Back in the mid-1990s, the New Zealand sheep industry missed a great opportunity. As sheep performance climbed so did the inputs driving this production increase.
The NZ sheep industry can be proud of the doubling of export lamb from half the breeding ewes but when you look closer at the increase, much of it came from increased reliance on the drench gun.
In 1994, the science behind selection for worm resistance was proven and packaged by Agresearch scientist John McEwan. However, the genetic focus of the day was only on production, regardless of the cost of that production and the wider industry missed a great opportunity
The stud industry has never embraced this selection policy. The big players, the franchises and brands that dominate our industry by supplying the bulk of rams, have never gone down this track. Yes, you can produce big strong looking rams if you keep drenching them and their progeny, but this is not a sustainable in the long term.
The high cost of parasitism to NZ sheep farmers was estimated at $300 M pa in decreased production and drench use back in 2000 (M& WNZ 2000).
Now some of those flocks will be stud breeders selling rams with susceptibility to our current drench families.
I support a prominent North Island breeder who suggests that all stud breeders should do a drench reduction test every 2- 3 years and this information should be released to the industry and their clients, just like B Ovis is.
There are only 37 flocks recorded as selecting for worm resistance in NZ. Perhaps 1 -2 % of rams sold with some resistance to internal parasites. In our own flocks, after 30 years of selection we can match performance genetically with the best Perendale flocks in NZ but do it on a maximum one life time drench and have lambs that can perform at 3000- 5000 epg challenge before their performance is compromised.
There are some flocks making great progress in this area and not at the expense of performance. How different our industry would have been if SIL had added selection for resistance in with overall production 23 years ago. There is too much focus on getting onto the front page of the SIL reports and too little thought given to the rams that we need to help us stay productive and do it sustainably well into the future.
