I haven't seen this suggested or rejected before, if I was blind and someone already did, I'll delete this thread.

Alright, Chasteberries will raise a lioness fertility by 10% and you can use a maximum of 5 Chasteberries per lioness. That's ok and should stay. However, I've ran into an issue today:

I do have a Tigon king and he can only breed to lionesses who have a fertility of 100%
I also have a lioness who has currently a natural fertility of 93%, if I give her a Chasteberry she gets a 7% boost and I can breed her just fine.
However, I wanted to breed a lioness with 81% today. Just give her 2 Chasteberries right?
But when I wanted to give her the second one, I got an error message:
 

I can't get her fertility to 100% . I used one Chasteberry on her and her fert is now 91%, but I can't use the other Chasteberry on her. It seems like the Chasteberry requires the lioness to have exactly 10% fertility that has to be raised, and she only needs 9% more.

I know that barely anyone has a hybrid king or has a required fertility of 100% in their Studding Services, but I'm sure there were already alot of people who wanted to breed to a hybrid king, didn't knew this and wasted a few hundred SB just to find out they won't be able to to breed to one.

If a lioness has a fertility between 51-89%, please let us use enough Chasteberries to get her to 100% fertility.