Makes my cats smell!

I fed my cats the old style Iams for years with no issues. Having swapped onto this one, I have found that the cats absolutely LOVE it - completely hooked. There is an almighty fuss made if food is put down late, and they hoover up everything in the bowl in seconds. Unfortunately, one of the flavours makes one of my poor girls absolutely HONK when using the litter box. Really, really awful - to the point we are going to have to change to something else because the stench is frankly eye watering.