Douglas Palmer, Vet Advisor from Norbrook Laboratories LTD discusses briefly what we might see with cattle worms over the coming months.
Well, no year is ever the same is it – and this year has been no exception.
In early December 2022, most of the UK had some particularly cold temperatures which for me meant lots of tap defrosting outside but did get many of us wondering if this was a sign of more to come over the winter. Lots of hard frost and thaw cycles will play a part in reducing the numbers of many infectious stages of parasites such as those of gut and lungworms on the pasture.
Read more: How to identify and treat lungworm in cattle
However, the rest of the winter was relatively uneventful and for many quite dry. The spring continued a similar theme although was cool, here in the north of England the spring was definitely a bit later than recent years. In general, warm dry weather will reduce infectious larvae on pastures over the late spring and early summer, May and June 2023 did warm up and were dry. However, by this time cattle turned out would have picked up and become infected with any remaining gut worm larvae. Small numbers of lungworm larvae may have also survived over the winter on the ground or some, in small numbers, may also overwinter in carrier animals.
Over this very dry period in May and June, in some parts the grasslands started to look a bit brown or yellow. What did this mean for the parasitic worms of cattle?
Typically, gut worms like Ostertagia ostertagi will mature in faecal pats and lie dormant there until the rain washes the faecal matter away. These are then in a prime position to migrate onto the sward as it starts to grow and infect cattle.
The infectious larvae of the lungworm Dictyocaulus viviparous, do not survive quite as well on very dry ground. But cattle holding a very small number of adult lungworms will be excreting huge numbers of young larvae. Once the conditions are right on the pasture these will then mature into infective larvae very quickly. This can happen in as little as five days in wet warm weather.
Be aware, as we have entered what looks to be a more prolonged wetter period of the summer. The incidence of lungworm disease is likely to increase now, and the rain will have released gut worm larvae from dry pats allowing them to infect cattle.
Read more: Why managing worms will help cattle farmers meet wider industry targets
