How will breeding make a difference?
Ultimately, you’re aiming to introduce more “resistant” animals into your flock – that is, sheep that actively fight off infection and have a reduced shedding of eggs. This lowers subsequent larval challenge to all stock.
Finding a breeder
Resistance to internal parasites is measured as low faecal egg counts (FEC). The relevant index is Dual Purpose WormFEC™ (DPF).
a) Download the FlockFinder App on your smartphone and find breeders recording for WormFEC (41 flocks). Or visit sil.co.nz and search “Health Traits”.
b) Ask your short list of breeders for the DPF index figures and genetic trends, in addition to the core production indexes for NZMW (New Zealand Maternal Worth).
c) If you are unsure at any point, ask the breeder to talk you through the figures.
Which breeder matches your operation?
Identify which breeders measuring FEC also measure other “must haves” for your operation. Check their complete set of genetic trend graphs to see that they are making progress in the traits that matter to you.
Choosing a ram
Finding the breeder is half the battle. But even within a flock there can be a lot of variation. Talk to your breeder about the breeding value range you are looking for – and be prepared to pay for it.
How long until you see progress?
Health traits, such as FEC, are moderately heritable. More importantly, they are very variable between individuals, so you can make relatively rapid progress.
Resources for farmers
- How good is your internal parasite management?
Take a three-minute self-assessment: Test yourself
- Wormwise website
- Wormwise handbook
- Request a printed copy of the Wormwise handbook
- Request a Wormwise workshop in your area: Contact your B+LNZ extension manager
- Podcast with Dr Dave Leathwick: Hear Dr Leathwick talk about good management practice for internal parasites and answer farmers’ questions
- Worms in refugia - a tool to delay drench resistance