Digestibility of power maize silage fed alone or in mixed rations

Power maize silage (WPMC) – a mixture of whole-plant maize and cobs used in cattle fattening – has different characteristics from whole-plant maize (WPM). A digestibility test was carried out to determine the nutritional value of WPMC, study the influence of the composition of the ration and verify the application of equations predicting digestibility. Four rations comprising 20 %, 50 %, 80 % or 100 % WPMC silage and hay were fed to wethers. Compared to the nutrient content of a maize silage containing 55 % cobs published in the tables, WPMC had a 58 % higher starch content, a 34 % higher fat content, a 31 to 62 % higher fatty-acid contents and an approx. 30 % lower parietal constituent content. The higher the WPMC content of the rations, the less favourable the digestibility of the parietal constituents. Digestibility of the organic matter, crude protein and cell walls (NDF) of power maize silage was not influenced by the composition of the ration (P > 0.1). The equation for whole-plant maize correctly predicted the digestibility of power maize silage from rations containing 50 to 80 % WPMC; with 100 % power maize silage, the equation for non-whole-plant maize was more appropriate. WPMC obtained energy values (NEL, NEV) 10 to 13 % higher than those of a common maize silage.