40 piglets were reared in separate cages from the 13th to the 28th day of age and received a liquid milk diet (controls) or a substituted liquid diet. Half of the protein requirements of the young pigs were covered from skim milk, the other half was supplied through fish meal, extracted soya bean meal or a combination of both meals. Whole wheat meal was used as source of substitution energy. The ration containing extracted soya bean meal reduced all the digestibility coefficients with the exception of NFE. As a result, the levels of energy and nutrient intake and the rates of weight increase were lower in the experimental groups receiving the soya bean meal diet than in the control group. The same performance level as with the control diet was achieved when 50% of the skim milk in the experimental diet were replaced by wheat and fish meal.