The sheep breeding programme in 2017/2018 continued to build on developments from earlier years.
High/low sheep lines continue to diverge and are currently on average 10% different for methane yield. The lines continue to segregate on maternal breeding worth with the low line favourable by ~$10 gross margin per mated ewe. However, breed proportion may play some role in the observed differences in maternal breeding worth so validation in other flocks with greater genetic diversity is required.
A trial with low and high methane yield selection line sheep fed cut pasture indicated consistent differences in methane per unit of intake across all four seasons, and excreted nitrogen was similar in two seasons, suggesting that breeding sheep for low methane will neither increase nor decrease excreta greenhouse gas emissions.