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M. Clauss R. R. Hofmann J. Hummel J. Adamczewski K. Nygren C. Pitra W.J. Streich & S. Reese 《Journal of Zoology》2006,270(2):346-358
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Comparative physiology applies methods established in domestic animal science to a wider variety of species. This can lead to improved insight into evolutionary adaptations of domestic animals, by putting domestic species into a broader context. Examples include the variety of responses to seasonally fluctuating environments, different adaptations to heat and drought, and in particular adaptations to herbivory and various herbivore niches. Herbivores generally face the challenge that a high food intake compromises digestive efficiency (by reducing ingesta retention time and time available for selective feeding and for food comminution), and a variety of digestive strategies have evolved in response. Ruminants are very successful herbivores. They benefit from potential advantages of a forestomach without being constrained in their food intake as much as other foregut fermenters, because of their peculiar reticuloruminal sorting mechanism that retains food requiring further digestion but clears the forestomach of already digested material; the same mechanism also optimises food comminution. Wild ruminants vary widely in the degree to which their rumen contents 'stratify', with little stratification in 'moose-type' ruminants (which are mostly restricted to a browse niche) and a high degree of stratification into gas, particle and fluid layers in 'cattle-type' ruminants (which are more flexible as intermediate feeders and grazers). Yet all ruminants uniformly achieve efficient selective particle retention, suggesting that functions other than particle retention played an important role in the evolution of stratification-enhancing adaptations. One interesting emerging hypothesis is that the high fluid turnover observed in 'cattle-type' ruminants - which is a prerequisite for stratification - is an adaptation that not only leads to a shift of the sorting mechanism from the reticulum to the whole reticulo-rumen, but also optimises the harvest of microbial protein from the forestomach. Although potential benefits of this adaptation have not been quantified, the evidence for convergent evolution toward stratification suggests that they must be substantial. In modern production systems, the main way in which humans influence the efficiency of energy uptake is by manipulating diet quality. Selective breeding for conversion efficiency has resulted in notable differences between wild and domestic animals. With increased knowledge on the relevance of individual factors, that is fluid throughput through the reticulo-rumen, more specific selection parameters for breeding could be defined to increase productivity of domestic ruminants by continuing certain evolutionary trajectories. 相似文献
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Cristina Gattiker Ian Espie Antoinette Kotze Emily P. Lane Daryl Codron Marcus Clauss 《Zoo biology》2014,33(5):426-432
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Jürgen Hummel Julia Fritz Ellen Kienzle E. Patricia Medici Stefanie Lang Waltraut Zimmermann W. Jürgen Streich Marcus Clauss 《Zoo biology》2008,27(1):70-77
Data from captive animals indicated that browsing (BR) ruminants have larger fecal particles—indicative of lesser chewing efficiency—than grazers (GR). To answer whether this reflects fundamental differences between the animal groups, or different reactions of basically similar organisms to diets fed in captivity, we compared mean fecal particle size (MPS) in a GR and a BR ruminant (aurox Bos primigenius taurus, giraffe Giraffa camelopardalis) and a GR and a BR hindgut fermenter (Przewalski's horse Equus ferus przewalskii, lowland tapir Tapirus terrestris), both from captivity and from the wild. As would be expected owing to a proportion of finely ground, pelleted feeds in captive diets, MPS was smaller in captive than free‐ranging GR. In contrast, MPS was drastically higher in captive than in free‐ranging BR of either digestion type. Thus, the difference in MPS between GR and BR was much more pronounced among captive than free‐ranging animals. The results indicate that BR teeth have adapted to their natural diet so that in the wild, they achieve a particle size reduction similar to that of GR. However, although GR teeth seem equally adapted to food ingested in captivity, the BR teeth seem less well suited to efficiently chew captive diets. In the case of ruminants, less efficient particle size reduction could contribute to potential clinical problems like “rumen blockage” and bezoar formation. Comparisons of MPS between free‐ranging and captive animals might offer indications for the physical suitability of zoo diets. Zoo Biol 27:70–77, 2008. © 2007 Wiley‐Liss, Inc. 相似文献
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Marcus Clauss Reinhold R. Hofmann Jörns Fickel W. Jürgen Streich Jürgen Hummel 《Journal of morphology》2009,270(8):929-942
Browsing and grazing ruminants are thought to differ in the degree their rumen contents are stratified—which may be due to different characteristics of their respective forages, to particular adaptations of the animals, or both. However, this stratification is difficult to measure in live animals. The papillation of the rumen has been suggested as an anatomical proxy for stratification—with even papillation indicating homogenous contents, and uneven papillation (with few and small dorsal and ventral papillae, and prominent papillae in the atrium ruminis) stratified contents. Using the surface enlargement factor (SEF, indicating how basal mucosa surface is increased by papillae) of over 55 ruminant species, we demonstrate that differences between the SEFdorsal or SEFventral and the SEFatrium are significantly related to the percentage of grass in the natural diet. The more a species is adapted to grass, the more distinct this difference, with extreme grazers having unpapillated dorsal and ventral mucosa. The relative SEFdorsal as anatomical proxy for stratification, and the difference in particle and fluid retention in the rumen as physiological proxy for stratification, are highly correlated in species (n = 9) for which both kind of data are available. The results support the concept that the stratification of rumen contents varies among ruminants, with more homogenous contents in the more browsing and more stratified contents in the more grazing species. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc. 相似文献
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Yazdy MM Autry AR Honein MA Frias JL 《Birth defects research. Part A, Clinical and molecular teratology》2008,82(3):147-154
BACKGROUND: Our objective was to evaluate the use of special education services by children with orofacial clefts (OFCs). METHODS: We linked the birth certificates of children born from 1982–2001 in five counties of metropolitan Atlanta to a population‐based birth defects surveillance system to identify children with OFCs, and to the special education files for the school years 1992–2004 to identify children who used special education services. The special education data contained exceptionalities and services rendered for each school year. Prevalence ratios (PRs) and 95% CIs were calculated. The data were stratified by race/ethnicity, maternal education, type of OFC, and the presence of associated major malformations. In addition, we assessed the age at which special education began and the amount of time spent receiving services. RESULTS: Of the 777 children with OFCs, 201 (26%) were in special education at least 1 year compared with 8% of the children who had no major birth defects, yielding a PR of 3.2 (95% CI: 2.9–3.6). The most common exceptionality or service for children with an OFC was speech and language services. Compared with children with no birth defects, children with an OFC were four times more likely to be in this exceptionality (PR 3.8; 95% CI: 3.3–4.3). After excluding children in speech and language services, children with OFCs were still more likely to use special education services (PR 2.4; 95% CI: 1.7–3.2). CONCLUSIONS: Children with OFCs used special education services more often than children without birth defects. This information can help in planning for future population needs. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc. 相似文献
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The succulent thicket of the Eastern Cape, South Africa, is characterized by densely wooded vegetation that is dominated by succulents with little understory of ephemeral and weakly perennial grasses and forbs. Studies have developed around the question: how do bulk grazers such as the African buffalo (Syncerus caffer) survive in the succulent thicket? In this study, the diet of the African buffalo at the Great Fish River Reserve (GFRR) was studied in two seasons (wet and dry). The diet profile was assessed from faecal matter, using the micro‐histological analysis method. During the wet season, grass species contributed 72% to the diet while 28% was contributed by browse species. In the dry season there was a significant increase in the intake of browse by 5% (χ2 = 19.94, df = 11, P < 0.05). There were species that were neglected in the wet season but became principal dietary items in the dry season, these included Setaria neglecta, Cymbopogon plurinodis, Capparis sepiaria and Portulacaria afra. Diet quality, as estimated from faecal samples, suggested that the buffalo were nutritionally stable; however, the presence of sarcoptic mange in the buffalo suggests nutritional stress. 相似文献
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The evolution of robust jaws, hypsodont teeth, and large chewing muscles among grazing ruminants is a quintessential example of putative morphological adaptation. However, the degree of correlated evolution (i.e., to what extent the grazer feeding apparatus represents an evolutionary module), especially of soft and hard tissues, remains poorly understood. Recent generation of large datasets and phylogenetic information has made testing hypotheses of correlated evolution possible. We, therefore, test for correlated evolution among various traits of the ruminant masticatory apparatus including tooth crown height, jaw robustness, chewing muscle size, and characters of the molar occlusal surfaces, using phylogenetic and nonphylogenetic comparative methods as well as phylogenetic evolutionary model selection. We find that the large masseter muscles of grazing ruminants evolved with the inclusion of grass in the diet, an increase in the proportion of occlusal enamel bands oriented parallel to the chewing stroke, and possibly hypsodonty. We suggest that the masseter evolved under two evolutionary regimes: i) selection for higher masticatory forces during chewing and ii) flattening of the tooth profile, which resulted in reduced tooth guidance and, thus, a requirement for more chewing muscle activity during each chewing stroke, in agreement with previous research. The linear jaw metrics (depth of the mandibular angle, mandibular angle width, and length of the superficial masseteric scar) all show correlated evolution with hypsodonty and the proportion of enamel bands oriented parallel to the chewing stroke. We suggest that changes in the shape of the mandible represent the combined effects of selection for a reorientation of the chewing stroke, so as to emphasize horizontal translation of the teeth, and accommodation of high‐crowned teeth. Our analyses show that the ruminant feeding apparatus is an evolutionary mosaic with its various components showing both correlated and independent evolution. J. Morphol. 275:1093–1102, 2014. © 2014 Wiley Periodicals, Inc. 相似文献
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Pascal Marchand Claire Redjadj Mathieu Garel Jean‐Marc Cugnasse Daniel Maillard Anne Loison 《Mammal Review》2013,43(4):275-291
- We reviewed data on the diets of mouflon (Mediterranean island populations Ovis gmelini musimon and introduced hybridized populations Ovis gmelini musimon × Ovis sp.) from 33 field studies (comprising 51 independent data points suitable for analysis) to detect general patterns in the botanical composition of the diet and identify ecological factors explaining its variation. We expected mouflon, generally classified as grazers, to include botanical entities other than grass in their diet, especially when they are forced to do so by low resource availability, and in certain seasons.
- Diet composition was investigated based on samples of rumen content and faeces. We combined these data with environmental characteristics at each site using a co‐inertia analysis.
- As expected, grass often constituted the highest proportion in the diet (in 28 of the 51 data points) and represented on average 35% (range = 0–91%) of mouflon diet, confirming the importance of this food for the species. However, referring strictly to commonly used thresholds (>75% or >90%) shows that the classification of mouflon as grazers could be questioned. Indeed, forbs and shrubs constituted 24% (range: 0–93%) and 16% (range: 0–55%) of their diet, respectively, so that mouflon should at least be considered as variable grazers. Forbs represented a high percentage of the overall diet in the Kerguelen Archipelago, southern Indian Ocean (autumn and winter: 73%) and Teide National Park, Canary Islands, Spain (autumn and winter: 83%), whereas shrubs represented a high proportion of the overall diet in Mediterranean areas (19%).
- Diet composition varied with spatio‐temporal variation in forage availability (documented as habitat related or seasonal variation), confirming that mouflon are able to feed on a large variety of plants.
- Further investigations concerning both digestive morphology and consequences of the inclusion of browse in the diet on population dynamics of mouflon are needed to understand the persistence of this species over a wide range of habitats despite a potential mismatch between its digestive ability and its observed diet.
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Abstract There has been debate over the cause of the extinction of ‘megafauna’ species during the late Pleistocene of Australia. One view is that environmental change, either natural or human‐induced, was the main factor in the extinctions. Some support for this comes from the observation that, among herbivores, most of the species that went extinct were apparently browsers rather than grazers. Browsers would presumably have been more dependent on shrubland and woodland habitats than grazers, and it has been argued that such habitats might have contracted in response to aridity or changed fire regimes in the late Pleistocene. Here, we test this idea by comparing extinction rates of browsers and grazers in the late Pleistocene, controlling for body mass in both groups. We show that in both browsers and grazers the probability of extinction was very strongly related to body mass, and the body mass at which extinction became likely was similar in the two groups. It is true that more browsers than grazers went extinct, but this is largely because most very large herbivores in the late Pleistocene were browsers, not because large browsers were more likely to go extinct than similarly sized grazers. This result provides evidence against some forms of environmental change as a cause of the extinctions. 相似文献
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Tamura T Munger RG Corcoran C Bacayao JY Nepomuceno B Solon F 《Birth defects research. Part A, Clinical and molecular teratology》2005,73(9):612-616
BACKGROUND: Findings from animal experiments suggest a link between poor maternal zinc status and increased risk of oral clefts in offspring; however, there are few human studies on this issue. METHODS: A case-control study was conducted using 74 case mothers of children with nonsyndromic cleft lip with or without cleft palate (CL/P, n=57) or cleft palate alone (CP, n=17), and 283 control mothers of unaffected children recruited in the Philippines in early 2003. Maternal zinc status was assessed by determining plasma zinc concentrations a mean of 5 years after delivery of the index child. Odds ratios (ORs) of estimates of the relative risk of oral clefts were calculated for quartiles of maternal plasma zinc concentrations. RESULTS: The mean plasma zinc concentration of CL/P case mothers (9.6+/-1.2, SD micromol/l) was significantly lower than that in control mothers (10.1+/-1.6 micromol/l; P<0.05). Low plasma zinc concentrations (<11.0 micromol/l) were found in 88% and 94% of CL/P and CP case mothers, respectively, and in 72% of controls (P<0.05). The ORs for CL/P and CP combined, adjusted for potential confounding factors, decreased with increasing quartile of plasma zinc as follows: 1.0 (lowest quartile reference), 0.83 (95% confidence interval 0.37-1.89), 0.70 (0.31-1.68), and 0.26 (0.10-0.70) (P trend=0.008). CONCLUSIONS: Low plasma zinc concentrations were common in Filipino women of reproductive age, and higher plasma zinc concentrations were associated with a lower risk for oral clefts in their children. 相似文献
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Jane C. Figueiredo Stephanie Ly Kathleen S. Magee Ugonna Ihenacho James W. Baurley Pedro A. Sanchez‐Lara Frederick Brindopke Thi‐Hai‐Duc Nguyen Viet Nguyen Maria Irene Tangco Melissa Giron Tamlin Abrahams Grace Jang Annie Vu Emily Zolfaghari Caroline A. Yao Athena Foong Yves A. DeClerk Jonathan M. Samet William Magee III 《Birth defects research. Part A, Clinical and molecular teratology》2015,103(10):863-879