Assessment of Animal-Based Methods Used for Estimating and Monitoring Rangeland Herbivore Diet Composition

Garnick, Sarah; Barboza, Perry S.; Walker, John W.

doi:10.1016/j.rama.2018.03.003

Cited by 60 publications

(55 citation statements)

References 67 publications

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“…Diet's dry matter digestibility was estimated for each grassland phenological stage through the botanical composition of the diet, which was estimated by the fecal microhistology procedure [37,38]. This technique is based on identifying vegetation epidermis fragments in the feces, which were then compared with the epidermis patterns previously obtained from the identified plant species collected in the study area [39][40][41].…”

Section: Diet's Dry Matter Digestibility (Dms Diet %)mentioning

confidence: 99%

Use of Fecal Indices as a Non-Invasive Tool for Nutritional Evaluation in Extensive-Grazing Sheep

Orellana

Parraguez

Arana

et al. 2019

Animals

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The aim of the present study was to assess the reliability of fecal indices as predictors of nutrient intake in sheep under extensive grazing conditions. Fecal concentrations of 2,6-diaminopimelic acid (DAPAf), nitrogen (FN) and phosphorous (FP) were determined in four sheep kept in an extensive grazing system on annual Mediterranean grassland in the vegetative, reproductive and dry phenological stages. Metabolizable energy (MEI), crude protein (CPI) and phosphorus (PI) intake were calculated using the botanical composition, metabolizable energy, crude protein and phosphorus concentrations in each vegetal species making up the animal’s diet. Significant differences were observed in the nutrient intake for each phenological stage (p < 0.0001). The highest MEI, CPI and PI were observed during the vegetative stage (p < 0.0001). FN and FP were different in each phenological stage (p < 0.0001), with significant correlations observed between these variables (r = 0.916; p < 0.0001). Regressions among nutrient intake and fecal indices were significant, except in the cases of DAPAf and MEI, and DAPAf and CPI. Based on these results, fecal indices could be used to estimate nutrient intake in sheep under extensive grazing on annual Mediterranean grassland.

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Section: Diet's Dry Matter Digestibility (Dms Diet %)mentioning

confidence: 99%

Use of Fecal Indices as a Non-Invasive Tool for Nutritional Evaluation in Extensive-Grazing Sheep

Orellana

Parraguez

Arana

et al. 2019

Animals

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“…Our solution was to extract cores around actual grazing targets of individual fish. Cores were analysed using microhistology (Garnick et al 2018), enabling prey items to be identified and quantified. Prey assemblages could then be compared to previous studies cataloging temporal changes in epilithic and endolithic coral reef successional communities (e.g.…”

Section: Introductionmentioning

confidence: 99%

Resolving resource partitioning in parrotfishes (Scarini) using microhistology of feeding substrata

Nicholson

Clements

2020

Coral Reefs

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Parrotfishes (Scarini) are considered key agents in coral reef health and recovery, but the drivers of parrotfish-coral dynamics remain contentious. The prevailing view of parrotfishes as ecosystem engineers is based on the perceived removal of algal turf, macroalgae and sediment, but these are effects of feeding, not causes. The recent proposal that most parrotfishes are 'microphages' that target microscopic photoautotrophs (particularly cyanobacteria) identifies the need to resolve dietary targets at a microscopic scale. Here, we investigate parrotfish dietary targets by posing the following two questions: (1) are microscopic photoautotrophs the most consistent and dominant elements of the prey community, and (2) do the prey community and substratum taphonomy vary between parrotfish species? In order to identify and quantify dietary targets, five parrotfish species were followed until focused feeding was observed at Lizard Island on the Great Barrier Reef, Australia. Feeding sites were photographed in situ and extracted as substratum bite cores. Cores were analysed microscopically to identify and quantify all epilithic photoautotrophs. Endolithic photoautotrophs accessible to excavating parrotfish were also investigated by vacuumembedding cores with epoxy resin followed by decalcification to expose endolith microborings. The dominant functional groups of epilithic biota on the cores were tufted cyanobacteria, turfing algae and crustose coralline algae (CCA). The only consistent feature across all cores was the high density of filamentous cyanobacteria, supporting the view that these parrotfishes target microphotoautotrophs. Macroalgae was absent or a minor component on cores, supporting the hypothesis that parrotfishes avoid larger algae. The microchlorophyte Ostreobium was the dominant photoautotrophic euendolith (true borer) in the cores of the excavating parrotfish Chlorurus microrhinos. Significant differences in CCA coverage, turf height and substrate taphonomy were found among the five parrotfish species, suggesting that interspecific resource partitioning is based on successional stage of feeding substrata.

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“…Inspiration can be drawn from primate (Felton et al, 2009;Johnson et al, 2013) and ungulate (McShea and Schwede, 1993;Parker et al, 1996) research where the ability to habituate wild individuals to the presence of researchers provides the opportunity to determine detailed dietary intake from free-ranging animals. In addition, there are emerging opportunities for researchers to quantify intake of food through observations of animalborne video (Hays, 2015;Garnick et al, 2018) that could be coupled with remote sensors that detect forage species and Physiologically based models for herbivores phytochemical concentrations (Stolter et al, 2006;Yule et al, 2015;Lim et al, 2017) as well as environmental conditions (Faye et al, 2016;Cristóbal et al, 2018) at the same spatial and temporal scales. The next challenge is to then develop mechanistic models that can accommodate known concentrations of phytochemicals in body compartments (PBMs), and resulting fitness consequences (GF), as well as genetic and metagenomic data (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…We suggest that coupling the manipulation of phytochemicals with the manipulation of host and microboime function would allow researchers to test model-predicted changes in a number of physiological and demographic parameters. Researchers could observe changes in intake of food of known phytochemistry through direct observations (McShea and Schwede, 1993;Parker et al, 1996;Felton et al, 2009;Johnson et al, 2013) or animal-borne video (Hays, 2015;Garnick et al, 2018). Fecal collections can be used to monitor changes in microbial communities from metagenomic studies and phytochemical exposure in the gut from metabolomic studies.…”

Section: In Vivo Manipulation To Test Demographic Modelsmentioning

confidence: 99%

Review: Using physiologically based models to predict population responses to phytochemicals by wild vertebrate herbivores

Forbey

Liu

Caughlin

et al. 2018

Animal

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To understand how foraging decisions impact individual fitness of herbivores, nutritional ecologists must consider the complex in vivo dynamics of nutrient–nutrient interactions and nutrient–toxin interactions associated with foraging. Mathematical modeling has long been used to make foraging predictions (e.g. optimal foraging theory) but has largely been restricted to a single currency (e.g. energy) or using simple indices of nutrition (e.g. fecal nitrogen) without full consideration of physiologically based interactions among numerous co-ingested phytochemicals. Here, we describe a physiologically based model (PBM) that provides a mechanistic link between foraging decisions and demographic consequences. Including physiological mechanisms of absorption, digestion and metabolism of phytochemicals in PBMs allows us to estimate concentrations of ingested and interacting phytochemicals in the body. Estimated phytochemical concentrations more accurately link intake of phytochemicals to changes in individual fitness than measures of intake alone. Further, we illustrate how estimated physiological parameters can be integrated with the geometric framework of nutrition and into integral projection models and agent-based models to predict fitness and population responses of vertebrate herbivores to ingested phytochemicals. The PBMs will improve our ability to understand the foraging decisions of vertebrate herbivores and consequences of those decisions and may help identify key physiological mechanisms that underlie diet-based ecological adaptations.

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Assessment of Animal-Based Methods Used for Estimating and Monitoring Rangeland Herbivore Diet Composition

Cited by 60 publications

References 67 publications

Use of Fecal Indices as a Non-Invasive Tool for Nutritional Evaluation in Extensive-Grazing Sheep

Use of Fecal Indices as a Non-Invasive Tool for Nutritional Evaluation in Extensive-Grazing Sheep

Resolving resource partitioning in parrotfishes (Scarini) using microhistology of feeding substrata

Review: Using physiologically based models to predict population responses to phytochemicals by wild vertebrate herbivores

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