Hostname: page-component-78c5997874-m6dg7 Total loading time: 0 Render date: 2024-11-05T08:56:50.468Z Has data issue: false hasContentIssue false
  • English
  • Français

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

Published online by Cambridge University Press:  02 September 2010

H. A. Birrell
H. A. Birrell
Affiliation:
Department of Agriculture, Victoria, Pastoral Research Institute, Hamilton, Victoria 3300, Australia
Get access

Abstract

In 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.

Type
Research Article
Information
Animal Production , Volume 31 , Issue 1 , August 1980 , pp. 57 - 62
Copyright
Copyright © British Society of Animal Science 1980

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Allden, W. G. 1962. Rate of herbage intake and grazing time in relation to herbage availability. Proc. Aust. Soc. Anim. Prod. 4: 163–166.Google Scholar
Arnold, G. W. 1960. Harness for the total collection of faeces from grazing ewes and wether sheep. Anim. Prod. 2: 169–173.Google Scholar
Arnold, G. W. and Birrell, H. A. 1977. Food intake and grazing behaviour of sheep varying in body condition. Anim. Prod. 24: 343–353.Google Scholar
Arnold, G. W. and Dudzinski, M. L. 1963. The use of faecal nitrogen as an index for estimating the consumption of herbage by grazing animals. J. agric. Sci., Camb. 61: 33–43.Google Scholar
Birrell, H. A. 1979. Aspects of pasture utilization by the grazing animal. M.Sc. Thesis, Univ. Melbourne.Google Scholar
Hamilton, B. A., Hutchinson, K. J., Annis, P. C. and Donnelly, J. B. 1973. Relationships between the diet selected by grazing sheep and the herbage on offer. Aust. J. agric. Res. 24: 271–277.Google Scholar
Hume, I. D. and Purser, D. B. 1974. Duodenal flow of dietary and microbial nitrogen in sheep fed subterranean clover harvested at four stages of maturity. Proc. Aust. Soc. Anim. Prod. 10: 399.Google Scholar
Langlands, J. P. 1967. Studies on the nutritive value of the diet selected by grazing sheep. II. Some sources of error when sampling oesophageally fistulated sheep at pasture. Anim. Prod. 9: 167–175.Google Scholar
Langlands, J. P. 1969. 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. Anim. Prod. 11: 379–387.Google Scholar
Langlands, J. P. 1975. Techniques for estimating nutrient intake and its utilization by the grazing ruminant. In Digestion and Metabolism in the Ruminant (ed. McDonald, I. W. and Warner, A. C. I.), pp. 320–333. University of New England Publishing Unit, Armidale.Google Scholar
Newman, D. M. 1972. A modified procedure for large scale pasture evaluation by digestibility in vitro. J. Aust. Inst. agric. Sci. 38: 212–213.Google Scholar
Tilley, J. M. A. and Terry, R. A. 1963. A two-stage technique for the in vitro digestion of forage crops. J. Br. Grassld Soc. 18: 104–111.Google Scholar
Walker, D. J., Egan, A. R., Nader, C. J., Ulyatt, M. J. and Storer, G. B. 1975. Rumen microbial protein synthesis and proportions of microbial and non-microbial nitrogen flowing to the intestines of sheep. Aust. J. agric. Res. 26: 699–708.CrossRefGoogle Scholar
Young, B. A. and Corbett, J. L. 1972. Maintenance energy requirement of grazing sheep in relation to herbage availability. II. Observations on grazing intake. Aust. J. agric. Res. 23: 77–85.CrossRefGoogle Scholar