An experiment was carried out to determine the ability of lactating cows to select a diet from two similar feeds differing in the ratio of metabolisable protein to energy (MP/ME) content and to investigate the effect of training through previous access to feeds separately on diet choice.

Holstein-Friesian cows (n=36), 1-5 months in lactation, yielding 37 (s.d.=5) kg of milk were housed in a cubicle shed equipped with 28 computer linked Hokofarm feeders which can be programmed to give or deny specific animals access and record intake, meal size and meal duration. All feeds were mixtures of grass silage and pelleted concentrates. Approximately 75 % of daily offer was given in the morning and topping up occurred during afternoon milking. After adapting to feeders and feed for at least two weeks, intake was recorded in week 1 when all feeders contained a standard mixed feed calculated to contain 8.3 g MP/MJ ME. In weeks 2-7 a low protein (lp) and a high protein (hp) feed were offered in 14 feeders each (in the order 7 lp, 7 hp, 7 lp, 7 hp).