Hostname: page-component-8448b6f56d-wq2xx Total loading time: 0 Render date: 2024-04-25T00:57:34.568Z Has data issue: false hasContentIssue false
  • English
  • Français

Comparison of faecal nitrogen regressions and in vitro estimates of diet digestibility for estimating the consumption of herbage by grazing animals

Published online by Cambridge University Press:  27 March 2009

G. W. Arnold  and
M. L. Dudzinski
G. W. Arnold
Affiliation:
Division of Plant Industry, Commonwealth Scientific and Industrial Research Organization, Canberra, A.C.T.
M. L. Dudzinski
Affiliation:
Division of Mathematical Statistics, Commonwealth Scientific and Industrial Research Organization, Canberra, A.C.T.
Get access Rights & Permissions [Opens in a new window]

Extract

The indirect estimation of intake of grazing animals is usually made from faecal index regression equations. Faecal nitrogen content or total faecal nitrogen are widely used to estimate intake. The most precise estimate of intake is obtained for a specific herbage (e.g. Phalaris) and condition (e.g. green, dry, etc,). Lambourne & Reardon (1963) found that the standard error of an estimate of the intake of a single animal, from a general regression equation, was 23%. Arnold & Dudzinski (1963) showed that the precision of estimates from general equations is improved by multiple regression including terms for faecal output. However, as regression relations are obtained from pen-feeding trials and are applied to field grazing, the following discrepancies axe likely to occur. We may have to extrapolate from low intakes in pens to higher intakes in the field; in addition selective grazing in the field can introduce a serious bias. To overcome the latter, when we are not sure about the exact condition of the forage eaten, as when green and dry herbage are both present, an average regression over two or more conditions has to be used. Naturally the precision of estimate then is much lower, because of the uncertainty as to what the animals are in fact selecting.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 68 , Issue 2 , April 1967 , pp. 213 - 219
Copyright
Copyright © Cambridge University Press 1967

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

Arnold, G. W. & Dudzlnski, 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.CrossRefGoogle Scholar
Arnold, G. W. & Dudzinski, M. L. (1966) The behavioural responses controlling food intake of grazing sheep. Proc. Xth Int. Orassld. Gongr., Helsinki, Finland, Sec. 2, 17–20.Google Scholar
Arnold, G. W., Mcmanus, W. R., Bush, I. G. & Ball, , Judith, (1964). The use of sheep fitted with oesophageal fistulas to measure diet quality. J. expt. Agric. Anim. Husb. 4, 71–9.CrossRefGoogle Scholar
Arnold, G. W., Ball, , Judith, , Mcmanus, W. R. & Bush, I. G. (1966). Studies on the diet of the grazing animal. I. Seasonal changes in the diet of sheep grazing on pastures of different availability and composition. Aust. J. agric. Res. 17, 543–56.CrossRefGoogle Scholar
Greenhalgh, J. F. D., Cobbbtt, J. L. & Mcdonald, I. (1960). The indirect estimation of the digestibility of pasture herbage. II. Regressions of digestibility on faecal nitrogen concentration; their determination in continuous digestibility trials and the effect of various factors on their accuracy. J. agric. Sci., Camb. 55, 377–86.CrossRefGoogle Scholar
Hutcktnson, K. J. (1958). Factors governing faecal nitrogen wastage in sheep. Aust. J. agric. Res. 9, 508–20CrossRefGoogle Scholar
Kermack, K. A. & Haidane, J. B. S. (1950). Organic correlation and allometry. Biometrika 37, 30–41.CrossRefGoogle ScholarPubMed
Lambouene, L. J. & Reardon, T. F. (1963). The use of chromium oxide and faecal nitrogen concentration to estimate the pasture intake of Merino wethers. Aust. J. agric. Res. 14, 257–71.CrossRefGoogle Scholar
Langlands, J. P., Corbett, J. L., Mcdonald, I. & Reid, G. W. (1963). Estimates of the energy required for maintenance by adult sheep. 2. Grazing sheep. Anim. Prod. 5, 11–16.Google Scholar
McManus, W. R., Dudzinski, M. L. & Arnold, G. W. (1967). Prediction of herbage intake from nitrogen, copper, magnesium and silicon concentrations in faeces. J. agric. Sci., Camb. (submitted).Google Scholar
Tilley, J. M. A., Deriaz, R. E. & Terry, R. A. (1960). The in vitro measurement of herbage digestibility and assessment of nutritive value. Proc. 8th Int. Orassld Congr. Reading, pp. 533–937.Google Scholar
Tilley, J. M. A. & Terry, R. A. (1963). A two stage technique for the in vitro digestion of forage crops. J. Br. Grassld. Soc. 18, 104–111.CrossRefGoogle Scholar
Van Dyne, G. M. & Heady, H. F. (1965). Dietary chemical composition of cattle and sheep grazing in common on a dry annual range. J. Range Mgmt. 18, 78–85.CrossRefGoogle Scholar
Van Soest, P. J. (1964). Symposium on nutrition and forage and pastures: New chemical procedures for evaluating forages. J. Anim. Sci. 23, 838–845.CrossRefGoogle Scholar