It definitely doesn't works like that. The taming effectiveness affects the Taming Bonus applied. Take in example, you tame a 150 Rex with kibbles and it rolls 49 pts into melee. With regular taming rate, it will have 413.8% melee for 99.7% effectiveness at level 224. However, when you will breed that Rex, any babies that inherits that melee will have 414% because it was re-calculated from 100% effectiveness. See it as just being "rounded"; no actual "level" or extra "pts" are given for free.