Collecting Bulls

At what age is it safe to get a bull collected? I have a Pb Simmental bull that is extremely mature for his age. He is nine months and is bigger than a lot of twelve month old calves.

It is not necessarily how big the bull is but how big his nutts are.  I have had 10-11 month old Simmental bulls that were 33-36 cm and they where producing good semen.  I have also had some that weren't ready until they were 15 months old.  It has a lot to do with genetics and how they are developed (fed). I would suggest getting a fertility test on your bull before having him collected.  It won't hurt him a but to try and collect him early but it will hurt your pocketbook if he is not ready.  Good luck.

My vet said he has bigger nuts than his full grown brangus bulls, lol.

There is much variation between bulls, and it involves more than just testicle size.  We leased CCS Marc Drive to ABS several years ago when he was 9 months old. He was sent to ABS in Wisconsin immediately as they had a truck going there. They did not think he would produce semen for a few months but to everyone's surprise they were freezing high quality semen before he was 10 months old. I have seen other bulls who do not have mature enough semen to freeze at 15 months of age. Hopefully your bull is one that will freeze at a young age. About the only way I can think of to know for sure is to have him collected, and see how he does.