Great care needed when selecting breeding traits
Published 03/04/2013 | 05:00
PROFESSOR Hugh Blair, also from New Zealand's Massey University gave a presentation that looked at the use of genetics to improve sheep farm profitability. He started off by highlighting the dangers of selecting for just one trait.
He used the example of how selection for wool production in the Romney had a negative impact on fertility.
The increased wool coverage of the Romney increased her body temperature, which in turn reduced embryo survival.
This trait has now been reversed and the Romney is much more similar, in physical appearance at least, to the animal which originally arrived in New Zealand.
Despite these drawbacks, genetic selection has lead to annual increases of 250g per year in weaning weight over the last 20 years.
The production of replacement rams was analysed. The total ram supply for commercial farms is dependent on the 10,000 rams that annually enter breeders' flocks.
This highlights the need for the nucleus flocks to select traits which reflect profitability on commercial farms, rather than those traits which are important in the show ring. It was also pointed out that the production costs are a relatively new consideration in New Zealand sheep breeding.
For this reason, there is a negative weighting on mature weight in the current breeding index to try to control maintenance costs. However, this can be adjusted if there is a fear that lambs are becoming too small.
The difference between the top-ranked ram and the ram ranked number 10 is an increased profit of NZ$2.37 (€1.54) per lamb produced.
This emphasises the importance of selecting on the appropriate criteria. Despite this, 30pc of rams are not being purchased on the basis of recorded breeding values. This means that more education of ram buyers is necessary to capture more of the benefits of recorded rams.
While the New Zealand sheep flock is often held up as a model to follow, a number of issues still persist which have a major impact on efficiency and profitability.
Many are similar to those we experience here, but there has been a really impressive improvement since 1990. That was from a relatively low base so future gains, while possible, will be more difficult. What is impressive is the level of funding going into sheep research and the new focus on farmer learning.