Intake of a dry or a moist ration by suckler cows

The effect of type of ration on feed intake was studied in a trial with 36 lactating cows of the Angus (AN), Limousin (LM) and Limousin x Red Holstein cross breeds (F1) during the first four months of lactation. Two iso-energetic rations fed ad libitum were compared: a dry ration (D) composed of hay and aftermath, and a moist ration (M, 53 % DM) composed of a mixture of hay and grass silage. The cows fed ration D consumed 0.87 kg DM more per day than those fed ration M from the second to the fourth month of lactation (P<0.001), and 0.76 kg DM more per day over the entire trial period (P=0.07). Major differences were observed between the different genetic types (F1>AN>LM; P<0.001). A comparison of the ingestion data measured in this trial with the prediction formulas currently used in Switzerland revealed a systematic underestimation of feed intake. Moreover, no prediction formula took simultaneous account of the effect of ration type on the one hand, and genetic type on the other. A new prediction equation taking these new data into account will be published shortly, once the 'suckler cow' chapter of the Swiss feeding recommendations for ruminants (Green Book) is updated.