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101.
Wade T. Walker Robert J. Callan Ashley E. Hill Kelly B. Tisher 《The Canadian veterinary journal. La revue veterinaire canadienne》2014,55(8):765-771
This study evaluated the effects of administering oral powder electrolytes on packed cell volume (PCV), plasma chemistry parameters, and incidence of colic in horses participating on a 6-day 162-km trail ride in which water was not offered ad libitum. Twenty-three horses received grain with powder electrolytes daily while 19 control horses received grain only. Horses were ridden approximately 32 km a day at a walk or trot. Packed cell volume and plasma chemistry parameters were analyzed daily. Episodes of colic were diagnosed and treated by a veterinarian unaware of treatment group allocation. Blood parameters and incidence of colic were compared between treatment groups. Electrolyte administration did not alter PCV or plasma chemistry parameters compared to controls. The incidence of colic was significantly higher in treated horses (P = 0.05). Oral powder electrolytes did not enhance hydration status or electrolyte homeostasis and may be associated with colic in horses participating on long distance trail rides similar to this model. 相似文献
102.
Cassidy L. Klima Trevor W. Alexander Steve Hendrick Tim A. McAllister 《Canadian journal of veterinary research》2014,78(1):38-45
Mannheimia haemolytica is the principal bacterial pathogen associated with bovine respiratory disease (BRD). As an opportunistic pathogen, M. haemolytica is also frequently isolated from the respiratory tract of healthy cattle. This study examined the characteristics of M. haemolytica collected using deep nasal swabs from healthy cattle (n = 49) and cattle diagnosed with BRD (n = 41). Isolates were analyzed by pulsed-field gel electrophoresis (PFGE), serotyped, and tested for antimicrobial susceptibility. Polymerase chain reaction (PCR) was used to screen isolates for virulence [leukotoxin C (lktC), putative adhesin (ahs), outer-membrane lipoprotein (gs60), O-sialoglycoprotease (gcp), transferring-binding protein B (tbpB) and UDP-N-acetyl-D-glucosamine-2-epimerase (nmaA)] and antimicrobial resistance [tet(H), blaROB-1, erm(X), erm(42), msr(E)-mph(E) and aphA-1] genes. Isolates were genetically diverse but in three instances, M. haemolytica with the same pulsotype, resistance phenotype, and genotype were collected from cattle with BRD. This occurred once between cattle located in two different feedlots, once between cattle in the same feedlot, but in different pens, and once among cattle from the same feedlot in the same pen. Isolates from healthy cattle were primarily serotype 2 (75.5%) while those from individuals with BRD were serotype 1 (70.7%) or 6 (19.5%). Resistance to at least one antibiotic occurred more frequently (P < 0.001) in M. haemolytica collected from cattle with BRD (37%) compared with those that were healthy (2%). Overall, tetracycline resistance (18%) was the most prevalent resistant phenotype. All tetracycline-resistant M. haemolytica encoded tet(H). Ampicillin resistance (6%) and neomycin resistance (15%) were detected and corresponded to the presence of the blaROB-1 and aphA-1 genes, respectively. Tilmicosin resistance (6%) was also detected, but the resistance genes responsible were not identified. The virulence genes lktC, ahs, gs60, and gcp were present in all isolates examined, while tbpB and nmaA were only detected in serotype 1 and serotype 6 isolates indicating they may be potential targets for serotype-specific identification or vaccine development. These results provide the first reported evidence of transmission and spread of antimicrobial-resistant M. haemolytica that have contributed to bovine respiratory disease in western Canadian feedlots. 相似文献
103.
104.
Jie Zhou Zhiqiang Zhang Ge Sun Xianrui Fang Tonggang Zha Jiquan Chen Asko Noormets Junting Guo Steve McNulty 《Journal of Forest Research》2014,19(6):483-492
The water-use efficiency (WUE) of an ecosystem—defined as the gross ecosystem production (GEP) divided by the evapotranspiration (ET)—is an important index for understanding the coupling of water and carbon and quantifying water–carbon trade-offs in forests. An open-path eddy covariance technique and a microclimate measurement system were deployed to investigate the WUE of a poplar plantation ecosystem in the Daxing District of Beijing, China, during the growing seasons in 2006, 2007, and 2008. We found that WUE values changed diurnally, peaking in early morning and showing a minimum between 2 pm and 3 pm. This pattern was regulated by photosynthetically active radiation, saturated vapor pressure deficit, and stomatal opening and closure. WUE had inter-daily variations but no substantial seasonal variation. The WUE decreased with increasing soil water content due to the higher sensitivity of ET than GEP to increased soil moisture. Under moist soil conditions (i.e., relative extractable water content >0.4), GEP was stable and WUE was generally low. These results suggest that the poplar plantation does not effectively use the available soil water for carbon uptake, and that soil moisture is lost to the atmosphere through ET. 相似文献
105.
Otomar Linhart Steve D. Mims Boris Gomelsky Ana E. Hiott William L. Shelton Jacky Cosson Marek Rodina David Gela Jan Bastl 《Aquaculture International》2003,11(4):357-368
Changes in ionic composition as Na+,K+, Ca2+ and Mg2+, osmolality inseminal fluid, percentage of motile spermatozoaand velocity were investigated in response toCPP and different dosage of LHRHa. The lowestvelocity of sperm was observed after use CPPtreatment. The velocity of spermatozoa,significant main effect of the treatment(P < 0.0001) and the time of sperm collection(P < 0.0104) were evaluated. The osmolality ofseminal fluid was different betweenexperimental groups of LHRHa (48.0–62.7mOsmol.kg–1) and CPP (33.0–46.3mOsmol.kg–1) treatments. The osmolalitywas significantly higher on the first day andone-half, then declined on day three, rangingfrom 33.0 to 62.7 mOsmol.kg–1. Analysisof variance showed significant main effects ofthe treatment (P < 0.0001) and the time ofsperm collection (P < 0.0002) on the osmolalityof seminal fluid. The level of Na+ andK+ ion was different between experimentalgroups of LHRHa and CPP treatment. The highestconcentration of 11.11 mmol.l–1 wasobserved at Na+ ion. Then theconcentrations declined on the level 1.56, 0.52and 0.36 mmol.l–1 for K+, Ca2+and Mg2+ ions, respectively. There werehighly positive correlations between osmolalityof seminal fluid and dosage of LHRHa treatment(r = 0.84), velocity of spermatozoa andosmolality of seminal fluid (r = 0.57) andosmolality of seminal fluid and Na+concentration at seminal fluid (r = 0.70).Injection with LHRHa increased quality of spermas velocity of sperm, level of Na+,K+ and osmolality at seminal fluidcompared to CPP treatments. 相似文献
106.
107.
Rainbow trout, Oncorhynchus mykiss, were exposed to 48h of environmental hypoxia (water partial pressure of oxygen = 8.0 kPa) at either 5 or 15°C. Blood was sampled during hypoxia via a dorsal aorta cannula to measure arterial blood partial pressure of oxygen and plasma catecholamine concentrations. After 48h, the number (Bmax) and dissociation constant (Kd) of red blood cell surface -adrenoceptors were determined using a radioligand-displacement binding assay. At 5°C, plasma catecholamine levels were elevated at 24h whereas at 15°C, levels were elevated at 48h. At either temperature, following 48h of hypoxia, there was no change in Bmax or Kd of red blood cell surface -adrenoceptors, compared to normoxic control fish. This study demonstrates that chronic exposure to moderate hypoxia does not affect the number or affinity of cell surface -adrenoceptors on trout red blood cells. 相似文献
108.
Bob Goodband Mike Tokach Steve Dritz Joel DeRouchey Jason Woodworth 《畜牧与生物技术杂志(英文版)》2014,(3):251-261
Immune system activation begins a host of physiological responses. Infectious agents are recognized by monocytes and macrophages which in turn stimulate cytokine production. It is the hormone-like factors called cytokines that orchestrate the immune response. The classic responses observed with immune system activation and cytokine production include: anorexia, fever, lethargy, recruitment of other immune cells, and phagocytosis. While production of immune system components is known to require some amino acids, increases in amino acid requirements are more than offset by the associated decrease in protein accretion and increased muscle protein degradation that also accompanies immune system activation. However, the biggest impact of cytokine production is a decrease in feed intake. Therefore, as feed intake decreases, the energy needed to drive protein synthesis is also decreased. This suggests that diets should still be formulated on a similar calorie:lysine ratio as those formulated for non-immune challenged pigs. The evidence is sparse or equivocal for increasing nutrient requirements during an immune challenge. Nutritionists and swine producers should resist the pressure to alter the diet, limit feed, or add expensive feed additives during an immune challenge. While immune stimulation does not necessitate changes in diet formulation, when pigs are challenged with non-pathogenic diarrhea there are potential advantages on gut health with the increased use of crystalline amino acids rather than intact protein sources (i.e., soybean meal). This is because reducing crude protein decreases the quantity of fermentable protein entering the large intestine, which lowers post weaning diarrhea. It also lowers the requirement for expensive specialty protein sources or other protein sources such as soybean meal that present immunological challenges to the gut. The objective of this review is two-fold. The first is to discuss immunity by nutrition interactions, or lack thereof, and secondly, to review amino acid re 相似文献
109.
Immune system activation begins a host of physiological responses. Infectious agents are recognized by monocytes and macrophages which in turn stimulate cytokine production. It is the hormone-like factors called cytokines that orchestrate the immune response. The classic responses observed with immune system activation and cytokine production include: anorexia, fever, lethargy, recruitment of other immune cells, and phagocytosis. While production of immune system components is known to require some amino acids, increases in amino acid requirements are more than offset by the associated decrease in protein accretion and increased muscle protein degradation that also accompanies immune system activation. However, the biggest impact of cytokine production is a decrease in feed intake. Therefore, as feed intake decreases, the energy needed to drive protein synthesis is also decreased. This suggests that diets should still be formulated on a similar calorie:lysine ratio as those formulated for non-immune challenged pigs. The evidence is sparse or equivocal for increasing nutrient requirements during an immune challenge. Nutritionists and swine producers should resist the pressure to alter the diet, limit feed, or add expensive feed additives during an immune challenge. While immune stimulation does not necessitate changes in diet formulation, when pigs are challenged with non-pathogenic diarrhea there are potential advantages on gut health with the increased use of crystalline amino acids rather than intact protein sources (i.e., soybean meal). This is because reducing crude protein decreases the quantity of fermentable protein entering the large intestine, which lowers post weaning diarrhea. It also lowers the requirement for expensive specialty protein sources or other protein sources such as soybean meal that present immunological challenges to the gut. The objective of this review is two-fold. The first is to discuss immunity by nutrition interactions, or lack thereof, and secondly, to review amino acid requirement estimates for nursery pigs. 相似文献
110.
Steve Edwards 《Aquaculture Research》2003,34(14):1361-1365
The early physiological response (3 days) of greenlip (Haliotis laevigata Leach) and blacklip (H. rubra Leach) abalone to a single abrupt change in salinity was monitored using a multi‐channel open‐circuit respirometer. The range of salinity tolerance for both species in this trial was 25–40 ppt. Indications from other trials were that a margin of 2 ppt outside this range will cause mortality. Serum volume was increased by reduced salinity as much as 25% in the short term, with equilibration of the concomitant whole body weight increase (9.2±0.5%) occurring within 1 h. The serum volume appeared to be decreased at high salinity. There was little underlying change in basal oxygen usage levels, but significant behavioural changes that affected overall oxygen consumption. Both high and low salinity appeared to reduce activity. Animals in low salinity exhibit partial recovery of activity levels after 1 day in a manner similar to other stress responses. Animals at high salinity (40 ppt) did not show recovery of activity levels over 3 days. Overall, these results suggest that greenlip and blacklip abalone will have little trouble tolerating moderately low‐salinity environments. 相似文献