遮光及增加UV-B辐射对高寒草甸矮嵩草光合色素以及光合作用的影响

以矮嵩草草甸上天然太阳辐射为背景,建立人工增强太阳UV-B辐射和遮光装置,分别模拟平流层臭氧损耗5%时近地面的太阳UV-B辐射和滤去40%-60%的太阳辐射强度。结果表明,经过40多天的增强UV-B辐射处理降低了矮嵩草光合色素的含量以及Chla/b的比值,而使Chlb/(a b)比值上升。增强UV-B辐射还使矮嵩草的光合速率、呼吸速率以及表观量子效率(AQY)下降。遮光处理使得矮嵩草光合色素含量上升,Chla/b和Chlb/(a b)比值基本不变。遮光处理还提高了矮嵩草的光合速率、呼吸速率以及表观量子效率(AQY)。     

高寒草甸矮嵩草种群光合作用及群落生长季节变化

对海北高寒草甸矮嵩草种群生长季光合作用及群落生长参数的测定表明,矮嵩草种群 最大光合速率及表观量子效率的季节变化为6月＞7月＞8月＞9月;群落地上净生物量及叶面积指数在生长季内呈上升趋势,地上净生物量增长速率和叶面积指数增长速率为6月＞7月＞8月＞9月,其中9月份均为负增长。矮嵩草种群季节内的光合作用能力与群落的生产力密切相关。     

不同环境条件下几种高寒草甸植物的非克隆繁殖投入和生长

通过对高寒草甸生态系统金露梅灌丛、矮嵩草草甸、围栏矮嵩草草甸以及模拟地球增温效应下5种植物繁殖投入和生长特性的测定,结果表明,矮嵩草、麻花艽、苔草以及美丽风毛菊的叶长沿对照矮嵩草草甸、0TC、围栏以及金露梅灌丛呈现上升趋势,只是灌丛中苔草和麻花艽两种植物的叶长较围栏和OTC有所下降,而环境变化对植物的叶宽的影响较小。苔草在金露梅灌丛中的繁殖投入最大,其次是矮嵩草草甸和围栏,OTC中苔草的繁殖投入几乎为零。围栏与矮嵩草草甸内苔草的繁殖投入差异不显著,而两者中植物的繁殖投入与金露梅灌丛相比,差异性显著(P<0.05)。矮火绒草在矮嵩草草甸中的繁殖投入最大,其次是0Tc和围栏,灌丛中矮火绒草的繁殖投入最小。OTC与矮嵩草草甸内矮火绒草的繁殖投入差异不显著,而OTC与围栏中矮火绒草的繁殖投入差异性显著(P<0.05)。由此我们可以得出一个结论:繁殖投入随环境梯度的变化,反映了植物繁殖对策和繁殖投入在整个生活史特征中的可塑性。     

放牧对高寒草地4种草光响应和荧光特性的影响

在祁连山东段天祝县南泥沟河谷地的披碱草-嵩草型草地设置禁牧(Non grazing grassland,NG)和放牧(Grazing grassland,G)两块样地,选取矮嵩草(Kobresia humilis)、垂穗披碱草(Elymus nutans)、扁蓿豆(Melissitus rutenica)、黄花棘豆(Oxytropis ochrocephala)4种优势植物,测定了4种植物的光合-光响应曲线(Pn PAR curves)和叶绿素荧光特性。结果显示,4种植物在放牧后：1)对强光的适应能力增强而对弱光的利用能力降低。垂穗披碱草、矮嵩草、扁蓿豆的最大净光合速率(Pmax)显著降低,即光合潜力降低;而黄花棘豆的Pmax却显著升高,光合能力增强。2)叶绿素初始荧光(F0)成像颜色加深,说明叶绿素含量有所降低,尤以垂穗披碱草、矮嵩草最为明显。3)PSⅡ最大量子产量(Fv/Fm)、光化学猝灭系数(qP)、电子传递速率(ETR)值显著降低,而非光化学猝灭系数(NPQ)值升高。综合各项指标来看,放牧后黄花棘豆这种毒草的光合能力提高,而其他3种优质牧草的光合能力下降。     

不同环境条件下几种高寒草甸植物的非克隆繁殖投入和生长

通过对高寒草甸生态系统金露梅灌丛、矮嵩草草甸、围栏矮嵩草草甸以及模拟地球增温效应下5种植物繁殖投入和生长特性的测定,结果表明,矮嵩草、麻花艽、苔草以及美丽风毛菊的叶长沿对照矮嵩草草甸、OTC、围栏以及金露梅灌丛呈现上升趋势,只是灌丛中苔草和麻花艽两种植物的叶长较围栏和OTC有所下降,而环境变化对植物的叶宽的影响较小.苔草在金露梅灌丛中的繁殖投入最大,其次是矮嵩草草甸和围栏,OTC中苔草的繁殖投入几乎为零.围栏与矮嵩草草甸内苔草的繁殖投入差异不显著,而两者中植物的繁殖投入与金露梅灌丛相比,差异性显著(P＜0.05).矮火绒草在矮嵩草草甸中的繁殖投入最大,其次是OTC和围栏,灌丛中矮火绒草的繁殖投入最小.OTC与矮嵩草草甸内矮火绒草的繁殖投入差异不显著,而OTC与围栏中矮火绒草的繁殖投入差异性显著(P＜0.05).由此我们可以得出一个结论繁殖投入随环境梯度的变化,反映了植物繁殖对策和繁殖投入在整个生活史特征中的可塑性.     

封育措施对退化与未退化矮嵩草草甸的影响

连续5年的封育处理对退化与未退化矮嵩草草甸产生了影响.研究表明,除了退化矮嵩草草甸内的均匀度指数下降不显著外,封育使两种矮嵩草草甸样地内的丰富度指数、多样性指数和均匀度指数下降都达显著水平.两种矮嵩草草甸的上下层高度均增加,其中未退化矮嵩草草甸增加显著,退化矮嵩草草甸增加不显著.两种矮嵩草草甸的枯草盖度增加显著,绿草盖度减少显著,各种群特征发生了有规律的消长.未退化矮嵩草草甸的莎草和杂类草地上生物量减少显著,枯草生物量增加显著,禾草和优良牧草的生物量以及总地上生物量增加不显著,优良牧草比例由0.57下降为0.48.退化矮嵩草草甸在封育条件下,枯草、禾草生物量增加显著,莎草、优良牧草的生物量及总生物量增加不显著,优良牧草比例则由0.29上升为0.48,达到显著水平.未退化矮嵩草草甸的草地质量指数明显下降,退化矮嵩草草甸的草地质量指数则明显上升.     

大麦黄矮病毒侵染对燕麦光合及叶绿素荧光参数的影响

为探究燕麦在蚜虫和大麦黄矮病毒（Barley Yellow Dwarf Virus,BYDV）为害后的光合生理响应,本试验测定了燕麦接种蚜虫和BYDV后不同时间（0,7,14,21,28和35 d）的叶片光合和叶绿素荧光参数。结果表明,随着为害时间的延长,叶片叶绿素a（Chl a）、叶绿素b（Chl b）以及总叶绿素（T-Ch1）含量显著降低（P<0.05）,类胡萝卜素（Car）含量显著增加（P<0.05）,Chl a/Chl b先上升后稍有下降,接种BYDV 21 d后,Chl a/Chl b均增加至最大值,比CK处理高57.37%（P<0.05）;叶片净光合速率和水分利用效率下降,胞间CO₂浓度、气孔导度和蒸腾速率上升;同时最大荧光、潜在光化学效率、最大光化学效率、光化学淬灭系数、PS Ⅱ光化学量子产量和表观光合电子传递速率均呈现下降的趋势,非光化学猝灭系数上升。本研究表明BYDV侵染严重损伤了燕麦叶片的光合作用能力,其光合参数发生了显著变化,为探讨BYDV与燕麦的互作机理提供了一定的参考依据。     

海北高寒草甸矮嵩草色素及抗氧化物质动态分析

对海北高寒草甸优势种矮嵩草色素以及多种抗氧化物质的含量分析研究,结果表明,矮嵩草（Kobresiahumilis）对其生存的环境有极其强的适应能力,对矮嵩草草甸的生产力的维持具有积极作用。矮嵩草的叶绿素a、b和总叶绿素含量6,7月份达到最大;Chlb／（a＋b）有微弱的下降趋势,Car／Chl（a＋b）有明显的下降趋势;O2-含量的变化呈现下降趋势,与抗坏血酸含量的变化是负相关;叶黄素循环组分玉米黄质于505nm波长处最大吸收峰在6月和7月达到最大,与叶绿素及光强的变化趋势相吻合;SOD的含量却呈现非规律变化。     

遮荫环境对白三叶草气孔和光合特性的影响

为弄清遮荫环境影响白三叶草Trifolium repens生长的机理,对不同光照条件下生长的白三叶草的气孔特性和光合特性进行了比较研究.较强生境光照条件下,白三叶草的气孔密度较大;中叶与侧叶气孔密度差异不显著,不同生境光照条件对气孔分布无显著影响.较强生境光照条件下,白三叶草的光合、气孔导度和胞间CO2浓度较高,而蒸腾却较小.不同生境光照条件下白三叶草对CO2和光的响应趋势类似,但较强生境光照条件下CO2补偿点、羧化效率和光合能力均较其他两区低,而表观量子效率和暗呼吸速率最高.结果表明,较强生境光照增加了白三叶草的气孔密度,提高了光合速率,但却降低了其光合能力.     

青藏高原高寒草甸土壤N_2O排放通量对温度和湿度的响应

试验采用室内培养的方法研究了青藏高原矮嵩草草甸土壤氧化亚氮(N2O)排放通量对土壤温度和湿度的响应过程。结果表明:随培养温度增加,培养初期矮嵩草草甸土壤N2O排放速率逐渐降低(P0.05),最高排放速率为4.75±0.24g/(kg·h),最低排放速率仅为2.92±0.19g/(kg·h);而经过7d培养,高寒草甸土壤N2O排放速率先降低,而且转变为弱汇,而后升高,30℃时最高,为0.67±0.06g/(kg·h),各处理均显著低于短期培养时排放速率(P0.05);随土壤湿度增加,短期培养矮嵩草草甸土壤N2O排放速率先降低随后升高,在土壤湿度为60%时排放速率最高,为(3.62±0.38)g/(kg·h),而在75%时排放速率最低,为(3.38±0.25)g/(kg·h);随着培养时间延长,高寒草甸土壤N2O排放速率逐渐降低,最高排放速率为(0.55±0.32)g/(kg·h);土壤湿度分别为45%和温度为20℃、以及60%和30℃时,1d和7d培养矮嵩草草甸土壤N2O排放速率最高;而在土壤湿度为45%和30℃、以及75%和30℃时,1d和7d培养矮嵩草草甸土壤N2O排放速率最低,后者呈现吸收现象,吸收速率约为-1.84g/(kg·h)。     

Effect of silage chop length on feed intake and feeding behaviour of finishing feedlot steers

This study determined the effects of silage chop length (20?mm; long or 10?mm; short) and diurnal time on feeding behaviour of 80 feedlots steers. Feed intake and feeding behaviour of each steer in each pen were measured continuously from 0:00 to 12:00?h (AM) and from 12:00 to 24:00?h (PM). Chop length had no effect on feed intake or the growth performance of steers, but longer chop length increased the duration of feeding and reduced the rate of intake. Head down time and head down time per feeding activities were greater during the PM than AM. There was a chop length?×?diurnal time interaction for feeding frequency with the number of bunk visits being greater in the PM than AM for both diets. Feeding activities were 50% higher during the PM than AM when steers were fed either long- or short-chopped silage diets twice daily.     

茬次和一天内不同收获时间对紫花苜蓿青贮发酵质量和体外发酵参数的影响

为了研究茬次和一天内不同收获时间对紫花苜蓿青贮饲料品质的影响,并进一步评价其饲用价值,本试验采用双因素设计,两茬紫花苜蓿于现蕾期同一天08：00（AM）,13：00（M）和18：00（PM）刈割并调制青贮饲料,室温下保存45 d后,取样分析并采用体外发酵法评价其饲用价值。结果表明,第1茬紫花苜蓿青贮饲料的相对饲喂价值（relative feed value,RFV）,干物质体外消化率（in vitro dry matter digestibility,IVDMD）及体外发酵挥发性脂肪酸（volatile fatty acids,VFA）、产气量均显著高于第2茬（P<0.05）。下午收获的紫花苜蓿青贮饲料有更高的干物质（dry matter,DM）含量及IVDMD （P<0.05）。因此,在实践生产中,要抓好第1茬的苜蓿生产,推迟刈割时间至中午或下午,可获得更高品质的紫花苜蓿青贮饲料。     

Postprandial changes in leptin concentrations of cerebrospinal fluid in dogs during development of obesity

OBJECTIVE: To evaluate postprandial changes in the leptin concentration of CSF in dogs during development of obesity. ANIMALS: 4 male Beagles. PROCEDURES: Weight gain was induced and assessments were made when the dogs were in thin, optimal, and obese body conditions (BCs). The fat area at the level of the L3 vertebra was measured via computed tomography to assess the degree of obesity. Dogs were evaluated in fed and unfed states. Dogs in the fed state received food at 9 AM. Blood and CSF samples were collected at 8 AM, 4 PM, and 10 PM. RESULTS: Baseline CSF leptin concentrations in the thin, optimal, and obese dogs were 24.3 +/- 2.7 pg/mL, 86.1 +/- 14.7 pg/mL, and 116.2 +/- 47.3 pg/mL, respectively. In the thin BC, CSF leptin concentration transiently increased at 4 PM. In the optimal BC, baseline CSF leptin concentration was maintained until 10 PM. In the obese BC, CSF leptin concentration increased from baseline value at 4 PM and 10 PM. Correlation between CSF leptin concentration and fat area was good at all time points. There was a significant negative correlation between the CSF leptin concentration-to-serum leptin concentration ratio and fat area at 4 PM; this correlation was not significant at 8 AM and 10 PM. CONCLUSIONS AND CLINICAL RELEVANCE: Decreased transport of leptin at the blood-brain barrier may be 1 mechanism of leptin resistance in dogs. However, leptin resistance at the blood-brain barrier may not be important in development of obesity in dogs.     

Evaluation of the Environmental Indices in a Beef Cattle Farm in the North of Xinjiang

In order to obtain the basic information of the environmental situation for beef cattle production in Yili area,the environmental indices detected from a typical collective beef cattle farm were evaluated.CO₂,NH₃ and CH₄,luminosity,temperature,humidity and noise,PM10 and TSP of the beef cattle cowshed were measured for consecutive 10 days in the spring.The results showed that in the spring,the daylight time was about 10 h from 08:00 to 18:00,and the average value of luminosity,temperature,humidity and noise were 105.61 Lux,16.30 ℃,49.56% and 64.59 dB,respectively;The average value of CH₄,CO₂ and NH₃ concentrations were 0.09,880.91 and 0.51 mg/m³,respectively;The average value of PM10 and TSP concentrations were 0.030 and 0.010 mg/m³,respectively.By zooming in the day and hour fluctuation of above measured environmental indices it was found that the average temperature in this cowshed was over the maximum limit of national standard from 11:00 to 24:00 lasting for about 13 hours.It was concluded that the general environment in this area was suitable for beef cattle production except the temperature in this cowshed needs to be improved for providing better welfare for beef cattle.     

新疆北疆地区某集约化肉牛养殖场春季环境指标评价

为了解新疆伊犁地区昭苏县肉牛养殖环境状况,评价其环境质量,本研究对该县某典型集约化肉牛养殖场的相关环境指标进行了测定。采用DT-8820四合一多功能环境表(光照强度、温度、湿度、噪音)、智能气体检测报警仪(二氧化碳(CO₂)、氨气(NH₃)、甲烷(CH₄))和LD-5C微电脑激光粉尘仪(可吸入颗粒物(PM10)和总悬浮颗粒物(TSP))对新疆昭苏县某集约化肉牛养殖场肉牛舍春季(4月下旬)上述环境指标进行为期10 d的测定。结果表明,该牛舍春季每天采光时间为08:00~18:00,约10 h;光照强度、温度、湿度和噪音平均值分别为105.61 Lux、16.30 ℃、49.56%和64.59 dB;CH₄、CO₂和NH₃浓度平均值分别为0.09、880.91和0.51 mg/m³;PM10和TSP浓度平均值分别为0.030和0.010 mg/m³。通过对上述指标的日周期和时周期变化可发现牛舍平均温度超过国标最高限值,持续时间为11:00~24:00,约13 h。综上所述,除牛舍温度指标外,该牛舍测定的各项环境指标参数均符合畜禽养殖环境标准,该牛舍春季环境较适宜肉牛生产,但需要采取相应措施对牛舍温度进行调节以保证动物的福利需求。     

Effect of high temperature on physiological parameters of Nelore (Bos taurus indicus) and Caracu (Bos taurus taurus) cattle breeds

The climate-related problems that affect animal production in tropical countries have encouraged seeking solutions to increase herd productivity and one alternative is the use of breeds adapted to high-temperature environments. The objective of this study was to evaluate the effect of temperature on 77 Caracu and Nelore males submitted to three different environments: morning period (8:00 to 10:00 AM), afternoon in the sun, and afternoon in a shaded environment (11:00 AM to 1:00 PM). The following physiological parameters were measured in each treatment: heart and respiration rates, rectal and dorsal surface temperatures, and cortisol level. The data were analyzed with the MIXED procedure (SAS) and the model included the fixed effects of treatment (morning, sun, and shade), breed (Nelore and Caracu), month of measurement (December and February), and the interaction between effects. A higher dorsal surface temperature was observed in animals of both breeds in the sun treatment compared with the shade treatment. Caracu animals had a higher dorsal surface temperature than Nelore animals, which probably caused the higher rectal temperature observed in the sun treatment compared with the shade treatment in both breeds over the 2 months of the study. All physiological parameters measured in this study were efficient to detect the thermal stress in both breeds. Despite the variations in rectal temperature observed during the treatments, the animals of the two breeds exhibited no significant changes in heart rate, respiration rate, and cortisol level for the maintenance of thermal homeostasis. In conclusion, both breeds were considered tolerant to sun exposure, demonstrating adaptation of these animals to high-temperature environments, without evidence of harm to its health and welfare.

     

Renal effects of carprofen administered to healthy dogs anesthetized with propofol and isoflurane

OBJECTIVE: To evaluate renal effects of carprofen in healthy dogs following general anesthesia. DESIGN: Randomized clinical trial. ANIMALS: 10 English hound dogs (6 females and 4 males). PROCEDURE: Dogs were randomly assigned to control (n = 5) or carprofen (5) groups. Anesthesia was induced with propofol (6 to 8 mg/kg [2.7 to 3.6 mg/lb] of body weight, i.v.) and maintained with isoflurane (end-tidal concentration, 2.0%). Each dog underwent two 60-minute anesthetic episodes with 1 week between episodes, and mean arterial blood pressure was maintained between 60 and 90 mm Hg during each episode. Dogs in the carprofen group received carprofen (2.2 mg/kg [1 mg/lb], p.o.) at 9:00 AM and 6:00 PM the day before and at 7:00 AM the day of the second anesthetic episode. Glomerular filtration rates (GFR) were determined during each anesthetic episode by use of renal scintigraphy. Serum creatinine and BUN concentrations and the urine gamma-glutamyltransferase-to-creatinine concentration (urine GGT:creatinine) ratio were determined daily for 2 days before and 5 days after general anesthesia. RESULTS: Significant differences were not detected in BUN and serum creatinine concentrations, urine GGT:creatinine ratio, and GFR either between or within treatment groups over time. CONCLUSIONS AND CLINICAL RELEVANCE: Carprofen did not significantly alter renal function in healthy dogs anesthetized with propofol and isoflurane. These results suggest that carprofen may be safe to use for preemptive perioperative analgesia, provided that normal cardiorespiratory function is maintained.     

Effect of time of cisplatin administration on its toxicity and pharmacokinetics in dogs.

Cisplatin (90 mg/m2) was administered in a 5-minute bolus IV infusion to dogs at 8 AM (n = 6) or 4 PM (n = 6). Blood and urine samples were collected over a 4-hour period for statistical moment pharmacokinetic analysis. Mean urinary excretion rate of total platinum was increased, whereas mean plasma residence time of ultrafilterable platinum was decreased, in the group treated at 4 PM (PM group), compared with those treated at 8 AM (AM group). Over a 2-week postinfusion-monitoring period, both groups of dogs developed decreases in creatinine clearance, urine/serum osmolality ratio (UOsm/SOsm), specific gravity, and increase in BUN, serum creatinine concentration, urine gamma-glutamyltranspeptidase/urine creatinine ratio (UGGT/UCr), fractional excretion of magnesium, and fractional excretion of phosphate. Urine specific gravity and UOsm/SOsm were significantly decreased, whereas UGGT/UCr and BUN were significantly increased in the AM group, compared with the PM group. The time of administration had a significant effect on the pharmacokinetics of cisplatin, which resulted in significant differences in cisplatin-induced renal toxicosis.     

谷氨酰胺对热应激肉鸡S-IgA、血液内毒素和细胞因子的影响

选用1日龄科宝-500肉鸡240只,随机分为6个处理,每处理4个重复,每重复10只,Ⅰ组饲喂玉米-豆粕型基础日粮,Ⅱ、Ⅲ、Ⅳ、Ⅴ和Ⅵ组分别在基础日粮中添加0.4%、0.8%、1.2%、1.6%和2.0%的谷氨酰胺,试验时间15～42日龄,共28d。试验期间从每天09：00-17：00温度维持在（35±1）℃8h,17：00至次日09：00温度维持在（30±1）℃,鸡舍相对湿度控制在70%～80%。试验测定了热应激条件下21、28、35、42日龄肉鸡小肠黏膜分泌型免疫球蛋白含量A,血浆中血液内毒素含量和白介素-1、肿瘤细胞坏死因子含量。结果表明,日粮中添加谷氨酰胺显著提高了21、28、35、42日龄热应激肉鸡小肠黏膜分泌型免疫球蛋白含量（P〈0.05）,降低血浆中血液内毒素、白介素-1、肿瘤细胞坏死因子的含量（P〈0.05）。因此,在基础日粮中添加一定水平的谷氨酰胺可改善热应激肉鸡的肠道免疫性能。