EFFECTS OF VARIETIES AND HARVEST STAGES ON SILAGE QUALITIES OF SWEET POTATO VINES

Background: Hawassa-83, Kabode, Alamura and one unimproved local variety are the main sweet potato varieties in the study area, but there has been no research on the silage produced from these four varieties.Objective: To evaluate the effects of varieties and harvest stages on the silage quality and nutritional characteristics of sweet potato vines.Methods: Plants were harvested at the 60-day and 120-day growth stages and then used to produce silage with and without additives (molasses and sweet potato roots). The nutritional quality of the resulting silages was analyzed. Results: Variety, harvest stage and additive level affected silage physical characteristics, chemical composition, and in vitro dry matter digestibility. Silage with molasses-based additives from both harvesting stages had a pleasant smell. The 60-day-old growth-harvested vine silages scored lower than the 120-day-old growth-harvested vine silages for smell, color, texture and moldiness. The addition of both molasses and sweet potato roots decreased the pH, CP, NDF, ADF, and ADL but increased the DM content and in vitro dry matter digestibility. Silages at all additive levels had good quality. Increased amounts of molasses and sweet potato roots reduced the pH of all the silage varieties. Silage without additives had greater pH content than silage with additives. Increased levels of molasses and sweet potato roots increased the silage dry matter content in all varieties. With respect to all varieties, increasing levels of molasses and sweet potato roots tended to decrease the crude protein content. Hawassa-83 and Alamura were revealed to be more suitable than Kabode or local varieties for producing silage in the study area. On the basis of the dry matter content and in vitro dry matter digestibility, Hawassa-83 and Alamura should be harvested at 120 days of growth to optimize silage quality. Implication: The higher silage qualities observed in Hawassa-83 and Alamura vines revealed that these vines could be used as potential feed, especially as a protein supplement to low-quality feed. Conclusion: Planting outperforming varieties, Hawassa-83 and Alamura, and harvesting at 120 days of age are considered suitable practices for vine production, and excess silage is preserved to feed livestock during the dry season.