We fitted locking yokes in one part of our cubicles, and diagonal barrier in the other. You can't lock them and leave them, so in practise you don't lock them. In which case, they just cost more, take more space, and are horribly noisy.
We had visions of locking up a beast we wanted the vet to see, or the AI to serve, but because only the head is locked it's not very safe to do AI because the beast can swing its body. So a race is preferable, a crush best. A good gate you can really hold steady up against them is probably better too.
If you do fit yokes, make sure you allow at least the distance per beast they recommend. In practise, again, a bully cow will still bully the beasts on either side of her, and if they're locked in, they can't evade. So they
must have enough space.
With only 6 beasts, you won't be able to use up a bale of silage before it's off anyway, so yes, use hay.
If your budget runs to it, cubicles and mattresses will save a fortune on straw. But they'll only work if all the beasts are a similar size; you need the width and length just right, otherwise you get pooing on the mats. Oh, and they only really work for females, of course - males just widdle on them.
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