[hotel4dogs]

Purina is one of the dog food companies that is NOT owned by Mars. Not sure where you're getting your information.
Mars owns about 50 brands, Purina about 30 or so. Mars owns Iams, Eukanuba, Royal Canin, and many others.
Regarding the recipe change, they are removing the probiotics, starting with their best sellers and working down to the lower selling varieties. Supply chain issues.

 

[hotel4dogs]

...At Pro Plan, we believe pet food with probiotics can be beneficial for their digestive and immune health, so we've added guaranteed live probiotics to many dog formulas we make. The specific strain chosen is known to be both robust and stable, guaranteeing it arrives alive to your dog's bowl.

Pro Plan Dog Food with Probiotics - Purina

Purina
https://www.purina.com › ... › Pro Plan Pet Food....

I am most definitely not an expert on the subject, fortunately I know people that are. A very good friend, and my all time favorite nerd, is a microbiologist.
As I understand it, probiotics in kibble are usually dead and therefore ineffective.
My friend recently did some research for her company on some probiotics offered by competitors. Looking for stolen technology and or patent infringement. She said many of the probiotics on the market are dead.
She told me the one I have been using, based on the advise of another mutual friend, is very much alive.

https://www.chewy.com/nutramax-proviable-probiotics/dp/101471