March 5, 2010

Breeding sheep to eliminate dags and worms. 9.

By Dr Clive Dalton


Getting the best from a 'Dag-Free' and 'Worm-Free' ram

This is an outstanding Romney ram. He was named 'The Colonel'.
Every time he has been tested he has had zero FEC, and had a FCS of 1 (marbles). Consequently, he has always remained clean regardless of the feed he was on. His sons have come through showing the similar traits.

If breeding is not for you

If the idea of breeding your own rams is not an option, and you are lucky enough to find a source of genuine Dag-Free and Worm-Free rams, how can you get maximum genetic benefit from them to improve your commercial flock -on 'fast track'.

  • Don't just turn a top ram loose at random in the flock. His genetic influence will be so diluted that you'll never live to see the benefits of eliminating dagging and drenching.

Must do
  • It's your job to make sure the ram or rams are mated to ewes that will speed up genetic gain in the flock - so you have to do some intense selection on the females side.
  • A ram only carries half his superior genes to his offspring, but he has the big advantage of influencing many more offspring than any single female in the flock.
Before you start
  • Do not drench any ewe at least two months (more if possible) before joining, no matter how convincing the advertising or sales promotions may be.
  • Mature ewes with their fully developed immune system should not need drenching, and if any do, then mate them to a terminal sire and cull them after weaning. Don't let their genes into the wider flock.
  • You can't identify genetically daggy ewes if they are full of drench.

Mating group options

Here are some options from lowest priority to highest from a technical viewpoint. Just do what suits your farm management system best.

  • Among each group, look for individuals that are structurally sound and have as clean backsides as possible.
  • Avoid like the plague any that have been regularly dirty.
  • Do a FCS to identify all those with marbles or hand grenades.
  • Do a FEC through a lab if you can afford it, and avoid using any ewes over 500 epg.
  1. Mixed age ewes.
  2. Two-tooth ewes.
  3. Cast-for-age ewes.
  4. Ewes scanning twins before lambing.
  5. Ewes that have reared a lamb to weaning - still with milk at their udder.
Mating ratios
  • Single sire each ram with 400 selected ewes for one cycle, to try to get as many progeny as possible.
  • Otherwise don't come down to less than 100 ewes per ram.

What to do with the progeny?
Just make sure you can identify them to put plenty 'selection pressure' on them as described in the earlier parts of this blog.

No comments:

Post a Comment