高产奶牛繁殖障碍的起因和调控因素

奶牛的管理、营养、产量和基因选择都与其生育能力有直接关系.从体况评分、营养信号、内分泌和生殖器官等方面综述了高产奶牛繁殖障碍的起因和调控因素.     

Diagnostic Methods for Evaluation of Stallion Subfertility: A Review

Classically, evaluation of the breeding stallion for reduced fertility has relied on physical examination of the reproductive system, as well as evaluation of sperm number, motility, and morphology. Over the past 20 years, a number of other diagnostic methods have become available to facilitate reproductive evaluation of the stallion. Specifically, ultrasound imaging has provided much-improved diagnostic methods for evaluation of the external and internal genitalia of the stallion, and these methods have now become routine in evaluation of the stallion. Biochemical analyses of semen can provide useful information for diagnosis of azoospermia (determination of alkaline phosphatase), detection of urine contamination, or changes in pH. Numerous sperm function assays provide information concerning subcellular compartments of the sperm including the plasma membrane, DNA, acrosome, and mitochondria. Data correlating these functional assays with fertility in the stallion are limited in most cases, with the exception of the sperm chromatin structure assay. Finally, the recent sequencing of the equine genome offers the possibility of both marker-assisted selection for fertility traits and more specific information about genetic mutations that may be associated with differing levels of fertility in the stallion.     

模拟干旱和盐胁迫下沙冬青种子硬实特性和抗逆性的研究

将1~5 d内每天吸胀的沙冬青(Ammopiptanthus mongolicus)种子视为不同硬实程度的种子T₁,T₂,T₃,T₄和T₅,与第5 d仍未吸胀的硬实种子(记作T_r)作为试材对其硬实特性和抗逆性进行研究,以期为沙冬青种子栽培驯化提供理论依据。结果表明:随着硬实程度的提高,种子的发芽势、发芽指数、活力指数呈上升趋势;电导率和丙二醛(MDA)含量逐渐下降;可溶性蛋白含量逐渐上升。不同处理对种子的硬实破除效果表明,80℃热水浸泡种子可达到最佳破除效果。通过测定模拟干旱胁迫和盐胁迫下不同硬实程度种子的超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性和脯氨酸(Pro)含量,表明在相同逆境条件下,随硬实程度的加深,除极个别外,各项指标值均有不同程度的升高,且一定胁迫强度下硬实种子萌发幼苗的各酶活性和脯氨酸含量均极显著高于其他萌发幼苗(P<0.01),因此,硬实种子比非硬实种子有较强的保护酶调节系统。硬实程度越高,耐旱和耐盐能力也随之升高。     

Resveratrol Reverses Cadmium Chloride-induced Testicular Damage and Subfertility by Downregulating p53 and Bax and Upregulating Gonadotropins and Bcl-2 gene Expression

This study was performed to investigate the protective and therapeutic effects of resveratrol (RES) against CdCl₂-induced toxicity in rat testes. Seven experimental groups of adult male rats were formulated as follows: A) controls+NS, B) control+vehicle (saline solution of hydroxypropyl cyclodextrin), C) RES treated, D) CdCl₂+NS, E) CdCl₂+vehicle, F) RES followed by CdCl₂ and M) CdCl₂ followed by RES. At the end of the protocol, serum levels of FSH, LH and testosterone were measured in all groups, and testicular levels of TBARS and superoxide dismutase (SOD) activity were measured. Epididymal semen analysis was performed, and testicular expression of Bcl-2, p53 and Bax was assessed by RT-PCR. Also, histopathological changes of the testes were examined microscopically. Administration of RES before or after cadmium chloride in rats improved semen parameters including count, motility, daily sperm production and morphology, increased serum concentrations of gonadotropins and testosterone, decreased testicular lipid peroxidation and increased SOD activity. RES not only attenuated cadmium chloride-induced testicular histopathology but was also able to protect against the onset of cadmium chloride testicular toxicity. Cadmium chloride downregulated the anti-apoptotic gene Bcl2 and upregulated the expression of pro-apoptotic genes p53 and Bax. Resveratrol protected against and partially reversed cadmium chloride testicular toxicity via upregulation of Bcl2 and downregulation of p53 and Bax gene expression. The antioxidant activity of RES protects against cadmium chloride testicular toxicity and partially reverses its effect via upregulation of BCl2 and downregulation of p53 and Bax expression.     

金属硫蛋白与应激反应

金属硫蛋白(MT)是一类低分子量,富含半胱氨酸,可以被金属、氧化剂、细胞因子和糖皮质激素等多种因素诱导的蛋白质。它参与多种应激反应,被誉为一种多功能的应激蛋白。本文就MT在各种应激反应中的产生、调控及发挥的功能进行了重点阐述。     

氧化应激与自噬

自噬是细胞依赖溶酶体对蛋白质和细胞器进行降解的过程,能帮助细胞适应各种不良刺激,在维持细胞内环境稳态和实现自我更新中起着重要作用。氧化应激是机体氧化和抗氧化系统之间的稳态被破坏而造成的应激状态。大量研究表明,氧化应激中产生的活性氧能诱导自噬产生,而自噬能缓解氧化应激造成的损伤,从而保护细胞存活。本文主要对自噬的形成过程、氧化应激诱导自噬产生机制以及自噬缓解氧化应激的途径等进行综述,以期为畜牧生产中通过调控自噬缓解氧化应激提供理论依据。     

低温和干旱胁迫下牧草的抗逆性机制

低温和干旱是限制牧草生长发育和产量的两个非生物胁迫因子。掌握牧草抗逆性机制,选育具有强抗寒性和抗旱性的牧草是寒旱地区草牧业高质量发展和退化草地生态系统恢复的重要基础。在形态学层面,低温和干旱胁迫条件下牧草会形成多种抗逆性形态结构,这些结构的变化能很好地反映牧草对逆境的响应和适应能力。在生理生化层面,牧草通过调节超氧化物歧化酶、过氧化物酶、过氧化氢酶、游离脯氨酸、可溶性糖、可溶性蛋白质、脱落酸、乙烯、赤霉素和细胞分裂素等的响应,以适应低温和干旱胁迫。在分子水平层面,牧草通过信号转导、应答和抵御基因的表达等综合作用,以适应寒旱胁迫。总之,本研究从牧草形态学、生理生化和分子水平三个层面综述了牧草对低温和干旱胁迫的响应和适应机制,以期为全面认识牧草抗逆机制提供重要参考。     

热应激与奶牛饲养管理

夏季的奶牛场,由于温度和湿度上升,奶牛普遍经历着“热应激”。母牛舒适度是奶牛生产性能能否达到最大的关键。一般来说,当温度超过20℃、湿度高于85%,母牛开始遭受热应激,其具体表现为牛场70%以上的奶牛呼吸频率超过80次/分钟,直肠温度超过39℃,干物质采食量降低10%以上,产奶量降低10%以上。泌乳母牛自身产生大量体热,如果畜舍内空气流通不利,母牛自身体温就与周围空气的温度十分接近,那么高温高湿就会降低奶牛的采食量,造成奶牛产奶量下降,进而降低奶牛繁殖性能。除此之外,在夏季新的饲草料的供应变化(饲料种类变化包括高浓度精饲料、新刈…     

奶牛与热应激

盛夏,气候炎热,空气潮湿,极易引起奶牛热应激。由于炎热对奶牛带来的负面影响远远高于寒冷对其产生的影响,所以在夏季避免奶牛热应激,是保证奶牛有较高生产性能的根本措施。因此,广大奶农要切实加强对奶牛的饲养管理工作,确保奶牛顺利度过夏暑季节,以保持牛场良好的经济效益。     

热应激对鸡的影响及抗热应激药物

对热应激引起鸡生长速度、繁殖能力、种蛋品质、胴体组成、采食量、行为、呼吸、循环、体温、消化、代谢、免疫应答的影响和糖皮质激素、中枢神经镇静剂、电解质、维生素C、维生素 E、中草药等抗热应激药物进行了简要的综述。并指出了热应激对鸡生理生化指标变化规律以及对免疫机能的影响和可能发生的机理。     

热应激诱发的氧化应激对羊的影响及其作用机制

热应激会破坏机体氧化系统和抗氧化系统之间的平衡,诱发机体的氧化应激。而机体抗氧化系统与免疫系统息息相关,其中核转录因子E2相关因子2(Nrf2)信号通路是联系二者的重要途径。本文阐述了热应激如何诱导羊发生氧化应激,以及热应激诱导的氧化应激对羊肠道组织、机体免疫细胞及相关细胞因子表达分泌的影响和Nrf2信号通路的调控机制,以期系统理解热应激诱导的氧化应激对羊的影响。     

热应激条件下机体发生氧化应激的机制

热应激是指机体在高温条件下对热暴露所做出的非特异性生理反应的总和。有研究表明热应激会引起机体氧化还原平衡紊乱,发生氧化应激,损伤细胞和组织,从而影响机体的生长发育及健康状况。热应激一直都是国内外研究的热点,随着全球气温的上升,热应激问题将会更加突出,本文就热应激条件下氧化应激发生的机制作一综述,以期为后续的相关研究提供参考。     

热应激对奶牛的危害以及缓解方法

在夏季高温高湿环境下,牛调节体温的中枢无法做到有效调节体温,会导致牛产生热应激.热应激会导致奶牛采食量降低,呼吸频率加快,营养物质消化率下降等,严重影响其生产性能.目前缓解热应激的方法主要是改善环境及使用缓解热应激的添加剂.主要从热应激的危害和缓解方法两方面来阐述热应激对牛生产性能的影响,以期为减少夏季奶牛热应激提供参...     

热应激与反刍动物营养

９０年代以来,全球牛肉的产量平均每年以１－３％的速度在增长。其中,发展中国家则平均每年以４－２％的速度在增长,而我国仅１９９０至１９９５年,牛肉的增长速度达到了２４－５％,牛肉在肉类总产量中的比例由４－１％升至７－９％（陈耀春,１９９６）。据农业部的规划,我国计划在２０１０年牛肉产量要达到１０００万ｔ才能满足人民生活的需要。但由于肉用反刍家畜的日粮代谢能转化为净能的效率（Ｋｆ）远远低于产奶牛和单胃动物,很难达到５０％（冯仰廉,１９９９）,加上我国优质粗饲料和精料又存在很大的缺口,这对我国长期以来…     

Stress and fertility. A review

The effect of both environmental and management related stressors on fertility is discussed. While environmental heat as a stressor is significant in disrupting normal reproductive cyclicity, management induced stress is becoming more important when related to the requirements of modern production methods. Deviations in hormonal patterns are noted, and the clinical manifestations brought about by these changes are described. Since reproduction is the ultimate measure of an animal's ability to adapt to an ever changing external milieu, as well as forming the basis of life-time productivity, research should be aimed at obtaining greater clarity of the hormonal interactions involved. The role of neurotransmitters in these physiological mechanisms should not be overlooked. Psychobiological studies must be extended so as to provide a positive input into management procedures that should be used in intensive production units for optimal fertility and productivity.