共查询到20条相似文献，搜索用时 62 毫秒
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大豆是人类膳食和畜禽饲粮中的主要蛋白质来源之一,其中富含大豆异黄酮等生物活性物质。近年来的研究表明,大豆异黄酮具有与哺乳动物内源性雌激素相似的化学结构,能与机体内的雌激素受体结合,发挥类雌激素作用和抗雌激素样作用。大豆异黄酮是否对雌性动物生殖系统产生促进作用,目前仍存在争议。本文从雌性动物生殖器官形态结构、发情周期和卵巢发育、生殖激素和繁殖性能等方面,系统综述和全面分析大豆异黄酮对雌性动物生殖系统的影响,为畜牧业中科学合理利用大豆异黄酮来提高畜禽的生殖性状提供科学依据。 相似文献
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镉致鸡肾脏的氧化损伤及乙酰半胱氨酸的保护效应 总被引：1，自引：0，他引：1
镉是一种广泛存在于自然界中的慢性蓄积性毒物,主要通过职业性接触和环境污染对人类和动物健康造成威胁[1].家畜和家禽镉中毒是由于饲料中富含镉和工业镉污染及高镉的自然环境引起的,家禽镉中毒主要表现为:贫血、生长受阻、产蛋量下降、蛋壳品质降低、孵化率下降和死亡率增加等.国内外对镉所致哺乳动物肾毒性进行了广泛研究[2],而镉对禽类的肾脏毒性机制及中毒后的解毒机理研究不多.N-乙酰半胱氨酸(N-acetyl cysteine,NAC)为一富含巯基的抗氧化剂,可以螯合游离的镉离子.研究表明,NAC具有清除和干扰自由基生成、调节细胞的代谢活性、预防DNA损伤、调整基因表达和信号转导系统、抗细胞凋亡等作用[3].因此,本研究通过在饲料中添加NAC来研究其对镉所致鸡肾脏损伤的保护效应,为预防镉中毒提供理论依据. 相似文献
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《畜牧与饲料科学》2017,(1)
三丁基锡(tributyltin,TBT)在环境中广泛存在且具有很强的毒性,有关其对动物生殖系统影响的研究多集中于组织结构的描述但缺乏量化分析。为探讨TBT对雌性小鼠生殖系统的影响,以雌性昆明小鼠为研究对象,分为对照组[0]、低剂量组[0.2μg/(BW·kg)]、中剂量组[2μg/(BW·kg)]、高剂量组[20μg/(BW·kg)],进行为期45 d的TBT暴露试验;采用石蜡切片和HE染色技术观察各组小鼠卵巢、输卵管、子宫的组织学变化,并对其组织结构的分层进行量化分析。结果显示,TBT暴露小鼠的卵巢中各期卵泡数量发生变化,初级卵泡数量有减少趋势,成熟卵泡数量明显减少,卵泡组织结构变化不明显;输卵管壁变厚,浆膜、黏膜变化较明显,输卵管内环肌细胞排列疏松;子宫壁各层结构均有不同程度变化,黏膜变化尤其明显,子宫壁随TBT暴露剂量的增加而增厚。TBT暴露影响雌性小鼠生殖系统的组织结构且呈现剂量效应。 相似文献
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魏静 《四川畜牧兽医学院学报》2009,(4):28-32
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。 相似文献
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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。 相似文献
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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。 相似文献
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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. 相似文献
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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. 相似文献