Animal studies suggest that fish oils are capable of modulating the cell functions of immune system and there is some evidence that the effects of fish oils on immune function are due to fatty acids rather than trace elements or antioxidants. The major objectives of this study were: i) to identify a fish species with high nutritional value able to improve pig feeding conditions; ii) to utilize diets that modulate the immune system early in life in pigs and; iii) to enhance growth rate on a physiological basis. With the aim of maximizing feeding intake after weaning in order to reduce stress and increase growth rate, a study was carried out on 300 pigs supplemented with different fish extracts obtained by advanced biotechnological methods. The results of this work suggest that the lipoproteins obtained from the Trachurus trachurus (E-JUR-94013) species may have a great effect as both an immunomodulating compound (acting mainly on the regulation of IgA synthesis and/or release) and as a hypocholesterolemic compound, reducing the total cholesterol level in the serum of treated pigs. Both effects resulted in better pig growth, demonstrating that E-JUR-94013 can also be used as a natural growth promoter and an immune enhancer.