Voluntary consumption of forage by sheep and its relation to the size and shape of particles in the digestive tract

Troelsen, J. E.; Campbell, J. B.

doi:10.1017/s0003356100026295

Cited by 70 publications

(40 citation statements)

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“…Differences in fracture patterns of grass and browse have been noted (Spalinger et al 1986;Kay 1993;Van Wieren 1996a). Several authors have reported more polygonal particles from herbaceous forage leaves and more longish particles from grass leaves (Troelsen and Campbell 1968;Moseley and Jones 1984;Mtengeti et al 1995). Although empirical studies are lacking, browse is thought to be a more heterogeneous material with different levels of tissue thicknesses and of resistance to breakage, whereas grass is considered more homogenous in this respect.…”

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The Morphophysiological Adaptations of Browsing and Grazing Mammals

2008

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(2008). The morphophysiological adaptations of browsing and grazing mammals. In: Gordon, I J [et al.]. The ecology of browsing and grazing. Berlin, 47-88. Postprint available at: http://www.zora.uzh.ch Posted at the Zurich Open Repository and Archive, University of Zurich. http://www.zora.uzh.ch Originally published at: Gordon, I J [et al.] 2008. The ecology of browsing and grazing. Berlin, 47-88. The morphophysiological adaptations of browsing and grazing mammals AbstractThere has been a continous debate whether there are fundametal morphophysiological differences in the ingestive apparatus (head, teeth) and the digestive tract between browsing and grazing herbivores. A particular characteristic of this debate appears to be that while there is a wealth of publications on such potential differences, the supposed undelying differences between browse and grass have rarely been analysed quantitatively. In this chapter, we first review the actual state of knowledge on those properties of browse and grass that appear relevant for the ingestive and digestive process, and then deduct hypotheses as to how one would assume that browsers and grazers differ due to these characteristics. We address the methodological issues involved in actually testing these hypotheses, with emphasis on the influence of body mass and phylogenetic descent. Finally, we present a literature compilation of statistical tests of differences between the feeding-types. Although in general, the published tests support many hypothesized differences, there is still both a lack of comparative data, and a lack of analyses with phylogenetic control, on different taxonomic levels. However, the published material appears to indicate that convergent evolutionary adaptations of browsing and grazing herbivores to their diet represent a rewarding area of research. The Morphophysiological Adaptations of Browsing and Grazing MammalsMarcus Clauss, Thomas Kaiser, and Jürgen Hummel IntroductionAnimals represent adaptations to particular ecological niches they occupy or once occupied.Studying the correlation between a given set of characteristics of an ecological niche and the morphological and physiological adaptations of organisms to these characteristics is one of the most basic approaches to comparative biology, and has fuelled scientific interest for generations (Gould 2002). However, current scientific standards cannot be met by mere descriptions of both the characteristics of the niche and the organism, and a (hypothetical) intuitive explanation for the adaptive relevance of the latter; the presence or absence of a characteristic must be demonstrated in sound statistical terms (Hagen 2003) 1 ideally supported by experimental data (from in vivo, in vitro, or model assays) on its adaptive relevance.In this chapter, we adopt an approach that first presents the relevant characteristics of the ecological niche of the 'grazer' (GR) and of the 'browser' (BR), outlines hypotheses based on these characteristics, and finally addresses examples where such hypotheses h...

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The Morphophysiological Adaptations of Browsing and Grazing Mammals

2008

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“…Since then a number of other workers have added to this basic information (e.g. Magee, 1932;Balch, 1949Balch, , 1958Balch & Kelly, 1950;Nichols, 1959;Campling & Freer, 1962;Welch, 1965;Pearce, 1967;Troelsen & Campbell, 1968).The rate of passage of digesta through the reticulo-rumen and the rate of breakdown of digesta in that organ are important determinants of the efficiency of digestion and of the rate of rumen emptying (Balch, 1950). Both rate of passage and rate of breakdown appear to be markedly influenced by the physical characteristics of the digesta.…”

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Changes in some physical characteristics of the digesta in the reticulo-rumen of cows fed once daily

Evans¹,

Pearce²,

Burnett³

et al. 1973

Br J Nutr

118

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I . Three cows were given 3, 5 or 7 kg hay once daily in a Latin-square design, and samples of digesta from four sites in the rumen and onc site in the reticulum were taken at six times within the 24 h period after the feed. Dry-matter content and distribution of particle size and of particle density were measured for each sample. The changcs in thcse mcasurements with time were studied, The incidence of rumination was also recorded.2. Dry-matter contents of samples ranged from 15 to 3 yo. Valucs for samples from the dorsal sacs of the rumen were considerahly higher than those for samples from the ventral sites; they also changed more with time after feeding and with level of feeding.3. Particlcs were fractionated by sieving into six size groups with mcan dimensions (mm) of 9.3 x 0.8, 4.4 x 0.6, 2.6 x 0 . 3 , 1.6 x o'zj, 0.5 x 0.1 and smaller than 0.5 x 0.1. Coarse particles occurred at highest concentrations in the dorsal sacs of the rumen and responded to effects of time and level of feeding; smaller particles showed less response. 4.. Particle densities ranged from 800 g/l to 1500 gil. The proportions of low-density particles were higher in samples from thc dorsal sacs of the rumen than in samples from ventral sites ; the latter samples had higher proportions of high-density particles than of low-density particles. The changes which occurred are discussed. .The density of coarse particles tended to he low and that of fine particles tcnded to be high.6. Rumination started at the time of maximum Concentration of particles of low density and minimum concentration of particles of high density. Conversely, rumination ended when the concentration of the low-density particles was a minimum and that of thc dense particles a maximum.7. The rcsults are discussed in relation to the possible movement of particles within the reticulo-rumen and the kinetics of particle breakdown.Schalk 8i Amadon (1928) described in some detail the structure of the reticulorumen, made observations on its functioning and referred to some of the physical characteristics of its contents for animals given different types of ration. Since then a number of other workers have added to this basic information (e.g. Magee, 1932;Balch, 1949Balch, , 1958Balch & Kelly, 1950;Nichols, 1959;Campling & Freer, 1962;Welch, 1965;Pearce, 1967;Troelsen & Campbell, 1968).The rate of passage of digesta through the reticulo-rumen and the rate of breakdown of digesta in that organ are important determinants of the efficiency of digestion and of the rate of rumen emptying (Balch, 1950). Both rate of passage and rate of breakdown appear to be markedly influenced by the physical characteristics of the digesta. Knowledge of the factors influencing the physical characteristics will be useful in understanding the effects of practices such as grinding, pelleting and wafering of roughages, the ' protection' of nutrients from digestion in the rumen, the granulation of trace minerals and the capsulation of drugs, medicinal compounds and inert fillers.

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“…The consumption of coarse roughage (Troelsen and campbell, 1968) is directly affected by its rate of physical breakdown dtning mastication and its rate of passage through the reticulo-omasal opening (Balch and Campling, 1965;Troelsen and Bigsby, 1964;Troelsen et al, l97O (Blaxter and wilson, 1962;Greenhalgh and Runcie, 1962;corbett et aI., 1963 …”

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“…"Coarse roughage" was defined by Troelsen and Campbell (1968) as forage of a quality and texture which will render its rate of passage and voluntary consumption by ruminants dependent on its rate of breakdown by mastication and fermentation in the reticulo-rumen. According to Blaxter (1950), it will be eaten by cattle and sheep at a rate directly proportionali to its concentration of digestible nutrients.…”

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CONSUMPTION OF DIGESTIBLE ENERGY BY SHEEP AS PREDICTED FROM THE CONCENTRATION OF IN VITRO DIGESTIBLE ENERGY, CELL-WALL CONSTITUENTS, AND CRUDE FIBER IN COARSE ROUGHAGE

Troelsen¹

1971

Can. J. Anim. Sci.

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Six forage species were harvested at four to similar concentrations of digestible energy seven maturity stages annually for four years and cell-wall fiber. The (Blaxter et al.,196I;Conrad et al., 1964; Troelsen and Beacom, 1970). Thus, the concentration of digestible nutrients may be regarded as an important measure of the feeding value of coarse roughage and other forage. However, the feeding value of coarse roughage for ruminants depends partially on its rate of physical breakdown (Troelsen and Bigsby, 1964), which regulates the rate of passage and ths Ermounts voluntarily eaten (Balch and Campling, 1965; Can.

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Voluntary consumption of forage by sheep and its relation to the size and shape of particles in the digestive tract

Abstract: Link to this article: http://journals.cambridge.org/abstract_S0003356100026295 How to cite this article: J. E. Troelsen and J. B. Campbell (1968). Voluntary consumption of forage by sheep and its relation to the size and shape of particles in the digestive tract.

Cited by 70 publications

References 5 publications

The Morphophysiological Adaptations of Browsing and Grazing Mammals

The Morphophysiological Adaptations of Browsing and Grazing Mammals

Changes in some physical characteristics of the digesta in the reticulo-rumen of cows fed once daily

CONSUMPTION OF DIGESTIBLE ENERGY BY SHEEP AS PREDICTED FROM THE CONCENTRATION OF IN VITRO DIGESTIBLE ENERGY, CELL-WALL CONSTITUENTS, AND CRUDE FIBER IN COARSE ROUGHAGE

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