I can't answer the question on Merricks because I feed Canidae.

But I have one that used to have bad gas.

I began giving him a teaspoon of plain, non-fat yogurt morning and evening. No more gas.
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Joanne

Eli

Chipper

Eva

Snowboy

Rosie(R.I.P. 1996-July 29, 2013)

Cocoa(R.I.P 1998-April 26, 2012):