Dosing strategies for dairy-beef animals

Kenneth Farrell, B&T Tillage/Beef Advisor, Teagasc Tullamore, takes a closer look at dosing strategies for dairy-beef animals.

Summer is a critical period for dairy-beef cattle. During these months, optimising liveweight gain from cheap, high-quality pasture is the primary goal. However, high stocking rates and warm, damp conditions create the perfect storm for parasite burdens which we are currently experiencing at the moment.

Managing gut worms, lungworms and flies is essential to prevent severe setbacks in animal performance.

Targeting the main parasites

• Gut worms (Ostertagia): These damage the stomach lining. They reduce appetite and nutrient absorption. First-season grazers are highly susceptible. They lack natural immunity.
• Lungworm (hoose): This is a massive threat in mid-to-late summer. It causes coughing and severe lung damage. It can kill quickly if left untreated.
• Flies: Flies cause irritation, reduce grazing time and spread summer mastitis or pinkeye. 

Strategic dosing

A blanket treatment approach is outdated, costly and accelerates anthelmintic resistance. Farmers should use a combination of monitoring and targeted treatments.

• Faecal Egg Counts (FECs): Take dung samples every 4 to 6 weeks. Dose for gut worms only when egg counts exceed 200 eggs per gram.
• The ‘hoose’ exception: Do not wait for FEC results if lungworm is suspected. Treat immediately if you hear a distinctive husky cough in the herd.
• Product selection: Rotate between the three main drug classes: Benzimidazoles (white), Levamisole (yellow), and Macrocyclic Lactones (clear). Clear drenches or pour-ons offer residual protection, which is highly useful during peak summer risks.

Managing first versus second season grazers

First-season calves have no immunity. They require monitoring and proactive dosing to prevent growth checks. Second-season animals have developed partial immunity to gut worms. However, they still remain vulnerable to lungworm. Target second-season animals based on average daily gain targets. If weight gains drop below 0.8 kg/day on good grass, parasites are the likely culprit.

Smart pasture management

Dosing must work alongside grazing management. Avoid turning freshly dosed animals onto ‘clean’ reseeds immediately. This practice breeds resistant worms. Instead, let them graze dirty pasture for a few days post-treatment. This allows a small population of susceptible worms to survive, delaying resistance.

Ultimately, a proactive summer dosing strategy protects animal welfare. It secures the daily liveweight gains needed to hit autumn slaughter or housing targets profitable.

Kenneth Farrell is a B&T Tillage/Beef Advisor in the Teagasc Laois/Kildare/Offaly Advisory Region.