scholarly journals Rumen physiology constrains diet niche: linking digestive physiology and food selection across wild ruminant species

2010 ◽  
Vol 88 (11) ◽  
pp. 1129-1138 ◽  
Author(s):  
Daryl Codron ◽  
Marcus Clauss
Keyword(s):  
Food Selection ◽  
Secondary Compounds ◽  
Maximum Amount ◽  
Digestive Physiology ◽  
Wild Ruminant ◽  
Plant Secondary Compounds ◽  
Fluid Content ◽  
Ruminant Species ◽  
The Mean ◽  
Physiological Heterogeneity

We propose a hypothesis for digestive constraints on the browsing and grazing options available to ruminants: that the diet-niche range (maximum and minimum grass intake) of a species is dependent upon its predisposition to stratified rumen contents, based on observations that this characteristic is a critical step towards enhanced fibre digestion and greater fluid throughput. We compare a physiological (heterogeneity of ingesta fluid content) and an anatomical (the intraruminal papillation pattern) measure with dietary evidence for a range of African and temperate species. Both measures are strongly related to the mean percentage of grass in species’ natural diets, as well as to the maximum and minimum levels of grass intake, respectively. The nature of these effects implies a stratification-level threshold, below which a species will not use a grass-based diet, but above which grass consumption can increase exponentially. However, above this threshold, a minimum percentage of grass in the diet is a prerequisite for optimal performance. We argue that this second constraint is crucial, as it depicts how a greater fluid throughput reduces potential for detoxification of plant secondary compounds, and therefore limits the maximum amount of browse a stratifying species will consume.

Attenuation of Schistosoma mansoni cercariae with a molluscicide derived from Millettia thonningii

Parasitology ◽  
1994 ◽  
Vol 109 (5) ◽  
pp. 559-563 ◽  
Author(s):  
S. Perrett ◽  
P. J. Whitfield ◽  
A. Bartlett ◽  
L. Sanderson
Keyword(s):  
Schistosoma Mansoni ◽  
Post Infection ◽  
Secondary Compounds ◽  
Chloroform Extract ◽  
West African ◽  
Elisa Assay ◽  
Plant Secondary Compounds ◽  
The Mean ◽  
Pre Treatment ◽  
Antibody Levels

A chloroform extract of molluscicidal plant secondary compounds from the seeds of a West African legume Millettia thonningii was used to attenuate cercariae of Schistosoma mansoni prior to infection of NMRI female mice. Exposure of cercariae to 0·3, 0·6, 1·3, 2·5, 10 or 20 mg/l concentrations of extract for 30 mm, immediately before standardized infection, was associated with a concentration-dependent decline in worm establishment at 55 days post-infection. The mean numbers of adult worms established declined from about 17 worms/mouse with control cercariae and those exposed to 0·3 mg/l Millettia to 0·1 worms/mouse after 10 mg/l pre-treatment. Mice exposed to cercariae after 20 mg/l pre-treatment had no adult worms at 55 days post-infection. The activities of cercariae 30 mm after exposure to Millettia extract at concentrations up to 2·5 mg/l were similar to those of control larvae: none was immobile. Exposure to higher concentrations of Millettia progressively reduced swimming activity and increased the proportion of immobile cercariae. After pretreatment with 20 mg/l Millettia the majority of larvae were immobile. Levels of anti-parasite antibodies (estimated by ELISA assay using an adult worm-based antigen preparation) rose between 21 and 55 days p.i. with control cercariae and those pre-treated with 2·5 mg/l Millettia. After 5 mg/l pre-treatment, cercariae induced a reduced antibody rise, while mice exposed to cercariae after 10 mg/l pre-treatment showed no rise in anti-parasite antibody levels. These results are discussed in the context of protocols which could possibly use Millettia-attenuated cercariae to induce useful levels of protection in mice towards further cercarial challenge.

scholarly journals Babesia spp. in European wild ruminant species: parasite diversity and risk factors for infection

2014 ◽  
Vol 45 (1) ◽  
pp. 65 ◽  
Author(s):  
Adam O Michel ◽  
Alexander Mathis ◽  
Marie-Pierre Ryser-Degiorgis
Keyword(s):  
Risk Factors ◽  
Parasite Diversity ◽  
Wild Ruminant ◽  
Ruminant Species ◽  
Babesia Spp

scholarly journals THE LUCK IN “TALENT VERSUS LUCK” MODELING

2020 ◽  
Vol 23 (03) ◽  
pp. 2050007
Author(s):  
SEAN ELVIDGE
Keyword(s):  
Mean Value ◽  
Maximum Amount ◽  
Random Numbers ◽  
Individual Parameter ◽  
Input Parameters ◽  
The Mean ◽  
Model Variability ◽  
The Impact ◽  
The Relationship

This paper further investigates the Talent versus Luck (TvL) model described by [Pluchino et al. Talent versus luck: The role of randomness in success and failure, Adv. Complex Syst. 21 (2018) 1850014] which models the relationship between ‘talent’ and ‘luck’ on the impact of an individuals career. It is shown that the model is very sensitive to both random sampling and the choice of value for the input parameters. Running the model repeatedly with the same set of input parameters gives a range of output values of over 50% of the mean value. The sensitivity of the inputs of the model is analyzed using a variance-based approach based upon generating Sobol sequences of quasi-random numbers. When using the model to look at the talent associated with an individual who has the maximum capital over a model run it has been shown that the choice for the standard deviation of the talent distribution contributes to 67% of the model variability. When investigating the maximum amount of capital returned by the model the probability of a lucky event at any given epoch has the largest impact on the model, almost three times more than any other individual parameter. Consequently, during the analysis of the model results one must keep in mind the impact that only small changes in the input parameters can have on the model output.

Plant secondary compounds as complementary resources: are they always complementary?

Oecologia ◽  
2012 ◽  
Vol 172 (4) ◽  
pp. 1041-1049 ◽  
Author(s):  
G. Copani ◽  
J. O. Hall ◽  
J. Miller ◽  
A. Priolo ◽  
J. J. Villalba
Keyword(s):  
Secondary Compounds ◽  
Plant Secondary Compounds ◽  
Complementary Resources

Interpreting the diet of extinct ruminants: the case of a non-browsing giraffid

Paleobiology ◽  
1988 ◽  
Vol 14 (3) ◽  
pp. 287-300 ◽  
Author(s):  
Nikos Solounias ◽  
Mark Teaford ◽  
Alan Walker
Keyword(s):  
Shape Analysis ◽  
Feeding Habits ◽  
African Buffalo ◽  
Giraffa Camelopardalis ◽  
Ruminant Species ◽  
Modern Species ◽  
Quantitative Analyses ◽  
The Mean ◽  
Connochaetes Taurinus ◽  
Rule Out

Modern ruminant species have traditionally been placed in three broad dietary categories (browsers, grazers and intermediates) based on their observed feeding habits. Shape analysis of premaxillary outlines of 31 species of ruminants shows that their premaxillae differ according to their dietary category. Browsers have pointed premaxillae and grazers square ones. Intermediate feeders have intermediate outlines.The Miocene giraffid Samotherium boissieri has always been viewed as a specialized browser similar to the modern okapi, Okapia johnstoni. However, the premaxillary shape of S. boissieri falls very close to the mean of the grazers and is most similar to that of the African buffalo (Syncerus caffer), a committed grazer.Quantitative analyses of the microscopic wear patterns on the molars reveal significant differences between three modern species from the three dietary groups. S. boissieri has more microscopic scratches on its teeth than either the modern giraffe Giraffa camelopardalis (a browser) or Grant's gazelle Gazella granti (an intermediate feeder). In this respect, it is indistinguishable from the wildebeest Connochaetes taurinus which is a committed grazer.Both of these analyses suggest that this extinct giraffid was a grazer, although we cannot rule out the possibility that it was an intermediate feeder. It was definitely not a specialized browser as are both living members of the Giraffidae.

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