you think.”
- Future Farm coping with drench resistance – Parasite management with Dr Dave Leathwick
- Systems change to deal with drench resistance on Lanercost