I only fed mine grains. Wheat, barley, rape and anything else we had on the dryer or in sheds that got swept up. I Collected it all for winter and just fed minimally in the good months, that, greens and free range. They did fine. In the hungry gap I'd go out everyday and turn some stones, logs or junk over so there was some fresh bugs too. And they stole half of the rodents that the cat brought in! ...cat food hasn't been around that long either. It's over a year (maybe 2years) since I've bought my cat proper cat food, just gets scraps and I make stock once a week and he gets all the skin, scraps and gristle off that. He looks fine for about £1.50 a week. Marketing.