Calves are a fertile breeding ground for worms, being a significant source of pasture contamination in their first year of life. A high worm larvae challenge in your calves can cause reduced weight gains and scouring. A successful worm management plan should look to minimise exposure of worms by incorporating grazing management with older stock classes and the use of highly effective drenches while also maintaining a population of worms in refugia. Faecal egg counts (FEC) are a great tool to both monitor the effectiveness of drenching and the adult worm burden.
As soon as calves graze grass they ingest infective larvae (L3), which have developed from eggs laid as long ago as last autumn. Under ideal conditions, an egg can become an infective larva in a few weeks and are concentrated in the lower 5cm of pasture and in the topsoil, so grazing to low pasture residuals will expose your calves to more larvae.
Once ingested, L3 are less likely to develop in older cattle, hence the value of having them in the grazing rotation. Understanding where and how your stock grazes and the potential risk of ingesting large numbers of L3 allows you to determine a drenching programme alongside the use of FEC and liveweight monitoring.
Once you have established that drenching is required, you will need to decide which drench is suitable for the stock you are treating considering age, weight, and worm burden. For cattle there are three main drench active families: Macrocyclic lactones (MLs or mectins) with abamectin being safe in cattle 100kg and heavier, benzimidazoles (BZ or white drenches) and levamisole's (LEVs or clear drenches), which can be toxic in dehydrated stock. These three drench families can be used in many different combinations or modes of action such as oral, pour on and injectable. Be aware some drenches have a minimum weight for application.
In a grazing system dominated by young stock it is recommended to monitor the need to drench every 28 days using faecal egg counts through the summer and autumn, incorporating targeted selection treatments where appropriate to lower reinfection rates and reduce the autumn L3 challenge. As the calf's immune system develops it becomes less reliant on drench for worm control.
Active+ Merge Oral utilises oxfendazole (white) and levamisole (clear) in combination to kill suspectable roundworm species such as Ostertagia and Cooperia and is safe for use in calves over 50kg.
Once calves weigh over 100kg, Active+ Treble Oral, containing all three of the major drench families - abamectin, oxfendazole and levamisole, at a 1mL/10kg dose rate is a good choice for highly effective worm kill. The use of drenches containing actives from the three drench families will both slow the development of resistance in some worm species while expanding the spectrum of worm kill.
Both Active Merge Oral and Active+ Treble Oral aid in the supplementation of selenium and cobalt and are proudly developed and made locally in New Zealand by Nexan Corporation Limited. Active+ has a comprehensive range of oral and pour on drenches available that may be beneficial to your farm animal health plan.
For more information on Active+ products, talk to your local TSR or visit your Farm Source store.
Registered pursuant to ACVM Act 1997, Active+ Treble Oral #A011495 and Active+ Merge Oral #A011494. Always read the registered label before use.