All thiesens have it. Farm fleet has comparable, etc, etc. You really can find it anywhere. If you get a brand that's not as "attractive" (I've found some are not as desireable) - I'd buy a bag of dried grain molasses and put like 5 lbs with your 50 lbs of mineral. Helps. Tractor supply pry even has something. But, anywhere, all the heartland coops, any coop period, call em up. MFA's have similar, you name it. Show em a label like attached & they find you comparable.
Oh - put out ASAP!!!! They need it starting in February to be honest. they really "seek it" then too. They need to rebuild their skeletal systems. If depleted, it will take from rack growth if they have deficiencies. I checked a cam I forgot about last night- big old pedicles like top of popcans just barely popping up on deer. So, their bodies have been building up for rack growth the last 1-2 months. sooner the better. By time July hits, almost pointless for racks BUT still benefits other stuff like immune system & stuff I'm gonna mix in for deterrent for flies biting them.