Winter Dosing Principles – Dairy Cows

Dairygold Agri Business at Buckley’s Farm, Rathduff, Co. Cork. Photo Joleen Cronin

A moderate gastrointestinal parasites burden can increase the costs of with wintering cattle by 30%

Anthelmintic resistance

The genes responsible for anthelmintic resistance are believed to be present in all worm

populations but at very low levels. When animals are treated with an anthelmintic, this kills all the susceptible worms allowing only the resistant worms to survive.

The surviving resistant worms output eggs with the dung onto pasture which results in resistant worms making up a much greater proportion of the worm population in subsequent generations.

A 2017 Teagasc survey found:

• Resistance to benzimidazole anthelmintic (white wormers) of 75% on dairy calf-to-beef farms
• Resistance to macrocyclic lactone anthelmintic (clear wormers) of 100% on dairy calf-to-beef farms

How to avoid resistance

• Read the manufacturer’s instructions
• Avoid under dosing animals, weigh cattle if possible, to get correct weight.
• Check dosing equipment to ensure correct amount is applied
• Avoid the continual use of wormers from the same class and only use a combination anthelmintic product when it is necessary to treat for both fluke and worms

AT this stage there is evidence of resistance to all classes.  All products within the same class have a similar mode of actions.  So, if a parasite has resistance against a class it will be resistant against all products within that class.

When switch products we need to switch to a different class of anthelmintic not just switch between products within the same class.  Focus on the class of the products not the product name.

• Use good biosecurity protocol for all bought in animals
• Reduce the amount of dosing and allow the animals build immunity.
• Take dung samples and only dose on rising counts or when animals coughing.
• Do not dose all the animals in the group target the low weight calves and those with dirty tails.
• After dosing leave in old paddock and move to clean pasture in 3 days
• Extend the period between doses by using bales or silage ground
• Dung sample before and 2 weeks after doses *1 week for the levamisoles) to ensure a response to treatment

We are mainly concerned with:

• Stomach worms/ Lungworm
• Liver Fluke
• Rumen Fluke
• Lice + mange

Lungworm & Stomach worms
Mature cattle can build an immunity to worms.  Our main concern is weanlings and animal heading for their 2^nd winter.  Mature animals should be dose if there’s an indication of a problem.

There are 3 families but only two families of drugs that give a full cover across the winter

1. Macrolytic Lactones-Ivomec, Mastermectin, Cydectin, Eprinex etc.
2. Albendazoles- Albex, Albencare, Tramazole etc
3. Levamisole’s – are to be avoided in winter dosing programmes as they do not cover Type 2 ostertagia.

Liver Fluke

Adult cattle do not have immunity.  The presence of Liver Fluke depresses Liver function. This will result in reduced production, poor immunity and reduced efficacy of vaccinations.

Treatment for Fluke only:

Triclabendazole (Fasinex 240, Tribex 10%) is the only product that will kill fluke from an early stage (2 weeks).   Because of this, one dose 2 to 3 after housing will cover liver fluke.

However, it does not kill worms and will need a worm dose separately.

Closantel (Solantel, NOT LICIENCED FOR DAIRY) kills fluke from 7 weeks.  One dose is sufficient if you wait for 7 weeks after housing to dose.  This is a long time especially for finishing animals on high levels of concentrates that need good liver function.

2 doses will be needed if you dose before 7 weeks.  It does not kill worms and will need a worm dose separately.

Oxyclosanide (Ruminil) and Albendazoles (Albex) only kill mature fluke (12 weeks old).  If used, you need to dose twice across the winter.  Ruminil is often used as the 2^nd dose with an albendazole as the 1^st (taking out the worms early).

Do not use Ruminil within 2/3 weeks of calving.  Ruminil does not kill worms and will need a worm dose separately.  It does kill rumen fluke.

Treatment for Fluke and worms combined:

Closantel + Ivermectin (Closomectin, NOT LICIENCED FOR DAIRY) kills fluke from 7 weeks.  One dose is sufficient if you wait for 7 weeks after housing to dose.

This is a long time especially for finishing animals on high levels of concentrates that need good liver function.  2 doses will be needed if you dose before 7 weeks.

Clorsulon + Ivermectin (Animec Super, Ivermec super, NOT LICIENCED FOR DAIRY) kills fluke from 12 weeks.  If they are used, you need to dose a 2^nd time to control fluke across the winter.

Albendazoles (Albex, Albex gold, ONLY DAIRY OPTION FOR COMBINATION FLUKE AND WORMS).  If they are used, you need to dose a 2^nd time to control fluke across the winter.

Oxyclosanide (Levafas Diamond, NOT LICIENCED FOR DAIRY).  kills fluke from 12 weeks. But does not kill type 2 ostertagia.  DO NOT USE

Lice:

No immunity developed.  Fill a shed at the one time.  The lifecycle of these parasites is typically completed in 2-3 weeks, so select products with a >3 week persistency.Injectable iver- MECTINS only kill sucking lice.  Pour-ons kill both.

Drench test – can be used to check resistance to a product used.

Do a faecal egg sample before dosing.  Depending on the wormer used sample again between 7 and 14 days later see table below.  Good kill is >95% reduction in faecal egg count.

Weanling:

Housing is a stressful time. Try and do a pre-housing dose (3 weeks prior to housing for lungworms).  Over winter dose for worms, fluke and lice.  Combination pour-ons that kill worms and most liver fluke and lice are a good option.

Store or finishing cattle:

Over winter dose for worms, fluke and lice.  Be conscious of meat withdrawals, it ranges from 60 to 143 days with differing products.  If feeding reasonable levels of concentrates, the liver needs to be in good health.  Don’t delay fluke dose too long.

Options Dry stock:

1. Use a combination product that kills worms, fluke and lice eg closamectin, ivomec super.  None of these tick all the boxes but they are good options and limit work load.  The best will generally only kill fluke from 7 weeks. The injectables only kill sucking lice.  If used at housing a 2^nd dose will be required for fluke.  Alternatively wait 7 weeks to dose – this may affect performance.

or

1. Dose for worms + lice at or 3 weeks after housing, use an ivermectin, doramectin, moxidectin product.  (Injectables will only kill biting lice)

2a. Treat for fluke after 2 weeks with a Triclabendazole product eg fasinex, tribex.

or

2b. Treat for fluke after 7-8 weeks later with a product like solantel or rumenil

or

1. Treat with an albendazole eg albex at or 3 weeks after housing. It will kill worms and fluke from 12 weeks.  Repeat the dose 9 weeks later to kill all fluke. You will need to treat for lice separately.  Repeat dose can be Rumenil if rumen fluke is a concern.

Dairy cows programme,

Eprinex (wormer, eprinomectin) is a macrocytic lactone like iver – MECTIN. As it’s the only wormer with zero milk withdrawal we should be preserving its use for summer dosing.  It is the same class as wormers like dectomac, noromectin and mastermectin etc.

Our winter worm dosing strategy should therefore be built around albendazoles like albex, endospec 10% etc.

Albendazoles kill worms and mature fluke.  If using an albendazoles wait 3 weeks after housing to allow maturity of all the worms.  After 3 weeks housing the albendazoles will not kill immature fluke.  Therefore a 2^nd dose will be needed later in the winter.  The 2^nd dose can be a repeat of albendazole or Rumenil to kill rumen fluke. If using Rumenil as 2^nd dose do not use within 2/3 weeks of calving.  If using Rumenil as 1^st and 2^nd dose avoid using at drying off.