Maize stovers for ruminant feed. Ammonia and urea preservatives and feed value

Abstract

It is possible to preserve maize stovers under an ammonia atmosphere when pressed in bales either the same day as harvest (their DM content about 35-40 %) or the day after (their DM content about 50 %) when harvesting is carried out using a combine fitted with a winrowing device. Either 3 kg NH₃ or 6 kg urea (that hydrolyses into 3 kg NH₃) per 100 kg DM of maize stovers is the minimum dose particularly when the stovers are wet, and must consequently be either injected few a hours after baling or directly incorporated at baling. After 1 1/2 month to 2 months of storage under plastic wrap the bales are stabilized and can be safely opened. Such techniques have to be considered as preserving ones rather than as feeding value improvement. The digestibility and the PDIE value of the treated stovers do not differ when compared with fresh material. However, their PDIN value increases from 30 to about 70 g/kg DM, due to the retained ammonia. The urea incorporation device remains to be improved in order to ensure an even preservation of the stovers within the bales.