Our breed of chicken is very good at laying eggs (and makes for good meat!)... but they are rubbish at sitting on their eggs.
Meanwhile, our ducks and turkeys have very strong motherly instincts. So when a duck or turkey starts sitting on eggs we add or replace chicken eggs. The new mum readily sits on them and accepts them as her own. When they hatch she then continues to protect and care for the adopted chicks as her own. They make great mothers.
