http://www.millpledge.com/preparations/nutrical.htm
Most Pet SuperStores carry it. It comes in a tube and is a syrupy looking substance.
It is high in calories and nutrients. Our babies are so tiny that when they use a lot of energy they can get low blood sugar. So after heavy activities, especially while your baby is young, give some nutrical. Also if they are not eating good, or maybe just give a dabble once or twice a day between meals.
You don't have to give much ... under 1/2 teaspoon ... I think they say 1-1.5tsp per 10lbs body weight ...