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Dugovich BS, Barton EP, Crum JM, Keel MK, Stallknecht DE, Ruder MG. Demographic Risk Factors Vary in the Invasion Front of Chronic Wasting Disease in West Virginia, USA. J Wildl Dis 2024; 60:839-849. [PMID: 38871352 DOI: 10.7589/jwd-d-22-00160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 04/15/2024] [Indexed: 06/15/2024]
Abstract
After detecting chronic wasting disease (CWD) in white-tailed deer (Odocoileus virginianus) in Hampshire County, West Virginia, USA, in 2005, we investigated the change of CWD apparent prevalence and potential factors influencing infection risk during the invasion front. Over eight sampling years (2006-2012 and 2017) during a 12-yr period within a 101-km2-area monitoring zone, we sampled and tested a total of 853 deer for CWD by ELISA and immunohistochemistry. Bayesian logistic regression of risk factors included collection year, age class, sex, and adjusted body weight (weight after accounting for sex, age, kidney fat index, and number of fetuses). In the whole-herd model (n=634), collection year, age, and adjusted body weight were associated with increased odds of CWD, whereas an age-weight interaction had a negative relationship. We found that males drove the positive associations with age and adjusted body weight, whereas females were responsible for the negative interaction effect. These findings suggest potential behavioral and physiological mechanisms related to sex that may influence CWD exposure. Older males exhibited higher CWD prevalence, aligning with previous studies. Notably, the novel finding of adjusted body weight as a risk factor in males warrants further investigation, and this study highlights the need for future research on social behavior and its role in CWD transmission within white-tailed deer populations.
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Affiliation(s)
- Brian S Dugovich
- Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, 589 D. W. Brooks Dr., University of Georgia, Athens, Georgia 30602, USA
- Present address: U.S. Geological Survey, Northern Rocky Mountain Science Center, 2327 University Way STE2, Bozeman, Montana 59715, USA
| | - Ethan P Barton
- Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, 589 D. W. Brooks Dr., University of Georgia, Athens, Georgia 30602, USA
- West Virginia Division of Natural Resources, Wildlife Resources Section, PO Box 67, Elkins, West Virginia 26241, USA
| | - James M Crum
- West Virginia Division of Natural Resources, Wildlife Resources Section, PO Box 67, Elkins, West Virginia 26241, USA
| | - M Kevin Keel
- Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, 589 D. W. Brooks Dr., University of Georgia, Athens, Georgia 30602, USA
- Present address: Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, California 95616, USA
| | - David E Stallknecht
- Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, 589 D. W. Brooks Dr., University of Georgia, Athens, Georgia 30602, USA
| | - Mark G Ruder
- Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, 589 D. W. Brooks Dr., University of Georgia, Athens, Georgia 30602, USA
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Munn AJ, Snelling EP, Taggart DA, Clauss M. Scaling at different ontogenetic stages: Gastrointestinal tract contents of a marsupial foregut fermenter, the western grey kangaroo Macropus fuliginosus melanops. Comp Biochem Physiol A Mol Integr Physiol 2021; 264:111100. [PMID: 34737157 DOI: 10.1016/j.cbpa.2021.111100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 10/19/2022]
Abstract
Prominent ontogenetic changes of the gastrointestinal tract (GIT) should occur in mammals whose neonatal diet of milk differs from that of adults, and especially in herbivores (as vegetation is particularly distinct from milk), and even more so in foregut fermenters, whose forestomach only becomes functionally relevant with vegetation intake. Due to the protracted lactation in marsupials, ontogenetic differences can be particularly well investigated in this group. Here, we report body mass (BM) scaling relationships of wet GIT content mass in 28 in-pouch young (50 g to 3 kg) and 15 adult (16-70 kg) western grey kangaroos Macropus fuliginosus melanops. Apart from the small intestinal contents, in-pouch young and adults did not differ in the scaling exponents ('slope' in log-log plots) but did differ in the scaling factor ('intercept'), with an implied substantial increase in wet GIT content mass during the out-of-pouch juvenile period. In contrast to forestomach contents, caecum contents were elevated in juveniles still in the pouch, suggestive of fermentative digestion of milk and intestinal secretion residues, particularly in the caecum. The substantial increase in GIT contents (from less than 1 to 10-20% of BM) was associated mainly with the increase in forestomach contents (from 25 to 80% of total GIT contents) and a concomitant decrease in small intestine contents (from 50 to 8%), emphasizing the shifting relevance of auto-enzymatic and allo-enzymatic (microbial) digestion. There was a concomitant increase in the contents-to-tissue ratio of the fermentation chambers (forestomach and caecum), but this ratio generally did not change for the small intestine. Our study not only documents significant ontogenetic changes in digestive morpho-physiology, but also exemplifies the usefulness of intraspecific allometric analyses for quantifying these changes.
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Affiliation(s)
- Adam J Munn
- Laboratory for Ecological and Applied Physiology, Otford, NSW 2508, Australia.
| | - Edward P Snelling
- Department of Ecology and Environmental Science, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia; Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa; Centre for Veterinary Wildlife Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.
| | - David A Taggart
- Department of Ecology and Environmental Science, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia.
| | - Marcus Clauss
- Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland.
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3
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Ontogenetic scaling of the gastrointestinal tract of a marsupial foregut fermenter, the western grey kangaroo Macropus fuliginosus melanops. J Comp Physiol B 2021; 191:371-383. [PMID: 33491137 DOI: 10.1007/s00360-020-01333-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 11/07/2020] [Accepted: 12/06/2020] [Indexed: 10/22/2022]
Abstract
As an animal grows, the relative sizes of their organs may grow proportionately or disproportionately, depending on ontogenetic changes in function. If organ growth is proportional (isometric), then the exponent of the scaling equation is 1.0. Relative decreases or increases in size result in exponents less than 1 (hypoallometric) or greater than 1 (hyperallometric). Thus, the empirical exponent can indicate potential changes in function. The entire gastrointestinal tract (GIT) of the foregut-fermenting western grey kangaroo Macropus fuliginosus melanops exhibited biphasic allometry across five orders of magnitude body mass (Mb; 52.0 g-70.5 kg). Prior to weaning at around 12 kg Mb, the entire empty GIT mass scaled with hyperallometry (Mb1.13), shifting to hypoallometry (Mb0.80) post-weaning. In addition, there were varying patterns of hyper-, hypo-, and isometric scaling for select GIT organs, with several displaying phase shifts associated with major life-history events, specifically around exit from the maternal pouch and around weaning. Mass of the kangaroo forestomach, the main fermentation site, scaled with hyperallometry (Mb1.16) before the stage of increased vegetation intake, and possibly after this stage (Mb1.12; P = 0.07), accompanied by a higher scaling factor (elevation of the curve) probably associated with more muscle for processing fibrous vegetation. The acid hindstomach mass showed hyperallometry (Mb1.15) before weaning, but hypoallometry (Mb 0.58) post-weaning, presumably associated with decreasing intake of milk. Small intestine mass and length each scaled isometrically throughout ontogeny, with no discernible breakpoints at any life-history stage. The caecum and colon mass were steeply hyperallometric early in-pouch life (Mb1.59-1.66), when the young were ectothermic, hairless, and supported solely by milk. After around 295 g Mb, caecum mass remained hyperallometric (Mb1.14), possibly supporting its early development as a nidus for microbial populations to provide for secondary fermentation in this organ after the young transition from milk to vegetation.
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Spilinek S, Reitz R, Weckerly F. Rumen–reticulum organ mass and rumen mucosa surface area of white-tailed deer (Odocoileus virginianus) consuming two energy diets. CAN J ZOOL 2020. [DOI: 10.1139/cjz-2020-0043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Flexibility in gut morphology has fitness consequences in herbivores. To accommodate dietary variation in energy concentration, rumen–reticulum absorptive capacity and organ mass might also covary. We hypothesized that low energy diets result in greater food intake but lower volatile fatty acid concentrations. The consequence would be heavy rumen–reticulum organs and low absorptive capacity. We measured rumen–reticulum organ mass and absorptive capacity in captive white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) from central Texas, USA. Deer consumed a pelleted ration, ad libitum, of 1.77 kcal/g (low) or 2.67 kcal/g (standard) digestible energy from the time animals were weaned. In December, 4.5- and 5.5-year-old deer were euthanized, the rumen–reticulum was extracted, thoroughly rinsed, wrung out, and weighed. Four 1 cm × 3 cm samples were extracted from four regions of the rumen and mucosal surface area was measured. Our surrogate of food intake and mastication intensity was first molar height. Molar height was lower in animals consuming the low energy diet. Analyses indicated sex-specific responses. Males eating the low energy diet had heavier rumen–reticulum organs, but females did not. Females consuming the low energy diet had a lower surface enlargement factor, but males did not. The processes driving variation in rumen–reticulum morphology from dietary variation require further examination.
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Affiliation(s)
- S.G. Spilinek
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - R. Reitz
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - F.W. Weckerly
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
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De Cuyper A, Meloro C, Abraham AJ, Müller DWH, Codron D, Janssens GPJ, Clauss M. The uneven weight distribution between predators and prey: Comparing gut fill between terrestrial herbivores and carnivores. Comp Biochem Physiol A Mol Integr Physiol 2020; 243:110683. [PMID: 32097716 DOI: 10.1016/j.cbpa.2020.110683] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 02/03/2020] [Accepted: 02/20/2020] [Indexed: 11/24/2022]
Abstract
The general observation that secondary consumers ingest highly digestible food and have simple short guts and small abdominal cavities intuitively results in the assumption that mammalian carnivores carry less digesta in their gut compared to herbivores. Due to logistic constraints, this assumption has not been tested quantitatively so far. In this contribution, we estimated the dry matter gut contents (DMC) for 25 species of the order Carnivora (including two strictly herbivorous ones, the giant and the red panda) using the physical 'Occupancy Principle', based on a literature data collection on dry matter intake (DMI), apparent dry matter digestibility (aD DM) and retention time (RT), and compared the results to an existing collection for herbivores. Scaling exponents with body mass (BM) for both carnivores and herbivores were in the same range with DMI ~ BM0.75; aD DM ~ BM0; RT ~ BM0.11 and DMC ~ BM0.88. The trophic level (carnivore vs herbivore) significantly affected all digestive physiology parameters except for RT. Numerically, the carnivore DMI level reached 77%, the RT 32% and DMC only 29% of the corresponding herbivore values, whereas the herbivore aD DM only reached 82% of that of carnivores. Thus, we quantitatively show that carnivores carry less inert mass or gut content compared to herbivores, which putatively benefits them in predator-prey interactions and might have contributed to the evolution towards unguligradism in herbivores. As expected, the two panda species appeared as outliers in the dataset with low aD DM and RT for a herbivore but extremely high DMI values, resulting in DMC in the lower part of the herbivore range. Whereas the difference in DMI and DMC scaling in herbivores might allow larger herbivores to compensate for lower diet quality by ingesting more, this difference may allow larger carnivores not to go for less digestible prey parts, but mainly to increase meal intervals, i.e. not having to hunt on a daily basis.
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Affiliation(s)
- Annelies De Cuyper
- Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Carlo Meloro
- Research Centre in Evolutionary Anthropology and Palaeoecology, School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, England, UK
| | - Andrew J Abraham
- School of Informatics, Computing and Cyber Systems, Northern Arizona University, Flagstaff, USA
| | | | - Daryl Codron
- Department of Zoology and Entomology, University of the Free State, Bloemfontein, South Africa
| | - Geert P J Janssens
- Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Marcus Clauss
- Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
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Bartareau TM. Estimating body mass of Florida white-tailed deer from standard age and morphometric measurements. WILDLIFE RESEARCH 2019. [DOI: 10.1071/wr18142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Context
Measuring a mammal’s body mass has importance in understanding nutritional condition, reproductive biology and ecology. It can be impractical for a researcher to measure the body mass when equipment needed to weigh individuals is inadequate or unavailable.
Aims
The purpose of this study was to develop a model to accurately estimate the body mass of hunter-harvested Florida white-tailed deer (Odocoileus virginianus osceola, Odocoileus virginianus seminolus) based on the relationship between scale mass, sex and standard age and morphometric measurement predictor variables easily obtainable in the field.
Methods
An information-theoretic approach was used to evaluate simple and multiple linear regression models with 67% of the data, and the best model in the set was validated using the remaining 33%.
Key results
Chest girth was the best single predictor of body mass. A global model including sex, age, age2 and body length variables was better supported than chest girth alone, and subspecies information did not contribute significantly to the body-mass–predictor-variable relationship. The best model explained 98.5% of the variation in body mass as follows: body mass (kg) = –18.41 + 6.53 × sex (0 = female, 1 = male) + 5.04 × age (year) – 0.49 × age2 (year2) + 4.76 × 10−3 × chest girth2 (cm2) + 0.12 × body length (cm). The 95% confidence interval on the bias of the estimated body mass of the best model was –0.50 to 0.59 kg. The difference between estimated and scale body mass was –0.04 kg ± 0.28 (s.e.).
Conclusions
Individuals maintained a similar proportion of body mass to predictor variables, and differences between the observed and estimated body mass of model applied to the validation dataset were not significant.
Implications
The validated body-mass-estimation model presented will enable accurate estimates of the body mass of white-tailed deer in cases where standard age and morphometric measurements are available, but the individuals were not weighed. These results provide a basis to formulate and parameterise body-mass-estimation models for other white-tailed deer subspecies and populations. Without the need for specialised equipment, the body-mass-estimation model can be used by personnel involved in white-tailed deer research, management and sport hunting to assess trends in individual and population health in support of this species’ conservation. Photograph by Carlton Ward Jr.
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Jones P, Strickland B, Demarais S, Wang G, Dacus C. Nutrition and ontogeny influence weapon development in a long-lived mammal. CAN J ZOOL 2018. [DOI: 10.1139/cjz-2017-0345] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Selection in male cervids should optimize allocation of nutritional resources to the competing demands of body growth versus weapon development. We investigated allocation decisions of growing and mature male white-tailed deer (Odocoileus virginianus (Zimmerman, 1780)) from three regions of low, moderate, and high diet quality. We tested (i) if deer under greater nutritional limitations would allocate proportionally less to antler growth, (ii) if antler and body mass became less variable with age, and (iii) if antler size consistently exhibited positive allometry with body mass across age classes and nutritional planes. Greater nutrition increased antler allocation in 2.5 to 4.5 year olds but not in yearlings or prime-aged males. Variability of antler mass decreased with age and was generally less in more fertile regions, but body mass was equally variable across all ages and regions. Antler mass was positively allometric with body mass for all combinations of age class and region but exhibited age- and region-related differences. Our results suggest that accruing body mass is more important to lifetime reproductive success than increasing weapon size. Reduced allometric coefficients in older males likely stem from increasing use of skeletal mineral reserves, selective pressures favoring greater body mass, and possible selection for optimal weapon strength and structure.
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Affiliation(s)
- P.D. Jones
- Department of Wildlife, Fisheries, and Aquaculture, Box 9690, Mississippi State University, Mississippi State, MS 39762, USA
| | - B.K. Strickland
- Department of Wildlife, Fisheries, and Aquaculture, Box 9690, Mississippi State University, Mississippi State, MS 39762, USA
| | - S. Demarais
- Department of Wildlife, Fisheries, and Aquaculture, Box 9690, Mississippi State University, Mississippi State, MS 39762, USA
| | - G. Wang
- Department of Wildlife, Fisheries, and Aquaculture, Box 9690, Mississippi State University, Mississippi State, MS 39762, USA
| | - C.M. Dacus
- Mississippi Department of Wildlife, Fisheries, and Parks, 1505 Eastover Drive, Jackson, MS 39211, USA
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Weckerly F, Bhaskar G, Duarte A, Luna R, Starns H. Heavier rumen–reticulum organs in white-tailed deer ( Odocoileus virginianus) is consistent with dietary bulk not quality. CAN J ZOOL 2018. [DOI: 10.1139/cjz-2017-0036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The organs that make up the gastrointestinal tract have high energy demands. Therefore, when these organs vary in mass, they should impact metabolic requirements. Mass of the rumen–reticulum organs, the organs that comprise the largest part of the gastrointestinal tract of ruminants, might vary from bulk or nutrient availability of the diet. We examined differences in mass of the rumen–reticulum organs in white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) from two sites in Texas, USA, with different diet types. Specifically, at one site deer were fed a pelleted ration and at the other site deer consumed a natural browse diet. Accounting for body mass, deer consuming the browse diet had rumen–reticulum organ masses that were about 1.7 times heavier than deer consuming the pelleted diet. Deer consuming the browse diet also had lower diet quality, as indexed by crude protein concentration, than deer consuming the pelleted diet. The digesta loads of deer, however, were similar for the two types of diet. Our study findings are consistent with increased mass of rumen–reticulum organs from greater bulk, not diet quality. Understanding variation in rumen–reticulum organ mass has implications for understanding energy conservation in white-tailed deer.
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Affiliation(s)
- F.W. Weckerly
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - G. Bhaskar
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - A. Duarte
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - R.S. Luna
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - H.D. Starns
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
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Debeffe L, Maren Rivrud I, Brekkum Ø, Meisingset EL, Mysterud A. Implications of the forage maturation hypothesis for activity of partially migratory male and female deer. Ecosphere 2017. [DOI: 10.1002/ecs2.2050] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Lucie Debeffe
- Centre for Ecological and Evolutionary Synthesis; Department of Biosciences; University of Oslo; P.O. Box 1066 Blindern Oslo NO-0316 Norway
| | - Inger Maren Rivrud
- Centre for Ecological and Evolutionary Synthesis; Department of Biosciences; University of Oslo; P.O. Box 1066 Blindern Oslo NO-0316 Norway
| | - Øystein Brekkum
- Department of Forestry and Forestry Resources; Norwegian Institute of Bioeconomy Research; Tingvoll NO-6630 Norway
| | - Erling L. Meisingset
- Department of Forestry and Forestry Resources; Norwegian Institute of Bioeconomy Research; Tingvoll NO-6630 Norway
| | - Atle Mysterud
- Centre for Ecological and Evolutionary Synthesis; Department of Biosciences; University of Oslo; P.O. Box 1066 Blindern Oslo NO-0316 Norway
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Fàbregas MC, Garcés‐Narro C, Bertschinger H, Koehler G. Carcass utilization by tigers: implications for calculating prey requirements. J Zool (1987) 2016. [DOI: 10.1111/jzo.12403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- M. C. Fàbregas
- Department of Production Animal Studies Faculty of Veterinary Science University of Pretoria Onderstepoort South Africa
| | - C. Garcés‐Narro
- Department of Production and Animal Health General Veterinary Health and the Science and Technology of Food Products Faculty of Veterinary Science University CEU Cardenal Herrera Valencia Spain
| | - H. Bertschinger
- Department of Production Animal Studies Faculty of Veterinary Science University of Pretoria Onderstepoort South Africa
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Munn A, Stewart M, Price E, Peilon A, Savage T, Van Ekris I, Clauss M. Comparison of gut fill in sheep (Ovis aries) measured by intake, digestibility, and digesta retention compared with measurements at harvest. CAN J ZOOL 2015. [DOI: 10.1139/cjz-2014-0314] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gut capacity is an important factor in digestive physiology and is often measured as dry matter fill (DMF) following dissection, which prevents repeated measures in the same animal. It was proposed to calculate DMF from food intake, digestibility, and gut mean retention time (MRT), but empirical tests of this are few. We calculated DMF from intake, digestibility, and the MRT of small-particle (1 mm) and large-particle (20 mm) markers in 20 sheep (Ovis aries L., 1758) fed at different intake levels and compared results with DMF at dissection at the end of the feeding trial. MRT for smaller particles was significantly shorter than for larger particles (34.4 ± 6.1 vs. 42.5 ± 7.6 h, respectively). Correspondingly, DMF calculated from smaller particles (0.98 ± 0.27 kg) was significantly lower than DMF calculated from larger particles (1.20 ± 0.30 kg). The latter was not significantly different from DMF measured at dissection (1.18 ± 0.34 kg). These results suggest that DMF can be estimated from measures of digestive physiology. The choice of particle marker to determine MRT is crucial for the accuracy of the proxy. In ruminants, where small particles are consistently eliminated faster than larger particles, considerations of marker particle size are particularly important.
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Affiliation(s)
- Adam Munn
- Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, The University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
- Faculty of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia
| | - Mathew Stewart
- Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, The University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
| | - Elizabeth Price
- Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, The University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
| | - Alice Peilon
- Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, The University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
| | - Tom Savage
- School of Geosciences, University of Sydney, Sydney, NSW 2006, Australia
| | - Irene Van Ekris
- Faculty of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia
| | - Marcus Clauss
- Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland
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Mitchell G, Roberts D, van Sittert S. The digestive morphophysiology of wild, free-living, giraffes. Comp Biochem Physiol A Mol Integr Physiol 2015; 187:119-29. [DOI: 10.1016/j.cbpa.2015.05.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Revised: 05/19/2015] [Accepted: 05/19/2015] [Indexed: 11/25/2022]
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13
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Aiken MR, Wolcott DM, Duarte A, Luna RS, Starns HD, Weckerly FW. Use of rumen–reticulum fill to examine nutrient transfer and factors influencing food intake in white-tailed deer ( Odocoileusvirginianus). CAN J ZOOL 2015. [DOI: 10.1139/cjz-2014-0286] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Estimating relationships of gut fill in mammalian herbivores is useful to understanding digestive functions. Large animals might have more fluid in the gut to facilitate nutrient transfer between the gut lumen and the gut wall. Furthermore, relationships between concentrations of dietary refractory and indigestible fiber (CRIF) and gut fill might indicate whether chemostatic factors or physical distension of the gut affects food intake. We collected white-tailed deer (Odocoileus virginianus (Zimmermann, 1780); 122 males, 152 females) from three sites in central and south Texas that varied in diet quality as indexed by rumen–reticulum crude protein concentrations. Large animals did not have more fluid in their rumina–reticula than small animals because the scalar between body mass and wet mass of rumen–reticulum contents was not greater than the scalar estimated for dry mass of rumen–reticulum contents. We expected a positive or an inverse relationship when rates of forage comminution, digestion, and particle passage were high or low, respectively. At the site where deer had access to a high-quality pelleted diet, we detected a positive relationship between CRIF and dry mass. At sites with free-ranging deer and lower quality diets, relationships between CRIF and dry fill were inversely related. Food intake of deer was probably influenced by chemostatic factors at the site with a high-quality pelleted diet and by physical distension of the gut at the other two sites.
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Affiliation(s)
- Meredith R.E. Aiken
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - Daniel M. Wolcott
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - Adam Duarte
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - Ryan S. Luna
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - Heath D. Starns
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - Floyd W. Weckerly
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
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Wolcott DM, Asmus J, Weckerly FW. Overcoming cohort effects in a Mediterranean ecosystem: The role of density and precipitation on southern mule deer body mass. J Wildl Manage 2014. [DOI: 10.1002/jwmg.777] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Daniel M. Wolcott
- Department of Biology; Texas State University; San Marcos TX 78666 USA
| | - Jim Asmus
- Resource Enforcement and Compliance Section; MCIWEST Environmental Security; Box 555008 Building 2648 Camp Pendleton CA 92055-5008 USA
| | - Floyd W. Weckerly
- Department of Biology; Texas State University; San Marcos TX 78666 USA
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Intraspecific Scaling of Rumen-reticulum Fill Might Depend on Dietary Fiber. AMERICAN MIDLAND NATURALIST 2014. [DOI: 10.1674/0003-0031-172.2.329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Aiken M, Duarte A, Luna R, Wolcott D, Weckerly F. Daytime declines in rumen–reticulum fill of male white-tailed deer (Odocoileus virginianus) from south Texas. CAN J ZOOL 2014. [DOI: 10.1139/cjz-2013-0232] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Understanding rumen–reticulum fill dynamics gives us insight into how environmental conditions influence animal behaviors that affect when animals access forage. We examined whether there were daytime declines in rumen–reticulum fill in response to high ambient temperatures in free-ranging white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) on a diurnal scale. We hypothesized that to reduce heat-producing digestive processes in the heat of the day, rumen–reticulum fill and digestion in the rumen–reticulum would decline throughout the day. We collected the rumina and reticula of adult males and females across 30 h in two autumns in south Texas, USA. We also measured dry digesta mass, organ mass, and crude protein and acid detergent fiber concentrations of rumen–reticulum contents. In males, dry digesta mass declined throughout the day and crude protein concentrations were greatest when wet digesta and organ mass were the largest. Additionally, declines in dry digesta and wet digesta mass coincided with declines in crude protein concentrations and organ mass. Females did not display declines in rumen–reticulum fill (wet mass). Females were probably less vulnerable to heat than males because of their smaller body size. Male white-tailed deer foraged primarily during the cooler nights to reduce foraging and digestion during the heat of the day.
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Affiliation(s)
- M.R.E. Aiken
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - A. Duarte
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - R.S. Luna
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - D.M. Wolcott
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - F.W. Weckerly
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
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Monteith KB, Monteith KL, Bowyer RT, Leslie DM, Jenks JA. Reproductive effects on fecal nitrogen as an index of diet quality: an experimental assessment. J Mammal 2014. [DOI: 10.1644/12-mamm-a-306.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Luna RS, Weckerly FW. Variation Across Years in Rumen-Reticulum Capacity and Digesta Load in White-Tailed Deer (Odocoileus virginianus). SOUTHEAST NAT 2013. [DOI: 10.1656/058.012.0204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Influence of Body Size on Dietary Nutrition of White-Tailed Deer Odocoileus virginianus. JOURNAL OF FISH AND WILDLIFE MANAGEMENT 2013. [DOI: 10.3996/092012-jfwm-085] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Abstract
Intraspecific competition is one of the major factors that can have an effect on the resources utilized within a habitat. Differences in diet quality of selected forage have been noted in size-dimorphic ungulates. However, on an intraspecific basis, data demonstrating a body size influence on diet quality are lacking. We examined diet quality across a range of body masses (14–76 kg) in white-tailed deer Odocoileus virginianus (n = 108) in a 2,628-ha enclosure at Kerr Wildlife Management Area, Kerr County, Texas, USA. The quality of the diet consumed was determined by crude protein, acid detergent fiber, and neutral detergent fiber content of digesta in the rumen–reticulum. Results indicated that in relation to body mass, the ratio of crude protein to acid detergent fiber was greater for smaller bodied white-tailed deer. By consuming a diet higher in crude protein than did large bodied individuals, small-bodied individuals should meet their high mass-specific metabolic demands more efficiently. Furthermore, selective foraging by different-sized individuals might also reduce intraspecific competition. Information presented herein is relevant to wildlife managers in that by increasing available high-quality forage, small-bodied individuals will more efficiently meet their metabolic demands, which could have ramifications on recruitment within that population.
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Effects of resource limitation on habitat usage by the browser guild in Hluhluwe-iMfolozi Park, South Africa. JOURNAL OF TROPICAL ECOLOGY 2013. [DOI: 10.1017/s0266467413000035] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Abstract:Resource depletion and associated increases in interspecific competition are likely to influence differential habitat usage amongst a guild. We tested some prominent theoretical concepts using observed differences in seasonal habitat use amongst the savanna browser guild (elephant, giraffe, impala, kudu and nyala) in Hluhluwe-iMfolozi Park, South Africa. Herbivore locations (n = 3108) were recorded over 2 y using repeated road transects and, for elephant, GPS collars (187 254 downloads). Densities were calculated using a novel GIS approach designed to be a cost-effective method for annual censuses, but also able to cope with abrupt changes in visibility. Selectivity for (Manly's α) vegetation types, and overlap (Schoener's index) in vegetation type usage were calculated. Resource depletion in the dry season resulted in all members of the guild increasing selectivity for vegetation types (sum of absolute values away from the neutral value for Manly's alpha for the guild: dry seasons 3.97, 5.16; corresponding wet seasons 3.12, 3.68), but decreasing interspecific overlap (80% of Schoener's indices lower in dry season versus wet season). These effects were more marked over the second, more severe, dry season. We found support for the niche overlap hypothesis and the niche compression hypothesis. The Jarman–Bell principle was generally supported, although unexpectedly during the severe dry season elephant showed the most selectivity for vegetation type. The greater the resource depletion, the more relevant interspecific differences in habitat usage become in relation to the differential impacts of guild members.
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Weckerly FW. Conspecific body weight, food intake, and rumination time affect food processing and forage behavior. J Mammal 2013. [DOI: 10.1644/12-mamm-a-066.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Luna R, Duarte A, Weckerly F. Rumen–reticulum characteristics, scaling relationships, and ontogeny in white-tailed deer (Odocoileus virginianus). CAN J ZOOL 2012. [DOI: 10.1139/cjz-2012-0122] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Scaling relationships between body mass and gut capacity are valuable to predicting digestive efficiency. Interspecific scaling relationships between body mass and gut capacity have consistently estimated a slope of 1.0; however, intraspecific scaling relationships between body mass and gut capacity have been highly variable. We examined the influence of demands of growth and production on scaling relationships of body mass and rumen–reticulum characteristics in white-tailed deer ( Odocoileus virginianus (Zimmermann, 1780)) because little is known about how juvenile and subadult ruminants accommodate increased digesta masses. We sampled 108 animals over a 2-year period and assessed the influence of body mass, time of kill, crude protein (%), and acid detergent fiber (%) in the rumen, lactation, sex, and back fat on rumen–reticulum organ mass, rumen–reticulum capacity, wet mass of the digesta, and the dry mass of the digesta. Juvenile and subadult white-tailed deer had rumen–reticulum organ masses, capacity, and digesta masses that were similar to adults because body mass and rumen–reticulum scaling relationships all had scalars similar to 1.0. Thus, under the confines of our study, ontogeny plays only a minor role in the physiological characteristics of the rumen–reticulum and the scaling relationships of body mass and rumen–reticulum capacity.
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Affiliation(s)
- R.S. Luna
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - A. Duarte
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - F.W. Weckerly
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
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Oehlers SA, Bowyer RT, Huettmann F, Person DK, Kessler WB. Sex and scale: implications for habitat selection by Alaskan mooseAlces alces gigas. WILDLIFE BIOLOGY 2011. [DOI: 10.2981/10-039] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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