Earlier studies at the Centre for Dairy Research have examined the effect on feed intake and milk production of a range of by-products used in a total mixed ration (TMR) based on maize silage. These studies showed that distillers grains and molassed sugar beet feed (MSBF) could be used to replace cereal and protein supplements, with no effect on milk yield and dry matter (DM) intake but with a large reduction in milk fat and a little change in milk protein content. The aim of the current study was to examine the effect on feed intake and milk production of lactating dairy cows offered a TMR in which Stockmol 20, a molasses supplement (92 g/kg DM crude protein and 12.3 MJ ME/kg DM) and Regumaize 44, a high protein molasses urea based liquid (440 g/kg DM crude protein and 10.7 MJ ME/kg DM) were used to replace conventional energy and protein sources.