Do you mean on the right rear? Odd...Perhaps the scute died off somehow and fell back. In any event, it will grow back eventually, but it may take some time. Just watch the spot VERY carefully, as I'd imagine it to be especially prone to fungus/rot. Just keep it clean.
For calcium...I don't. I have bred and raised red foots for over 10 years; never used calcium powder. Do you know why...I take a look at the ca;p (calcium to phosphorous) ratio of the foods we feed. Collard greens is something like...14.6:1. Wayyy over the top. Turnip greens are high up there to. I would recommend just keeping a cuttlebone in the cage; they sell them for birds. The tortoises chew on them at their will; much better then forcing them to eat it in their food. In my opinion, over-calcification is a far bigger danger then under-supplementation. Very dangerous...If your really worried, I would say once a week small amount of calcium dusting, and a cuttlebone.
The point is, just the amount of calcium in the food you feed is over sufficient (if your following the list, that is). Reptiles should have a ca;p ratio of 1.2:1 minimum. The reason of more calcium is to add some to the bone stores; the body can take whats needed, and what isn't can be passed out in urine. It can be over that, however. Now, when to much calcium is provided, the body has a hard time regulating it, and it can cause calcification of the spine, or internal organs.
If you don't know, MBD is what happens when the ca;p ratio is inverted. For phosphorous to be absorbed, it must be bound with calcium. When the calcium is unavailable to the phosphorous, the needed calcium is taken from the bone stores. This weakens the bones, causing many growth issues. Eventually, they will die.
For calcium...I don't. I have bred and raised red foots for over 10 years; never used calcium powder. Do you know why...I take a look at the ca;p (calcium to phosphorous) ratio of the foods we feed. Collard greens is something like...14.6:1. Wayyy over the top. Turnip greens are high up there to. I would recommend just keeping a cuttlebone in the cage; they sell them for birds. The tortoises chew on them at their will; much better then forcing them to eat it in their food. In my opinion, over-calcification is a far bigger danger then under-supplementation. Very dangerous...If your really worried, I would say once a week small amount of calcium dusting, and a cuttlebone.
The point is, just the amount of calcium in the food you feed is over sufficient (if your following the list, that is). Reptiles should have a ca;p ratio of 1.2:1 minimum. The reason of more calcium is to add some to the bone stores; the body can take whats needed, and what isn't can be passed out in urine. It can be over that, however. Now, when to much calcium is provided, the body has a hard time regulating it, and it can cause calcification of the spine, or internal organs.
If you don't know, MBD is what happens when the ca;p ratio is inverted. For phosphorous to be absorbed, it must be bound with calcium. When the calcium is unavailable to the phosphorous, the needed calcium is taken from the bone stores. This weakens the bones, causing many growth issues. Eventually, they will die.