热应激对种公牛精液品质的影响

作者阐述了热应激对种公牛精液品质的影响及使公牛的促黄体素(LH)、睾酮水平降低，精子生成受阻，精液品质严重下降。热应激所致的精液品质下降需经7～9周才能恢复正常。降温可减缓热应激对种公牛繁殖机能的危害。     

热应激对种公牛繁殖机能的影响及对策

本文从种公牛热应激的原因入手,综述了热应激对种公牛的危害,以及如何采取饲养管理、营养调控等抗热应激措施,以减少或杜绝不良应激所造成的损失。     

奶牛热应激的发生与预防

长期以来，奶牛热应激直影响着奶牛业的发展，国内外专家很早就开始研究热应激对奶牛的影响，并取得了大量的研究成果。本文从热应激发生的原因及对母牛的影响、热应激对公牛生殖能力的影响、奶牛热应激的测定方法和奶牛热应激的综合调控措施四个方面综述了国内、外的研究进展。     

热应激对种公牛的影响及防治措施

热应激是指动物机体受到夏季炎热气候的刺激,超过了本身体温调节能力而引起的生理上和行为上的非特异性反应。种公牛经过长期的适应,遭受的热应激大都属于慢性热应激,而近几年我国北方地区夏季气温升高,热应激对种公牛的精液品质造成了严重的影响,现已成为夏季饲养种公牛不容忽视的问题。     

热应激对种公牛的影响及对策

随着全球气温升高的趋势不断加剧,很多生物的生存环境都受到了影响。对于种公牛而言,其自身有着相应的温度调节功能,但是气温的持续升高已经超出了种公牛所能承受的范围,因此当气温过高时,种公牛可能会出现热应激的情况。当种公牛长时间处于热应激情况下时,其生理健康会受到很大影响,并且年龄不同的种公牛受到的影响也各不相同。因此需要为种公牛制定合理、可行的饲养管理方案,采取科学、有效的热应激处理办法。只有降低甚至避免热应激对种公牛的影响,其健康状况和生产能力才能得到有效保障。     

热应激对种公牛精液品质的影响

任何生物都依赖于其所处的环境 ,它对气候变化的适应及利用有效资源的能力是其存活的关键 ,因此 ,各种环境因子均可造成动物的生理应激 ,从而给动物的生产带来不利影响 ,牛也不例外。从经济角度看 ,在各种应激反应中 ,对牛影响最大的是热应激 ,而热应激对牛生殖机能会产生非常重要的影响。在热应激的作用下 ,种公牛的精液品质和受精率均显著下降 ,体内的一些血液生化指标也会发生明显变化。本文参考近年来国内外研究热应激的文献 ,论述了其对公牛繁殖性能的影响 ,以便于生产中制定缓解种公牛热应激的技术措施。1　热应激对种公牛繁殖机能的…     

不同研究水平提高种公牛抗热应激能力的方法探讨

荷斯坦种公牛培育作为奶牛繁育体系中重要环节,承担着为牧场提供优秀冻精、扩繁高产奶牛、推进奶牛群体改良计划的重要任务。然而夏季热应激导致的种公牛繁殖性能下降等功能障碍大大影响着种公牛的正常生产。文章对近年来国内外不同课题组在种公牛热应激问题上的研究成果予以归纳整理,对营养调控水平和遗传选育水平上缓解热应激的最新研究进展进行综述,以期为夏季种公牛高效生产提供必要的科学依据。     

种公牛热应激反应与精液品质的探讨

<正>夏季持续的高温高湿环境对种公牛的生产性能会产生很大影响。在生产实践中,如何掌握环境温度是否引发种公牛热应激反应界限,适时采取必要的调控措施,减缓种公牛的热应激是种公牛夏季饲养关键。本文从实际出发,采用不同调控措施及营养方式,观察种公牛的原精质量与状态,客观切实从种公牛热应激的生理机制入手,解决环境温度对种公牛造成的危害。     

热应激对荷斯坦种公牛精液品质的影响及机理

用5头荷斯坦种公牛研究了热应激对其生理常值，精液品质，血清生化指标，精清生化指标的影响。结果表明：（1）热应激可造成种公牛精液品质显著下降，使原精活力，冻精活动，精子密度，活精子百分数和顶体完整率分别比春季下降3．13％（P＜0．01），1．11％（P＜0．01），34．8％（P＜0．01），15．0％（P＜0．01）和17．8％（P＜0．01），精子畸形率比春季上升25．5％（P＜0．01）。（2）夏季慢性热应激使荷斯坦种公牛的直肠温度和呼吸频率极显著高于春，米，立3个非热应激季节（P＜0．01）。（3）夏季荷斯坦种公牛血清睾酮，T3，皮质醇和促黄体素的含量分别为3.41ng/L,1.29ng/L,5.05ng/L和45.11ng/L，与非热应激季节相比，均处于较低的水平。（4）热应激可降低血糖和血清钠，钾，钙，镁水平（P＜0．01），使血清GPT，GOT处于最高水平（P＜0．01）。（5）夏季荷斯坦公牛精清睾酮含量仅为4.31ng/L，极显著低于非热应激季节（P＜0．01）。（6）热应激造成荷斯坦种公牛精清钾，钙，镁处于最低水平（P＜0．01），精清ALP，ACP处于最高水平（P＜0．01），使精清钠由春季至夏季呈显著下降趋势。上述结果显示：热应激使体内微环境发生了显著变化，抑制了下丘脑－垂体－睾丸轴的功能，从而影响了精子的生成和贮存。     

热应激对种公牛精液品质及血清激素水平的影响

以荷斯坦、利木赞、夏洛来三个品种的种公牛各5头为试验材料，对热应激期和非热应激期的种公牛精液品质及血清内激素进行测定。结果表明：热应激使种公牛精子密度、活精子百分数和顶体完整率分别比春季下降30.6％（P＜0.01）、20.9％（P＜0.01）和19.4％（P＜0.01），精子畸形率比春季上升42.3％（P＜0.01）。夏季热应激期血清皮质醇、T3、LH和睾酮含量最低，分别为4.94pg/ml、1.17pg/ml、47.11pg/ml和3.90pg/ml，其中皮质醇和LH极显著低于春、秋、冬三个非热应激季节（P＜0.01），睾酮与T3比最高水平分别下降了77.2％（P＜0.01）和25.9％（P＜0.01）。     

癸氧喹酯干混悬剂含量测定的改进

采用高效液相色谱法测定癸氧喹酯干混悬剂的含量,在2-250μg/mL范围内,峰面积的常用对数与进样量浓度的常用对数呈良好的线性关系,R^2=1(n=5),平均回收率为99.24%~99.51%,RSD在0.05%~0.28%。此方法分析时间短,样品前处理简便、定量结果准确,重现性好,结果满意,为其质量控制提供了依据。     

猪毛色遗传的研究进展

本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。     

商会自治的基石——商会自治规范研究

在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。     

Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF

Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo.     

Mechanism of Action of Probiotic Function of Lactobacilli

乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制.     

中华人民共和国农业部公告 第267号

为贯彻落实《兽药生产质量管理规范》(简称《兽药GMP》),进一步推动兽药GMP实施进程,我部制定了《兽药生产质量管理规范检查验收办法》,现予公告。本公告自2003年6月1日起施行。附件:兽药生产质量管理规范检查验收办法二○○三年四月十日第一章 总则 第一条 为推动《兽药生产质量管理规范》(以下简称兽药GMP)的实施,规范兽药GMP检查验收工作,制定本办法。 第二条 农业部负责全国兽药GMP管理和检查验收工作;负责制修订兽药GMP检查验收管理规定;负责兽药GMP检查员队伍建设和监督管理工作,负责国际兽药贸易中GMP互认工作。 …     

鸡败血支原体垂直传播模式及其阻断方法

以国际标准强毒Ｒ株人工感染非免疫产蛋鸡,定时扑杀,分别从鼻窦、眶下孔、气管、肺、气囊、卵巢和输卵管分离ＭＧ,并收集感染鸡所产蛋分离ＭＧ。结果表明,人工感染４８小时后上、下呼吸道及肺已被全面感染,９６小时气囊已被感染,１２０小时输卵管已能分离到ＭＧ,卵巢始终分离不到ＭＧ。人工感染鸡自１４４小时便能在其所产蛋中分离出ＭＧ。药物治疗能在７２小时内消除感染,油乳剂苗则需２４天后逐渐降低蛋内ＭＧ分离率,药物卵内注射、种蛋药浴、高温处理均能杀死卵内ＭＧ,但以研制的种蛋浸泡剂药浴效果为最好。     

Comparison of 2 methods of centesis of the bursa of the biceps brachii tendon of horses

REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air.     

不同样本商品蜂蜜中硒含量的测定

用硝酸和高氯酸消化蜂蜜,使硒游离出来,在微酸性环境下,硒和2,3-二氨基萘(DAN)生成有较强荧光的物质,用环己烷萃取,在激发波长378nm,荧光波长518nm处测定其荧光强度。蜂蜜中硒含量范围:0.10～0.82μg/g。表明:蜂蜜应视为天然富硒营养品。