Protein nutrition of underfed beef cows suckling two calves was studied during early lactation using Hereford x British Friesian cows. Feeding the cows with white fish-meal in each of the three years produced calves with a high growth rate (0,97 kg/day). The use of either groundnut meal or soyabean meal gave a response which was less than that obtained with fish-meal. It would seem that the more undegradable the protein source, the greater is the response in calf growth rate. The change in weight loss altered and could be related to a change in the nature of weight loss, from mainly fat tissue to less protein and water.