It has been estimated that grass and pasture (fresh and conserved) are responsible for over 90% of the energy intake of sheep in UK sheep systems (AHDB, 2021). This makes grazing fundamental to sheep production, and if of sufficiently high quality, all the energy, protein and mineral requirements of sheep and lambs can be satisfied by grazed grass alone (Peers, 2009; Stout and Frater, 2021). The feed demand for a flock of spring lambing ewes fits the classical grass growth curve characteristic of UK conditions (Genever and Buckingham, 2016; CIEL, 2024; see e.g. data provided by GrassCheck GB: https://grasscheckgb.co.uk/ ) and lambs can be sold finished or as stores by the autumn, reducing flock feed demands as winter approaches. However, for farmers to move towards systems with a higher proportion of grass and forage, there is a requirement to change behaviour and approaches.