Worming your dairy cows can be a complex issue as there is a need to consider the responsible use of anthelmintics and the environment whilst ensuring efficiency for milk production.

It is important that the use of anthelmintics is done responsibly to prevent the emergence of resistance. We don’t want to end up like some sheep farms with multiple resistance worms on the farm making the management and economics of the farm more challenging.

Why is it important for dairy cows?

Adult cattle may be sub-clinically affected by gut worms as well as lungworm. There are differences in the immunity cattle develop to both gut and lungworm and so different approaches can be necessary to maintain health and productivity.

Dairy cattle with Ostertagia ostertagi (gut worm) infections can have decreased milk production from their potential due to damage to the stomach and the subsequent negative impact on feed intake and digestion. Following treatment with a wormer, the increase in yield is variable with data from 0.35 – 2.35kg per day. It is known that higher yielding cows appear to be more susceptible to the effects of gastrointestinal nematodes. Consider treating individual animals that are more at risk (targeted selective treatment) such as high yielders and heifers, and also treating them close to calving so the yield benefit is seen through peak lactation. Treating at calving may also help reduce negative energy balance and so ease the transition period.

Lungworm is an ongoing challenge that requires a balance of exposure to maintain immunity and treatment if clinically affected. It can be difficult to predict and control due to weather factors, carrier animals and also the challenge of diagnosis in adult cattle, where the parasite may not complete its life cycle. Lungworm treatment needs to be rapid and accurate to prevent continuing issues.

For all adult dairy cattle treatment a product with zero milk withhold is useful.

There are various options for worming dairy cows, but we advise speaking to your vet so we can advise the best option for your system.

Worming Dairy Cattle