HGG Community Forums

Embryo transfer now automatically comes with a bonus equivalent to 15 days in the pasture. So even if you use a Surrogate with 0 Pasture days, you get that bonus.
If you use a 30+ day pasture surrogate, you get those 15 days plus the 30 days from the mare being in the pasture, for a 45 day total bonus.

The quality of the surrogate mare herself does not matter.

"Embryo transfer now automatically comes with a bonus equivalent to 15 days in the pasture." That actually has been in the game for many real-life years. The ability of the AI bonus and pasture bonus to stack is what is relatively new.