Carrot-fed beef

Remember when carrot-fed cows were supposed to take over grass-fed cows as the next big thing in beef? A diet of carrots was said to produce beef with the most perfect marbling affect and mouthfeel. Did that trend ever take off? It didn't in my area. I find the idea interesting, but I'm not looking to change my operation so I didn't look further into it.

Was that a trend in big cities or something? This is the first time that I've heard of it, but I live in a rural area that is just now experimenting with alternatives to cows' milk. Maybe we're just behind the times.

I've heard of it, but I don't know anyone who took that route. Corn isn't the most healthy for cows, but it's cheap and it makes cows grow quickly. Grass/pasture is the healthiest choice for cows, but cows grow more slowly on that diet. Where do carrots stand among that continuum?