Ram mix to ewes no problem, although pre- and post-lambing they maybe would be better with a ration formulated especially for the job they are doing

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Ewe mix to rams - no, never. The males (entires and castrated, so rams and wethers) can get urinary calculi from feed which isn't formulated especially for them. If you
are feeding a non-specific feed to males, make sure they have plenty of water, and salt licks.