Ducks better off without bread
A great part of the so called park ducks dies untimely due to obesity and a shortage of vitamins, chalk, and minerals. This is caused by one-sided and unnecessary supplements of bread. Except during a winter period with enduring frost, feeding ducks is completely unnecessary.
Most bread contains oil to keep it well longer. Bread which falls in the water, forms a layer of oil around it, which causes the ducks feathers to lose their water-resistant capacity. The extra feed also causes the ducks to move less, making them fat and lazy.
Another disadvantage is that mouldy bread attracts water rats, who may carry diseases. The bread also causes extra excrement, polluting the water surface.
Better is to prevent having old bread at all. But if there is any bread left over, it is better to throw it away. Especially when the bread is mouldy, as mould is not healthy.