Comparing estimates of herbage digestibility from faecal nitrogen and in vitro determinations

1980 ◽  
Vol 31 (1) ◽  
pp. 57-62
Author(s):  
H. A. Birrell
Keyword(s):  
Organic Matter ◽  
Digestible Organic Matter ◽  
Faecal Nitrogen ◽  
Feeding Trials ◽  
Grazing Sheep ◽  
Organic Matter Digestibility ◽  
Image Position ◽  
Stocking Rates

ABSTRACTIn a grazing experiment, the organic matter digestibility of herbage selected by sheep grazing at two stocking rates was determined at monthly intervals over a 9-month period by (i) the in vitro determination of organic matter digestibility of the material collected from sheep fitted with an oesophageal fistula, and (ii) derivation from the prediction of digestible organic matter intake with a faecal nitrogen regression. A comparison of the two techniques confirms the view of other workers that faecal nitrogen indices based on pen feeding trials of green herbage are unreliable for predicting digestibility of green herbage in the field. The bias which is produced by faecal nitrogen regression appears to be associated with the time spent grazing by the animal each day. Relating organic matter digestibility directly to nitrogen content of faeces of grazing sheep (N, g nitrogen/100 g faecal organic matter) and their grazing time (T,h) yielded the following equation:The expression has standard errors (±2·6) similar to those involved in an in vitro determination. It provides a simple technique for estimating digestibility of herbage eaten by grazing sheep, but this may only be applicable to the particular sward conditions.Field estimates of digestibility over summer and autumn by this equation were found to be similar to estimates by a faecal nitrogen expression established from hand feeding sheep with dry summer herbage.

The use of cell wall organic matter components and in vitro degradability characteristics to predict intake and digestibility of white clover for sheep

1995 ◽  
Vol 46 (6) ◽  
pp. 1111 ◽  
Author(s):  
KS Nandra ◽  
VH Oddy ◽  
JF Ayres ◽  
PJ Nicholls ◽  
B Langevad ◽  
...  
Keyword(s):  
Cell Wall ◽  
Organic Matter ◽  
White Clover ◽  
Good Precision ◽  
Digestible Organic Matter ◽  
Predictive Relations ◽  
Voluntary Intake ◽  
Organic Matter Digestibility

The relations of the laboratory measurement of cell wall organic matter (CWOM) components and of the in vitro degradability characteristics of CWOM with in vivo digestibility and voluntary intake for high quality white clover were investigated. The voluntary intake, apparent digestibility and apparent rumen retention time of CWOM of white clover harvested at various stages of maturity were measured in rumen-cannulated Merino wether sheep. The in vitro degradability characteristics of CWOM of these diets were also measured. This study has quantified strong predictive relations between structural fibre constituents or degradation parameters and both digestibility and intake for white clover. The CWOM, cellulose and hemicellulose contents and potential degradability of CWOM of the white clover predicted in vivo organic matter digestibility with good precision (r2 = 0.74, 0.67, 0.72 and 0.72 respectively). The voluntary intakes of organic matter and digestible organic matter of the white clover were strongly related to CWOM, cellulose and hemicellulose contents and to the rate of degradation of CWOM in the rumen and the fits of these relations were at least as good as those predicting organic matter digestibility. The predictive equations based on CWOM: OMD (g/kg) = 97.6-0.081 (� 0.012) CWOM OMI (g/kg) = 83-0.085 (� 0.018) CWOM DOMI (g/kg) = 71.4-0.098 (� 0.015) CWOM are recommended because of the ease of analysis of CWOM in the laboratory.

Studies in the wool production of grazing sheep. 4. Variation between sheep in intake, wool production, and efficiency

1966 ◽  
Vol 6 (20) ◽  
pp. 96 ◽  
Author(s):  
WR McManus ◽  
GW Arnold ◽  
ML Dudzinski
Keyword(s):  
Organic Matter ◽  
Wool Production ◽  
Digestible Organic Matter ◽  
Grazing Sheep ◽  
Stocking Rates

The results of a three-year experiment with Merino wethers grazed at four stocking rates were examined. There were consistent differences between individual sheep at all times of the year in their intake of digestible organic matter (DOMI), clean wool production (WP), and in their efficiency of conversion of food to wool (E). Within stocking rates there were no consistent relationships between DOMI and WP.

A MODIFIED METHOD FOR THE IN VITRO DETERMINATION OF DRY MATTER AND ORGANIC MATTER DIGESTIBILITY

1973 ◽  
Vol 53 (2) ◽  
pp. 251-256 ◽  
Author(s):  
R. E. LARSEN ◽  
G. M. JONES
Keyword(s):  
Organic Matter ◽  
Dry Matter ◽  
In Vitro Fermentation ◽  
Modified Method ◽  
Initial Stage ◽  
Fermentation Period ◽  
Organic Matter Digestibility ◽  
Stage 1

Several modifications were made to the two-stage in vitro fermentation techniques for dry matter and organic matter digestibility (IVDMD and IVOMD) determinations developed by Tilley and Terry (J. Brit. Grassland Soc. 18: 104–111, 1963) and Alexander and McGowan (J. Brit. Grassland Soc. 21: 140–147, 1966). These modifications included: (1) changing the buffer medium, which resulted in a pH of 6.8–7.0 in the fermentation tubes during the initial (stage 1) 48-h fermentation period, and (2) shortening the acid-pepsin incubation period from 48 to 24 h, and thus reducing time for estimation of both IVDMD and IVOMD by 24 h. Modification (1) eliminated pH adjustments during fermentation and acidification at the end of the fermentation period. Acid-pepsin digestion of substrates was completed within 24 h instead of 48 h. Both IVDMD and IVOMD values were obtained on the same substrates. These modifications were evaluated using 65 samples that arose from 13 forages, comprised of corn and grass silages and their mixtures, which had been dried by five different methods. IVDMD and IVOMD were determined on all samples, comparing the modified method with the parent methods. IVDMD and IVOMD coefficients within each method were not statistically different between the Tilley and Terry method and the modified method.

A note on the storage of sodium hydroxide-treated whole-crop barley beneath grass and lucerne silage

1983 ◽  
Vol 36 (1) ◽  
pp. 143-146 ◽  
Author(s):  
A. Moore ◽  
C. Harris
Keyword(s):  
Organic Matter ◽  
Chemical Analysis ◽  
Thin Layer ◽  
Dairy Cows ◽  
Sodium Hydroxide ◽  
Dry Matter ◽  
Microbiological Examination ◽  
Digestible Organic Matter ◽  
Organic Matter Digestibility

ABSTRACTOne hundred tonnes of spring-sown barley harvested as whole crop were treated on a commercial farm with pearl sodium hydroxide at 46 g/kg dry matter.The treated material was stored in a silage clamp beneath grass and lucerne silage. A thin layer of grass, cut and wilted to hay-making dry matter, was placed immediately on top of the barley to absorb any silage effluent.Monthly samples were taken for microbiological examination and chemical analysis throughout winter storage, while the material was fed to British Friesian dairy cows. There was no evidence of fermentation by clostridia in the whole-crop barley or wilted grass and there was no spoilage of the exposed feeding face. The treatment increased the in vitro organic matter digestibility and the in vitro digestible organic matter in the dry matter of the whole-crop barley. No excessive urination or other ill effects were observed in the stock.The method proved practical for the satisfactory storage and feeding of sodium hydroxide-treated whole-crop barley.

Studies on the nutritive value of the diet selected by grazing sheep V. Further studies of the relationship between digestibility estimated in vitro from oesophageal fistula samples and from faecal and dietary composition

1969 ◽  
Vol 11 (3) ◽  
pp. 379-387 ◽  
Author(s):  
J. P. Langlands
Keyword(s):  
Nitrogen Content ◽  
Nutritive Value ◽  
Live Weight ◽  
Faecal Output ◽  
Faecal Nitrogen ◽  
Grazing Sheep ◽  
Predicted Values ◽  
Stocking Rates ◽  
The Relationship

SUMMARYDigestibility was estimated in vitro from a total of 167 oesophageal fistula samples collected over a period of 16 to 24 months from adult sheep grazing eight Phalaris tuberosa-Trifolium repens pastures stocked continuously at rates of from 2·5 to 37·1 sheep per ha. Corresponding estimates of the nitrogen content of the faeces and of the fistula samples, the live weight and faecal output of the sheep, and of the herbage availability of the pasture were obtained.The observations were stratified on the bases of stocking rate, digestibility, month of the year, herbage availability or organicmatter intake. Relationships between digestibility estimated by the fistula technique and faecal nitrogen content (model B) and between digestibility and faecal nitrogen content, nitrogen content of the dietary dry and organic matter, and faecal output per unit live weight (model A) were calculated for each stratum.There were significant differences between relationships derived for the various stocking rates, levels of digestibility, times of year, levels of intake and levels of herbage availability; predicted values of digestibility for given values of the independent variables differed by as much as 20 units of digestibility. Model A was substantially more precise than model B.Differences between estimates of digestibility, derived by the fistula technique and by a general faecal nitrogen—digestibility relationship, established by Lambourne and Reardon (1963a) were calculated. The differences were related to digestibility and to herbage availability.The implications of these results are discussed and it is concluded that faecal nitrogen content is not a satisfactory index of the digestibility of the diet selected by grazing sheep.

The estimation of the intake of grazing sheep II. Application of faecal nitrogen regressions to a group of grazing sheep

1962 ◽  
Vol 59 (3) ◽  
pp. 349-353 ◽  
Author(s):  
G. R. Pearce ◽  
J. E. Vercoe ◽  
D. E. Tribe
Keyword(s):  
Organic Matter ◽  
Feed Intake ◽  
General Pattern ◽  
Live Weight ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Lolium Rigidum ◽  
Digestible Organic Matter ◽  
Faecal Nitrogen ◽  
Grazing Sheep

1. Recordings of faecal organic matter (O.M.), faecal N% (O.M. basis) and live weight, were made over 52 consecutive weekly periods on ten Corriedale wethers grazing a pasture consisting mainly of Wimmera rye-grass (Lolium rigidum Gaud.) with some subterranean clover (Trifolium subterraneum) in a Mediterranean-type environment. The amount of available O.M. and its N% were also recorded.2. By applying regressions of (i) the ratio of O.M. feed intake to O.M. faecal output on faecal N% and (ii) the N% in the O.M. intake on faecal N%, to the above observations it was possible to estimate the following quantities: O.M. and digestible organic matter (D.O.M.) intake, N and digestible N intake and O.M. digestibility percentage.3. The patterns of O.M. and D.O.M. intake, and N and digestible N intake are described. Similar patterns exist for each of these quantities. Two maxima, a large one in the spring and a smaller one in the autumn, and two minima, one in the summer and one in the winter, are exhibited. The values for these various maxima and minima are presented in the text.4. Attention is drawn to variations from the general pattern for these quantities and factors which could influence these patterns are mentioned.

The prediction of digestibility by rumen fluid and enzymatic methods

1996 ◽  
Vol 1996 ◽  
pp. 211-211
Author(s):  
Peter Young ◽  
F. P. O'Mara ◽  
M. Rath ◽  
P. J. Caffrey
Keyword(s):  
Organic Matter ◽  
Rumen Fluid ◽  
Organic Matter Digestibility ◽  
Enzymatic Methods

Rumen fluid and cellulase based techniques are widely used to predict the digestibility of compound feeds and their ingredients. Recently gammanase enzymes have been added to some cellulase based techniques (Dowman, 1993; De Boever et al., 1994). Few comparisons of these techniques have involved by-product concentrate ingredients. The objective of this experiment was to compare the ability of three techniques, in vitro rumen fluid (RF), pepsin cellulase gammanase (PCG), and neutral detergent cellulase gammanase (NCDG), to predict the in vivo organic matter digestibility (OMD) of concentrate ingredients.

Estimates of the energy required for maintenance by adult sheep 2. Grazing sheep

1963 ◽  
Vol 5 (1) ◽  
pp. 11-16 ◽  
Author(s):  
J. P. Langlands ◽  
J. L. Corbett ◽  
I. McDonald ◽  
G. W. Reid
Keyword(s):  
Organic Matter ◽  
Energy Cost ◽  
Functional Relationship ◽  
Adult Sheep ◽  
Maintenance Requirement ◽  
Digestible Organic Matter ◽  
Faecal Nitrogen ◽  
Grazing Period ◽  
The Mean ◽  
Maintenance Requirements

SUMMARYThe mean daily digestible organic matter intake (D) of each of 47 adult sheep during a grazing period of mean length 48 days was estimated by the chromium sesquioxide/faecal nitrogen technique. Mean live-weights (W) and mean daily weight gains (G) were also measured.The regression of D on W and G, and the underlying or functional relationship between D, W and G were both estimated. From the underlying relationship, the preferred equation, the maintenance requirement of a 100 lb. sheep at pasture is estimated to be 1·02 lb. digestible organic matter daily. This value is 24% higher than the corresponding value for housed sheep obtained previously by us.This result is compared with other estimates of the energy cost of grazing and it is concluded that further work is needed in order to define those circumstances which elevate the maintenance requirements of grazing animals.

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