Nutritive Evaluation of some Natural Pasture Grasses in Southern Sudan

Abstract

The potential nutritive value for some pasture grasses and frobs from Southern Sudan were studied. Twelve pasture species, seven grasses (Dactyloctenium aegyptiacum "Korib", Ischaemum afrum "Ankooj", Cymbopogon nervatus "Naal"s, seteria verticillata "Zanab alkadis", Sorghum virgatum"Adar" , Typha angustifolia "Burdi", and Echinochloa colona "Difra" and five forbs Iopomea cordufana "Tabar", Iopomea aquitica "Arkelah", Rhynchsia memnomia "Umsheriet", Farsetia longsiliqua "Um grairat" and Commelina imberbis "Boyad" were collected during the rainy season (September, 2006) from El Rank County, Southern Sudan. The chemical composition, mineral concentration, in vitro dry matter digestibility (IVDMD), estimated metabolizable energy (ME) and the in vitro gas production profiles varied significantly (P<0.05) among the different species. The mean CP in grasses was 10.5%, while in the forbs was 19.36%. NDF and ADF contents were higher in grasses than in forbs. The NDF was 22.97% - 45.14%, and 62.9 - 69.64% for forbs and grasses respectively. The IVDMD for all species were much higher than 45%, except for Rh. memnonia (45.9%) and S. verticillata (44.07%). ME values were below 8 MJ/kg DM for all pasture species in except of C. nervatus, however, grasses had higher values than forbs. Forbs contained higher Ca levels than grasses, the means value were 6.78 and 2.19 g/kg respectively. As expected, phosphorus concentration was as low as less than 1.5 g/kg for all species. A higher Ca:P ratio was recorded for forbs (10.0) compared to 2.8 for grasses. All grasses contain less than 2.5 g/Kg of Mg except D. aegyptiacum. ix The micro elements level ranged widely from 7.05 to 26.25, 7.83 to 36.28, 53.68 to 860, 0.7 to 23.58, and 1.82 to 11.83 for Cu, Mn, Fe, Zn and Co respectively. The mean of the total gas production after 24, 48, 72 and 96 was higher in grasses than in forbs. The mean of b in the forbs was 31.51, and in grasses was 50.19 ml/200mg/kg. There was a negative correlation between CP and gas production (p<0.05), while the NDF correlated positively with gas production. The presence of forbs in the pasture generally improve the quality of the nutritive value of the forage grazed by animals because of its good content of CP and minerals.