Silage Fermentation Characteristics and its Nutritive Value on Adding Different Rates of Molasses to selected Forage Sweet Potato Cultivars

Robert Kamau IRUNGU



Forage sweet potatoes (Ipomoea batatas (L) Lam) have not been adequately evaluated in silage making in Eastern Africa. The objective of the study was to determine silage fermentation characteristics and its nutritive value on adding different rates of molasses to selected forage sweet potato cultivars. The design was completely randomized design in factorial arrangement. Cultivars K158, Marooko and Wagabolige, harvested at 120 days, formed main treatments and  laboratory silos maintained at room temperature, for 60 days, then sampled to assess pH, nutritive value, total titratable acidity (TA), ammonia nitrogen (NH3-N) and butyric acid (BA). Molasses rates affected these silage parameters. Silage fermented at 5 and 10 % molasses rates contained similar pH, organic matter (OM) and neutral detergent fibre (NDF) but differed in dry matter (DM) and crude protein (CP). The DM and CP at 0 and 10 %; 0 and 5 % molasses were similar respectively and all three rates fermented silage of similar acid detergent fibre (ADF) and acid detergent lignin (ADL). Molasses at 5 % produced silage of higher DM than at 0 and 10 % molasses in all cultivars. All silages differed in NH3-N and TA and the lowest and highest NH3-N was recorded at 5 % and 0 % molasses respectively. Lowest and highest TA was recorded at 0 and 10 % molasses respectively. Five and 10 % molasses silage contained similar BA concentration which was lower than at 0 % molasses. Molasses reduced NDF, ADF and ADL in silage as it enhanced silage fermentation. Also molasses improved silage quality through increased DM and titritable acidity, reduced ammonia and butyric acid. Molasses application at 5 % was recommended in making high quality silage from forage sweet potato cultivars. Silage making can avail nutritious diets to livestock throughout the year.

Key words: Silage, molasses, sweet potato, fermentation

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