Are mineral blocks essential?

My answer would have to be “Yes” from what l have been observering. The breeding season in the UK is in full swing mainly to accommodate BS show season. 

The mineral blocks are mainly used in my main and junior flights and are proving very popular. Fixed to the flight wire by the green ties, they could not be easier to use.

Below is the list of ingredients found in these blocks :

Plaster of Paris, charcoal, Ferti-vit, grit, garlic, herbs, seaweed, pink mineral, charcoal, murphy/s mineral, diatoms and water.