The effect of level of inclusion of the legume Desmodium uncinatum and the use of molasses or ground maize as additives on the chemical composition of grass- and maize-legume silages

The effect of the inclusion rate of legume and use of molasses or ground maize as additives on the chemical composition of grass- and maize-legume silages was investigated in two experiments. In experiment 1 the effects of adding molasses or ground maize to star grass (Cynodon nlemfluensis) with or without legume (Desmodium uncinatum) at ensiling were studied. Four additive treatments (no additive, molasses, 50 and 100 g ground maize/kg fresh weight) were combined with four levels of legume (no legume, 150, 300 and 450 g/kg fresh weight) in a factorial arrangement of treatments. Sealed plastic bags containing about 15 kg of compressed material were used and each treatment was replicated three times. In experiment 2 the effect of adding graded levels of legume (D. uncinatum) to maize (Zea mays) at ensiling was studied in a completely randomised block design. Four levels of legume were used at ensiling: no legume, 150, 300 and 450 g/kg fresh weight. The same procedure as that used in experiment 1 was applied. All the grass silages were well fermented. Addition of ground maize and molasses increased the dry matter content of grass silage (P < 0.001). Molasses addition resulted in lower (P < 0.05) levels of volatile nitrogen and higher (P < 0.05) lactic acid content compared to the control and the ground maize treatments. The inclusion of legume above 300 g/kg fresh weight raised the pH, volatile nitrogen and total nitrogen content of grass silages (P < 0.001). The increase in pH and volatile nitrogen content was less when the silages were treated with additive, especially molasses. All the maize silages were well fermented, with low pH and volatile nitrogen levels. Crude protein level was increased from 60 to 90 g/kg dry matter in the silage with no legume and at the highest level of legume (450 g/kg) respectively. The pH increased from 3.7 in silages with no legume to 4.2 when legume was added at the rate of 450 g/kg. The inclusion of D. uncinatum improved the quality of both grass and maize silages. However, the inclusion of legume above 300 g/kg fresh weight of grass silage would require the use of additives.