New genetic traits
Lambing Ease and Gestation Length
The Lambing Ease and Gestation length ASBVs have been developed to reduce the impact of lambing difficulties in the Australian sheep flock.
Lambing difficulties have an obvious economic impact by increasing ewe and lamb mortality rates and increasing labour requirements.
Sheep Genetics is now reporting two Lambing Ease ASBVs,
- Lambing Ease Direct (LE DIR) describes how easily a sire’s lambs will be born, and
- Lambing Ease Daughters (LE DTR) describes how easily a sire’s daughters will have lambs.
Llambing ease has been slowly declining over the last ten years, due to selection pressure on lifting growth rates.
This is also reflected in correlated increases in birth weight.
The good news is that the introduction of LE ASBVs has identified a huge range in animals with the potential for improving lambing ease.
In the terminal LAMBPLAN database, there is a range of 33% for LE DIR from the best to the worst 2008 drop animals.
This translates to the best animal having 16.5% fewer progeny potentially needing assistance to be born when compared to the worst animal.
The Gestation Length (GL) ASBV provides an estimate of the genetic differences between animals in gestation length.
It is important that GL ASBVs are used to optimise performance for this trait at moderately short values as both very long and very short gestation lengths will have a negative effect on lamb survival.
Breeders who would like to have these breeding values reported for their animals will need to collect lambing ease scores when ewes are lambing for LE ASBVs; and recorded AI dates and hand mating