EFFECT OF STAGE OF MATURITY AND FORAGE BOTANICAL COMPOSITION AT ENSILAGE ON NUTRITIVE VALUE OF COLUMBUS GRASS (SORGHUM ALMUM) SILAGE
EFFECT OF STAGE OF MATURITY AND FORAGE BOTANICAL COMPOSITION AT ENSILAGE ON NUTRITIVE VALUE OF COLUMBUS GRASS (SORGHUM ALMUM) SILAGE
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Date
1998
Authors
MOHAMMED, Baba
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Abstract
A study was conducted on field grown columbus grass (Sorghum
almum)at the National Animal Production Research Institute
(NAPRI), Shika, Ahmadu Bello University, Zaria, Nigeria during
the rainy season of 1992. The objective of the trial was to
determine the ensiling characteristics of the forage at five
maturity stages and evaluate the nutritive potentials of the
resultant silages in ruminant feeding systems. Forage sown on
30th July, 1992 was harvested at pasture stages of 50, 60, 70,
80, and 90 days post-planting and ensiled fresh in laboratory
silos. Following an incubation period of 21 days the resultant
silage was scored for colour and aroma. The pH was determined
and sample analyzed for nutrient constituents.
The forage declined in moisture content (85.1 to 54.6%) and
leafiness (46.0 to 26.0%) with time to maturity. Bloom content
and fodder yield rose (10.3 to 95.1% and 1.3-8.40t DM/ha) with
time to maturity. Fodder accumulation was rapid with mean
daily increment of 177.0kg DM/ha within the growing period.
Forage materials at all phenological stages resulted in
satisfactory silages with agreeable colour and aroma. The
materials consolidated well and fermentation was complete with
moderately acidic pH values (4.6 to 4.1) . The HCN concentration
was low and declined with stage of maturity (244.0 to 183.0 mg
HCN/kg DM) . Plant factors favouring digestibility such as CP,
EE and carotene declined with stage of maturity, while
structural constituents (NDF and ADF) showed positive
relations. Silages of the late vegetative to the hard dough
stages declined in contents of N, P, K, Na and Fe. There was
no consistent trend in concentrations of Ca, Mg and Cu, while
the concentration of the Mn was fairly constant. Based on
ruminant nutritional standards the nutrient composition of the
silages are apparently sufficient in supplying the requirement
of N, Ca, Mg, Mn, Fe, Cu and carotene for production. The
silages are deficient in P and border-line in Na concentration.
Results in this study indicate that satisfactory silages were
obtained from columbus grass (S. almum) at varying phenological
stages from the late vegetative to the hard dough stages
(i.e., 50 to 90 days post-planting) . As a compromise between
fodder yield and nutritional quality, the soft dough stage (ca
80 days post-planting) is recommended as the optimum stage of
harvesting the forage material for ensiling. Such silage could
however be deficient in N, P, and Na relative to the
requirements of ruminant for productive functions.
Supplementation of these nutrients may thus be essential.
Animal studies involving feeding trials are advocated to
elucidate and further define the limits of the S. almum silage
in ruminant feeding systems.
Description
A Thesis submitted to:
Ahmadu Bello University,
In partial fulfilment of the requirements
for the degree of Master of Science.
Department of Animal Science
Faculty of Agriculture
Ahmadu Bello University, Zaria. Nigeria.
Keywords
STAGE OF MATURITY,, FORAGE BOTANICAL,, COMPOSITION,, ENSILAGE ON NUTRITIVE VALUE,, COLUMBUS GRASS,, (SORGHUM ALMUM),, SILAGE