I don't give my goats salt blocks. They would pig out on table salt and ignore the loose mineral feeder that actually has what they need to be healthy. Mineral blocks are also almost all table salt, it is what holds it together in block form. So unless your area isn't low on anything in the soil and thus hay, blocks can lead to deficiencies. Here, the soil is incredibly low in selenium and very high in iron (which binds what copper there is, leading to copper deficiencies). I have to supplement my herd with multimin 90 in addition to free choice loose mineral (which has very little table salt).
This short article on it is also somewhat of an ad for Sweetlix near the end of the article, but explains the problem in more detail.
This short article on it is also somewhat of an ad for Sweetlix near the end of the article, but explains the problem in more detail.