Have you done any test lines yet to see what kind of flow and
water levels you are going to be facing?
Also, what kind of materials do you have access to on your
land? A simple gravel embankment can let a surprising amount of water through, which
should be more than
enough to allow cross
feed along a level swale. (My understanding of them is that if they are well placed then the flow is mostly limited to after the rains have stopped and one section naturally drains faster than another.)
What kind of surface stone do you have around? Dry stone 'bridges' need not be complex affairs if all they are doing is letting a bit of water flow under a cow-track.
How are you managing your animal containment anyway to keep the animals from trampling the swale down?