Digestive Enzymes & Probiotics for Older Male Cat with IBD?

My friend’s 10+ year-old male tuxedo cat could probably use a return to enzymes & probiotics. Over the years he’s overcome urinary crystals & has occasional bouts of constipation &/or vomiting, probably from IBD. He does use Wysong Biotic pH- sprinkles and is now primarily fed Stella & Chewy’s Freeze-dried Raw Chicken, Duck/Goose, & Rabbit, Caru’s Chicken Broth, and occasionally Hill’s Prescription Z/D Diet canned. We are looking for good, hopefully laboratory tested & proved, digestive enzymes & probiotics to start him back on.