Over the past year, I've had 3 chickens just become poor eaters, and eventually die. They do eat, just not enought. The last one was always offered extra food on my patio, and even separated with a buddy at one point thinking that she'd eat more, but didn't. But she died today. I've lost 3 that way out of 33 chickens. Other than that , all three (6 months or so apart) looked and acted healthy up till the end. Just weren't eating enough. There was never any forseeable reason with the three, just not eating enough. Why?