Why do we give a prelamb drench?

Traditionally ewes are given a drench pre-lambing to help control the “periparturiant rise”. This is when, around lambing time, a ewe’s natural immune defences are reduced and their normal capacity to remove worms from pasture is lost. We drench at this time to help maintain ewe condition in late pregnancy and early lactation and reduce the pasture challenge for young lambs.

 

Which drenches should be given prelamb?

 

Long acting drenches

Long acting drenches such as Marathon LA injection and capsules such as Bionic plus, have frequently been used for this and, are still indicated in some classes of stock. However as this is a time of year when there is generally low larval challenge, there are other options available that are more in keeping with modern wormwise principles.

 

Fluke treatment

If you routinely use a fluke drench in the winter e.g. Flukecare, then this is a good opportunity to give this drench; the timing is usually good for a fluke drench and treating pre-lambing is appropriate and effective.

 

No Drenching

If MA ewes are in good condition (BCS>2.5), then they can be left un-drenched pre-lambing, and given a drench such as Switch at docking. At docking, drenching can be targeted to ewes that need it, and if they are still in good condition, they can be left un-drenched. Some farmers using this method, can move gradually to less and less drenching of MA ewes, and sometimes leave MA ewes un-drenched year round. Sufficient nutrition is vital if ewes are to be left without drenching. The immune response necessary to fight worm challenge requires ewes to have good body reserves.

 

Short acting drenches

Short acting drenches such as Arrest, Switch and Matrix are also frequently sufficient to give ewes a boost pre-lambing. If some ewes (particularly singles) are in good body condition, they can safely be left un-drenched.

 

Targeted long acting drenching

Younger sheep i.e. hoggets and 2Ts have fewer reserves, lower immunity and take longer to recover than MA ewes. It is generally these sheep that we would advise have a capsule or long acting drench, especially if they are carrying twins. It has been well documented that it is very cost effective to use these products in young sheep. As long as they are not used as ‘whole flock’ treatments their use is justifiable.

 

Do you have questions regarding prelamb drenches?

If you have any questions regarding which prelambing drench is right for your sheep or if you are interested in a drenching programme specific to your farm, get in touch with your local Anexa vet.

 

 

Vaccines for Colostral Immunity 

Unlike many other mammals, lambs do not get any maternal antibodies through the placenta. This means they are born without any immune system, getting all of their antibodies through their mothers’ colostrum until they can create their own. 

Antibodies bind to a specific pathogen, sending signals to white blood cells that then destroy them. In new-borns, antibodies are absorbed through the gut into the blood stream but there is a limited time before the gut ‘closes’ and these large molecules cannot pass through. This process is called passive transfer and if it fails, our new-born animals are left defenceless, meaning increased disease, increased death rates and longer term detrimental effects on growth rate and reproductive performance.

Therefore, it is important to get enough colostrum into our new-borns, and within the time frame mentioned. We can also ‘boost’ our animals’ colostrum by vaccinating the mother before lambing. They require 10-15% of their birthweight over the first 6-12 hours, which means a lamb requires over a litre (based on an average birthing weight of 5-6kg) of colostrum. Their stomachs cannot hold this much fluid at once so this has to be split into several feeds. Usually our lambs are left to drink alone, but this is good to know if we have to hand rear them. 

Vaccinations in the mother will increase the antibodies in the colostrum and so we recommend annual clostridial vaccines in sheep talk to your vet about which one best suits your needs.