At the Quilamapu Research Station, INIA, the effect of wet sugar beet pulp on beef production was evaluated. This by-product was given adlibitum fo 48 Holstein-Friesian steers, either alone or comhined with different quantities of hay (0.25; 0.50; 0,93 and 1.30 kg/100 kg L.W.) and rapeseed meal (0.25 kg/100 kg L.W.). Steers fed wet sugar beet pulp alone presented low intake, which eventually produced losses in liveweight (L.W.), diarrhea and ruminal paralisis. It was concluded that wet sugar beet pulp could not be the only food in a diet. The addition of 0.25 kg of rapeseed meal/100 kg L.W., drastically increased the gain of steers, The inclusion of hay improved L.W. gain of steers. An interaction between periods of feeding and Ievels of hay was found. During the first three months of fattening, 0.25 kg of hay/100 kg L.W. were sufficient; after that, this level should be increased fo about 1 kg /100 kg L.W. A financial analysis of the treatments showed that maximum marginal return was achieved when 0.25 kg of hay/100 kg L.W. were included in the ration.