DNA parentage testing can pick out finest of the flock

With lambing over, our thoughts turn to which of our tups are producing more, higher value lambs?

We do not have the facility to bring down all our ewes into fields for mating or to tag and record lambs as they are born.

In our Auchtertyre highhill flock we use multiplesire mating groups, where four or five tups are put out with each larger group of ewes in different areas of the hill. We also put out chaser tups to try catch any ewe not mated first time around.

For the past few years we have been using DNA testing to try to get close to 100% accurate assignment of both paternity and maternity.

At the start of the process in 2014, all of our ewes and tups on Auchtertyre were DNA-sampled using an Allflex “punchgun”, which takes a tissue sample from the ear and stores it in a small tube.

Once these samples are collected, we only need to take tissue samples from the lambs born each year when brought in for marking, and from any new tups introduced into the flock. The tissue samples are sent off to Zoetis for “Shepherd-Plus” parentage testing, where they seek to match the DNA-profile of each lamb with the ewes and tups already on file.

Of the lamb samples sent in 2017, 96% were matched with both a sire and a dam in the flock and only 13 lambs had a damonly match, suggesting neighbours’ tups got to their mothers first.

Each year the DNA data usually shows marked differences in the performance of individual tups within the multiplesire mating groups.

At best an individual tup will be shown to have fathered the majority of the lambs in a group, and at worst another will have fathered few or no lambs.

Although DNA-testing is an additional expense, it is the only practical way to obtain parentage information which can allow us to make informed decisions when selecting tups for use in future years and lambs to use as replacements into the flock.

l Davy McCracken heads up SRUC’s hill and mountain research centre at Kirkton and Auchtertyre.

“In our hill flock we use multiple sire mating”

TESTING TIME: DNA analysis helps to inform the breeding performance of tups and ewes