As seasonal conditions are changing sheep breeders across eastern states of Australia are showing greater intent to turn off lambs earlier as a risk management tool.
With this in mind increasing the Bundilla PWWT or 200 day weights is a key selection point for our breeding program for the next 10 years. The 2014 drop Bundilla ewe lambs (1306 full pedigreed) averaged 39.7kg at 200 days and we have set a breeding goal to increase this by 20% by 2025. The top 10% of the ewes 200 day weights averaged 47.4kg, so the genetics to achieve these goals is available. The key selection point is to identify dams and sires that do not forgo other key traits such as fleece value, carcase quality or fertility.
Why is 200 day (PWWT) weights and 300 day (YWT) so important to your breeding program? ASBVs continue to be the best genetic tool in identifying genetics that have the largest impact on selecting sires that can maximise genetic efficiency of your breeding flock. Often we get asked how to quantify the genetic merit of a high growth sire. Firstly the average for all sheep processed by Sheep Genetics in 2014 had a YWT of 3.8.
If we joined a sire such as Bundilla RR14 (111265) that has an YWT ASBV of 11.6 (Top 1%), the expected genetic result of the joining to ewes with an average ASBV YWT of 3.8 is (3.8+11.6)/2 giving the progeny an expected genetic YWT of 7.7.
So what does this mean for a commercial breeder? For every +1 in YWT equals 8 days faster that a lamb will reach 50kg in your breeding program, or the progeny from Bundilla RR14 will reach 50kg 31 days faster than the progeny of a sire with an average YWT (3.8) under the same management conditions.