Question:

Why are there differences in the level of vitamin E in mineral or premix products?

 What is better, organic or inorganic selenium?

Answer:

The reason there is such a difference in levels of vitamin E between products most likely depends on how they are "carried" or what they are "bound" to.  Some supplements need higher levels in order for an adequate amount to be delivered to the animal.  The best advice I can give you is to feed a reputable well supported mineral supplement as per label instructions.  Feed it for at least one month and then check blood levels of the mineral in question.  Take approximately 10% of the herd for a good representation.

With respect to selenium, there are two types.  Selenite (inorganic) and organic.  It is harder to get the selenium level where it needs to be by feeding selenite because it is very unpalatable, whereas the organic selenium is very palatable and easily absorbed by the cow.  Organic selenium is more expensive but if you spend money on the selenite and it doesn't get you the levels you require, that I feel is more expensive.