REDUCTION IN PARTICLE SIZE DURING RUMINATION IN CATTLE

1984 ◽  
Vol 64 (5) ◽  
pp. 339-340 ◽  
Author(s):  
K. CHAP ◽  
L. P. MILLIGAN ◽  
P. M. KENNEDY

Measurements of chewing behavior and of large particle breakdown during rumination were made with two steers given chaffed alfalfa or brome grass once daily for 4 h. Large particle content of boli retained in the mouth for chewing was enhanced by 38% compared to that in the regurgitated bolus, since some small particles were swallowed immediately with fluid. 58–75% of this coarse material was reduced to small particles by rumination. Specific fragility of both roughages was doubled at 16 vs. 4 h after feeding. Key words: Rumination, chewing, cattle

1988 ◽  
Vol 68 (3) ◽  
pp. 915-922 ◽  
Author(s):  
F. J. PORTELLA ◽  
L. J. CASTON ◽  
S. LEESON

Trials were designed to investigate the effect of feed particle size on apparent feed intake of laying hens. Feed was offered to five different groups of four birds each as either regular crumbles, mash, large crumbles (trained birds), large crumbles (untrained birds) or small crumbles, respectively. Except for the untrained birds, all birds were given a 15-d adaptation period. In each trial hens were offered 200 g of feed at 05:00 h and at each subsequent hour, until 20:00 h, feed was removed from the trough, sieved, weighed, remixed and returned to the feeders. Chemical analysis of the diet and various diet fractions was undertaken. There was marked disappearance of larger particles when birds were fed regular crumbles. However, smaller particles disappeared as the concentration of large ones decreased throughout the day. There was no marked disappearance of particles smaller than 0.60 mm. Feed intake was comparable when regular crumbles or mash rations were fed. Overall feed intake increased when small particles were offered, while intake decreased when the feed was changed abruptly to one of only large particles. It is concluded that particle size in regular crumbled layer feed is not uniform, and that particle size influences disappearance rate. Key words: Layer, particle preference, nutrient preference


1989 ◽  
Vol 40 (3) ◽  
pp. 643 ◽  
Author(s):  
RH Weston

Feed intake and digestion transactions for diets based on wheaten straw and mature ryegrass diets, both supplemented to provide additional essential nutrients, were compared with those for lucerne hay and high quality forage oats diets in lambs weighing c. 24 kg. The data obtained and comparable published data were used to examine relationships between a range of variables. Decrease in roughage quality, as evidenced by decrease in digestible organic matter (OM) intake, was accompanied by increase in (i) times spent eating, ruminating and chewing rumination boluses, (ii) the quantities of digesta or digesta OM in the reticula-rumen and omasum. It was not associated with increase in the large particle content of rumen or omasum digesta. Over the range of diets, close direct relations were demonstrated between (i) ruminating time and the amount of digesta in the reticulo-rumen, (ii) the amounts of digesta in the reticulo-rumen and omasum, (iii) the OM concentrations in rumen and reticulum digesta, (iv) the OM concentrations in reticulum and omasum digesta, (v) the OM concentration of reticulum digesta and of digesta flowing to the omasum, and (vi) the increase in OM concentration from reticulum to omasum digesta and OM concentration of reticulum digesta. Reticulum digesta were of finer texture than rumen digesta, and the bulk density of digesta particle fractions varied between diets, and sometimes between rumen and large intestine digesta. With a straw-based diet, relative to lucerne hay, small particles ( <600 �m sieve) were cleared more slowly from the reticula-rumen, associated with a larger reticulo-rumen particle pool. The data are discussed in relation to (i) the flow of digesta through the alimentary tract and (ii) the regulation of roughage intake. They were considered to be consistent with a concept that energy metabolism and digesta load in the reticulo-rumen interact in the regulation of roughage intake.


1985 ◽  
Vol 22 (2) ◽  
pp. 215-225 ◽  
Author(s):  
T. C. Kenney ◽  
D. Lau

Internal stability of a granular material results from its ability to prevent loss of its own small particles due to disturbing forces such as seepage and vibration. Internal instability results from the inability of a soil to act as a filter to prevent loss of its own small particles.Within pores in the load-bearing fabric of a cohesionless, granular material there can exist loose particles, and whether or not these particles can be removed by seepage depends on (i) particle size distribution curve of the whole material, (ii) density of the compacted material, and (iii) severity of the disturbing forces.Results of seepage tests are presented for a variety of compacted, cohesionless materials, some of which experienced loss of small particles (unstable gradings) and others of which experienced no such loss (stable gradings). From a synthesis of these results a method is proposed for evaluating the potential for grading instability based on the shape of a material's grain size curve. However, the surest method of making such an evaluation is to perform seepage tests following the procedure described in the paper. Key words: internal stability, grading stability, suffosion, tests, filters.


2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Hyun-Chang Lim ◽  
Kyung-In Ha ◽  
Ji-Youn Hong ◽  
Ji-Young Han ◽  
Seung-Il Shin ◽  
...  

The aim of the present study was to compare bone-collecting capacity of bone harvesting device and minimally irrigated low-speed drilling using three implant systems. One bone harvesting device and three commercially available drill systems were compared using the osteotomies on bovine rib bones. The amount of the collected bone particle and particle size (<500 μm: small, 500–1000 μm: medium, and >1000 μm: large) were measured. Total wet (1.535±0.232 mL) and dry volume (1.147±0.425 mL) of the bone particles from bone harvesting device were significantly greater than three drill systems (wet volume: 1.225±0.187–1.27±0.29 mL and dry volume: 0.688±0.163–0.74±0.311 mL) (P<0.05). In all groups, the amount of large sized particles in wet and dry state was the greatest compared to that of medium and small particles. The dry weight of the bone particles showed the same tendency to volumetric measurement. In conclusion, total bone particles and large sized particles (>1000 μm) were harvested significantly greater by bone harvesting device than minimally irrigated low-speed drilling. The composition of particle size in all harvesting methods was similar to each other.


2003 ◽  
Vol 18 (4) ◽  
pp. 804-816 ◽  
Author(s):  
Shou-Yi Chang ◽  
Chia-Jung Hsu ◽  
Cher-Hao Hsu ◽  
Su-Jien Lin

Static-gap, single-spark tests were used to investigate the arc erosion behavior of newly developed silicon carbide and alumina particle reinforced silver matrix composites (SiCp/Ag, Al2O3p/Ag). Craters and hills exist on the surfaces of eroded silver matrix composites, and their depths and sizes decrease as the particle content increases and the particle size decreases. Obvious melting, flow, severe splash of molten silver, and the segregation of particles are present on the surfaces of eroded composites containing low volume percents of large particles. Easier silver flow results in smooth surfaces and reduces the total surface areas of the eroded composites containing large particles. The flow and splash of silver decreased with increasing particle content and decreasing particle size, exhibiting a better erosion resistance to single-spark tests. The static-gap, single-spark erosion behavior of silver matrix composites is dominated by the flow and splash of molten composites. A high viscosity of the liquids provides the composites a good arc erosion resistance.


1939 ◽  
Vol 31 (12) ◽  
pp. 1509-1512 ◽  
Author(s):  
J. McGavack

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 236
Author(s):  
Xuebang Huang ◽  
Zizhao Zhang ◽  
Ruihua Hao ◽  
Zezhou Guo

Particle size grading impacts salt-frost heaving and dissolution collapse events of salinized soil on northwestern China’s arid and cold region highways. However, the influencing mechanisms remain unclear and the impact of varying particle size grading needs further investigation. Hence, this study focused on these effects and the number of freeze–thaw cycles on the characteristic changes in highway salinized soil in arid and cold regions. Three soil columns with different gradations were prepared to explore the gradation and the number of freeze–thaw cycle affects on salinized soil’s salt-frost heaving and dissolution collapse characteristics. The multi-functional physical simulation platform conducted multiple freeze–thaw cyclic tests in the laboratory. Test results confirmed significant and conclusive effects of gradation and the number of freeze–thaw cycles on salinized soil’s salt-frost heaving and dissolution collapse behaviors. Poorly graded salinized soil with high coarse particle content caused repeated freeze and thaw engineering hazards, significantly affecting salinized soil’s displacement and deformation behaviors during freezing. Contrarily, an increased range of fine particles more easily involved the characteristics of salinized soil during thawing. Therefore, the fourth freeze–thaw cycle was a crucial time node. After four freeze–thaw cycles, the displacement and deformation of original salinized soil and B-grade salinized soil samples (poorly graded with high fine particle content) tended to be stable. In contrast, the displacement and deformation of A-grade salinized soil samples (poorly graded with high coarse particle content) increased the growth rate. The present research results contribute to in-depth knowledge of the effects of gradation and freeze–thaw cycles on the characteristics of salinized soil in northwestern China, providing excellent referenced data support for the prevention and control of highway salinized soil failures and other engineering projects in arid and cold regions of northwest China.


Nature ◽  
1955 ◽  
Vol 175 (4455) ◽  
pp. 506-507 ◽  
Author(s):  
A. L. GREENBAUM ◽  
T. F. SLATER ◽  
E. REID

Fuel ◽  
2021 ◽  
Vol 289 ◽  
pp. 119838
Author(s):  
Xiaogang Mu ◽  
Jinfang Liu ◽  
Fei Gao ◽  
Cunbao Deng ◽  
Zhixin Jin ◽  
...  

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