Real sorry for your loss. That's tragic. That's a good start, but the openings in that cattle panel are too large for some predators plus predators could dig under the frame. Can you build a shelter inside that can be secured at night? As you can see from my avatar, that's what I've done. At dark I go out, collect eggs, make sure that the door which works on a light sensor has lowered, and do a head count. Mine is a hoop house frame covered with plastic and is only there to give them shelter from rain or snow. The protection from predators is provided by the coop. I did lose one hen to a daytime aerial attack while they were free ranging in the orchard in which they are located. One hen taken, one wounded hen survived. I thought they would return, but apparently, the wounded hen put up enough of a fight that they decided to go for easier pickings. I've added two bantam roosters now so the hens will have some warning in the future of possible attacks.