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Two experiments were conducted to measure effects of source and level of roughage on the flow of corn residues through the gastrointestinal tract of cattle. In Exp. 1, steers (195 kg) were fed diets of ground corn with 0, 30 or 60% of ground Coastal bermudagrass hay (Cynodon dactylon) [L.] Pers.) at intakes of 1, 1.5 or 2% of BW in a 9 x 9 Latin square. Experiment 2 consisted of two 4 x 4 Latin squares with either rice hulls (square 1) or ground Coastal bermudagrass hay (square 2) providing 0, 7.5, 15 or 30% of the total diet fed at 1.5% of BW. After a 28-d adjustment period, a portion of the corn in one meal was replaced with cracked corn stained with brilliant green. The concentrations of stained corn residues appearing in the feces subsequent to dosing were fitted to a one-compartment, age-dependent model and compartmental mean residence time (CMRT) and time delay (tau) were estimated. In Exp. 1, increasing the level of intake of the ration from 1% to 1.5 or 2.0% of BW increased (P less than .05) CMRT by 52% and reduced (P less than .05) tau by 41%. In Exp. 2, source of roughage had no effect (P = .95) on CMRT or tau. Combined results of the two experiments indicated that increasing proportion (P) of either roughage was associated with an exponential decline in CMRT of stained corn residues (CMRT = 1211 * e-.0315P) from rations consumed at 1.5 and 2.0% of BW. No consistent effect of roughage type or proportion was noted on time delay in the two experiments collectively. These results indicate that increasing the proportion of roughage in the diet exponentially reduces residence time of corn residues in the ruminoreticulum (CMRT) without affecting residence time in the postgastric segments (tau). 相似文献
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Effects of diluting the energy content of a corn-soybean meal diet with either alfalfa meal or corn cobs on nutrient digestibility and rate of passage of feed residues and particle markers were measured in crossbred (Yorkshire X Landrace X Chester White X Large White) barrows with a mean body weight of about 80 kg. The excretion pattern in the feces of Cr-mordanted diet and of rare earths initially bound individually to the mixed diet or to the corn or soybean meal suggested a model having a single age-dependent compartment with time delay. The compartmental turnover rate parameter (lambda 1) estimated by this model did not differ for the rare earths individually used to mark the corn-soybean meal diet (Yb), the corn (La) or the soybean meal (Sm). In contrast, lambda 1 for Cr was smaller (P less than .001) than that of the mean for the three rare earths. The residence time due to displacement flow (tau) did not differ among markers. These results were interpreted to indicate that the high specific gravity of Cr-mordanted feed slowed flow due to mixing but not due to displacement. Correlations between lambda 1 and tau were less than .71. These results suggested that the flow of rare earths initially bound to feed ingredients provides a reasonable estimate of the flow of their undigested residues through the gastrointestinal tracts of nonruminant animals. Inclusion of the fibrous feeds reduced digestibility of dry matter, cell contents, crude protein and acid detergent lignin and increased digestibility of cell walls, cellulose and acid detergent fiber. Digestibilities of cellulose and acid detergent fiber were greater with alfalfa than with corn cobs as the fiber source. Differences in digestibility of crude protein and acid detergent fiber existed due to litter in one replicate of the experiment. Variation in digestibility was not significantly related to variation in lambda 1 or tau within or among treatments and litters. This suggests that variations in lambda 1 and tau were not important causes of the observed variation in digestibility. 相似文献
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Dobenecker B Kasbeitzer N Flinspach S Köstlin R Matis U Kienzle E 《Journal of animal physiology and animal nutrition》2006,90(9-10):394-401
Numerous investigations and reports have covered the potential negative effects of an excess of calcium (Ca) in the skeletal development of young dogs. However, it still remains unclear why not all puppies, particularly of larger breeds, develop clinical signs of skeletal disorders after an overexposure to Ca. This trial with the small Beagle breed and a larger Foxhound-crossbred dog (with an adult weight of around 35 kg) investigated the effects of Ca-excess on parameters of bone growth. The employed small breed is known for its chondrodystrophic predispositions, no such data are reported for the slender hound-type Foxhound-crossbred dogs. The Ca-supply had no influence on weight development and general health of the dogs. The measurements of bone lengths and widths in X-rays of the forearm of Beagles and Foxhound-crossbred dogs at 6 weeks of age, and again after a period of overexposure to Ca at about 27 weeks of age, revealed a growth-reducing influence only in Beagles, without influence on clinical parameters of skeletal health. 相似文献
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K Zahn R Frei D Wunderle B Linke K Schwieger B Guerguiev O Pohler U Matis 《Veterinary and comparative orthopaedics and traumatology》2008,21(3):185-194
OBJECTIVE: To compare the stiffness and strength of AO bone plates (DCP, LC-DCP, VCP, RCP, and LP) and the Clamp-Rod Internal Fixation System (CRIF). Study design: In vitro. Sample size: 12 individual implants of 18 plate dimensions and four sizes of CRIF, each corresponding to 2.0, 2.4/2.7, 3.5, or 4.5 mm screw sizes. METHODS: Implant-constructs of each plate and CRIF were created using Canevasit rods as a bone substitute in an unstable gap fracture model. Six implant-constructs of each type were tested under single cycle four-point bending loading, and six were tested under single cycle torsional loading until permanent plastic deformation occurred. RESULTS: Torsional stiffness and yield load of the DCP were always significantly greater than the CRIF within the same group. Bending properties of the 2.0 DCP were not significantly different to the 2.0 CRIF. The 2.7 DCP had significantly higher bending values than the 2.7 CRIF. The bending stiffness of the 3.5 DCP and 4.5 DCP was significantly less than their CRIF counterparts. While the bending yield load of the 3.5 DCP was significantly greater than the 3.5 CRIF, the bending yield load of the 4.5 DCP was significantly less than the 4.5 CRIF. CONCLUSION: A weakness was found in the torsional resistance of the CRIF constructs compared to the DCP constructs. CLINICAL SIGNIFICANCE: Bone holding power and applied screw torque should be considered when using the CRIF system in clinical application. 相似文献
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Matis K. A. Zouboulis A. I. Zamboulis D. Valtadorou A. V. 《Water, air, and soil pollution》1999,111(1-4):297-316
Arsenate oxyanions were removed from aqueous solutions by sorption onto synthetic goethite, which was applied as fine particulate suspension during laboratory experiments. The main parameters affecting this treatment process were investigated, namely the concentrations of goethite and of arsenic(V), contact time, temperature, solution pH values and ionic strength variations, and typical adsorption isotherms were calculated. The study of flocculation of goethite particulates in bench scale was subsequently carried out in presence of pentavalent arsenic (being a toxic pollutant), by applying an appropriate optical technique. The flocculation dynamics of dispersed goethite particles was examined, complemented by turbidity and electrophoretic mobility measurements. 相似文献
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A modification of Chalman's and Slocum's surgical approach to the elbow joint is presented and compared to lateral exposures of the anconeal process. The caudolateral approach guarantees best visual control and minimal tissue damage at the same time. 相似文献
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Selection of amino acid sequences in the beta chain of the T cell antigen receptor 总被引：29，自引：0，他引：29
S M Hedrick I Engel D L McElligott P J Fink M L Hsu D Hansburg L A Matis 《Science (New York, N.Y.)》1988,239(4847):1541-1544
The induction of an immune response in mammals is initiated by specifically reactive T lymphocytes. The specificity of the reaction is mediated by a complex receptor, part of which is highly variable in sequence and analogous to immunoglobulin heavy- and light-chain variable domains. The functional specificity of the T cell antigen receptor is, however, markedly different from immunoglobulins in that it mediates cell-cell interactions via the simultaneous recognition of foreign antigens and major histocompatibility complex-encoded molecules expressed on the surface of various lymphoid and nonlymphoid cells. The relation between the structure of the receptor and its functional specificity was investigated by analyzing the primary sequences of the receptors expressed by a series of T lymphocyte clones specific for a model antigen, pigeon cytochrome c. Within this set of T lymphocyte clones there was a striking selection for amino acid sequences in the receptor beta-chain in the region analogous to the third complementarity-determining region of immunoglobulins. Thus, despite the functional differences between T cell antigen receptors and immunoglobulin molecules, analogous regions appear to be important in determining ligand specificity. 相似文献