Egg Bound Chickens

[Kibbutz Farmer]

Am having trouble with some of our chickens that are repeatedly getting egg bound and in such a state that it is killing them. The ones that have it happening to the most are "Black Sexlink" and it has taken 3 in the past month. Nothing has happened to their feed excepting that they now get more greens in their diet. I recently moved to this Kibbutz and have raised chickens before on my own and never had this problem before and am feeding these chickens the same way as I fed my other hens. Does anyone know why a hen gets egg bound in the first place and how to stop this from happening???

Shalom

[bluemoon]

Is it possible that they have some sort of disease/illness and becoming egg bound is just a symptom of it rather than the root cause? I only ask this because three deaths in a month seems a little extreme and it seems more like something contagious than something physiological