Differences in carbohydrate fractions between Lolium perenne and two tropical grasses of similar dry-matter digestibility

1974 ◽  
Vol 82 (3) ◽  
pp. 449-454 ◽  
Author(s):  
M. N. McLeod ◽  
D. J. Minson

SUMMARYFour samples each of Lolium perenne, Chloris gayana and Setaria splendida grown under similar conditions and having similar in vivo dry-matter digestibilities with sheep were used in a comparison of the chemical composition of tropical and temperate grass. L. perenne had less lignin, crude fibre, neutral-detergent fibre, acid-detergent fibre and cellulose than the two tropical grasses but more neutral-detergent solubles. In vivo digestibilities of the cell-wall polysaccharides of the tropical grasses were not reduced by their higher lignin contents. The digestibilities of the cell wall were generally higher than the digestibilities for the dry matter and neutral-detergent solubles. It is suggested that the effect of lignin on the digestibility of cell-wall polysaccharides is dependent on the area of protection, and better predictions may be achieved if the cell wall is divided into two fractions, an unlignified fraction that is completely digested and a completely indigestible fraction containing all the lignin.It is concluded that differences may be found in the carbohydrate composition of temperate and tropical grasses but that these differences may not cause differences in the overall in vivo digestibility of the dry matter.

1972 ◽  
Vol 25 (6) ◽  
pp. 1377 ◽  
Author(s):  
RFH Dekker ◽  
GN Richards

The dry matter digestibility (DMD) of poor quality roughages such as spear grass (Heteropogon contortus) by sheep and cattle has been shown to increase on addition of sulphur to the diet. The sulphur is added most frequently as inorganic sulphate, either alone (Playne 1969) or supplemented with urea (Bray and Hemsley 1969; Kennedy and Siebert 1972; Siebert and Kennedy 1972) or gluten (Playne 1969). These supplements have also increased feed intake in sheep (Playne 1969; Kennedy and Siebert 1972; Siebert and Kennedy 1972) and cattle (Siebert and Kennedy 1972), and have improved the nitrogen and sulphur balance (Moir, Somers, and Bray 1967; Bray and Hemsley 1969; Playne 1969; Kennedy and Siebert 1972) within the animal. Sulphates have been shown to increase the in vitro rumen digestion of starch (Kennedy, Mitchell, and Little 1971), crude fibre (Bray and Hemsley 1969), and acid-detergent fibre and cellulose (Barton, Bull, and Hemken 1971).


1973 ◽  
Vol 80 (2) ◽  
pp. 283-296 ◽  
Author(s):  
W. R. McManus ◽  
M. L. Bigham

SummaryFood intake prediction relationships were developed from in vitro dry-matter digestibility determinations on food and resultant faecal material for a number of diets ranging from low quality roughage to high quality irrigated pastures.The relationship between true digestibility in vitro and in vitro food dry-matter digestibility was curvilinear, although true digestibility of food dry matter in vivo was highly correlated with apparent digestibility of food dry matter in vivo. The latter relationship was linear.For 122 sheep observations on voluntary dry-matter intake incorporating 11 diet types, introduction of either of the terms, cell-wall concentration in food: cell-wall concentration in the resultant faeces (CWFo/CWFe), or its converse, into conventional faecal index relationships did not increase precision of intake prediction using faecal nitrogen as an indicator substance. However, significant intake prediction relationships using food:faeces cell-wall ratios were generated.Values for in vitro digestibility of food and resultant faeces dry matter expressed as either a ratio (R) or as a difference (delta) yielded useful prediction relationships. For ‘green’ and for ‘dry’ classifications of the feedstuff's investigated some of these new relationships were either equal to or superior to the predictive efficiency of conventional faecal index relationships.Reasons are discussed for use of maximum potential in vitro digestibility values for food and faecal dry matter in such relationships in future work rather than a conventional 48 h fermentation.


Author(s):  
E.A. Dodsworth ◽  
R.H. Phipps ◽  
J.A. Bines

Estimates of organic matter digestibility derived from the concentration of indigestible acid detergent fibre CIADF) in the diet and the faeces compared favourably with in vivo values when a variety of forages was fed to wether sheep (Penning and Johnson, 19B3). The purpose of this trial was to evaluate IADF as an internal marker to estimate dry matter digestibility (DMD) of lactating dairy heifers fed ad libitum grass silage with one of three levels of concentrate supplementation.


1979 ◽  
Vol 19 (98) ◽  
pp. 344 ◽  
Author(s):  
WJF McDonald ◽  
JH Ternouth

Seventy samples of browse feeds, collected during late autumn and spring of 1971 from 42 western Queensland shrubs and trees, were subjected to laboratory analyses of the proximate fractions and in vitro digestibility. Crude protein, crude fibre and nitrogen-free-extract fractions ranged between 65 and 242, 55 and 353 and 425 and 71 1 g kg-1 dry matter, repectively. The in vitro dry matter digestibility coefficients ranged between 0.22 and 0.86. Comparisons of 15 browse feeds collected in April-May and October indicated a higher crude protein content (P < 0.05) and in vitro digestibility (P .= 0.01) and lower crude fibre (P < 0.01) and ash (P < 0.01 ) content in spring samples for most species. Nine browse feeds of known in vivo dry matter and organic matter digestibility were subjected to in vitro digestibility analysis. Whilst the in vitro and in vivo dry matter digestibilities were similar (0.43 and 0.45, respectively) the mean in vitro organic matter digestibility was substantially lower than the corresponding in vivo digestibility (0.40 and 0.46, respectively).


1984 ◽  
Vol 24 (127) ◽  
pp. 494 ◽  
Author(s):  
DJ Minson

Data are reported on the voluntary intake and digestibility by sheep of five species of Digitaria when grown as swards, cut at five different stages of growth and analysed for neutraldetergent solubles, hemicellulose, cellulose, lignin, N, S, Na, K, P, Ca, Mg, Si, Cu, Mn, and Zn. Digitaria setivalva was superior to the other four species in in vivo digestibility of the dry matter, organic matter and energy (5.2 percentage units), content of metabolizable energy (5.3%), voluntary intake of dry matter (8 0%) and voluntary intake of metabolizable energy (18.1 %). This superiority was associated with a higher content of digestible neutral-detergent solubles and cellulose. The metabolizable energy contents of the grasses were significantly correlated with dry matter digestibility and organic matter digestibility, content of digestible dry matter and concentrations of crude protein, neutral-detergent fibre, acid-detergent fibre, lignin and combinations of these different fractions.


1988 ◽  
Vol 68 (3) ◽  
pp. 787-799 ◽  
Author(s):  
V. GIRARD ◽  
G. DUPUIS

In view of the large variation found in plant cell wall digestibilities with ruminants, an attempt was made to group 124 feeds into different lignification classes (clusters) on the basis of chemical characteristics. Each feed cluster was described using a structural coefficient [Formula: see text] that related the potentially digestible fiber (PDF, %) to the ratio between lignin and cell wall volume. The optimum number of clusters was determined iteratively by performing a regression of the apparent digestibility of dry matter at maintenance level (DDM1, %) against the PDF and cell soluble (SOL, %) contents of feeds. The [Formula: see text] coefficients varied from 0.05 (grains, N = 13) to 1.85 (corn silage, N = 3) and increased with the maturity of the grasses from 0.88 (legumes, vegetative cool season grasses, N = 26) to 1.33 (mature, cool season grasses, N = 19). Predicted PDF were closely correlated (r > 0.9, P < 0.01) to in vitro cell wall disappearances (IVCWD). Apparently digestible cell wall in four grasses and four legumes increased linearly with 96-h IVCWD and standard error (SE) was similar to the SE of predicted apparent digestible SOL from SOL concentrations. Assuming that similarity between SE could be also observed in larger samples, PDF and SOL were used in summative equations to predict apparent dry matter digestibility. DDM1 discounted for intake (DDM1 – 4, %) was regressed against SOL and PDF concentrations of 87 feeds:[Formula: see text]with ds and df, the true digestibilities of SOL and PDF. Estimates of ds and df were 0.98 and 0.95 for a zero-production (maintenance) level of intake, and 0.91 and 0.79 for an intake level four times maintenance. Since the true digestibility of the PDF component was only 4% – 13% lower than that of the cell soluble component, the concentration of PDF in cell wall was the major determinant in the variation in apparent digestibility of forages. Key words: lignin, neutral detergent fiber, true digestibility, cluster analysis, feeds


2009 ◽  
Vol 49 (7) ◽  
pp. 563 ◽  
Author(s):  
David B. Coates ◽  
Robert J. Mayer

In a study that included C4 tropical grasses, C3 temperate grasses and C3 pasture legumes, in vitro dry matter digestibility of extrusa, measured as in vitro dry matter loss (IVDML) during incubation, compared with that of the forage consumed, was greater for grass extrusa but not for legume extrusa. The increase in digestibility was not caused by mastication or by the freezing of extrusa samples during storage but by the action of saliva. Comparable increases in IVDML were achieved merely by mixing bovine saliva with ground forage samples. Differences were greater than could be explained by increases due to completely digestible salivary DM. There was no significant difference between animals in relation to the saliva effect on IVDML and, except for some minor differences, similar saliva effects on IVDML were measured using either the pepsin–cellulase or rumen fluid–pepsin in vitro techniques. For both C4 and C3 grasses the magnitude of the differences were inversely related to IVDML of the feed and there was little or no difference between extrusa and feed at high digestibilities (>70%) whereas differences of more than 10 percentage units were measured on low quality grass forages. The data did not suggest that the extrusa or saliva effect on digestibility was different for C3 grasses than for C4 grasses but data on C3 grasses were limited to few species and to high digestibility samples. For legume forages there was no saliva effect when the pepsin–cellulase method was used but there was a small but significant positive effect using the rumen fluid–pepsin method. It was concluded that when samples of extrusa are analysed using in vitro techniques, predicted in vivo digestibility of the feed consumed will often be overestimated, especially for low quality grass diets. The implications of overestimating in vivo digestibility and suggestions for overcoming such errors are discussed.


2001 ◽  
Vol 41 (2) ◽  
pp. 169 ◽  
Author(s):  
Y. J. Ru ◽  
J. A. Fortune

The nutritive value of 26 cultivars of dry, mature subterranean clover was evaluated at Shenton Park, Perth, Western Australia. The cultivars were divided into 3 maturity groups according to flowering time and each cultivar was sown in blocks comprising 4 replicates. The plots were grazed by sheep at 2-week intervals during the growing season. Dry mature plant material and soil were sampled in summer to examine the effect of grazing and cultivar on seed yield and nutritive value of feed residues. Cultivars heavily grazed in spring had a low herbage mass. There was no difference in seed yield and seed weight between heavily and lightly grazed cultivars. Dry matter digestibility and mineral content of dry residues was inconsistent for the 2 grazing treatments. The dry matter digestibility of dry, mature subterranean clover ranged from 40 to 56%, with a wide range of crude fibre, nitrogen and mineral content for the 26 cultivars. While most minerals in the dry residues were above the requirement for sheep, 7 cultivars had a zinc content less than the maintenance requirement for sheep. There was an imbalance for all cultivars in calcium: phosphorus with a range of 4–10: 1. Concurrent estimates on the yield and composition of seed indicated that seed can be resource of minerals for grazing animals in summer. Most cultivars had a seed yield over 100 g/m2 with that of 9 cultivars being over 130 g/m2. Seed was rich in nitrogen, sodium, phosphorus, potassium, magnesium, zinc and copper, and poor in sodium, calcium and manganese. However, there were no cultivars with an appropriate ratio of calcium and phosphorus. The imbalance in nitrogen and sulfur was a result of high nitrogen content with the ratio ranging from 19: 1 to 29: 1.


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