was it's feet ok a few days ago or did they hatch like this. They also look splayed legged as well toe problems.
There are three common reasons, in no particular order :
1. - genetic, as a result of inbreeding. Do you know their lineage?
2. - incubator foot, this just happens occasionally to incubator raised chicks. This seems too bad a case to be this, normally this just results in the odd curved toe.
3. - Mineral/vitamin deficiency. parental probably as most chick feeds are very good. Do you own the parents?
They may be some treatment but they are probably a bit old. it involves making a small pair of duck feet out of thin plywood and silicone tubing ( or straws )for the toes and using it as a splint to straighten the toes . you may need some matches as well.
You probably shouldn't breed form this bird either way.
The chick was healthy and very active since hatched like other 7 chicks. It is only the last two days stopped walking normally and had this problem. Legs are not splayed. The parents are healthy with no problems.
I will try your treatment method making a small pair of duck feet in addition to adding vitamins in the water.
If the chicks was fine and this has developed it may be perosis which is a deformity of the bones caused by a manganese deficiency. it causes the tendons to slip out of place.
If you give the birds water from a chlorinated ( or with fluoride) source allow it to stand for 24 hours before use.