Effect of Feed Mixtures and Preservation Period on the Nutritive Value and Fermentation Characteristics of Ensiled Maize Stover

Abstract

The study was designed to investigate the fermentation processes and subsequent nutritional quality of silage made from dry maize stover, ensiled with selected types of feed mixtures. Stover of maize variety HB614 harvested at about 150 days after planting was chopped into 2.5-cm pieces and mixed with a single or combination of two feed mixtures to constitute 4.5 kg on fresh weight basis in each treatment. The treatments were fresh maize stover alone (farmers’ practice) and ensiled maize stover with a single or combination of a feed mixture comprising effective micro-organisms (EM), spent brewers’ grain (SBG), molasses, urea and Desmodium intortum. The materials were ensiled in laboratory mini-silos with a capacity of 5 kg for zero, 30 and 60 days and analysed for indicators of fermentation quality (pH, lactic acid and NH3-N) and nutritive quality (CP, NDF and ADF). Addition of SBG, D. intortum and urea significantly increased the crude protein (CP) of maize stover silage. However, CP content declined over the ensilage period in all the treatments with the greatest decline being observed in the urea and D. intortum treatments. Treatments with SBG showed a decline in NDF content from 80 (control) to 68% while those with the legume D. intortum + molasses declined from 80 (control) to 67%, which are acceptable levels in ruminants. Treatments with EM had lower NDF except where D. intortum was included. Acid Detergent Fibre (ADF) content increased progressively over the ensilage period in all the treatments, except where EM alone and urea were included, which tended to have curvilinear graphs. The fermentation characteristics of stover ensiled with EM were similar to those ensiled with molasses. Therefore, EM can be used as a silage additive and a potential fibre degrading agent. Addition of N-rich feed mixures like the urea, spent brewers’ grains and legumes such as Desmodium intortum, improves the protein content of low quality crop residues. There is a need to test the activity of EM in low dry matter silages like Napier grass since it is a major feed in the smallholder dairy farming systems. Feed conservation technologies geared at reducing proteolysis in the silo as in the case of grass/legume silages are required.