How long does it take for change in feed to take effect?

[rosie-ellie]

I was asked the above question at our yard because someone had put there gelding on turbo food and it hasnt started taking effect after 4 weeks, i thought it was anything from 4-6 weeks but someone else said 2-4 and that its not working. I just thought give it a bit more time.
So could someone tell me if i'm right or wrong. My time wasnt including the 5 day change over it was after the change was made.

 

[Magnetic Sparrow]

Accidental turbo-food changes mine in less than a week. I normally reckon about a week to start seeing a change in a horse, but I would normally make a major change over several days to avoid possible digestive upsets. No effect in four weeks to me sounds like no effect likely at all.