| dc.description.abstract | Two commonly used napier grass (Pennisetum
purpureum) cultivars, Bana grass and French
Cameroon were grown under irrigation to assess
the changes in nutritive value at different
stages of growth in Naivasha, Kenya. The
experimental design was a split-plot with cutting
stage (subplot) nested within variety (main plot).
There were three replications per treatment. The
response variables were evaluated at 4, 6, 8, 10,
12 and 14 weeks of age.
Dry matter yields and grass height at cutting
ranged from 1.24 to 10.01 tons/ha and 22.11 to
189.99 cm respectively and significantly (P<0.05)
increased with age. The differences between the
cultivars for the two parameters were not
significant (P)0.05). The leaf:stem ratio
declined (P<0.05) with age but the differences
between the cultivars were insignificant (P)0.05).
The variations for leaf:stem ratio ranged from
5.03 at 4 weeks to 0.53 at 14 weeks of age.
Considerable changes (P(0.05) were observed in
CP, ash and carbohydrate contents as the
napiergrass matured. Crude protein decreased
(P<0.05) from 14.84 to 3.98% while CF and NFE
ranged from 23.39 to 39.01% and 33.74 to 39.86%
respectively. Ash and EE contents decreased
(P<0.05) from 26.41 to 15.75% and 3.42 to 1.49 at
4 and 14 weeks respectively. Ash. crude fibre and
NFE increased (P<O.OS) as the grass matured but
the variation between the cultivars was
insignificant (P)O.OS). The dry matter percent
varied from 15.81 to 17.70% and significantly
(P<O.OS) increased with age. Although French
Cameroon had consistently lower DM values.
varietal differences were insignificant (P)O.OS).
Calcium and phosphorus levels decreased from 0.39
to 0.30% and 0.31 to 0.21% at 4 and 14 weeks of
age respectively. The effect of both age and
variety for these two components were however
statistically insignificant (P>O.OS). Potassium
levels were high and ranged from 11.70 to 4.21%.
Although these levels decreased significantly
(P<O.OS) with age, varietal differences were
insignificant (P>O.OS).
The detergent fibres NDF and ADF increased
(P<O.OS) with age and rose from 54.44 to 72.68%
and 25.97 to 42.00% respectively. Lignin (ADL)
increased (P<O.OS) with age and ranged from 2.26
to 5.77 from 4 to 14 weeks. Varietal differences
in these constituents were not evident Silica
levels increased (P<O.OS) with age from 4 to 14
weeks ranging from 4.07 to 6.67% respectively with
Sana grass variety showing correspondingly higher
(P<O.OS) values.
Dry matter and organic matter digestibility
in vitro decreased (P<O.OS) with age from 72.04 to
58.30% and 75.72 to 62.22% respectively but the
varietal differences were insignificant (P)0.05).
The nylon bag dry matter loss in sacco increased
(P<0.05) with increase in incubation time and was
higher (P<0.05) the younger the napier grass. The
ranges were from 71.09 to 27.57% at 72 and 12
hours .of incubation res~edtivelY.
Significant (P<0.05) differences were observed
in grass height, ash and percent dry matter with
changes at cutting age. Silica content increased
(P<0.05) with increased maturity and differences
between the varieties were significant (P<0.05).
However, it was concluded under the conditions of
the experiment that dry matter yields, in vitro
and in sacco DM digestibility, CP, CF, EE, NFE,
detergent fibres, lignin and the minerals studied
varied with the stage of cutting although varietal
differences were insignificant (P)0.05). | en |
