Okay, the chemistry of salt & sodium on food labels is murky, and probably intentionally so. When we say "salt," we are usually talking about Sodium Chloride (NaCl), the major ingredient in table salt, and the ingredient listed on the bags as "salt." Salt (NaCl) is what doctors worry with in humans because of the sodium (Na) content, typically... when they recommend a "low sodium" diet for certain medical conditions. "(Table) Salt alternatives" such as potassium chloride tend to taste more bitter, but don't have the sodium component.
Chemically, there are many things which are "salts" such as that same potassium chloride (KCl) and even copper sulfate. Chemically, "salts" are ionic compounds. Some salts disassociate in water which is helpful in some conditions, such as in trying to get one or both parts absorbed into the body. So preparing some element into a "salt" may make it easier for the body to absorb.
I noticed, in going through the feed bags, that "salt" (apparently NaCl, table salt) is listed separately from the other ingredients, many of which are chemical "salts" (which are being used to deliver supplemental elements or vitamins). So for example, the sodium selenite that you mentioned is a way to deliver trace amounts of selenium, which is an essential element.
I don't know whether the veterinary concern in a normal, healthy animal would be related to the total level of sodium (Na) or the total level of NaCl, table salt. But the labels do not give a total sodium content at all. The supplemental elements and amino acids that are being delivered as "salts" are probably important contributors to animal health.
Those things way down the list at the bottom end are in the feed in fairly minute quantities...
Both my roosters have frostbitten wattles. Just got thru Vaseline-ing both of them, Bandit is much worse than Barney. Boy I sure do hope all the Pea toes are okay.
