The Role of Diet Quality and Energy Need in the Nutritional Ecology of a Small Herbivore, Microtus ochrogaster

Hammond, Kimberly A.; Wunder, Bruce A.

doi:10.1086/physzool.64.2.30158190

Cited by 124 publications

(104 citation statements)

References 19 publications

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“…Gut plasticity in herbivorous mammals has often been associated with dietary fiber content (Gross et al 1985;Hammond and Wunder 1991), but our data indicate that phenotypic plasticity of the wallaby hindgut can be dissociated from these hardto-digest fractions. Teasing apart the functional and mechanistic basis for this plasticity is difficult, and our data are relevant for understanding that some animals increase gut capacity when diet quality is unchanged, such as when increased energy demands drive higher food intakes under cold acclimation (e.g., Gross et al 1985;Hammond and Wunder 1991) or during lactation (e.g., Hammond and Diamond 1992;Derting 1996;Hammond and Kristan 2000).…”

Section: Discussionmentioning

confidence: 63%

“…Teasing apart the functional and mechanistic basis for this plasticity is difficult, and our data are relevant for understanding that some animals increase gut capacity when diet quality is unchanged, such as when increased energy demands drive higher food intakes under cold acclimation (e.g., Gross et al 1985;Hammond and Wunder 1991) or during lactation (e.g., Hammond and Diamond 1992;Derting 1996;Hammond and Kristan 2000). Presumably, increasing gut capacity under these circumstances helps to accommodate increased food intakes while maintaining MRTs to maintain digestive efficiency and digestible intake (Hammond and Wunder 1991;Hume 2005).…”

Section: Discussionmentioning

confidence: 96%

“…It is difficult to interpret the functional (adaptive) significance of the hindgut plasticity that we observed in pellet-fed wallabies. In other herbivores, low-quality foods apparently induce compensatory increases in gut size (Gross et al 1985;Hammond and Wunder 1991), helping to maintain digestible intakes. However, lower-quality (high-fiber) diets are normally associated with larger, not smaller, ingesta particle sizes, at least in ruminants (Grenet 1989;van Bruchem et al1991) and swine (Robertson et al 1992).…”

Section: Discussionmentioning

confidence: 99%

“…Remarkable plasticity of the gut has been observed in a wide variety of vertebrate species, including carnivores (e.g., Secor and Diamond 1998;Starck and Beese 2001;Starck 2005), omnivores (e.g., Derting 1996;Karasov and McWilliams 2005), and herbivores (e.g., Gross et al 1985;Hammond and Wunder 1991) and under a range of circumstances, including long-distance migrations in birds (e.g., Piersma et al 1999;Karasov et al 2004), diet switching in birds (e.g. , Starck 1999a;van Gils et al 2003) and mammals (e.g., Gross et al 1985;Hammond and Wunder 1991), and after arousal from hibernation (e.g., Hume et al 2002;see also Carey 2005). In mammals at least, the gut is arguably the most energetically expensive organ system to maintain, contributing disproportionately to basal metabolism and whole-body protein turnover (Stevens and Hume 1995).…”

Section: Hindgut Plasticity In Wallabies Fed Hay Either Unchopped or mentioning

confidence: 99%

“…Among mammals, gut plasticity has been extensively studied in small herbivorous rodents, which increase gut size in response to low-quality diets or when faced with thermal challenges that drive increased food intakes (e.g., Gross et al 1985;Hammond and Wunder 1991). For herbivorous mammals, diet quality is typically related to the level of lignified cellulose and hemicellulose in plant cell walls (fiber; Robbins 1993); that is, the higher the fiber content, the lower the quality.…”

Section: Hindgut Plasticity In Wallabies Fed Hay Either Unchopped or mentioning

confidence: 99%

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Hindgut Plasticity in Wallabies Fed Hay either Unchopped or Ground and Pelleted: Fiber Is Not the Only Factor

Munn

Clissold²,

Tarszisz³

et al. 2009

Physiological and Biochemical Zoology

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Phenotypic plasticity of the gastrointestinal tract is crucial for optimal food processing and nutrient balance in many vertebrate species. For mammalian herbivores, gut plasticity is typically correlated with the fiber content of forage; however, we show here that other factors such as ingesta particle size may effect profound phenotypic plasticity of the fermentative hind-gut in a medium-sized (10-kg body mass) marsupial herbivore, the red-necked wallaby (Macropus rufogriseus). When dietary fiber contents were comparable, red-necked wallabies that were fed a finely ground, pelleted hay for 60-72 d had hindguts that were some 28% heavier (empty wet mass) than those fed unchopped hay. The hindguts of pellet-fed wallabies contained more wet ingesta, which was also of a finer particle size, than those fed hay, indicating some separation of large-and small-particle fermentation between the foregut and the hindgut, respectively. Such a digestive strategy would benefit animals by allowing fermentation of a range of ingesta particle sizes that are expected for free-ranging animals faced with a spectrum of diet types and qualities. The heavier hindgut of pellet-fed wallabies was correlated with increased concentrations of short-chain fatty acids (SCFAs) in the fermentative hindgut (cecum and proximal colon) and particularly with increases in the molar proportions of n-butyric acid. The mechanisms facilitating gut plasticity in herbivorous mammals are uncertain, but we suggest that manipulating ingesta particle size rather than dietary fiber could provide a useful tool for evaluating causal explanations. In particular, altering ingesta particle size could help to distinguish possible direct processes (e.g., the favoring of smaller intestinal microbes and production of specific SCFAs) from indirect affects of feed structure (e.g., muscular hypertrophy to compensate for increased intakes and digesta bulk or the fermentation of mucus secreted to promote the flow of viscous, fine-particle material). ABSTRACT Phenotypic plasticity of the gastrointestinal tract is crucial for optimal food processing and nutrient balance in many vertebrate species. For mammalian herbivores, gut plasticity is typically correlated with the fiber content of forage; however, we show here that other factors such as ingesta particle size may effect profound phenotypic plasticity of the fermentative hindgut in a medium-sized (10-kg body mass) marsupial herbivore, the red-necked wallaby (Macropus rufogriseus). When dietary fiber contents were comparable, red-necked wallabies that were fed a finely ground, pelleted hay for 60-72 d had hindguts that were some 28% heavier (empty wet mass) than those fed unchopped hay. The hindguts of pellet-fed wallabies contained more wet ingesta, which was also of a finer particle size, than those fed hay, indicating some separation of large-and smallparticle fermentation between the foregut and the hindgut, respectively. Such a digestive strategy would benefit animals by allowing fermentation of a range of in...

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Section: Discussionmentioning

confidence: 63%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Section: Hindgut Plasticity In Wallabies Fed Hay Either Unchopped or mentioning

confidence: 99%

Section: Hindgut Plasticity In Wallabies Fed Hay Either Unchopped or mentioning

confidence: 99%

See 3 more Smart Citations

Hindgut Plasticity in Wallabies Fed Hay either Unchopped or Ground and Pelleted: Fiber Is Not the Only Factor

Munn

Clissold²,

Tarszisz³

et al. 2009

Physiological and Biochemical Zoology

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Vertebrate Gastrointestinal System

Karasov

Hume

1997

Comprehensive Physiology

107

137

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Energy acquisition and allocation in Peromyscus maniculatus exposed to aldicarb and cool temperatures

French

Porter

1994

Enviro Toxic and Chemistry

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We hypothesized an energetic effect of the pesticide Aldicarb (an acetylcholinesterase inhibitor) through its action on gut innervation, and hence digestive efficiency, and tested this in deer mice (Peromyscus mamculatus Rafinesque) exposed to both the pesticide and cold temperature. Growing deer mice were exposed to Aldicarb in their drinking water at concentrations of 0, 10, and 10,000 ppb and housed at 11 and 23°C. There were no changes due to Aldicarb in several measures of physiological energetics, including energy intake (food consumption, digestive efficiency, gut size) or in the allocation of energy to growth or activity. Two of eight measures of gut size (length and weight of the large intestine) increased significantly with exposure to Aldicarb at the high concentration. Also, there was significant interaction effect of exposure to Aldicarb and cool temperatures on the ratio of mucosal to serosal mass in the small intestine, such that mucosal mass increased when mice were exposed to low doses of Aldicarb at low temperatures but not under other conditions. Although increased absorptive area of the gut (i.e., size or mucosal mass) can be a compensatory response to energy shortfalls, there was no indication of that cause in Aldicarb‐exposed mice. Cold‐temperature treatment did increase energy costs, however, and both food consumption and gut size increased in mice housed at 11°C, so that digestive efficiency and allocation to growth and activity were no different from those of mice housed at warmer temperatures. Thus, Aldicarb is unlikely to produce any chronic effects on these mice in the wild through disruption of digestion or other causes of energetic shortfall.

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The Role of Diet Quality and Energy Need in the Nutritional Ecology of a Small Herbivore, Microtus ochrogaster

Cited by 124 publications

References 19 publications

Hindgut Plasticity in Wallabies Fed Hay either Unchopped or Ground and Pelleted: Fiber Is Not the Only Factor

Hindgut Plasticity in Wallabies Fed Hay either Unchopped or Ground and Pelleted: Fiber Is Not the Only Factor

Vertebrate Gastrointestinal System

Energy acquisition and allocation in Peromyscus maniculatus exposed to aldicarb and cool temperatures

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