It is designed to make strong muscles and bones, whereas breast milk is brain food. Also, by introducing cow's milk too early - even in small doses - you significantly increase the risk of an allergic reaction to dairy products. And cow's milk is hard on an infant's kidneys and digestive system.

Your pumped milk is the best thing you can put in those bottles. If that isn't possible, talk with your doctor about an appropriate formula to use for those feedings you will miss.