In vivo digestibility of maize silages harvested with different techniques

A trial was carried out to determine the organic-matter digestibility and nutritional value of whole-plant maize silages (WPMS’s) harvested in different ways. Four methods were compared: standard WPMS from the tower silo removed with a silo unloader, standard WPMS in bales, WPMS shredlage, and cob-enriched WPMS (power maize). According to the chemical analyses, the nutritional content of the two standard WPMS and WPMS shredlage were comparable. By contrast, power maize differed from the other processes owing to its lower content of cell-wall components and higher starch content. There were no differences with the WPMS in terms of digestibility of organic matter (DOM), crude protein, crude fibre, ADF, NDF and gross energy. Power maize DOM was 4.5 % higher (P = 0.046) than that of both standard WPMS’s. With the exception of power maize, neither the harvest method (standard vs. shredlage) nor conservation method (silo vs. bales) influenced WPMS digestibility. There were no differences in terms of the nutritional values of the various WPMS silages. The regression equations for predicting DOM obtained from the Feed Recommendations for Ruminants permitted a precise estimate of the DOM values in comparison to the DOM obtained in vivo. In terms of particle fractions, WPMS shredlage is composed of more long particles than the two standard WPMS’s, but at 21 % the total failed to achieve the 25 % score announced by CLAAS. The WPMS conservation method did not influence the percentage of particles: the proportions of the different particle fractions were similar for both silo and bales. Removal with the silo unloader thus had no influence on particle lengths.