We examined the effect of replacing wheat hay with soya hulls on energy balance and feeding behaviour in mid-lactating dairy cows fed with concentrate diets and raised under summer condition. Cows were individually fed and faecal output was assessed by internal marker. Heat production was estimated from heart rate monitoring. Metabolizable energy intake, milk energy, heat production and energy balance, and pattern feed intake were similar in the two dietary groups. It was concluded that replacing forage NDF with NDF from non forage source, like soya hulls, is not an efficient means to reduce metabolic heat production in heat stressed cows.