Mid-season dosing for dairy-bred calves

Dairy-bred calves may have been at grass for 5-6 weeks. Despite the poor weather, lungworm and gut worm exposure may result in the requirement for treatment for these animals at this stage of the year, Alan Dillon, DairyBeef 500 Campaign Co-Ordinator tells us more.

Parasites of importance for calves in the first grazing season are: gut worms; lungworms; and liver fluke. Dairy calves have no immunity to parasites and are at risk of sub-clinical and clinical disease. Suckler calves are initially at a lower risk of parasite infestation, due to their milk diet and limited grass intake.

Monitoring is essential in the lead up to dosing. Clinical signs of parasites in calves are weight loss and scour (gut worms) and coughing, especially after exercise (lungworm). Daily live weight gain (DLWG) should be above 0.8kg/day.

It is advisable to carry out a faecal egg count (FEC) for gut worm eggs two months after turnout. A reading >200epg requires treatment. Frequent FECs should be considered if strategic dosing is to be used.

Fluke egg counts may be carried out when calves are at grass for more than 12 weeks, if the risk of fluke over wintering on pasture is deemed high. If there is any suspicion of harmful infections at a younger age, blood samples can be taken to check for the levels of liver enzymes.

It is important to aim to control gut worms by grazing management and good nutrition. This can offset some of the negative effects of parasites.

Appropriate use of anthelmintics

Appropriate use of anthelmintics is essential in young calves. Farmers should turn out calves onto the cleanest possible pasture. Calves should be treated within three weeks if required and repeat (check residual activity of drug used to calculate interval between doses) until mid-July. Calves should be kept on low risk pasture. Lower risk pastures include: new or reseeded pastures; silage after grass; pastures grazed by sheep for 1-2 months; or pastures that are grazed rotationally. Higher risk pastures are pastures recently grazed by young stock or permanent pasture. Further treatment may be required if calves are moved to a high risk pasture.

Lungworm infections are less predictable than gut worm infections and they make their main impact through clinical disease - hoose or husk. Fatalities can occur. Close monitoring for early clinical signs of respiratory disease, particularly coughing, is the best approach for management of lungworm infection. Management strategies are similar to that of gut worms, which include:

• Grazing management - turn calves out onto low risk pasture as one group;
• Appropriate use of anthelmintic - anthelmintic must be used therapeutically when calves are coughing and may be used strategically in conjunction with pasture management.
• Anthelmintics used to treat gut worms are also effective against lungworm

The most important thing to remember for farmers is to act now in terms of dosing and assessing when to begin dosing calves and faecal sampling is the first step to take.

Also read: Combating anthelmintic resistance on calf-to-beef farms

Also read: A journey to improve dairy beef profits in Donegal

For more information on the DairyBeef 500 Campaign, click here.