I live in central Texas, our Selenium is listed as .45+/-.16 ppm, my does love BOSS sunflower seeds! Should I have BoSe on hand at the birthing of my kids...expected in mid Feb....And if so, should I give shots to newborns even if no sign of white muscle disease, (I don't want to poison my...

We live in a low selenium area. Some breeders say to give Bose shot before breeding. Just wondering if this is necessary when free choice minerals are available which contain selenium.