Some people enjoy playing with fire.  This discussion blends with cow size discussion below.  Much can be said for understanding that a cow works for me, not me work for the cow.  Mature cow size is linked to birth wt.  Easy to talk cow size then allow it to creep up, because others, breeder's ect. do not practice what they preach.  Current AI and Embryo programs great example.  School of hard knocks have supplied to many lessons here to play with Birth Wt.  Terms like cow killers.  Repro tracts that have been abused by an egg beater.  Rape of 14 mth heifers, enough horror stories.  Have heard experts say if you never pull a calf you are leaving pounds on the table.  I like moderation not to big and not to small.  Have a Good Day.