QLF branded tub is what I have been using. I'm not putting QLF on a pedestal. QLF is what's available in my area.
What are you trying to achieve by feeding tubs? What are you hoping to gain nutritionally?
For whatever it is worth to curiouscattlejockey, allow me to explain what I feed and why I feed it...
Feeder calves are being backgrounded. They are grained twice daily and fed my better hay. They have loose salt/mineral in a feeder, a trace block, and a mineral or IGR tub. Licking a tub provides something to do when first weaned. Licking is more productive than bawling and pacing the lot. My suspicion is not all calves utilize the feeder, so I continue a mineral tub after the bawling has ceased.
Group #1 is grained daily and eats the same better quality hay as the feeder calves. They do not get a tub. They have loose salt/mineral and a trace block.
Group #2 is lactating to feed their Fall-born calves. They have loose salt/mineral and trace blocks. They are grained daily and eat the lower quality hay. They have a 20% protein tub. The tub supplements the hay and the cows' nutrition for rebreeding. Calves enjoy the protein tub, too. Calves have creep feed available, but I ration it. A couple calves gorge and have poopy butts.
Group #3 is grained daily and eat lower quality hay. They have loose salt/mineral in a feeder. They are finishing their last 20% protein tub. These cows will be entering their third trimester of gestation. No more protein tubs, but I hope to supplement their hay with some other roughage.
Each group is about 20 cows more or less. It's a small operation and 20 head is a manageable group I can run in the chute by myself. I don't test my hay. I look at it and make a judgement call.