Internal parasites of ruminants can impact the performance of cattle at any age and should be dealt with if they are an issue.
Post drying-off offers dairy farmers a good opportunity to treat cows for parasites such as fluke, lungworms and stomach worms.
Wormers usually have a milk withdrawal period, so they are not normally administered during lactation.
Faecal egg count
Before administering a dose to cows, a faecal egg count should be taken to determine if there is a parasite burden.
Dung samples should be taken to get a representation of the parasite burden that the animals face.
You can also use bulk milk tank sampling to determine if parasites are an issue within the herd.
Cows should only be dosed if it is recommend to do so. The days of dosing cattle based on the calendar are over.
Parasites
Anti-parasitic drugs currently account for 27% of products sold for animal health in Ireland – the largest for any single product.
Anti-parasitic drugs refer to medications that are meant for the purpose of treating various parasitic diseases, such as those caused by parasitic fungi, protozoa, helminths, ectoparasites and amoeba, among many others.
Currently, there are five anthelmintic drugs available for the control of ruminant nematodes on the market; three are available over the counter, while two are prescription based.
Anti-parasitic resistance is already an issue, with all of the five products available having some form of resistance.
For example, 56% of cattle farms have resistance to benzimidazole, or the white dose; for Levamisole, or the yellow dose, this figure is 17%; while for macrocyclic lactone, or the clear dose, it is up to 100%.
Because of this the use of faecal egg counts or bulk milk sampling is important to ensure that we can continue to use these products in the future.