I have noticed in the past two weeks that my flock of mixed hens and roos seem to have very runny bowel movements. The entire flock of 15 all seem very healthy and I continue to get 7-10 eggs each day out of my 10 hens. They are on pasture 24/7, but do not free range. They are fed 16% pellets and I have used the same brand for the past two years. They get an occasional scrap of veggies or fruit from leftovers as well as scratch feed from time to time. Their coop is very large, well ventilated and has 4-6 inches of pine shavings on the floor. They roost above a structure filled with sand and I clean the "sandbox each morning before going to work. The coop is cleaned regularly and twice per year it is completely cleaned, disinfected and allowed to dry out for a coupe of days before putting new flakes, sand and straw in the coop. I have treated this particular flock for lice once in 1.5 years and have had no recurrences as of now. I have four roos in with this flock which is way too many and this soon shall be rectified. Last week I walked into the coop and one of my orp hens was dead. No wounds whatsoever. In fact, I have never lost a chicken to a predator except my own dog. Fences are buried a foot below ground level and coops are closed and locked at night. I can think of no reason why my two or three hens have diahrrea. Any suggestions would be welcomed! Thanks in advance.