Safe wormer to use on steers?

Our kids have 2 steers for county fair in 50 days. Both have a very nice hair coat at this time and getting better every day. Both steers weighed 1325 a week ago (yes we are holding them some now) My question is they were wormed in December and April with injectable wormer.  Dot hey need wormed again? If so what do we use?  Last year we wormed 40 days from fair and one of the steers shucked his entire hair coat the week before fair.  Not sure if it was a coincidence or not but we are leery to take a chance again.  Thanks for any and all help!!!

Take fecal samples and have your veterinarian either do - or submit to the diagnostic lab for - fecal egg counts.  Will give accurate numbers of 'worm eggs' and coccidia, to help determine if these animals actually need to be treated.

I've always gotten along great with ivemec injectable