Sheep - Meat RATES OF GENETIC GAIN IN NEW ZEALAND SHEEP

Rates of genetic gain in New Zealand sheep doubled in 140 Dual Purpose flocks, from 30 to 60 cents/yr, and 62 Terminal Sire flocks, from 35 to 60 cents/yr, after establishment of the Sheep Improvement Ltd (SIL) genetic evaluation system in 1999. Further incremental gains of a similar magnitude led to triple the rates of gain pre-SIL after establishment of the Meat & Wool New Zealand Central Progeny Test and the start of SIL-ACE across-flock, across-breed genetic evaluations in 2004. Flocks were classified based on genetic merit for 2004-2006 as; “Leader” high merit / high rate of gain; “Gaining” below average merit / high rate of gain; “Slipping” high merit / low rate of gain; and “Trailing” below average merit / low rate of gain. Leader and Gaining flocks were more likely to make use of high merit sires from other flocks. Slipping and Trailing flocks were more likely to make repeated use of older sires of low genetic merit. These data show that high rates of gain are achievable by flocks adopting optimal ram selection and use policies. The challenge is getting more flocks to adopt such policies.