Nowhere, but trying to speak verbal components is hard when all you can say is baaah, hard to do somatic hand gestures with cloven hooves, and really hard to use material components that have melded into your sheep form.
Yeah I got that, but I was questioning the OP's statement about the 8 in the ability score being required.
You can change form and maintain concentrations, you can't cast spells because it says you can't use any gear/equipment (so no material components or foci) and it says you can't cast anything that needs verbal or somatic components.
You can have 1's in Int/Wis/Cha and still maintain concentration.
The only things that break concentration are.
Damage (forces a check DC 10 or half damage use higher)
Casting another concentration spell (automatic)
Environmental hazards (DM can force a check DC 10)
Being incapacitated or killed (automatic)
Period end of story, those 4 things.
Changing form, reducing ability scores, conditions like (restrained, blinded, charmed, frightened), none of these things call for a concentration check.
So if some creature attacks you with a toxic cloud that makes you suffer the blind and poison condition but does no damage, you maintain concentration. If some spell turns you into a newt either by your own hand or that of another you maintain concentration. If some creature drains your casting stat down to that of an animal you maintain concentration.