A5 Q2 Torch Summer Magazine 2024 - Flipbook - Page 22
THE USE OF WORMERS IN GRAZING CATTLE
By Hana Ward BVetMed PGDip VCP MRCVS &
Daniele Scovenna MRCVS
Parasi琀椀c gastroenteri琀椀s (gut worms) and lungworm are costly and widespread in
the UK ca琀琀le herd. Many control strategies to target gut worms and lungworm in
our grazed ca琀琀le involve using wormers for the en琀椀re group at known risk periods
throughout the grazing season. On many farms, the same product or class of product have been used at the same 琀椀me each year for a number of years.
Changing this approach and reducing wormer use could result in an increase in
ca琀琀le worm immunity, allow a greater popula琀椀on of natural organisms and reduc琀椀on in resistance, keeping wormers e昀昀ec琀椀ve for longer. This is crucial to remember
when considering wormer use, as there are no new wormers coming!
One of these natural organisms that aids our pasture management is the dung beetle. Dung beetles drink moisture out of cowpats, drying them out much faster than
when le昀琀 on non-populated pasture, and making them more appealing for earthworms to pull into the soil. Increasing the speed of breakdown of the pats significantly reduces the burden of worms on pasture, as well as reducing nutrient loss
and reducing 昀氀y popula琀椀ons. Regular use of wormers has a nega琀椀ve e昀昀ect on dung
beetle popula琀椀ons, with clear wormers (Macrocyclic lactones e.g. Cydec琀椀n) being
directly lethal to beetle popula琀椀ons.
So, what can we do to reduce our reliance on wormer? Firstly, vaccina琀椀ng for lungworm before turnout. There is no way to easily predict when lungworm will hit, and
wai琀椀ng un琀椀l ca琀琀le start coughing is less than ideal. The vaccine, when administered in enough 琀椀me, provides cover from Day 1 grazing and should allow the 昀椀rst
season grazers to develop enough of an immunity through exposure to lungworm
larvae, without seeing the nega琀椀ve clinical signs that pose a serious risk to grazing
youngstock.
