How Does Heat-Stress Intensity Affect the Stability of Microbial Activity and Diversity of Soil Microbial Communities in Outfields and Homefields’ Cultivation Practices in the Senegalese Groundnut Basin?

Agroecosystems in the Senegalese groundnut basin experience long periods of high temperatures and drought, which disrupt the stability of soil microbial communities. This study evaluated how that stability is affected by homefields and outfields’ agricultural practices and the duration of heat stress. Specifically, we collected soils from organically farmed fields that receive continual high inputs of manure (homefields), and from fields that are rarely manured (outfields). Soil samples were submitted to artificial heat stress at 60°C for 3, 14, and 28 days, followed by 28 days of recovery at 28°C. We examined the functional stability of microbial communities by quantifying C mineralization, and characterized the stability of the communities’ taxonomic compositions via high-throughput DNA sequencing. We found that the microbial communities have a low resistance to heat stress in soils from both types of fields. However, the manuring practice does affect how the functional stability of microbial communities responds to different durations of heat stress. Although functional stability was not recovered fully in either soil, microbial community resilience seemed to be greater in homefield soils. Differences in manuring practices also affected the structural taxonomic stability of microbial communities: relative abundances of Bacilli, Chloroflexia, Actinobacteria and Sordariomycetes increased in the homefield stressed-soils, but decreased significantly in outfield soils. In contrast, relative abundances of α-Proteobacteria, γ-Proteobacteria and Eurotiomycetes increased significantly in outfield stressed-soils, while decreasing significantly in the homefield soils. Relative abundances of Bacilli changed little in outfield soils, indicating that this taxon is resistant to heat stress. In summary, the microbial communities’ capacities to resist heat stress and recover from it depend upon the organic richness of the soil (i.e., manuring practice) and the adaptation of soil microbes to environmental conditions.

Physiological and Biochemical Effects of 24-Epibrassinolide on Heat-Stress Adaptation in Maize (Zea mays L.)

Brassinosteroids (BRs) are a family of about 70 structurally related polyhydroxy steroidal phytohormones that regulate a number of physiological processes in plants. Among these, brassinolide (BL), 28-homobrassinolide (28-homoBL) and 24-epibrassinolide (24-EpiBL) are more common. The present study aims at studying the usefulness of 24-epiBL in ameliorating the impacts of heat-stress in maize along with its role in regulating cellular antioxidant defense system. Maize hybrid PMH 3 was grown in pots in a green house maintained at 14 hours day (25℃)/10hours night (17℃). A solution of 24-epiBL (1 μM) was applied externally at V4 stage. Leaf tissues were sampled from both treated and control plants. Subsequently, both the groups of pots were placed in plant growth chamber maintained at high temperature (48℃;RH 50%). Plants were sampled for biochemical analysis after 3, 6, 9, 24 and 48 hours of high temperature exposure. Exogenous application of 24-EpiBL arrested protein degradation and enhanced cell membrane stability, as compared to the control. The biochemical activities of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD) and peroxidase (POX) were found to be dynamically and variably modulated post 24-epiBL treatment. Thus, the study supports the role of BRs as anti-stress agents.

Effects of Compound Acidifier on Growth Performance and Serum Biochemical Parameters of Heat-stressed Wenchang Chickens

[Objective]The paper was to investigate the effects of compound acidifier on growth performance and serum biochemical parameters of heat-stressed Wenchang chickens.[Method]A total of 28881-day-old Wenchang chickens with the same genetic background and similar initial weight(985.63±20.35 g)were randomly divided into four groups,four replicates per group and 18 chickens per replicate.Birds were fed the basal diet supplemented with 0 g/kg(control group),1 g/kg(groupⅠ),2 g/kg(groupⅡ)and 3 g/kg(groupⅢ)compound acidifier.The trial lasted 35 d.[Result]The daily gain of experimental groupⅠwas significantly higher than those of control group and groupⅢ(P<0.05),and the feed intake of experimental groupⅠwas also markedly higher than that of control group(P<0.05),but the feed gain ratio of experimental groupⅠwas significantly lower than that of groupⅢ(P<0.05).Compared with control group,the serum total protein and albumin levels of experimental groupⅠincreased(P>0.05),but the serum uric acid concentration decreased(P>0.05).[Conclusion]Supplementing 1 g/kg compound acidifier could improve the growth performance of heat-stressed Wenchang chickens.

Milk production and composition and metabolic alterations in the mammary gland of heat-stressed lactating dairy cows

This experiment was conducted to investigate the effects of heat stress(HS) on the feed intake, milk production and composition and metabolic alterations in the mammary gland of dairy cows. Twenty Holstein cows were randomly assigned to one of two treatments according to a completely randomized design. Half of the cows were allocated to the HS group in August(summer season), and the other half were assigned to the HS-free group in November(autumn season). HS reduced(P<0.01) dry matter intake(DMI), milk yield, milk protein and milk urea nitrogen(MUN) of cows compared with HSfree control, but increased(P<0.01) milk somatic cell counts(SCC). We determined the HS-induced metabolic alterations and the relevant mechanisms in dairy cows using liquid chromatography mass spectrometry combined with multivariate analyses. Thirty-four metabolites were identified as potential biomarkers for the diagnosis of HS in dairy cows. Ten of these metabolites, glucose, lactate, pyruvate, lactose, β-hydroxybutyrate, citric acid, α-ketoglutarate, urea, creatine, and orotic acid, had high sensitivity and specificity for HS diagnoses, and seven metabolites were also identified as potential biomarkers of HS in plasma, milk, and liver. These substances are involved in glycolysis, lactose, ketone, tricarboxylic acid(TCA), amino acid and nucleotide metabolism, indicating that HS mainly affects lactose, energy and nucleotide metabolism in the mammary gland of lactating dairy cows. This study suggested that HS might affect milk production and composition by affecting the feed intake and substance metabolisms in the mammary gland tissue of lactating dairy cows.

Effects of Bupleurum extract on blood metabolism, antioxidant status and immune function in heat-stressed dairy cows

This experiment was conducted to evaluate the effects of Bupleurum extract （BE） on blood metabolites, antioxidant status, and immune function in dairy cows under heat stress. Forty lactating Holstein cows were randomly assigned to 1 of 4 treatments. The treatments consisted of 0, 0.25, 0.5, and 1.0 g of BE kg-1 dry matter. Supplementation with BE decreased （P〈0.05） blood urea nitrogen （BUN） contents and increased blood total protein （TP） and albumin （ALB） levels compared with control cows, but it had no effects （P〉0.05） on blood glucose （GLU）, nonesterified fatty acid （NEFA）, total triglycedde （TG）, low-density lipoprotein cholesterol （LDL-C）, and high density lipoprotein cholesterol （HDL-C）. Compared with control cows, cows fed BE had higher （P〈0.05） superoxide dismutase （SOD） and glutathione peroxidase （GSH-Px） activity. However, supplementation with BE had no effect （P〉0.05） on total antioxidant capacity （T-AOC） or malondialdehyde （MDA） levels. The immunoglobulin （Ig） A and G contents increased （P〈0.05） in cows fed 0.25 or 0.5 g of BE kg-1. Interleukin （IL）-2 and IL-4 levels were higher （P〈0.05） in cows fed 0.5 and 1.0 g of BE kg-1, and IL-6 was significantly elevated （P〈0.05） in cows fed 0.5 g of BE kg-1. There were no treatment effects （P〉0.05） on the CD4＋ and CD8＋ T lymphocyte ratios, CD4＋/CD8＋ratio, or tumor necrosis factor-α （TNF-α） level among the groups. These findings suggest that BE supplementation may improve protein metabolism, in addition to enhancing antioxidant activity and immune function in heat-stressed dairy cows.

Predicting heat-stressed EEG spectra by self-organising feature map and learning vector quantizers——SOFM and LVQ based stress prediction

Self-Organising Feature Map (SOFM) along with learning vector quantizers (LVQ) have been designed to identify the alterations in brain electrical potentials due to exposure to high environmental heat in rats. Three groups of rats were considered—acute heat stressed, chronic heat stressed and control groups. After long EEG recordings following heat exposure, EEG data representing three different vigilance states such as slow wave sleep (SWS), rapid eye movement (REM) sleep and AWAKE were visually selected and further subdivided into 2 seconds long epoch. In order to evaluate the performance of artificial neural network (ANN) in recognizing chronic and acute effects of heat stress with respect to the control subjects, unsupervised learning algorithm was applied on EEG data. Mean performance of SOFM with quadratic taper function was found to be better (chronic-92.6%, acute-93.2%) over the other two tapers. The effect of LVQ after the initial SOFM training seems explicit giving rise to considerable improvements in performance in terms of selectivity and sensitivity. The percentage increase in selectivity with uniform taper function is maximum for chronic and its control group (4.01%) and minimum for acute group (1.29%) whereas, with Gaussian it is almost identical (chronic-2.57%, acute-2.03%, control- 2.33%). Quadratic taper function gives rise to an increase of 2.41% for chronic, 1.96% for acute and 2.91% for control patterns.

Overall Performance, Carcass Yield, Meat Safety Potentials and Economic Value of Heat-Stressed Broilers Fed Diets with Balanced Electrolytes

Tropical regions across the globe are characterized by an annually prolonged hot weather conditions that showcase limiting production efficiency in livestock industry, as domesticated animals leave the zone of maximum comfort, under heat stress, with death and reduced carcass yield accompanying the subsequent alteration in body chemistry and behavior. However, pen house orientation, cooling systems, genetic modification and different dietary manipulations have been employed in poultry industry, but many of such did not account for the body’s acid-base equilibrium and the potentials of aggregate levels of dietary electrolytes in enhancing carcass yield of broilers under severe heat stress conditions. Therefore, this study was conducted to investigate the effects of different electrolyte-balanced diets on overall performance, carcass yield, meat safety potentials and economic value of heat-stressed broilers reared for five weeks. Arbor Acre broiler chicks (n = 300) were randomly allotted to diets with aggregate electrolyte balance of 210 (T1), 240 (T2), 270 (T3), 300 (T4), 330 (T5) and 360 (T6) mEq/Kg, in a completely randomised design. On day 35, birds whose weights were closest to the mean class weight were selected from each replicate pen for carcass yield assessment. Also, data on performance and cost-benefit analysis were analysed using descriptive statistics and ANOVA at α = 0.05. Electrolyte-balanced diets though contained salts that presumably could have improved satiety, yet they do not enhance appetite in heat-stressed broilers. However, dietary protein efficiency was enhanced at an electrolyte balance levels of 240 and 270 mEq/kg, which translated into increased body weight gain. Weights of primal parts of birds on 270 mEq/kg DEB were highest at 35 days. Feed cost values (per kilogram weight gain) of rations with 240 mEq/kg and 270 mEq/kg DEB were lower and showcased promising economic buoyancy to both rural and commercial poultry farmers, while ensuring a high food safety standard under tropical conditions.

热处理对选区激光熔化Al-Mn-Mg-Sc-Zr合金力学性能和腐蚀行为的影响

以Al-4.77Mn-1.37Mg-0.67Sc-0.25Zr(质量分数,%)合金粉末为原料,在激光功率330 W和扫描速率700 mm/s下进行选区激光熔化(Selective laser melting,SLM)形成SLM Al-Mn-Mg-Sc-Zr合金,结合慢应变速率拉伸实验、电化学测试、析氢浸泡实验及显微组织表征手段,分析了(350℃,8 h)热处理对SLM Al-Mn-Mg-Sc-Zr合金力学性能和腐蚀行为的影响。结果表明:SLM Al-Mn-Mg-Sc-Zr合金力学性能优异,抗拉强度、屈服强度和伸长率分别为423 MPa、376 MPa和25.1%。热处理后,SLM Al-Mn-Mg-Sc-Zr合金晶内析出大量针棒状纳米Al_(6)Mn相,抗拉强度和屈服强度分别提升至509 MPa和478 MPa。此外,SLM Al-Mn-Mg-Sc-Zr合金具有良好的耐蚀性能,热处理可以促进SLM Al-Mn-Mg-Sc-Zr合金的钝化,在-0.5 V极化电位时出现钝化台阶,降低SLM Al-Mn-Mg-Sc-Zr合金的电流密度,增加SLM Al-Mn-Mg-Sc-Zr合金的阳极极化率,使SLM Al-Mn-Mg-Sc-Zr合金的平均析氢速率从0.242 mL/(cm^(2)·h)降至0.216 mL/(cm^(2)·h),应力腐蚀敏感因子从3.379%降至0.405%。与此同时,热处理也促进了晶内微米富Si相以及晶界富Mn相和Mg相的析出,增加了SLM Al-Mn-Mg-Sc-Zr合金点蚀形核位置,增大了SLM Al-Mn-Mg-Sc-Zr合金的晶界电化学成分非均匀性,降低了SLM Al-Mn-Mg-Sc-Zr合金的点蚀和晶间腐蚀抗力。

斜拉桥施工阶段π型混凝土梁翼缘板裂缝成因分析与防裂措施研究

为了解斜拉桥施工阶段π型混凝土梁翼缘板斜向裂缝成因并制定合理的防裂措施,以某主跨120 m的π型预应力混凝土梁斜拉桥为背景,针对其悬臂施工阶段主梁翼缘板下表面出现斜向裂缝的现象进行分析。采用ANSYS软件建立该桥施工阶段杆系模型与混凝土梁实体模型,分析梁体自重、斜拉索张拉、预应力张拉、混凝土收缩、混凝土水化热作用下主梁翼缘板下表面应力情况。结果表明:梁体自重及斜拉索张拉作用下,翼缘板下表面未出现拉应力;横向及纵向预应力张拉作用下,翼缘板下表面产生一定的拉应力,但未超过混凝土抗拉强度标准值;混凝土收缩作用下,翼缘板下表面产生极小的拉应力,不会引起裂缝;混凝土养护过程中水化热作用下,翼缘板下表面混凝土与周边混凝土存在一定温差,部分测点第一主应力超过混凝土抗拉强度标准值,是开裂的主要原因。针对混凝土水化热作用影响,提出主肋布置冷却水管与翼缘板下方火炉加热并用的防裂措施,建立热流耦合模型分析防裂效果。结果表明:所采用的措施能够改善主梁养护过程中水化热温度场分布,各测点第一主应力均未超过混凝土抗拉强度标准值。

热刺激后小胶质细胞细胞外囊泡对神经元的损伤作用

目的探究热刺激后小胶质细胞细胞外囊泡对神经元损伤的影响。方法热刺激BV2小胶质细胞后收集上清,通过不同的超速离心速度获取细胞外大囊泡和小囊泡。利用纳米粒度分析仪检测粒径,利用Western blot检测囊泡上TSG101、CD63和flotillin-1的表达。PKH67标记BV2来源的囊泡后与N2a细胞共孵育,检测神经元对小胶质细胞细胞外囊泡的摄取情况。分别将热刺激后BV2来源的大囊泡和小囊泡与N2a共孵育,通过CCK-8、细胞外乳酸脱氢酶(lactate dehydrogenase,LDH)、台盼蓝染色和TUNEL染色法评价热刺激后N2a的损伤情况。结果小囊泡粒径介于30~120 nm,高表达TSG101和CD63,大囊泡粒径介于90~1000 nm,高表达flotillin-1;BV2来源的细胞外囊泡可被N2a细胞摄取并参与热刺激对N2a细胞损伤的调节,其中CCK-8检测结果表明小胶质细胞来源的大小囊泡均能降低热刺激后N2a细胞的活力(P<0.05)。LDH检测、台盼蓝染色及TUNEL检测结果表明大囊泡(P<0.05)和小囊泡(P<0.01)均能显著提高热刺激后N2a细胞LDH的释放水平、N2a细胞的蓝染水平及凋亡程度,且小囊泡处理组中N2a细胞的LDH释放水平、蓝染和凋亡水平高于大囊泡处理组。结论热刺激后小胶质细胞通过细胞外囊泡加剧了神经元的损伤。

紫花地丁对热应激下肉鸡生长性能、肉品质和肠道菌群的改善作用

旨在评估紫花地丁(Viola yedoensis Makino,VYM)对热应激下AA肉鸡生长性能、肉品质和肠道菌群的改善作用。将60只1日龄雄性AA肉鸡随机分为6个组,分别为:对照组(NT组),高剂量紫花地丁组(NT+VYM-H组);热应激组(HS组),低、中、高剂量紫花地丁热应激组(HS+VYM-L、HS+VYM-M和HS+VYM-H组,紫花地丁添加量分别为0.5%、1.5%、4.5%),2~42 d,热应激组肉鸡暴露于高温中,紫花地丁组全程饲喂添加相应剂量紫花地丁的日粮。所有肉鸡均在42日龄时屠宰,对生长性能、血清生化指标、肉品质、十二指肠形态、酶活性相关基因表达水平以及肠道菌群组成等进行检测。结果显示,在热应激条件下,与热应激组相比,1.5%紫花地丁组肉鸡29~42 d平均日增重显著升高,料重比显著降低(P<0.05);热应激条件下,添加紫花地丁显著降低肉鸡35 d血清HSP70水平(P<0.05),添加0.5%紫花地丁显著提高十二指肠脂肪酶活性(P<0.05),与肉鸡胸肌生肌因子相关的Pax3、Pax7、Myog、Myod、Myf5 mRNA表达显著上调(P<0.05),与十二指肠消化吸收功能相关的Pparα、Fatp1、B^(0)at1、Pept1、Cat1、Eaat3 mRNA表达显著上调(P<0.05);在热应激条件下,添加1.5%的紫花地丁显著降低了肉鸡的肌肉剪切力、肉色(P<0.05);盲肠中,紫花地丁显著提高了肠道菌群的丰富度和多样性(P<0.05),在门水平上,增加了拟杆菌门的丰度,且与肌肉pH(45 min)呈显著正相关;属水平上,降低了Subdoligranulum属丰度,且与十二指肠淀粉酶活性呈显著负相关。综上,在本试验条件下,日粮中补充1.5%和4.5%紫花地丁可有效减轻热应激导致的肉鸡生长性能和肉品质的降低,并能够调节其肠道菌群的平衡。本研究为紫花地丁在肉鸡生产中的应用提供了科学依据,对家禽养殖临床中热应激的防治具有参考意义。

微波强化煤层气井压裂开采的物性规律

为探究微波加热对煤岩性能的影响,通过室内实验及数值模拟方法对微波作用下煤岩的升温及致裂规律进行研究。研究表明:煤岩含水率对微波加热效果有直接影响,且岩体内温度的升高速度具有各向异性,导致煤岩各部位受热不均,从而产生热应力;微波功率越大,煤岩破碎越严重,微波作用于压裂后的煤岩,可使人工裂缝进一步扩展;压裂液中的添加剂也具有改善煤岩介电性能的功效,滑溜水压裂液增产效果显著,有望代替KCl活性水对煤层进行高效增产技术改造。在施工初期采用水力压裂技术,使压裂液尽可能充填到裂缝深处,可增强煤层介电性能;在施工后期选用微波加热技术,可强化煤层气开采效果。该研究对煤层气的重复压裂工艺具有重要的参考价值。

阴囊热应激对山羊血睾屏障结构和功能的影响

旨在探究热应激对山羊血睾屏障(BTB)结构和功能的影响,为山羊热应激防治提供理论依据。本研究选择6只1~1.5岁的健康雄性关中山羊,随机分为2组,每组3只。对照组正常饲喂,试验组采用改良后的阴囊热刺激法建立山羊睾丸热应激模型。利用CASA法检测精液质量变化,光镜与透射电镜观测睾丸结构,生物素示踪法显示BTB通透性改变,蛋白质印记法与免疫组织化学法检测BTB关键蛋白表达定位。热应激组中山羊睾丸指数、精子数量、精子活率、精子总运动性和精子前进运动率均显著降低(P<0.05)。热应激导致睾丸组织形态受损明显,生精细胞数量减少且排列紊乱;支持细胞内质网扩张,并出现大量空泡;支持细胞间紧密连接结构松散且不连续。热应激引起BTB通透性升高,关键连接蛋白表达水平显著降低(P<0.05),但分布定位未受影响。热应激损伤山羊睾丸组织形态,破坏支持细胞结构并降低BTB关键蛋白表达,从而导致BTB结构和功能完整性受损,造成精子质量下降,影响雄性山羊繁殖性能。

百香果果壳提取物对热应激小鼠的保护作用

为研究百香果果壳提取物对热应激小鼠的保护作用,本试验选取健康清洁级ICR雄性小鼠40只,随机分为对照组、热应激组、低剂量组和高剂量组共4个组,每组10只。所有小鼠饲喂基础颗粒饲料,正常饮水。低剂量组和高剂量组分别按100和200 mg/(kg·bw·d)剂量灌胃百香果果壳提取物,对照组和热应激组小鼠每天灌胃等量生理盐水。持续灌胃14 d后,除对照组外,其余3个组小鼠每天热处理2 h,连续7 d,期间持续给药。试验结束时,空腹称量小鼠体重;分析小鼠体重变化;采集血液检测血清中谷氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)、肌酐(Cr)、尿素氮(BUN)和热休克蛋白70(HSP70)生化指标,以及肿瘤坏死因子α(TNF-α)、白介素6(IL-6)、白介素2(IL-2)和γ干扰素(IFN-γ)细胞因子含量;收集小鼠肝脏和肾脏,观察其组织病理学变化。结果显示,热应激结束后,4个组小鼠体重无显著差异(P>0.05),但热应激组减重最多;与对照组比较,热应激组血清生化和细胞因子各指标均显著升高(P<0.05);与热应激组相比,低剂量组和高剂量组小鼠血清生化和细胞因子各指标均显著降低(P<0.05),小鼠肝脏和肾脏组织损伤有所减轻,且高剂量组优于低剂量组。结果表明,百香果果壳提取物对热应激小鼠具有一定的保护作用。

复方中药对热应激条件下肉牛生理指标、生长性能及血清生化指标的影响

试验旨在探讨复方中药对热应激条件下肉牛生理指标、生长性能及血清生化指标的影响。选取体况良好、体重相近的育肥期夏南牛24头,随机分为4组,每组6个重复,每个重复1头牛。对照组饲喂基础饲粮,试验组分别在基础饲粮中添加0.5%、1.0%和1.5%的复方中药。试验期30 d。结果显示:整个试验期间牛舍内环境温湿指数(THI)大于72,牛处于热应激状态。在试验第20、30 d,1.0%组和1.5%组牛的呼吸频率显著低于对照组(P<0.05)。与对照组相比,1.0%组牛的干物质采食量和平均日增重显著升高(P<0.05),0.5%和1.0%组的料重比显著降低(P<0.05);1.0%组的总蛋白(TP)、白蛋白(ALB)、球蛋白(GLB)含量、总抗氧化能力(T-AOC)以及谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)活性显著升高(P<0.05),尿素氮(BUN)、葡萄糖(GLU)和丙二醛(MDA)的含量显著降低(P<0.05);1.0%和1.5%组的免疫球蛋白G (IgG)和白细胞介素-6 (IL-6)含量显著升高(P<0.05)。研究表明,饲粮中添加复方中药可以改善肉牛的热应激反应,添加量以1.0%效果较好。

姜黄素对热应激状态下波槐杂交羊生长性能和血液生化指标的影响

本研究旨在评价不同添加剂量的姜黄素对热应激条件下波槐杂交羊生长性能及血液生化指标的影响。试验将30头体重为(28.03±0.32)kg的健康波槐杂交公羊随机分为3组,每组10只,分别饲喂0 mg/头/d(CON组)、450 mg/头/d(CUL组)、900 mg/头/d(CUH组)的姜黄素,预饲期15 d,正试期60 d。结果显示:(1)CUL组波槐杂交羊的平均日增重和总增重显著高于CON和CUH组(P<0.05)。(2)CUL组波槐杂交羊血清中的总蛋白和球蛋白含量显著高于CON和CUH组(P<0.05)。(3)CUL组杂交羊血清中的免疫球蛋白G含量显著高于CON和CUH组(P<0.05),CON和CUH组杂交羊血清中的丙二醛含量显著高于CUL组(P<0.05)。综上所述,日粮中添加450 mg/头/d的姜黄素可以改善热应激条件下波槐杂交羊的应激状态和健康状态,并进一步提高生长性能。

中药添加剂对热应激生长兔生长性能、屠宰性能、肠道微生态和血清生化指标的影响

本试验旨在研究饲粮中添加中药添加剂对热应激生长兔生长性能、屠宰性能、肠道微生态和血清生化指标的影响。选取48只健康、体重相近的2月龄新西兰白兔,随机分成2组,每组24只(公母各占1/2),单笼饲养。在夏季热应激状态下,对照组饲喂基础饲粮,中药组在基础饲粮中添加1%中药添加剂。预试期7 d,正试期42 d。结果表明:1)对照组和中药组之间末重、平均日增重和料重比差异不显著(P>0.05)。中药组的成活率较对照组有所增加(83.3%vs.70.8%,P>0.05)。2)中药组的半净膛重和半净膛率显著高于对照组(P<0.05)。3)中药组的盲肠内容物干物质含量显著高于对照组(P<0.05),盲肠内容物乙酸和丙酸含量有低于对照组的趋势(P=0.092)。4)对照组和中药组之间盲肠内容物细菌总数和alpha多样性差异不显著(P>0.05)。中药组的盲肠内容物栖粪杆菌属、普氏栖粪杆菌相对丰度显著高于对照组(P<0.05),盲肠内容物阿克曼菌属和大肠杆菌相对丰度有高于对照组的趋势(P=0.080、P=0.088)。5)中药组的粪便球虫圆小囊数有低于对照组的趋势(P=0.082)。6)对照组和中药组之间血清生化指标差异不显著(P>0.05)。综上所述,饲粮中添加中药添加剂可调控热应激生长兔肠道微生态,提高屠宰性能和肠道健康。

热应激对肉鸡的生理危害与缓解措施

环境温度超过动物机体等热区中的舒适温度上限后会产生热应激现象。肉鸡体毛丰厚、生长速度较快、无汗腺,受饲养密度的影响,在高温环境下易出现热应激现象。热应激容易造成肉鸡采食量减少、生长速度减缓,降低肉鸡免疫防御功能,抑制免疫器官的生长发育,增加组织炎性细胞因子表达。热应激能够降低肠道绒毛高度,增加隐窝深度,使肠道结构受损,肠道微生物菌群的数量发生改变。热应激轻则导致肉鸡生理功能紊乱,严重时会导致肉鸡死亡,造成经济损失。文章总结了热应激对肉鸡生产性能、免疫性能、肠道形态和肠道屏障方面的影响以及预防和缓解热应激的措施,为生产实践中预防和缓解热应激提供参考。

铬对奶畜热应激的调控作用及其研究进展

随着奶畜养殖业集约化程度的不断提高,如何避免热应激对奶畜养殖业乃至畜牧业造成重大的影响成为集约化牧场亟待破解的难题之一。热应激会引起动物生产性能、免疫力及繁殖性能下降等一系列变化。研究发现,微量元素铬(Chromium,Cr)对热应激引起的多种不良反应有抑制作用,从而减轻对动物机体的危害。本文结合了国内外学者对铬在奶畜热应激下的作用研究,综述了铬对奶畜热应激的调控作用及其研究进展。

黄芩提取物对热应激蛋鸡产蛋性能、蛋品质和免疫功能的影响

文章旨在探讨黄芩提取物对热应激蛋鸡产蛋性能、蛋品质和免疫功能的影响。试验将600只产蛋性能相近、70周龄左右的健康罗曼粉蛋鸡随机分为5组,每组8个重复,每个重复15只。其中对照组和热应激组分别饲喂基础日粮。试验Ⅰ、Ⅱ和Ⅲ组分别在基础日粮中添加15、30和60 mg/kg黄芩苷提取物的,试验为期9周。结果表明:1~3周,试验Ⅱ和Ⅲ组蛋鸡产蛋率较热应激组分别显著提高8.27%和11.92%(P<0.05),料蛋比显著降低7.21%和9.34%(P<0.05),软破蛋率分别显著降低7.38%和26.57%(P<0.05);4~6周,试验Ⅱ和Ⅲ组蛋鸡产蛋率较热应激组分别显著提高11.35%和10.98%(P<0.05),料蛋比显著降低10.50%和10.45%(P<0.05),软破蛋率分别显著降低15.33%和16.11%(P<0.05);7~9周,试验Ⅱ和Ⅲ组蛋鸡产蛋率较热应激组分别显著提高4.08%和7.71%(P<0.05),料蛋比显著降低2.95%和6.01%(P<0.05),软破蛋率分别显著降低14.09%和15.28%(P<0.05)。试验Ⅱ和Ⅲ组蛋壳强度较热应激组显著提高(P<0.05),试验Ⅲ组哈氏单位较热应激组显著提高(P<0.05),试验Ⅱ和Ⅲ组蛋粗蛋白质和钙含量较热应激组显著提高(P<0.05),试验Ⅱ和Ⅲ组蛋鸡血清白细胞介素-10(IL-10)和肿瘤坏死因子α(TNF-α)含量显著降低(P<0.05),免疫球蛋白A(IgA)和免疫球蛋白G(IgG)含量显著提高(P<0.05);总之,试验数据显示,补充黄芩提取物(60 mg/kg)可通过增强热应激蛋鸡免疫力提高蛋鸡生产性能,改善蛋品质。