Fiber Composition and Forage Digestibility by Small Ruminants

Short, Henry L.; Blair, R.; Segelquist, Charles A.

doi:10.2307/3800724

Cited by 99 publications

(58 citation statements)

References 13 publications

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“…Grass should yield more energy from fermentation per unit forage (Codron et al 2007a), which explains why both in vivo and in vitro overall digestibility (generally measured as digestibility after fermentation times >24 h) are often found to be higher in grass than in woody browse (Wofford and Holechek 1982;Wilman and Riley 1993;Van Wieren 1996b;Hummel et al 2006). However, the evidence is equivocal, as some other references give higher digestibilities for woody browse than for grass (Short et al 1974;Blair et al 1977;Holechek et al 2004). All references agree that forbs have a comparatively high digestibility.…”

Section: Digestion/fermentation Characteristicsmentioning

confidence: 84%

“…Grass contains more fibre, and a greater proportion of this fibre is cellulose, while browse has less total but more lignified fibre (Short et al 1974;Oldemeyer et al 1977;Owen-Smith 1982;McDowell et al 1983; Cork and Foley 1991;Robbins 1993; Van Wieren 1996b;Iason and Van Wieren 1999;Holechek et al 2004;Hummel et al 2006; Codron et al 2007a). These differences are more pronounced if C4 grasses are compared to browse (Caswell et al 1973).…”

Section: Grass and Browsementioning

confidence: 99%

“…Browse is fermented at a faster rate than grass during the initial stages of fermentation (Short et al 1974;Holechek et al 2004;Hummel et al 2006). This characteristic distinction has been well established for alfalfa (higher fermentation rate; lower digestibility) and for grass (lower fermentation rate; higher digestibility; Waldo et al 1972).…”

Section: Digestion/fermentation Characteristicsmentioning

confidence: 99%

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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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Section: Digestion/fermentation Characteristicsmentioning

confidence: 84%

Section: Grass and Browsementioning

confidence: 99%

Section: Digestion/fermentation Characteristicsmentioning

confidence: 99%

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The Morphophysiological Adaptations of Browsing and Grazing Mammals

2008

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“…Also, as the proportion of soluble carbohydrates declines with maturity in grasses, the relative content of hard-to-digest structural carbohydrates (i.e. cellulose and hemicellulose) increases, thereby reducing overall dry matter digestibility (Short et al, 1974;Ballard et al, 1990).…”

Section: Discussionmentioning

confidence: 99%

“…However, during dry seasons fresh plant growth is quickly eaten out and mature, fibrous grasses predominate (Bailey et al, 1971;Barker, 1987). Increasing fibre content is a major factor reducing the digestibility of most grasses (Burton et al, 1964;Terry and Tilley, 1964;Short et al, 1974;Ballard et al, 1990). During dry seasons, fibrous grasses provide up to 90% of the adult red kangaroo diet (Dawson and Ellis, 1994), though the extent to which smaller, juvenile red kangaroos can utilise fibrous forage is uncertain.…”

Section: Introductionmentioning

confidence: 99%

Forage fibre digestion, rates of feed passage and gut fill in juvenile and adult red kangaroosMacropus rufusDesmarest: why body size matters

Munn

Dawson

2006

Journal of Experimental Biology

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SUMMARY Using red kangaroos Macropus rufus Desmarest, a large (>20 kg)marsupial herbivore, we compared the digestive capabilities of juveniles with those of mature, non-lactating females on high-quality forage (chopped lucerne Medicago sativa hay) of 43±1% neutral-detergent fibre (NDF)and poorer quality, high-fibre forage (chopped oaten Avena sativahay) of 64±1% NDF. On chopped lucerne apparent dry matter (DM)digestibilities by young-at-foot (YAF) red kangaroos (an age that would normally be taking some milk from their mother), weaned juveniles and mature females were similar (55–59%). On chopped oaten hay apparent DM digestibility was lower in the YAF (35.9±2.3%) followed by weaned(43.4±2.8%) and mature females (44.6±1%). The digestion of NDF and its components (mainly cellulose and hemicellulose) was lowest among the YAF followed by weaned and then mature females. The YAF and weaned kangaroos could not sustain growth on the poor-quality diet, and appeared to be at or near maximal gut fill on both forages; the values being 114–122 g DM for YAF and 151–159 g DM for weaned kangaroos. Mean retention times (MRT) of particle and solute markers were significantly longer for the YAF and weaned kangaroos on oaten hay than on lucerne hay, and DM intake (g d–1) was ∼50% lower on the oaten hay. In contrast, solute and particle MRTs in the mature females were not significantly affected by diet; they maintained DM intakes by increasing DM gut fill from 264±24 g on chopped lucerne to 427±26 g DM on chopped oaten hay. Clearly, the mature female kangaroos did not maximise gut fill on the high-quality forage,presumably as a consequence of their proportionally lower energy requirements compared with still-growing juveniles. Overall, we have provided the first mechanistic link between the physiological constraints faced by juvenile red kangaroos in relation to their drought-related mortalities, rainfall and forage quality.

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The burden of size and growth for the juveniles of large mammalian herbivores: Structural and functional constraints in the feeding biology of juveniles relative to adults in red kangaroos, Osphranter rufus

Dawson

Norton

Rodoreda

et al. 2021

Ecology and Evolution

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Juvenile mammals in their postweaning developmental stages face many challenges in transitioning to adulthood. Among large grazing species such as ruminant bovids and cervids, an overarching challenge is acquiring and processing sufficient nutrients to survive and grow, with a gut that may not yet be fully developed. Marsupial kangaroos of Australia face similar challenges; they also digest vegetation by fermentation in a large foregut. In red kangaroos, Osphranter rufus (= Macropus rufus ), the dominant species of Australia's arid interior, females may breed continuously; however, juvenile recruitment to the adult population is irregular and coincident with sporadic rainfall. As compared with adult females, the nutritional requirements of juvenile O. rufus are high in relation to their body mass (BM), largely due to the cost of their rapid growth. We examined processes that juveniles have in their morphology, physiology, and behaviors to meet their elevated nutritional needs, by comparing recently weaned juveniles of both sexes and adult female O. rufus in their desert habitat. Features studied include relative body sizes, relative dimensions, and capacities of principal gut regions, the foregut, small intestine, caecum, and large intestine with rectum. Also examined were digesta attributes and rates of digesta excretion. Additionally, the rates of change in skull parameters and dental characteristics to maturity were assessed. Field determinations of diet choice were made for both age classes. In juveniles, the content masses of major gut structures were related to body mass (BM), as were those of adult females, that is, ~BM 1.0 . In both age classes, the digesta mass of the foreguts exceeded 75% of the total digesta mass. Diets of both juvenile and adult O. rufus largely focused on grasses. Juveniles had higher rates of digesta excretion while foraging than adults. In addition, the foregut contents in juveniles occupy proportionally less of the total gut than in adult females. Together, the higher excretion rate and smaller relative foregut of juveniles suggest that they necessarily focus on forage that can be rapidly digested, such as young, green grasses, or herbage. Comparison of the skulls of juveniles and adults revealed how this harvest can occur. Relative to BM, juveniles had skulls of larger volume than adults. Additionally, during growth the skull lengthens proportionally faster than increasing BM. By weaning, the dimensions of the incisor bite of juveniles neared those of adult females. The area of wear on premolars/molars increased only slowly relative to the development of incisors, further pointing to juveniles selecting more digestible forage than adults. The intermittent availability of such forage, pr...

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Fiber Composition and Forage Digestibility by Small Ruminants

Cited by 99 publications

References 13 publications

The Morphophysiological Adaptations of Browsing and Grazing Mammals

The Morphophysiological Adaptations of Browsing and Grazing Mammals

Forage fibre digestion, rates of feed passage and gut fill in juvenile and adult red kangaroosMacropus rufusDesmarest: why body size matters

The burden of size and growth for the juveniles of large mammalian herbivores: Structural and functional constraints in the feeding biology of juveniles relative to adults in red kangaroos, Osphranter rufus

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