Can animals be fed with food that is past its expiry date?

Is a man sinning if he feeds animals such as dogs and cats with food that is past its expiry date or with leftovers such as meat or milk?.

Praise be to Allaah.  

If it will not cause them any harm, there is nothing wrong with giving them this food. 

It is well known that these animals are better able than humans to tolerate food that has gone off. Allaah has given them sense by means of which they know what is good for them and what is not, in addition to the fact that these food containers usually have an expiry date that errs on the side of caution.