How do I genotype a sheep?

Finding an approach to sampling sheep that works for you

Sheep can have their DNA sampled in a number of ways.

1). Blood Cards 

Blood sample cards are used to collect blood (and semen) for DNA processing and archiving.  Cards are usually supplied with a lancet (small needle) that is used to prick the nose of the sheep to obtain the blood spot required. It is imperative that there is enough blood to fill the black circle outlined on the cards and that the sample is allowed to dry before folding down the top flap of the blood card for shipment. Samples should be sent to laboratories quickly and protected from extremes of temperature or moisture. More information can be found here for Neogen cards, other companies have similar technology. 

2). Tissue Sampling Units (TSUs)

The use of TSU's is imperative if the sample is to be sent overseas (to laboratories in New Zealand for example) and where long term storage is required. TSU's provide a fast and efficient way to sample large numbers of sheep, generating a clean and uncontaminated sample for testing purposes - with the genetic material sealed in a specially designed preservative. Each TSU is fully sealed and can thus be uniquely identified by a barcode reader. Users will need to obtain a set of specialist pliers to sample their sheep. Information about the TSU's provided by Allflex can be found here - other manufacturers produce similar technology, but there always check with your laboratory on their preferred supplier.

3).  Nasal Swabs

Often the sampling method of choice for doing a small number of animals, in a non-invasive manner, quickly and easily. This form of sampling can be performed by anyone and is routinely used with good results when the SRUC team are sapling sheep prior to them being CT scanned. Again, once the sample has been collected try and get it to the laboratory quickly and avoid exposure to extreme environmental conditions.  

Can I genotype semen? 

Yes, the easiest way to do this is to get an extra straw or pellet delivered to the farm on the day of insemination. 

• If semen is frozen as straws you can simply take a straw from each sire of interest, leave the straw sealed, ensure that the labelling is clear and send this to the laboratory in the post.
• If semen is frozen as pellets, then place a pellet into an aliquot vial which is clearly labelled.

Semen does not need to remain frozen and should be posted the next day for delivery in a thawed state. Ensure samples are accompanied by the relevant paperwork and that the laboratory is expecting them.