Is electric fence necessary?

[PlumpChicken]

I am looking into buying some poultry netting from Premier 1 and wanted to know if electrifying it is necessary. Also I wanted to know if I should get the 48' height or if 42" is good enough.

 

[PlumpChicken]

I will mention that the chickens will be fenced in inside of a horse pasture during the day only. So I don't think ground predators will be a big issue during the day. The chickens will obviously go back to the coop during the night.