| dc.description.abstract | This study was designed to compare ten dual purpose sorghum varieties on the basis of
nutritional composition and digestibility with a view to recommend the best suited for arid and
semi-arid areas. The materials used in the study were from a trial carried out during 2006/2007
short rain season at three Kenya Agricultural Research Institute (KARl) stations situated in semiarid
parts of Kenya namely; Kambi ya Mawe, Kiboko and Machang'a. The ten varieties from
local and international collection were selected on the basis of agronomic criteria which included
overall agronomic expression in terms of biomass yield, grain yield, number of leaves, number
of tillers, low leaf senescence, plant height among others. At the age of 14 weeks, destructive
sampling was conducted to obtain samples for chemical and digestibility evaluation. The
samples were separated into panicles, leaves, stems and whole plant. In the laboratory the
samples were analyzed for dry matter (DM), crude protein (CP), neutral detergent fibre (NDF),
acid detergent fibre (ADF), acid detergent lignin (ADL) and in vitro dry matter digestibility
(IVDMD).
The dry matter content of the ten sorghum varieties ranged from 91.2 to 92.57%, while
crude protein was in the range of 5.13 - 6.61%. The neutral detergent fibre was highest (P:S0.05)
in NGUUGU (73.79%) and lowest in IESV99006 DL (58.52%). The acid detergent fibre
content followed the same pattern with NGUUGU showing the highest (P:S0.05) value (34.23%)
and IESV99006 DL with the lowest value (23.94%). The hemicellulose and Acid detergent
lignin contents were similar with values of 33.85 -39.56% and 4.55 - 5.8%, respectively. In case
of plant parts, the leaves had higher (P:S0.05) dry matter content (92.34%) than panicles
(91.71 %) and stems (91.28%). The panicle showed the highest (P:S0.05) crude protein content
(7.07%) while stem had lowest value (3.92%). The NDF values obtained were highest (P:S0.05)
(7.07%) while stem had lowest value (3.92%). The 1\TJ)Fvalues obtained were highest (P:S0.05)
for stems (70.68%) and lowest in panicles (60.25%). The ADF, Hemicellulose and ADL showed
higher (p:S0.05) values in leaves and stems and lower values in panicles. The in vitro dry matter
digestibility (IVDMD) was highest (p::SO.05)in Variety IESV99006 DL (67.29%) followed by
IESV92165 DL (65.95%) while NGUUGU had the lowest value (55.92%). The plant part on the
other hand recorded higher (P:SO.05) IVDMD values in panicles and whole plant at 66.99 and
66.15% respectively, while stems value was lowest at 53.59%.
A combination of ability to produce relatively higher dry matter digestibility, crude protein
and low fibre constituents, in addition to biomass yield led to ranking varieties IESV99006DL,
IESV92165DL and SDSL90162-2 highly for dual purpose production. NGUUGU had high fibre
component and low dry matter digestibility. Varieties such as Macia and IESV99027 DL
displayed characteristics for grain sorghum. NGUUGU with highest DM yield/ha, improving of
protein content, digestibility and possibly lowering of fibre content through breeding would
produce a good forage sorghum variety. Finally animal feeding trials need to be conducted in
order to evaluate these varieties in terms of animal performance. | en |
