Novel nutritional compositions and methods for their manufacture, administration and use are disclosed. The nutritional compositions of the present invention are useful for the feeding of immature mammals, particularly those used for food, and/or performance animals, such as horses, and for companion animals, such as dogs and cats. The nutritional compositions and supplements of the present invention are effective in supporting the growth and health of the immature mammal, in supporting and stimulating its immune system, and in mitigating undesirable infections and other. Additionally, particular fractions of the unique peptides produced by the disclosed methods can be separated and utilized as therapeutic agents.