Hostname: page-component-cd9895bd7-mkpzs Total loading time: 0 Render date: 2024-12-27T19:15:34.079Z Has data issue: false hasContentIssue false
  • English
  • Français

Rumen degradation of straw 4. Selection and degradation of morphological components of barley straw by sheep

Published online by Cambridge University Press:  02 September 2010

P. K. Bhargava ,
E. R. Ørskov  and
T. K. Walli
P. K. Bhargava
Affiliation:
Rowett Research Institute, Bucksburn, Aberdeen AB2 9SB
E. R. Ørskov
Affiliation:
Rowett Research Institute, Bucksburn, Aberdeen AB2 9SB
T. K. Walli
Affiliation:
Rowett Research Institute, Bucksburn, Aberdeen AB2 9SB
Get access

Abstract

Experiments were made to study the proportion, chemical composition, and rumen degradability of the morphological components of barley straw (Corgi variety) and to study the selection of these components by sheep. The proportions in the harvested straw dry matter (DM) as leaf blade, leaf sheath, stem and chaff were 128, 314, 500 and 58 g/kg DM, respectively. The different components of straw on analysis proved to have very different concentrations of nitrogen and neutral-detergent cellulase digestibility. The leaf blades had the highest and the stems the lowest values. The degradabilities of DM in the components and in the whole straw were determined by measuring DM loss from samples incubated in nylon bags for various periods in the rumen of sheep. Responses were measured using the mathematical model p = a+b (1–e−ct) where p is DM loss, (a+b) potential degradability, c the rate constant of DM loss and t is the time of incubation. DM losses decreased in the order leaf blades > leaf sheath > whole plant > chaff > stems. Leaf blades also had the highest potential degradability and rate of degradation.

In another trial, five sheep were offered unchopped barley straw ad libitum. There were five treatment periods in which sheep were allowed to leave uneaten proportionately 0·2, 0·3, 0·4, 0·5 and 0·7 of the straw on offer for assessing the animal's selection of the morphological components of that straw. The amount of leaf blade in the material consumed increased in largely a linear (P < 0·01) fashion with the amount of excess allowance. The proportion of stem eaten varied conversely. The selection of leaf sheath was less apparent. Little stem was consumed until the proportion of leaf blade in the food available decreased below proportionately 0·4. The practical significance of the study is discussed.

Type
Research Article
Information
Animal Production , Volume 47 , Issue 1 , August 1988 , pp. 105 - 110
Copyright
Copyright © British Society of Animal Science 1988

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

Atchison, J. E. 1976. Agricultural residues and other nonwood plant fibers. Science 191: 768–772.CrossRefGoogle ScholarPubMed
Davidson, J., Mathieson, J. and Boyne, A. W. 1970. The use of automation in determining nitrogen by the Kjeldahl method, with final calculations by computer. The Analyst, London 95: 181–193.CrossRefGoogle ScholarPubMed
Dowman, M. G. and Collins, F. C. 1982. The use of enzymes to predict the digestibility of animal feeds. Journal of the Science of Food and Agriculture 33: 689–696.CrossRefGoogle Scholar
Mehrez, A. Z. and Ørskov, E. R. 1977. A study of the artificial fibre bag technique for determining the digestibility of feeds in the rumen. Journal of Agricultural Science, Cambridge 8: 645–650.CrossRefGoogle Scholar
Ministry of Agriculture, Fisheries and Food. 1986. Feed composition. UK Tables of Feed Composition and Nutritive Value for Ruminants. Chalcombe Publications, Marlow.Google Scholar
Ørskov, E. R. 1985. Cereals and the road to a rational agriculture. New Scientist 108: September 12. 35–37.Google Scholar
Ørskov, E. R. and McDonald, I. 1979. The estimation of protein degradability in the rumen from incubation measurements weighted according to rate of passage. Journal of Agricultural Science, Cambridge 92: 499–503.CrossRefGoogle Scholar
Ramanzin, M., Ørskov, E. R. and Tuah, A. K. 1986. Rumen degradation of straw. 2. Botanical fractions of straw from two barley cultivars. Animal Production 43: 271–278.Google Scholar
Rexen, F. and Munck, L. 1984. Cereal crops for industrial use in Europe. European Economic Community Publication EUR96I7EU.Google Scholar
Shand, W., Shehata, O., Ørskov, E. R. and Morrice, A. F. 1987. Studies on botanical proportions and nutritive value of varieties of cereal straws and the ability of sheep to select the botanical part with the greatest value. Animal Production 44: 480–481 (Abstr.).Google Scholar
Snedecor, G. W. and Cochran, W. G. 1976. Statistical Methods. 7th ed. Iowa State University Press, Ames, la.Google Scholar
Wahed, R. A. and Owen, E. 1986. Comparison of sheep and goats under stall-feeding conditions: roughage intake and selection. Animal Production 42: 89–95.Google Scholar
Zimmelink, G. 1980. Effect of selective consumption on voluntary intake and digestibility of tropical forages. Agricultural Research Report 896, Wageningen.Google Scholar