Chemical Mixtures and Combinations

Multi-active products contain more than one parasitic chemical active responsible for killing parasites. The active ingredients within a multi-active product may target the same, or different parasites.

Multi-active products can be separated into:

• Mixtures of different actives that work against multiple parasite groups (e.g. liver fluke and roundworm).
• Combinations of different actives that target a single parasite.
• Both a combination and a mixture that target multiple parasite groups and have more than one active against at least one of the parasites.

Multi-active products or chemical mixtures and combinations have higher efficacy than the individual ingredients and are effective against more than one type of parasite. The benefits of combining actives are:

1. Better results against parasites can be expected, as parasites resistant to one of the components are likely to be killed by the other components, or their combined effect.
2. The rate of development of resistance is reduced, as very few parasites are likely to be simultaneously resistant to all components.
3. Reduces labour by combining multiple treatments into one (i.e. when it is beneficial to treat cattle against multiple types of parasite at the one time).

Do not mix different actives together unless the label states you can, or under veterinary advice, as different products may be incompatible. Proprietary ready-made products have been tested to ensure the actives are compatible with each other and achieve the desired combination or mixture effect.

Mixtures

A mixture contains two or more active ingredients that target different parasite groups (e.g. roundworms and flukes). Mixtures have the convenience of a single treatment when quite different parasites are targeted; however, they should be considered ‘single-active’ against each parasite.

The mixtures available for use in cattle are mainly employed to treat round worms and fluke with one treatment.

Mixtures available for this purpose are listed in Table 1. below.

Your choice of mixture should be guided by the parasite you mainly need to control, i.e. whether liver fluke or roundworm is causing your greatest economic loss. Note that product mixtures and combinations containing macrocyclic lactones will affect both internal and external parasites, depending on the formulation and application method. To prevent increased selection for resistance in non-target parasites consider other parasites when choosing a product.

Combination treatments

A combination treatment has more than one active ingredient to target the same parasite. It offers more than one way to kill the same parasite—the number of different ways is determined by the number of actives from different chemical groups included in the combination treatment.

Available combination treatments are listed in Table 1. below.

The benefit of including more than one active in a product is that the chance of a parasite being resistant to all active ingredients in the combination is much lower than for each individual active on its own. Therefore, combination treatments are more likely to be completely effective against the targeted parasites, including parasites that have developed resistance.

Research conducted in 2012 on WA Farms, confirmed the presence of resistance to three single actives available for use in cattle at that time. This work indicated that small intestinal worm (Cooperia oncophora) resistance against ivermectin (macrocyclic lactone) was present on two-thirds of farms. Importantly, ivermectin was fully effective when tested against brown stomach worm (Ostertagia ostertagi). The benzimidazole (white) and levamisole (clear) drenches were fully effective against small intestinal worms, but resistance was present in brown stomach worms on about half of the farms tested. Research in other states also showed the presence of similar or greater resistance.

While certain cattle worms had resistance to individual actives, the results showed that using combination products could fully control these parasites and prevent further development of resistance.

Combination and mixtures

Both dual (2 actives) and triple (3 actives) combinations are available.

Available combination and mixture treatments are listed in Table 1 below.

Types of mixtures and combinations

A guide to the different chemical actives and the pests they affect are in Table 1. See the Products Search Guides for FlyBoss, LiceBoss, WormBoss and TickBoss for the appropriate formulation and application method for your target pest.

Table 1. Mixtures and combinations, their actives and a summary of the targeted parasites against which formulations are registered for. Boxed check marks indicate the pest targeted by multiple actives.