Digestion of polysaccharide constituents of tropical pasture herbage in the bovine rumen Part II. Spear grass (Heteropogon contortus)

1973 ◽  
Vol 27 (1) ◽  
pp. 1-4 ◽  
Author(s):  
R.F.H. Dekker ◽  
G.N. Richards
1970 ◽  
Vol 10 (42) ◽  
pp. 32
Author(s):  
MJ Playne

A survey was made of the sodium concentration in eight grass and legume pasture species in the Townsville region. The grass species could be characterized according to sodium concentration. Panicum maximum, Chloris gayana, and Cenchrus setigerus were 'high-sodium' species (>0.40 per cent Na), whereas Urochloa mosambicensis had a medium sodium concentration, and Cenchrus ciliaris, Heteropogon contortus, and the legumes Stylosanthes humilis and Phaseolus atropurpureus were `low-medium� species (<0.10 per cent Na). The sodium concentration in five species grown at five sites located within 257 kilometres of Townsville, Queensland, was also examined at one stage of growth. Since several common pasture species contained low levels of sodium (<0.05 per cent of dry matter) deficiency symptoms could occur in grazing stock under certain circumstances.


1970 ◽  
Vol 23 (11) ◽  
pp. 2353 ◽  
Author(s):  
JD Blake ◽  
GN Richards

The total carbohydrate content of spear grass stalk and leaf at several different stages of growth has been separated into fractions by a sequence of extraction procedures and each major polysaccharide fraction has been analysed for its monomer composition. As growth advanced the low molecular weight carbohydrates (sucrose, glucose, fructose) decreased, while hemicelluloses and cellulose increased in relative amount. Hemicelluloses, which are the major type of component in the plant, were predominantly of the B-type in the leaf, but both A- and B-types were present in the stem. The hemicellulose A-fractions contained proportionately less arabinose and uronic acid and more xylose than the corresponding B-fractions.


1970 ◽  
Vol 10 (42) ◽  
pp. 32
Author(s):  
MJ Playne

A survey was made of the sodium concentration in eight grass and legume pasture species in the Townsville region. The grass species could be characterized according to sodium concentration. Panicum maximum, Chloris gayana, and Cenchrus setigerus were 'high-sodium' species (>0.40 per cent Na), whereas Urochloa mosambicensis had a medium sodium concentration, and Cenchrus ciliaris, Heteropogon contortus, and the legumes Stylosanthes humilis and Phaseolus atropurpureus were `low-medium� species (<0.10 per cent Na). The sodium concentration in five species grown at five sites located within 257 kilometres of Townsville, Queensland, was also examined at one stage of growth. Since several common pasture species contained low levels of sodium (<0.05 per cent of dry matter) deficiency symptoms could occur in grazing stock under certain circumstances.


1970 ◽  
Vol 23 (11) ◽  
pp. 2361 ◽  
Author(s):  
JD Blake ◽  
GN Richards

Alkaline extraction of spear grass holocellulose gave a xylan which was purified by fractional precipitation as a copper complex. Acid hydrolysis yielded L-arabinose, D-xylose, and an aldobiouronic acid consisting of D-xylose and 4-O-methyl-D-glucuronic acid. Hydrolysis of the methylated xylan gave 2,3,5-tri-O-methyl-L- arabinose, 2,3,4-tri-, 2,3-di-, and 2-O-methyl-D-xylose, and 3-O-methyl-2-O-(2,3,4-tri-O-methyl-D-glucopyranosyluronic acid)-D-xylose. The conditions for isolation of the methylated sugars for gas chromatography were investigated with particular reference to difficulties arising from volatility of the tri-O-methyl pentoses. The xylan is composed of chains of 1,4-linked �-D-xylopyranose residues to which are attached single units of L-arabinofuranose at position 3 and 4-O-methyl-D-glucuronic acid at position 2 of the basal residues.


1972 ◽  
Vol 23 (1) ◽  
pp. 45 ◽  
Author(s):  
PM Kennedy ◽  
BD Siebert

Sheep and cattle were used to study the influence of nitrogen and sulphur on the consumption and digestion of spear grass. With sheep, additions of sulphur to the diet increased the digestibility and intake of the feed. The relatively high levels of plasma urea which were found in sheep fed on spear grass alone, decreased with sulphur intake. In cattle, sulphur supplementation did not increase the digestibility of feed. The levels of plasma urea were comparable with those of sheep receiving additional sulphur, which suggested that sufficient sulphur was returned to the bovine rumen to maintain digestion. As previously shown, feed intake was further raised in cattle receiving supplements of nitrogen and sulphur. With the addition of sulphur to the diet of spear grass and urea, the concentration of rumen ammonia was reduced and more nitrogen was retained. The levels of serum sulphate in groups of heifers fed in yards or at pasture demonstrated that sulphur may be limiting for the optimum utilization of spear grass in particular situations.


1972 ◽  
Vol 22 (1) ◽  
pp. 173-185 ◽  
Author(s):  
R.F.H. Dekker ◽  
G.N. Richards ◽  
M.J. Playne

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