Important Info - We strongly recommend all iOS device owners to update to iOS7 (or above) as soon as possible. The next Hay Day update is just around the corner, and there are some changes for playing the same farm on multiple devices running iOS4.x, iOS5.x and iOS6.x. Read more -> http://supr.cl/1rHv6ai
Here's how to update to iOS7: http://support.apple.com/kb/HT4623
If your device doesn't support iOS7 (or you don't want to update), you will need to connect to Facebook to be able to play your farm on a new device running iOS4.x, iOS5.x or iOS6.x. Note that this is for iOS (Apple) device owners only, and doesn't affect Android users.