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21.
Walz LS Ellis WC White TW Matis JH Bateman HG Williams CC Fernandez JM Gentry LR 《Journal of animal science》2004,82(2):508-520
A sequence of eight twice-daily meals, each marked with different rare earth elements, was fed to 24 Spanish goats (BW = 20.6 +/- 1.94 kg) to produce meal-based profiles of rare earth markers within segments of the gastrointestinal digesta on subsequent slaughter. Accumulative mean residence time and time delay of rare earths and segmental and accumulative mean residence times of indigestible NDF (IDF) were estimated for each sampled segment. Diets consisted of ad libitum access to bermudagrass hay with a limit feeding of one of four supplements: 1) minerals (basal, B); 2) B + energy (E); 3) B + CP (CP); or 4) B + E + CP for 84 d. Mean daily intake (g/kg of BW) during the 5 d before slaughter differed (P < 0.05) via diet for DM but not for IDF (8.0 +/- 0.35 g/kg of BW). Larger estimates of cumulative mean residence time for IDF vs. rare earths were suggested to be the consequence of a meal-induced bias in the single measurement of IDF pool size by anatomical site. The rare earth compartment method was considered more reliable than the IDF pool dilution method because it yielded flow estimates based on the flux of eight meal-dosed rare earth markers over 4 d and was independent of anatomical definitions of pool size. Statistically indistinguishable estimates for gastrointestinal mean residence times for IDF and rare earths conform to assumed indelibility for the specifically applied rare earths and indigestibility of IDF. The potentially digestible NDF (PDF):IDF ratio of dietary fragments (0.8) progressively decreased in the following order: caudodorsal reticulorumen (0.390) > crainodorsal reticulorumen (0.357) approximately reticulum (0.354) > mid-dorsal reticulorumen (0.291) approximately ventral reticulorumen (0.286), to that within the omasal folds and in the abomasum (0.259). Such a gradient of progressively aging mixture of plant tissue fragments is consistent with age-dependent flow paths established in the reticulorumen and flowing to the omasum and abomasum. Such heterogeneity of fragment ages within the reticulorumen is also indicated by the superior fit of marker dose site double dagger marker sampling site model assumptions. Additionally, cyclic meal- and rumination-induced variations in escape rate occur. Estimates of mean escape rates over days, needed for the practice of ruminant nutrition, must consider the complex interactions among plant tissues and the dynamics of their ruminal digestion of PDF. 相似文献
22.
Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献
23.
A. A. Ivanov N. V. Yudina E. V. Mal’tseva E. Ya. Matis L. I. Svarovskaya 《Eurasian Soil Science》2010,43(2):210-215
The influence of humin preparations obtained from low-moor peat by the mechanochemical method on the changes in the microflora
number and hydrocarbon composition in oil-polluted soils was studied. The intense growth of the microorganisms in number especially
in the oil-polluted soil was observed upon the application of humin acids (at a concentration of 0.005 wt %) extracted from
mechanically processed peat. In this case, the content of the extracted bitumoids decreased down to 40 wt %. The soil microflora
stimulated by the humin preparations was shown to have highly destructive oil-oxidizing activity reflected in the indices
of the hydrocarbon biodegradation. The mechanochemical activation of peat allows raising the efficiency of extracting the
humic acids and can be a reason for increasing the availability of their individual components and parts of molecules, including
micro- and macroelements that are used by microbial cells as sources of nutrition and energy. 相似文献
24.
The results of a retrospective investigation of 25 cases of mandibular fractures in cattle are reported; 19 animals were treated and 6 slaughtered without therapy. Five cases of unilateral fracture of the pars molaris healed with conservative therapy, whereas the same method of treatment was unsuccessful in four cases with compound fractures (2 x pars incisiva, 1 x diastema, 1 x pars molaris) and in one with multiple fractures of the corpus and ramus of the mandible. For animals with symphyseal fractures, surgical fixation using cerclage wire (three cases) proved successful, as did percutaneous fixation in six animals with fractures of the diastema or body of the mandible. The fractures healed well in 14 out of 19 treated cattle and the animals were retained, on average, for a further four years. 相似文献
25.
The preparation of immunoglobulin A (IgA) from porcine colostrum, intestinal content and serum is described. The best results were achieved with colostrum, from which an antigen of satisfactory purity was prepared by purification on Sephadex G-200, on DEAE cellulose and subsequent filtration on Sephadex G-200. The serum to this antigen raised in rabbits was adsorbed to an immunoadsorbent from porcine serum (PS) or porcine IgG. The adsorbtion of the serum against secretory IgA (SIgA) to PS removed its undesirable heterologous and nonspecific reactivity. The anti-SIgA serum adsorbed in this way still reacted with IgA from porcine serum. In the direct and indirect immunofluorescent staining we detected the main antigenic determinants of the SIgA molecule, i. e. the heavy chains and the secretory component. 相似文献
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27.
Structure and specificity of a class II MHC alloreactive gamma delta T cell receptor heterodimer 总被引：7，自引：0，他引：7
L A Matis A M Fry R Q Cron M M Cotterman R F Dick J A Bluestone 《Science (New York, N.Y.)》1989,245(4919):746-749
Two distinct CD3-associated T cell receptors (TCR alpha beta and TCR gamma delta) are expressed in a mutually exclusive fashion on separate subsets of T lymphocytes. While the specificity of the TCR alpha beta repertoire for major histocompatibility complex (MHC) antigens is well established, the diversity of expressed gamma delta receptors and the ligands they recognize are less well understood. An alloreactive CD3+CD4-CD8- T cell line specific for murine class II MHC (Ia) antigens encoded in the I-E subregion of the H-2 gene complex was identified, and the primary structure of its gamma delta receptor heterodimer was characterized. In contrast to a TCR alpha beta-expressing alloreactive T cell line selected for similar specificity, the TCR gamma delta line displayed broad cross-reactivity for multiple distinct I-E-encoded allogeneic Ia molecules. 相似文献
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29.
F B Wells S J Gahm S M Hedrick J A Bluestone A Dent L A Matis 《Science (New York, N.Y.)》1991,253(5022):903-905
The alpha beta and gamma delta T cell receptors for antigen (TCR) delineate distinct T cell populations. TCR alpha beta-bearing thymocytes must be positively selected by binding of the TCR to major histocompatibility complex (MHC) molecules on thymic epithelium. To examine the requirement for positive selection of TCR gamma delta T cells, mice bearing a class I MHC-specific gamma delta transgene (Tg) were crossed to mice with disrupted beta 2 microglobulin (beta 2M) genes. The Tg+beta 2M- (class I MHC-) offspring had Tg+ thymocytes that did not proliferate to antigen or Tg-specific monoclonal antibody and few peripheral Tg+ cells. This is evidence for positive selection within the gamma delta T cell subset. 相似文献
30.
The clinical and radiological findings of three related Miniature Poodles with multiple enchondromatosis (Ollier's disease) are presented. Persisting, in part ossified growth plate cartilage foci were found bilaterally in the humerus, radius, ulna, femur, tibia and fibula of each dog and in one dog in some metacarpal and metatarsal bones. The ribs and many vertebral bodies were also affected. There was evidently no bone formation in the sternebrae. All three dogs first attracted attention at the ages of four to six months, with spontaneous bilateral femoral neck fractures. The mode of inheritance of the condition is not yet clear, but based on the known pedigree data a dominant effect appears unlikely. 相似文献