体外试验中不同粗精比对山羊瘤胃细菌氨态氮利用效率的影响

利用体外发酵法研究了4种粗精比(10∶0、8∶2、6∶4和4∶6)底物对山羊瘤胃细菌产量、15NH3-N利用效率的影响。结果表明:混合培养液的pH值与氨态氮浓度在8h内急剧下降,而后至24h呈缓慢下降;经24h培养的细菌产量在8∶2、6∶4和4∶6组中差异不显著(P>0.05),但都极显著地高于10∶0组(P<0.01);细菌体15N丰度以8∶2及4∶6组较高,显著高于10∶0和6∶4组(P<0.05);细菌体15N富集量以8∶2组最高,底物547.43μg15N中有120.44μg被细菌体富集,显著高于10∶0组(P<0.05),但6∶4、4∶6组与10∶0组间差异均不显著(P>0.05)。细菌赖氨酸的相对百分组成随精饲料比例的增加而显著增加,胱氨酸在粗饲料组(10∶0)显著高于其它组,但各精饲料添加组间差异不显著,组氨酸以8∶2组为最高,显著高于10∶0组,但与其它精饲料添加组间差异不显著(P>0.05)。     

密花香薷挥发油成分的分析研究

采用水蒸气蒸馏法和气相色谱-质谱-计算机联用法对密花香薷的挥发性成分进行了分析和鉴定.分离出93个峰,确认了其中的84种化合物,其含量占全油的88.34%.主要化学成分为大根香叶烯(18.83%);D-柠檬烯(11.17%);2,5,5-三四基-1,3,6-庚三烯(6.30%);6-亚甲基-双环[3,1,0]己烷(5.90%);氧化石竹烯(3.94%);石竹烯(3.36%);4-碳-3,5-二甲基环己-1-烯(2.88%);α-3-环己烯-1-醇(2.06%).     

2种组胺受体拮抗剂对低温诱发的肉鸡肺动脉高压的影响

为探讨组胺H1受体拮抗剂扑尔敏和H2受体拮抗剂西咪替丁对低温诱发的肉鸡肺动脉高压的影响,并由此推测组胺在低温诱发的肉鸡肺动脉高压形成过程中的作用。140只17日龄AA肉鸡随机分为4组。(1)常温组:40只在常温条件下饲养(22～23℃),每日注射生理盐水2次;(2)低温组:40只在低温环境中饲养(9～11℃),每日注射生理盐水2次;(3)扑尔敏组:40只在低温环境中饲养(9～11℃),每日注射扑尔敏2次;(4)西咪替丁组:20只在低温环境中饲养(9～11℃),于24日龄至38日龄期间每日注射西咪替丁2次。分别于低温处理后1周(24日龄)、2周(31日龄)、3周(38日龄)、4周(45日龄)从常温组,低温组,扑尔敏组中各随机抽取10只,西咪替丁组在低温处理后2周(31日龄)、3周(38日龄)各随机抽取10只,称取体重,然后利用右心导管法测定肺动脉压(PAP),并测定红细胞压积(PCV),腹水心脏指数(AHI)。结果发现:(1)24日龄、31日龄、38日龄时,低温组肺动脉收缩压,舒张压显著高于(P<0105)或极显著高于(P<0101)同日龄常温组。24日龄时扑尔敏组肺动脉收缩压显著低于(P<0105)同日龄低温组。38日龄时西咪替丁组肺动脉收缩压,舒张压极显著低于(P<0101)同日龄低温组。(2)24日龄、31日龄、38日龄、45日龄时,低温组PCV极显著高于(P<0101)同日龄常温组。24日龄时扑尔敏组     

BQ123对低温诱发的肉鸡肺血管重塑的影响

动态观察了肺小动脉中膜平滑肌的增殖及管腔面积的改变,探讨内皮素受体拮抗剂BQ123 对低温诱发的肉鸡肺血管重塑的影响。200只16日龄AA肉鸡随机均分为4组: 常温(20 ℃)对照组、低温(7~9 ℃)组、低温低剂量BQ123组和低温高剂量BQ123组。23日龄、30日龄时测定肺动脉压,并取肺组织做石蜡切片, 以Weigert间苯二酚复红染色,形态学计算机图象分析法测定肺细小动脉外径和内径、管总面积和管腔面积,计算中膜厚度占外径百分值(%)mMTPA及管壁面积/管总面积WA/TA(%)。结果显示:(1)BQ123 抑制低温肉鸡平均肺动脉压的升高,23日龄时低温高剂量BQ123组显著低于低温组(P<0 05),30 日龄时低温低剂量BQ123 组和低温高剂量BQ123组均极显著低于低温组(P<0 01);(2)BQ123 抑制低温肉鸡肺小动脉WA/TA(%)的升高,30~50μm的肺小动脉,低温组极显著高于低温低剂量BQ123 组及低温高剂量BQ123 组(P<0 01),其它分级的肺小动脉组间差异性与此类似;(3) BQ123抑制低温肉鸡肺小动脉的mMTPA的升高,30~50μm的肺小动脉,23日龄时低温组极显著高于低温低剂量BQ123 组和低温高剂量BQ123 组(P< 0 01), 30 日龄时低温组显著高于低温低剂量BQ123组(P<0 05)、极显著高于低温高剂量BQ123组(P<0 01),30μm以下的肺小动脉组间差异性与此类似,50~120μm     

马动脉炎病毒RT-PCR检测方法的建立

根据已报道的马动脉炎病毒基因组保守基因核苷酸序列，设计并合成了1对引物，通过对影响PCR扩增因素的筛选，成功地从病毒感染的细胞中扩增出约200bp的片段，与理论设计值(204bp)大小一致。而正常的RK-13、BHK-21和Vero细胞和同为动脉炎病毒科的猪繁殖与呼吸道综合征病毒(PRRSV)作为对照的扩增结果均为阴性。敏感性试验表明，该方法可以检测出10^-4个TCID50的病毒含量，说明具有较好的敏感性。     

致麻鸭产蛋下降的副粘病毒的分离和鉴定

从浙江省某麻鸭养殖基地产蛋锐减的病鸭生殖器官分离到1株致产蛋下降、不致鸭死亡的病毒株(YH99V)。该病毒易感蛋鸭，经SPF鸡胚传至第9代时致病性突然增强，第11代出现对鸡红细胞的血凝特性，通常在42～80h致死SPF鸡胚，EF15EID50为10^1.8。经磷钨酸负染电镜观察，YH99V粒子呈现圆形、杆状形、葫芦状形等多形态，直径70～400nm不等，病毒外表有囊膜，囊膜外层有排列整齐的纤突。病毒粒子和包涵体位于细胞浆内。病毒抵抗力由弱到强依次为：0．2%甲醛、24h-56℃、45min→紫外线、1h→乙醚≈氯仿≈37℃、16h—pH9→pH5→1％Try。对人眼结膜易感，鸭眼结膜不易感。接种传代细胞BHK-21、IBRS-2均能引起细胞病变。YH99V株与同样引起鸭产蛋下降的AIV、鸭源EDSV无抗原相关性，而能被禽副粘病毒Ⅰ型阳性血清中和。根据试验结果，初步将YH99V判定为鸭副粘病毒。     

苓桂术甘汤对肉鸡腹水综合征的防治作用

将15日龄艾维茵肉鸡分成5组,一组在常温(21±1)℃下饲养,作为正常对照组(N);其余4组在低温(11±1)℃下饲养以诱发腹水综合征,其中模型对照组(C)不给任何药物,维生素组(V)饮水中添加VC(0.5 g/L)和VE(0.1 g/L),2个试验组(T1和T2)分别给予不同剂量(0.4和0.8 mL/kg bw)的苓桂术甘汤。结果显示,C组的腹水发病率、腹水心脏指数(AHI)、红细胞压积(PCV)、红细胞数、血红蛋白(Hb)及丙二醛(MDA)含量、血清α-羟丁酸脱氢酶(-αHBDH)、谷草转氨酶(GOT)和谷丙转氨酶(GPT)均显著高于N组;而3种抗氧化酶[超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-Px)]的活性则显著降低;2个试验组及V组的上述检测指数都得到明显改善,表明苓桂术甘汤能增强肉鸡的抗氧化能力,具有防治肉鸡腹水综合征的作用。     

草原灌丛化入侵:过程、机制和效应

草原灌丛化已成为全球性问题,也是生态学、畜牧学研究的热点问题。紧扣草原灌丛化过程、发生机理及其生态学后效等关键问题,介绍了国内外的最新研究进展。灌木入侵途径包括有意识引进入侵和自然入侵2类,入侵过程分为传播到达、定居建群和扩散入侵3个阶段。放牧、火烧、温室气体增加,干旱以及降水格局改变等均可导致草本向木本的转化,且机制复杂,主要有影响草本,木本植物盖度、水分利用效率、化感作用等。木本植物入侵打破了草原生态系统的稳定,表现出沃岛效应,影响动植物的分布以及生态系统的功能和服务。阐明草原“草本-木本”群落演替机制,可为我国研究草原灌丛化和管理提供理论借鉴。     

Methyl donors dietary supplementation to gestating sows diet improves the growth rate of offspring and is associating with changes in expression and DNA methylation of insulin‐like growth factor‐1 gene

The study aimed to investigate the effects of maternal dietary methyl donors on the performance of sows and their offspring, and the associated hepatic insulin‐like growth factor‐1 (IGF‐1) expression of the offspring. A total of 24 multiparous sows were randomly fed the control (CON) or the CON diet supplemented with methyl donors (MD) at 3 g/kg betaine, 15 mg/kg folic acid, 400 mg/kg choline and 150 μg/kg VB₁₂, from mating until delivery. After farrowing, sows were fed a common lactation diet through a 28‐days lactation period and six litters per treatment were selected to be fed until at approximately 110 kg BW. Maternal MD supplementation resulted in greater birthweight (p < 0.05) and increased the piglet weights (p < 0.01) and litter weights (p < 0.05) at the age of day 28, compared with that in CON group. The offspring pigs in the MD group had greater ADG (p < 0.05) and tended to lower F:G ratio (p = 0.07) compared with that of CON group from day 28 to 180 of age. The offspring pigs from MD group had greater serum IGF‐1 concentrations and expressions of hepatic IGF‐1 gene and muscular IGF‐1 receptor (IGF‐1r) protein at birth (p < 0.05), and greater hepatic IGF‐1 protein (p = 0.03) and muscular IGF‐1r gene expressions (p < 0.05) at slaughter, than that from the CON group. Moreover, the methylation at the promoter of IGF‐1 gene in the liver of newborn piglets and finishing pigs was greater in the MD group than that of the CON group (p < 0.05). In conclusion, maternal MD supplementation throughout gestation could enhance the birthweight and postnatal growth rate of offspring, associated with an increased expression of the IGF‐1 gene and IGF‐1r, as well as the altered DNA methylation of IGF‐1 gene promotor.     

Effects of five cryoprotectants on proliferation and differentiation‐related gene expression of frozen‐thawed bovine calf testicular tissue

The cryopreservation of testicular tissue is a potential method for preserving male fertility. However, the effect of cryopreservation on bovine calf testicular tissue is scarce. This study investigated the effect of different cryoprotectants on bovine calf testicular tissue at the molecular level. Testicular tissue from ten immature bovine calves (6 months) was collected after slaughter and cryopreserved in an extender containing different concentrations of the following five cryopreservation solutions (CP): bovine serum albumin (BSA) with 5% dimethyl sulfoxide (DMSO), trehalose with 5% DMSO, DMSO and glycerol and ethylene glycol (EG). After 7‐day cryopreservation, the expression levels of three spermatogonial stem cell (SSC)‐related genes, octamer‐4 (OCT4), KIT ligand (MGF/SCF) and kit oncogene (C‐KIT), were investigated by quantitative PCR (qPCR). The cell viability was highest for the tissues preserved with 30 mg/ml BSA (77.82% ± 1.22) and 40 mg/ml trehalose (74.23% ± 1.16) compared with other groups (p < 0.05), and the level of expression of the three genes was highest with 30 mg/ml BSA (p < 0.05). Compared with other CPs, the 30 mg/ml BSA and 40 mg/ml trehalose have the better cryopreserve protection. The 30 mg/ml BSA is the most viable media for the cryopreservation of testicular tissue from cattle.