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

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 (lVDMD) 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.Graansorghum, voersorghum, sonneblom en mielies is op laboratoriumskaal ingekuil. Sonneblomme, geoes op die melkerige saadstadium van ontwikkeling, het 'n kuilvoer met 'n droëmateriaal (DM)-inhoud van slegs 13,54% gelewer. Mielie-, graansorghum- en voersorghumkuilvoer het ongeveer 30% DM bevat. Beide mielie- en sonneblomkuilvoer het 'n in vitro droëmateriaal verteerbaarheid (IVDMV) van ongeveer 70% gehad. Graan- en voersorghumkuilvoer het IVDMV van ongeveer 60% en 53%, onderskeidelik, gehad. Sonneblomkuilvoer het die hoogste (P < 0,01) ruproteïeninhoud (13,55%) gehad, gevolg deur graansorghum (9,42%), mielies (8,23%) en voersorghum (7,26%). Die stikstof (N)-inhoud van N-bevattende komponente is as persentasie van totale N-inhoud uitgedruk met die uitsondering van ruproteïen en ware proteïen wat as persentasie DM uitgedruk is. Nie-proteïen N-inhoud van die kuilvoere was ongeveer 50% met die uitsondering van graansorghumkuilvoer (56,16%). Suuronoplosbare N-inhoud was die hoogste (P < 0,01) in voersorghumkuilvoer (16,61%). Suuronoplosbare veselinhoud van voersorghum- en sonneblomkuilvoer (38,6 en 35,2%, onderskeidelik), was aansienlik hoër as in mielie- en graansorghumkuilvoer (29,5 en 32,9%, onderskeidelik). Beide sorghums het die laagste (P < 0,01) inhoud van wateroplosbare koolhidrate voor inkuiling, bevat. Die hoeveelheid fermentasieprodukte was baie hoog (P < 0,01) in sonneblomkuilvoer (64, 77, 39 en 57% meer melk-, botter- en asynsuur en totale vlugtige vetsure, onderskeidelik, as in mieliekuilvoer). Ammoniak N-inhoud was ook die hoogste (P < 0,01) in hierdie kuilvoer. Die analitiese resultate van die plantmateriaal en kuilvoere is statisties vergelyk. Mielies het as verwysingsgewas gedien.Keywords: Chemical composition; fermentation; silage; sunflower; grain sorghum; forage sorghum.