I have heard a few people say that they can taste the commercial feed they fed their meat birds...
Is this true? If so, how do you prevent it?
I think some people do have super-sensitive taste buds and can tell differences that normal human beings can't. Then you have me on the other end of that spectrum, I'm not a sensitive guy. I think most people in the middle can tell differences. There is a lot more to taste than just taste buds too. Appearance, texture, and smell are big factors. I think preconceived notions can have a big effect. Some people like the taste of our chicken, some don't.
I believe what they eat does affect the taste some. There is a special diet for Bresse chickens to get that Bresse taste. I wonder if the Bresse breed or the Bresse diet has more impact on that taste? It's pretty common to finish off certain meat animals like beef or pigs with certain feeds just before butchering them. You may have heard of the difference in grain-fed versus grass-fed beef?
I think breed can make some differences. Some of that is that certain breeds have more white meat, some more dark. Some flesh out faster while others are mostly bone for a while.
I think the biggest difference is due more to age and how we cook them. The older a chicken gets the more texture and flavor they have. I typically butcher my dual purpose cockerels around 23 weeks of age and my pullets around 8 months after I've decided which should join my laying flock. The pullets certainly have more flavor and texture than store bought chicken that is butchered between 6 to 8 weeks but not as much as the cockerels. The hormones the cockerels release as they go through puberty makes a big difference in texture and flavor. Herbs, spices, and other seasonings can have a big effect on what you taste.
Aging is where you let rigor mortis pass. That can be the difference in shoe leather and a nice texture. Brining is where you soak the meat in a salty mixture, which mainly increases moisture retention. If you are going to cook the meat using a moist method that's not important but if you are grilling or frying it can make a difference. Marinading is where you put the meat in an acid solution which breaks down the texture. Barbecue sauce is an example. If you are cooking an old rooster, such as Coq au Vin, marinading it in wine is an important part of that recipe. If you marinade the store bought meat or Cornish X that you raised for very long it can turn it mushy since it is so tender to start with.
I think their are a lot of different things that factor into how our chicken tastes. Some like age and sex can be pretty blatant, some other things can be a lot more subtle. What it boils down to is whether you and yours enjoy it or not. Good luck!