Title : Legume residues can enhance the quality of maize straw silage
Abstract:
Maize (Zea mays) straw silage is one of the most commonly used feeds across the world, due to its high-energy content. However, it contains low crude protein (CP) content of <7 g/kg DM. To meet the nutrient requirements for ruminants, the CP of maize straw silage must be increased to required levels. Cowpeas and lablab residues (leaves and vines) are widely used as protein source for livestock in South Africa, after fruit harvesting. However, legumes cannot be ensiled alone due to their high buffering capacity and their low water soluble carbohydrates (WSC), with the risk of producing butyric acid. Mixing maize and legume forage for silage production is a feasible strategy for increasing the CP of maize silage to provide adequate fodder during dry periods. Therefore, the objective of this study was to enhance the quality of maize straw silage using legume foliage. Four legumes species (Lablab purpureus and Vigna unguiculata (Dr Saunders, betswit, and indigenous cowpea varieties)) were grown at North-West University farm (Campus field). Maize was also planted in the same fields but different plot. Harvesting was done after the reproductive stage (After fruits harvest). The proportion of legume to maize was 20:80% (maize-lablab (ML), maize-indigenous cowpea (MI), maize-Betswit (MB) and maize-Dr Saunders (MD)). Maize alone (M) was used as control making up five treatments. Silages were opened after 45 days, and samples were taken for chemical composition (AOAC, 2012), in vitro dry matter degradability (IVDMD), fermentation characteristics analysis and aerobic stability test. All data were subjected to a one-way analysis of variance (SAS, 2010). For a statistical test, significance was declared at P<0.05. Maize-lablab had the highest (P<0.05) CP content (116.0 g/kg DM) than other silages. Maize-Dr Saunders had highest ash content (160.9 g/kg DM) than other silages. Maize-Betswit had the lowest (P<0.05), neutral detergent fibre (NDF), acid detergent fibre (ADF), and acid detergent lignin (ADL) content (493.1, 365.2 and 118.6 g/kg DM, respectively) when compared with other silages. The MI had the lowest (P<0.05) Ether extract content (21.0 g/kg DM) and carbon dioxide (CO2) concentration (5.4 g/kg DM) when compared to other silages. The highest (P<0.05) IVDMD was recorded for ML silage from 24 hrs up to 72 hrs. The lowest (P<0.05) pH (3.66) was recorded for maize silage. All silages had similar (P>0.05) amounts of lactic acid (LA), water-soluble carbohydrates (WSC), yeast and mould counts. All the legumes foliage were capable to be used in silage in enhancing low-maize straws for the sustainability of livestock, especially during the dry season. In this study, maize-lablab silage performed better in terms of CP and IVDMD (24-72 hr). The CP content of MD, MB, MI and ML was greater than 80 g/kg DM, which is considered enough for optimal ruminal microorganisms’ activity. The silages had low pH values, which is a good indication of well-preserved silage. The inclusion of legumes to maize straw showed that legume foliage could stimulate LA production, which could influence the bacterial community from diverse forages and can be ascribed to the high buffering capacity of legumes.
Audience Take Away Notes
- Audience would be able to put what they learn into practical as it would have been emphasized in the methodology section. There is a hand on task that needs a proper application of ensiling methods.
- Once the audience learn the proper management practices required. The final factor that may directly influence nutrition is the formation of moulds and mycotoxins in silage and once fed to animals, this will have an influence in the economics status of the farmers.
- Technically, this can be introduced to students as part of experimental exposure during their studies
- Feed scarcity during winter and drought times is a challenge to developed and developing countries, hence as part conservation methods, the use of silage can be a part of mitigation strategy to minimize feed shortage during those times.
- Continuous assessment of legumes using different conservation methods can be vital for the productivity of animals. Even though there is no additional new information added to the study, in an attempt to understand the potential nutritive value that the legume can provide to livestock, there is therefore a need for continuous screening of the herbaceous legumes species to ensure that local farmers can contribute to animal protein production in the country in a sustainable manner.
