I keep seeing people advertise offspring of a backup breeding... What does that mean, exactly? :/

A back up is a pairs first born that is usually breed for just in case the final is missed so that you still have the lines. Most people also use back ups as a way to make some good money. If you have a popular breed that sells easily I highly suggest this as it can make up for not having much money. (:

Owners generally breed their horses just before they retire (21 for horses 16 for dogs) so you breed at 20 and 15 for the "final breeding" so the horses have the optimal points for the Foal (or puppy).

If you want backups which is a second offspring from the pair to sell or as an insurance policy of sorts (if you forget... As im known to do! But we have convenient retirement breedings in the cash shop). Then you'd do a early breeding (at 18 and 13 for horses and dogs respectively). So you have two offspring for each pair :) 

Sorry its a bit jumbled... I'm on my phone watching forgetting Sarah marshal but feel free to send me a quick inbox with any questions :) 

The main reason for breeding backups USED to be because there was a chance of offspring being born sterile (born a gelding, like on HL). So breeders would breed a backup when their horse turned 18/dog turned 13, and then breed a final baby when the horse turned 20/dog turned 15, just in case the final baby was born sterile and couldn't be used to continue lines.

It was a huge pain in the butt and nobody liked it, so Sam took out the sterile/gelding possibility so foals/pups can only be born male or female, so now most people breed backups just in case they forget to breed their animals before they retire. I myself only breed backups if I plan to sell them.

Also useful if you were hoping for certain genders.

Thanks for the clarification!