Hose connection to automatic water trough

[Myamya]

I would be extremely grateful to receive advice how to attach a hose to an automatic water trough (for horses) in a field, that has no tap, it has a float - like in a toilet, that is in the water and refills automatically when the water goes down

 

[ShaunCorbs]

I’m guessing it has a 1/2 connection or a blue mdpe connection