In order to learn more about the feeding value of stovers and straws,
seven diets were compared in
one experiment and nine in another. The diets in the first experiment were:
the upper and lower parts
of lucerne (Medicago sativa) hay, the leaves, upper stem and lower
stem of maize (Zea mays) stover
and the leaves and stem of sorghum (Sorghum vulgare) stover. The
diets in the second experiment
were: the upper and lower parts of lucerne hay, the leaves, stem and whole
stover of millet (Setaria
italica), the straw and chaff of wheat (Triticum aestivum),
rice (Oryza sativa) straw and sweet potato
(Ipomoea batatas) haulm. The diets were fed to sheep to record
rate of intake, voluntary intake and
in vivo digestibility. The diets were analysed for cell wall (as
neutral detergent fibre), crude protein and
lignin. Organic matter degradation and cell wall degradation were recorded
in nylon bags in the
rumen of cattle.The highest rates of intake (6·8–9·6 g dry matter/min)
and voluntary intake (75–103 g dry
matter/kg W0·75/day) were with sweet potato haulm
and the upper, leafy part of lucerne hay. The
voluntary intake of millet leaves, wheat chaff and the lower, stemmy part
of lucerne hay was
moderately high (46–70 g dry matter/kg W0·75/day).
Voluntary intake of leaves was higher than that
of stems in the case of millet, sorghum and to a lesser extent maize. The
lowest rates of intake were
with millet stem, sorghum stem and rice straw (1·8–2·4
g dry matter/min). In vivo digestibility of
organic matter was highest (59–67%) for the upper part of lucerne
hay, sweet potato haulm, the lower
part of maize stem and millet leaves. The leaves of maize were less digestible
than the stem, while the
reverse was the case with millet. Cell wall content was particularly high
(74–78% of dry matter) in
millet stem, wheat straw and chaff, rice straw and sorghum stem. Lignin
content was low (3·6–4·2%
of dry matter) in millet leaves, maize leaves and the upper part of maize
stem. Organic matter
degradation after 24 h incubation in the rumen was highest (80%) in sweet
potato haulm and lowest
(39–44%) in millet stem, wheat straw and chaff and rice straw. Cell
wall degradation after 96 h in the
rumen was highest (76–81%) with the leaves of maize, sorghum and
millet and lowest (40–59%) with
lucerne hay, millet stem and stover, wheat straw and chaff and rice straw.
Effect of Sodium Hydroxide Treatment of Rice Straw on Cell Wall Composition and Digestibility of Dry Matter