Comparison of breeding values between sheep ranked for resilience and resistance

摘要

The sheep industry has put considerable resources into studying selection for resistance by measuring faecal egg count (FEC). Resistance can also have reduced pasture larval challenge as an important spin off. Fewer resources have been put into selecting for increased resilience, animals which are able to grow under challenge, possibly because methods of selecting resilient animals are more labour intensive and difficult to standardise. Te Whangai, which has a flock of 9,000 ewes, 2,500 of which arerecorded ewes for breeding industry rams, has been working with AgResearch monitoring resilience and resistance in their flock since 2001. An analysis using data from ram lambs born in 2007 and 2008 found the top ranked animals on resilience had higher than average breeding values for growth and wool weights, whereas the top ranked animals for resistance with a low FEC, had lower than average breeding values for growth and wool weights. In 2007, the average breeding value for eight month live weight forthe top 60 resilient lambs was 6.55 kg greater than that for the top 60 resistant rams. These findings suggest caution is advised in selecting animals on FEC. Resilience is likely to be a better alternative.