Some animals display no nurturing actions at all such as turtles. As soon as they have laid their eggs, they abandon them. At the other extreme are bonobo monkeys who nurse their infants for four years while other species fall between these two extremes. In the case of many such as the leopard, it is the arrival of new mating season when the mother abandons their young. Lion cubs have a different set of considerations. If a new male takes over the pride, the incoming male will kill all the cubs as they are not his offspring.
Interspecies nurturing is uncommon in the wild but instances have been noted. With domesticated animals on the other hand, it is more prevalent.