Fat is often fed to dairy cows as a means of increasing dietary energy concentration; however feeding fat often reduces feed intake. For many fat supplements this can be due to negative effects on rumen digestion, however feeding rumen inert fat and post ruminal infusions of fat can also depress intake although the mechanism by which this happens is not clear. The effect of fat on intake may also be influenced by stage of lactation as in early lactation fatty acid levels in the blood can be elevated. The aim of the present study was to investigate the effects of fat infusion into the abomasum on dry matter (DM) intake, milk production and metabolism of splanchnic tissues (portal drained viscera (PDV) and liver) in early and mid lactation cows.