747 research outputs found
Effects of condensed tannins on goats experimentally infected with Haemonchus contortus.
Although the use of tanniferous plants or condensed tannins as an alternative to anthelmintics to
control gastrointestinal nematodes has been largely documented in sheep, studies remain scarce in
goats. The objective of this study was therefore to assess the possible impact of condensed tannins
in goats infected with adult Haemonchus contortus. Two groups of cull goats were experimentally
infected with 10.000 L3 of H. contortus. After 4 weeks, quebracho extracts, representing 5%
of the diet DM, were administered for 8 days to one of the two groups. Goats of the second
group remained as controls. One week after the end of quebracho administration, the goats were
euthanised. Individual egg excretion and pathophysiological parameters were measured weekly
during the study. At the end of the study, worm counts were assessed and histological samples
from the abomasa were taken to count the numbers of mucosal mast cells, globule leukocytes
and eosinophils. The administration of tannins was associated with a significant decrease in egg
excretion, which persisted until the end of experiment. This reduction was not associated with
any difference in worm number but with a significant decrease in female fecundity. No significant
changes in the mucosal density of the three inflammatory cell types were detected between the
two groups. These results indicate that the major consequence of tannin consumption in goats is a
reduction in worm fecundity and egg output, which does not seem related to significant changes in
the local mucosal response
Neutron capture on ^{205}Tl: depicting the abundance pattern of lead isotopes in s-process nucleosynthesis
Proposal: Neutron capture on 205Tl: depicting the abundance pattern of lead isotopes in s-process nucleosynthesisWe propose to use the TOF technique to measure the neutron capture cross section of 205Tl(n,gamma) over the full energy range of stellar interest. An accurate measurement of this cross section is needed for a complete and consistent understanding of the s-process nucleosynthesis of the heaviest nuclei which are produced in low-mass and low metallicity AGB-stars. The only previous TOF measurement has yield only a partial information, insufficient for a reliable analysis of the complex branching pattern around 205Pb and 205Tl. Furthermore, there is also a discrepancy of 40% between the two previous activation measurements made at kT=24 keV. The cross section of 205Tl(n,gamma) is particularly relevant because it affects the equilibrium that is established in some stellar conditions between the 205Tl -> 205Pb bound-state Beta-decay and the 205Pb -> 205Tl E.C. decay. This effect induces a complex interplay which influences the final s-process abundance of both nuclei. We propose to measure accurately and with high resolution the 205Tl(n,gamma) cross section by using a set of four C6D6 detectors in combination with the pulsed neutron-source of CERN n_TOF.Preprin
Interactions between nutrition and gastrointestinal infections with parasitic nematodes in goats
Parasitic nematodes of the digestive tract remain one of the main constraints to goat production both in temperate and tropical
countries. The usual mode of control of these gastrointestinal nematodes (GIN) based on the repeated use of anthelmintics
is now strongly questioned because of the increasing development of resistance to these molecules. Among the alternative
methods to anthelmintics currently available, the manipulation of host nutrition in order to improve the host resistance and/or
resilience to parasitic infections seems to represent one of the most promising options to reduce the dependence on conventional
chemotherapy and to favour the sustainable control of gastro intestinal nematode infections. This paper will review the available
information on the interactions between nutrition and nematode parasitism in dairy or meat goats both in temperate and tropical
conditions. It will refer to quantitative aspects of the diet (influence of the protein and/or energy parts) as well as to qualitative
components (effects of plant secondary metabolites on worm biology) and will discuss the specificities of goats in regard of
theses interactions
Gestion non chimique du parasitisme par les nématodes chez les petits ruminants.
L‘agriculture biologique est particulièrement touchée par le parasitisme en raison de son utilisation intensive du pâturage, alors que les traitements anthelminthiques y sont
très encadrés.Cet article propose plusieurs méthodes naturelles de lutte contre les nématodes
Intérêt du pâturage mixte entre ovins et bovins dans la gestion du parasitisme digestif en système d’élevage Agriculture Biologique
Gastrointestinal trichostrongylosis represent one of the main constraint associated with the breeding of ruminants on pastures which is associated with Organic Farming. Besides the repeated use of anthelmintic treatments, the control of these parasitic infections can also be based on an improvement of the host response and on the reduction of animal infection by decreasing the contact with infective larvae through pertinent grazing management. Mixed grazing between different hosts species, particularly between cattle and small ruminants, represents one of the method to reduce the infestivity of pastures. This method is based on the relatively high specificity of many nematode species for one host. The advantages and limits of mixed grazing practices, either by alternate or simultaneous mode, are discussed both in regard of parasite infection and production measurements
Differences in receptivity to gastrointestinal infections with nematodes in dairy ewes: Influence of age and of the level of milk production
Resistance to anthelmintics in populations of gastrointestinal nematodes is a major concern in small ruminants. One solution
to limit the spread of anthelmintic resistance is to apply treatments selectively by targeting the most susceptible animals within
a flock. In dairy goats, previous studies have shown that, within a flock, goats in first lactation and those with high level of milk
production were highly receptive to nematode infections. These results provided the rationale for targeted treatments. In dairy
ewes, such epidemiological information on possible factors modulating the susceptibility to parasitism were still lacking. The
objective of the current study was therefore to examine differences in the level of parasite infection and in the pathophysiological
consequences in dairy ewes, depending on the age or on the level of milk production. In three farms, parasite egg excretion, and the
serum concentrations of pepsinogen and inorganic phosphate were compared on one hand between primiparous and multiparous
ewes; on the other hand, between ewes with the highest and the lowest level of milk production, within a cohort of 3–5-year
old animals. Overall, the results did not indicate significant differences for both either the parasitological or pathophysiological
measurements depending on the level of milk production. In contrast, significant differences were found according to age,
indicating higher levels of infections in the primiparous ewes than in the multiparous ones and suggesting that this category of
animals represents a particular parasitic risk within a flock
An SIS-based sideband-separating heterodyne mixer optimized for the 600 to 720 GHz band
The Atacama Large Millimeter Array (ALMA) is the largest radio astronomical enterprise ever proposed. When completed, each of its 64 constituting radio-telescopes will be able to hold 10 heterodyne receivers covering the spectroscopic windows allowed by the atmospheric transmission at the construction site, the altiplanos of the northern Chilean Andes. In contrast to the sideband-separating (2SB) receivers being developed at low frequencies, double-side-band (DSB) receivers are being developed for the highest two spectroscopic windows (bands 9 and 10). Despite of the well known advantages of 2SB mixers over their DSB counterparts, they have not been implemented at the highest-frequency bands as the involved dimensions for some of the radio frequency components are prohibitory small. However, the current state-of-the-art micromachining technology has proved that the structures necessary for this development are attainable. Here we report the design, modeling, realization, and characterization of a 2SB mixer for band 9 of ALMA (600 to 720 GHz). At the heart of the mixer, two superconductor-insulator-superconductor (SIS) junctions are used as mixing elements. The constructed instrument presents an excellent performance as shown by two important figures of merit: noise temperature of the system and side band ratio, both of them within ALMA specifications
Homotopy on spatial graphs and generalized Sato-Levine invariants
Edge-homotopy and vertex-homotopy are equivalence relations on spatial graphs
which are generalizations of Milnor's link-homotopy. Fleming and the author
introduced some edge (resp. vertex)-homotopy invariants of spatial graphs by
applying the Sato-Levine invariant for the constituent 2-component
algebraically split links. In this paper, we construct some new edge (resp.
vertex)-homotopy invariants of spatial graphs without any restriction of
linking numbers of the constituent 2-component links by applying the
generalized Sato-Levine invariant.Comment: 16 pages, 13 figure
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