Alot of my Larger Jersey Giant - Rhode Island Red cross hens have begun having problems with dislocations in their "hips" or where their legs join the body. Once I was observing a young pullet who was otherwise normal, no extra weight or anything, suddenly start bobbling around out of nowhere while scratching in the yard. Her leg was so badly dislocated it would not pop back in. She didn't seem to be in any pain at all, which was strange, so we just kept her as is--she fumbles around the coop but always manages to get her way and also lays on a daily basis. I thought it was just a fluke. Then, another prize hen just out of the blue started limping. Same thing. And yet another. I just wonder if it is some kind of genetically predisposed condition affecting larger meat birds, or if I am doing something wrong. It's only these cross birds that are affected.

Gayle, that sounds really interesting. When they fly off the perch, do they have any obstacles that could cause physical injury? I know my RIRs bump into things once in a while, but they seem to always come out just fine.

I would highly suggest making sure they have crushed oyster shell.
Also, start giving them bonemeal and/or bio stress pack.

They seem to get along normally. I have started feeding them oyster shell, and I'm worried that they are getting too much to eat in general and are overweight. How do you assess when a bird is over weight? I would think that these breeds have been bred to w/stand a higher body weight and joint stresses...