Hi, I am in the processing of switching my 11 ...

Hi, I am in the processing of switching my 11 month old son from formula to cows milk. Initially he was having 2 bottles of formula and 1 bottle of cows milk per day. Seeing he handled 1 bottle of cows milk fine, I have started giving him 2 bottles of cows milk and 1 bottle of formula per day. I have noticed that his bowl movements have changed. His No 2's are a dark brown and a little hard, previously they were a mustard brown type colour and reasonably soft - plastescene. Could the change be due to cows milk? Was just wondering if any one your toddlers No 2's changed when introducing cows milk. I hope he does not become constipated. Thanks for you assistance.