If said animal has given birth and nurses the calve that species has the advantage of the mother being able to protect and care for the calves.The down side is that you can only have a few amount of children.While if you are the salmon and laid thousands of eggs you would have that advantage of a lot of offspring so if one of them dies the others will still live to continue on the species or survie the next day.The con is that without either of the parents protecting the children it increases the risk of them dying.
