Dosing ewes around lambing season is still a common practice but is not always necessary, according to Animal Health Ireland (AHI) SPARC (Sustainable Parasite Control Programme in Grazing Ruminants) team.

In the past, this was often encouraged as a way to combat the 'peri-parturient rise' i.e., an increase in parasite egg shedding around lambing.

The ewe’s immune system weakens near the end of gestation, often due to nutritional constraints where there is insufficient protein to meet demands.

This weakening of the immune system can lead to a rise in worm egg production in the gut. It can begin to occur two weeks prior to lambing and last for about six to eight weeks into early lactation.

This increase in egg shedding is a source of contamination on the pasture – a risk for lambs as they start grazing.

Out of convenience, many farms blanket dose; however, with the rise of anthelmintic resistance (AMR), farmers are advised to consider taking a closer look at dosing management. 

Dosing

What can be done?

Take a look at your feed: Ewes with adequate protein levels are at much less risk to this drop in immunity. Lamb weight increases by 70% during the last six weeks of pregnancy and feeding should increase to meet the substantial increase in demand for nutrients during late pregnancy;
Ewes that are underweight are under more pressure: Go back to basics and think about body condition score (BCS); ewes should be lambing down at a BCS of 2.5-3.5 (depending on type). Ewes should not fall below a BCS of 2.0. Correct BCS comes with a wealth of other benefits;
Ewes carrying twins or triplets are under more strain than ewes carrying singles and are more at risk in this rise of egg shedding. This may be related to the greater nutritional demand for these ewes;
Ewe lambs/hoggets are more at risk if the nutritional or other stresses are not managed; 
Consider taking dung samples for faecal egg count before dosing. 

This drop in immunity does not occur in all ewes or farms; however, it is important to be aware of it. If you are to treat ewes, try to dose only those who need it, the AHI has said. 

Liver fluke survey

Meanwhile, liver fluke remains one of the most significant parasitic challenges affecting sheep across Ireland and Europe, contributing to substantial production losses, welfare concerns, and mortality.

Increasing triclabendazole resistance has made effective control more difficult.

As a response to this, University College Dublin (UCD) has become involved a project called MAP-TCBZR (MAPping TriCleBendaZole Resistance).

The project hopes to identify genetic variants within liver fluke that carry triclabendazole resistance and to gain a better understanding of how liver fluke become resistant, with the aim of maintaining and improving livestock production.

In order to do this, the researchers are looking for sheep farmers to participate in a 15–20 minute anonymous survey designed to help map the connections between liver fluke infection, management strategies, and triclabendazole resistance on sheep farms.

Submissions to the survey, which is available through the UCD vet school website, will support efforts to improve fluke control, strengthen flock health, and enhance the sustainability of sheep farming in Ireland and Europe.