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排序方式: 共有90条查询结果,搜索用时 15 毫秒
1.
Effects of β‐cyclodextrin diallyl maleate (CD‐M) on methane production, ruminal fermentation and digestibility were studied both in vitro and in vivo. In in vitro study, diluted ruminal fluid (30 mL) was incubated anaerobically at 38°C for 6 and 24 h with or without CD‐M using hay plus concentrate (1.5:1) as a substrate. The CD‐M was added at different concentrations (0, 1.25, 2.5, 5.0 and 7.5 g/L). The pH of the medium and numbers of protozoa were not affected by the addition of CD‐M. Total volatile fatty acids were increased and ammonia‐N was decreased, molar proportion of acetate was decreased and propionate was increased (P < 0.05) by CD‐M. Methane was inhibited (P < 0.05) by 14–76%. The effect of CD‐M on methane production and ruminal fermentation was further investigated in vivo using four Holstein steers in a cross‐over design. The steers were fed Sudangrass hay and concentrate mixture (1.5:1) with or without CD‐M (2% of feed dry matter) as a supplement. Ruminal proportion of acetate tended to decrease and that of propionate was increased (P < 0.05) 2 h after CD‐M dosing. Total viable counts, cellulolytic, sulfate reducing, acetogenic bacteria and protozoa were unaffected while methanogenic bacteria were decreased (P < 0.05) by CD‐M. The plasma concentration of glucose was increased, whereas that of urea‐N was decreased (P < 0.05). Methane was inhibited (P < 0.05) from 36.4 to 30.1 L/kg dry matter intake by the addition of CD‐M. Apparent digestibilities of dry matter and neutral detergent fiber were not affected while that of crude protein was increased (P < 0.05) in the medicated steers. These data suggested that dietary supplementation of CD‐M decreased methane production and improved nutrient use.  相似文献   
2.
The effects when adding cyclodextrin‐iodopropane complex (CD‐IP) to a diet, on ruminal fermentation and microbes, digestibility, blood metabolites and methane production, were evaluated using four Holstein steers in a cross‐over design. The steers were fed Sudangrass hay plus concentrate mixture at a ratio 1.5:1, and CD‐IP (1% of dry matter) was given twice daily by mixing with concentrate mixture. Rumen and blood samples were collected at 0, 2, and 5 h after morning dosing. Ruminal pH and numbers of protozoa were unaffected by CD‐IP treatment. Ruminal molar proportion of acetate was decreased (P < 0.05), and propionate was increased (P < 0.01) at 2 h after CD‐IP dosing. Proportion of butyrate was increased (P < 0.05) and ammonia‐N was decreased (P < 0.05) at 2 and 5 h after CD‐IP dosing. Adding CD‐IP had no effect on the feed intake and digestion of nutrients. Plasma glucose was increased and urea‐N was decreased (P < 0.05) at 2 and 5 h after CD‐IP dosing. Methane production was decreased (P < 0.05) by approximately 18% in the treatment steers. Numbers of methanogenic bacteria were decreased (P < 0.05), while total viable counts, cellulolytic, sulfate reducing and acetogenic bacteria were unaffected. The present results are the first to show that CD‐IP can partially inhibit in vivo ruminal methanogenesis without adverse effects on digestion of nutrients.  相似文献   
3.
Objectives of this study were to compare fatty acid (FA) composition of ruminal bacterial (B) and protozoal (P) cells, and to investigate effect of protozoa on FA profile in the rumen of cattle. Three cows were used to prepare ruminal B and P cells. Four faunated and three defaunated cattle (half‐siblings) were used to study effect of protozoa on ruminal FA profile. Proportions of C16:0 and C18:0 in total fatty acids in B cells were 20.7% and 37.4%, whereas those in P cells were 33.4% and 11.6%, respectively. Proportions of trans‐vaccenic acid (VA) and cis‐9, trans‐11 conjugated linoleic acid (CLA) in B cells were 3.9% and 1.0%, and those in P cells were 5.5% and 1.6%, respectively, being higher in P cells. Proportions of C18:1, C18:2 and C18:3 in P cells were two to three times higher than in B cells. Proportions of unsaturated fatty acids, VA and CLA in B cells of faunated cattle were higher than those of defaunated. VA and CLA in the ruminal fluid of faunated were also 1.6 to 2.5 times higher than those of defaunated. This tendency was similar for cell‐free fraction of ruminal fluid. These results indicate that protozoa contribute greatly in VA and CLA production in the rumen.  相似文献   
4.
Hydroxyethyl starch (HES) is a nonpenetrating extracellular cryoprotectant. In contrast to glycerol, it does not require labor-intensive removal from thawed red blood cells (RBCs) prior to transfusion. In this study, we compared glycerol and HES, and assessed HES as a substitute for glycerol in cryopreserved canine RBCs. The RBCs were preserved for 2 months in liquid nitrogen using a 20% (w/v) glycerol solution, and variable concentrations of HES solution. We evaluated the two cryoprotectants by the percentage of post-thaw hemolysis from the total free hemoglobin, saline stability, osmotic fragility, and by observing the erythrocyte morphology using a scanning electron microscope after thawing. The optimal concentration of HES was 12.5% (w/v) for the cryopreservation of canine RBCs. The thaw hemolysis, saline stability, and osmotic fragility index were 25.6 +/- 4.7%, 87.8 +/- 6.9%, and 0.445 +/- 0.024% NaCl respectively. These parameters resemble the results of RBCs frozen in a 20% (w/v) glycerol solution, which are 24.7 +/- 5.2%, 99.2 +/- 0.1%, and 0.485 +/- 0.023% NaCl respectively. From a morphological point of view, 12.5% (w/v) HES showed the best cryoprotection of RBCs compared to the other concentrations of HES. These results suggest that HES could be a possible substitute for glycerol for the cryopreservation of canine RBCs.  相似文献   
5.
Eight lactating Holstein cows were divided into two groups ( n  = 4) and used in a double reversal trial with three periods of 14 days each, to evaluate diets containing propylene glycol (PG) and ruminally undegradable protein (RUP) blend on milk yield and composition, ruminal fermentation and blood metabolism. The control diet contained 20% chopped Sudangrass hay, 20% cubed alfalfa hay, 12% corn silage, and 48% of the respective concentrate mixtures (dry matter basis). The experimental diet (PG + RUP) partially replaced the concentrate mixture from the control diet with 1.4% PG and 2.1% RUP. Both diets contained about 16% crude protein and 71% total digestible nutrients. Dry matter intake was similar between the two diets. Daily production of milk, milk lactose and milk solids-not-fat increased by 9.0%, 11.3% and 9.3%, respectively ( P  < 0.1), for cows fed diets with PG + RUP; milk composition was unchanged. Although the concentration of ruminal total volatile fatty acids was unchanged, the proportion of propionic acid increased, and the proportion of acetic acid decreased with PG + RUP. The concentration of ruminal ammonia nitrogen and number of ciliate protozoa was not significantly affected by PG + RUP. The concentration of glucose in blood plasma increased, the concentration of urea nitrogen was unaffected, and the concentration of some essential free amino acids decreased with PG + RUP. It is suggested that these changes might be caused predominantly by PG, and the addition of PG may exert a favorable effect on milk production through increased metabolism.  相似文献   
6.
To investigate seasonal variations in the digestive functions of sika deer, five female sika deer were provided with an amount of alfalfa hay cubes equivalent to voluntary food intake during winter. We measured the rate at which the food passed through the digestive tract, digestibility and rumen fermentation during the summer (August), autumn (November), winter (February) and spring (May). Total mean retention time in the digestive tract during summer and autumn was numerically longer than that in winter and spring, but the difference did not reach significance. Organic matter and fiber were less digestible in summer and autumn than in winter and spring (P < 0.05), whereas the digestibility of the dry matter tended to vary with the seasons (P < 0.1). Ruminal pH values seasonally changed (P < 0.01), and were the lowest in autumn. The concentration of ruminal ammonia‐nitrogen differed significantly among the seasons (P < 0.05), increasing in winter and decreasing during spring and summer. The numbers of protozoa changed significantly among the seasons (P < 0.05), being higher in autumn than in winter and spring, and intermediate in summer. The concentration of total volatile fatty acids was not seasonally affected, but the molar percentages of propionic acid and butyric acid significantly changed according to season (P < 0.05 and P < 0.01, respectively), and the ratio of acetic to propionic acid tended to change with the seasons (P < 0.1). The results of this study suggested that the digestive functions in sika deer, fed a commercial diet at a restricted level, differed notably among the seasons and these variations might partially be due to environmental effects.  相似文献   
7.
To further our understanding of wood decay in living light red meranti (Shorea smithiana) trees, microscopic characteristics of the cell and cell wall degradations of S. smithiana wood in the presence of the decay fungi, the identity of the causal fungi, and the decay potential and pattern by an isolated fungus were investigated. Cell wall degradations, including cell wall thinning, bore holes formation, rounded pit erosion, and eroded channel opening were clearly observed under light and scanning electron microscopy. In transverse view, many large voids resulting from a coalition of degraded wood tissue appeared in the decayed canker zone. All these observations suggest the well-known simultaneous decay pattern caused by white-rot fungi. By phylogenetic analysis based on the sequences of internal transcribed spacer region of ribosomal DNA, a basidiomycete fungus isolated from the decayed wood was identified as Schizophyllum commune. The degradation caused by this fungus on sound S. smithiana wood in an in situ laboratory decay test was classified as the early stage of simultaneous decay, and showed a similar pattern to that observed in the wood samples naturally decayed.  相似文献   
8.
We investigated the effects of warming the basal ends of Carolina poplar (Populus × canadensis Moench.) softwood cuttings at controlled low-air-temperature on their root growth and leaf damage after planting. The warming treatment was applied to the cuttings by soaking 10 mm beyond the cut end in warmed water maintained at 30 °C in a cold chamber maintained at an air temperature of 10 °C and a photosynthetic photon flux density (PPFD) of 10 μmol m?2 s?1 (near the light compensation point at 10 °C) until rooting was observed. The warmed cuttings were then grown in a growth chamber at an air temperature of 30 °C, relative humidity 85–90 %, and a PPFD of 100 μmol m?2 s?1. Control cuttings were grown in the growth chamber throughout the experiment. Rooting occurred simultaneously for both warmed and control cuttings, irrespective of air temperature. Root development was greater and leaf damage, evaluated on the basis of extent of necrosis, was less for warmed cuttings than for control cuttings. The reduction of leaf damage for warmed cuttings probably resulted from reduced post-planting water stress and leaf senescence, because of improved root development as a result of the pre-planting warming treatment. This technique could improve the propagation of cuttings of woody plants, because it would ensure that the cuttings are ready to develop roots with minimum loss of carbohydrates, irrespective of weather conditions.  相似文献   
9.
To improve the propagation of Japanese cedar (Cryptomeria japonica D. Don), we investigated the effects of apical and basal temperatures during a water soaking treatment on the adventitious root formation of 70-mm long shoot tip cuttings which have an apical bud. The basal portion of the cuttings was soaked for 28 days in water with temperatures ranging from 10 to 35 °C, at an air temperature of 5 or 10 °C. Control cuttings were soaked in water at 25 °C, with an air temperature of 25 °C. Treated cuttings were then planted in vermiculite rooting medium and grown at an air temperature of 25 °C for 35 days. Adventitious roots initiated earlier and developed more in the cuttings treated with apical temperatures of 5 or 10 °C and basal temperatures of 20–30 °C than in the control cuttings. The rooting percentage was greatest (93 %) in the cuttings treated with a 10/25 °C apical/basal temperature, whereas few control cuttings rooted (13 %). This suggests that the temperature gradient created by warming the basal portion of the cuttings while cooling their apical end stimulates adventitious root formation. When we tested seasonal variation of rootability at 10/25 °C, the rooting percentage increased from early autumn to winter, and decreased from winter to summer. The soluble sugar contents did not directly affect the formation of adventitious roots in the present study.  相似文献   
10.
The inhibitory effects of 102 methanol extracts of 40 mycelia, 9 culture fluids, and 53 fruiting bodies of 40 strains of Ganoderma lucidum on 5-reductase were investigated. The methanol extract of the fruiting body of each strain was found to show the strongest 5-reductase inhibitory activity among the extracts tested.  相似文献   
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