Correct size to breed??

[allenslabs]

My little jersey/angus cross heifer is going to be a year the first part of march. I know that beef people breed so that the heifer calves at 2 so that would mean breeding Bonnie in like Julyish?? But, I didn't know if her size should be considered. Although her dad was angus and her mom jersey, she is on the smaller jersey size. I stink at guesstimating weight but I would guess right now, at 10 months she only weighs like 5-600lbs. I will try to post pictures and weight tape her to get a better guess for you all.
I would be AI'ing her to a jersey bull. I had picked out T-Bone for Elenore and so would probably just stick with him and get the sexed semen in hopes of a heifer.
My dad talked to the guy we got Elenore from and he said that although he hadn't had time to look through what he had, he was pretty sure that he had sold most all his low producers and if he sold one it would be one that milked quite a bit more than Elenore and I'm not sure I want a high producer. He also said it would cost quite a bit more than Elenore. I guess here lately he's had a rush of people looking for a family milk cow. So, I'm in no rush but am looking.

[Karin L]

The best rule of thumb to go by is to breed her when she's around 65% of her mature weight. If you have a good idea what her mature weight will be (which I'm guessing may be around 1000 lbs, since you say she's a small-framed heifer), then you can breed her using that criteria instead of doing the age thing. Is she already showing signs of heat, or is that to come about yet?

[allenslabs]

I haven't noticed her being in heat as of yet. I will start looking. So, once she get to about 650lbs then start thinking about it??

[Karin L]

Yes, but also make sure she's showing signs of heat. If not, it's best to wait for a bit longer. Another good rule of thumb I forgot to mention was that a heifer is normally bred after going into heat a few times.