A laboratory study of the composition and fermentation of various crop silages

Author: C.H.M. de Brouwer, H.J. van der Merwe and L.D. Snyman
Year: 1991
Issue: 1
Volume: 21
Page: 21 - 27

Grain sorghum, forage sorghum, sunflower and maize were ensiled on laboratory scale. Sunflowers, harvested at the milky seed stage of maturity, resulted in silage containing only 13,54% dry matter (DM). Maize, grain sorghum and forage sorghum silages, contained approximately 30% DM. Both maize and sunflower silage had an in vitro dry matter digestibility (IVDMD) of approximately 70%. Grain and forage sorghum silages had approximate IVDMD values of 60% and 53%, respectively. Sunflower silage was found to have the highest (P < 0,01) crude protein content (13,55%), followed by grain sorghum (9,42%), maize (8,23%) and forage sorghum (7,26%). The nitrogen (N) content of N-containing components was expressed as a percentage of total N content with the exceptions of crude protein and true protein which were expressed as a percentage of DM. Non-protein N content of the silages was found to be approximately 50%, with the exception of grain sorghum silage (56,16%). Acid detergent insoluble N content was highest (P< 0,01) in forage sorghum silage (16,61%). Acid detergent fibre content of forage sorghum and sunflower silages (38,6 and 35,2%, respectively) was appreciably higher than in maize and grain sorghum silages (29,5 and 32,9%, respectively). Both sorghums contained the least (P < 0,01) water soluble carbohydrates prior to ensiling. The amount of fermentation products was very high (P < 0,01) in sunflower silage (64, 77, 39 and 57% more lactic, butyric, acetic and total volatile fatty acids, respectively, than in maize silage). Ammonia N content was also highest (P < 0,01) in this silage. The analytical results of the plant matter and silages were statistically compared. Maize served as reference crop.


Keywords: Chemical composition; fermentation; silage; sunflower; grain sorghym; forage sorghum
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