When milking a Wyvern you need a preserving bin with salt, a player with salt and put salt in your baby Wyvern to prevent spoilage, though you can do this alone with a Wyvern trap it's much easier with a friend. Oh and only trap female Wyverns.
I got a level 150 lightning egg and I was so excited to hatch the egg...that when I went to put the egg down I accidentally ate it instead. :( ps4 users: R2 ISN'T GONNA DROP THE EGG YOU'RE GONNA EAT IT LIKE ANY OTHER EGG. REMEMBER THIS. LOGIC BEFORE EXCITMENT.