4个青贮玉米品种的青贮发酵品质及瘤胃降解特性的比较

为筛选出适合在苏中地区种植的青贮玉米(Zea mays L.)品种,本试验对4个青贮玉米品种进行全株青贮,比较青贮品质和瘤胃降解特性。试验结果表明：‘雅玉8号’全株玉米青贮的乳酸含量较高(P<0.05),pH值、氨态氮含量和乙酸含量低于‘扬大109’(P<0.05)。全株玉米青贮的瘤胃干物质有效降解率由高到低依次为‘康源01号’(40.98%)、‘扬大109’(39.25%)、‘雅玉8号’(37.69%)和‘牧场06号’(35.29%)。瘤胃中性洗涤纤维有效降解率由高到低依次为‘扬大109’(29.91%)、‘雅玉8号’(28.75%)、‘牧场06号’(27.12%)和‘康源01号’(21.20%)。综上所述,在本试验选取的4个青贮玉米品种中,‘牧场06号’是最适宜在苏中地区推广种植的青贮玉米品种。     

基于CiteSpace的草地鼠害研究现状及热点分析

草地鼠害严重威胁草地生态安全。中国在草地鼠害研究领域做了大量的工作,发表了大量学术论文。本研究通过文献计量方法,统计了1977—2021年中国草地鼠害研究领域Web of Science(WOS)和中国知网(China National Knowledge Infrastructure, CNKI)数据库收录论文的数量、被引情况、H指数等指标,同时利用CiteSpace对论文的研究力量和研究热点等进行分析。结果表明：1977—2021年,中国草地鼠害研究领域共发表1 140篇文章,其中CNKI发文584篇,WOS发文556篇,且整体上逐年增加;中国科学院和兰州大学在草地鼠害研究中处主导地位,但不同的研究机构、不同的作者之间联系不够紧密;研究对象集中于高原鼠兔(Ochotona curzoniae)和高原鼢鼠(Myospalax baileyi),研究地点集中于青藏高原和高寒草甸,研究方向以种群密度、多样性和土壤有机碳为主。     

靶向cofilin2基因RNAi对鸭病毒性肠炎病毒增殖的影响

旨在探讨cofilin2基因的表达在鸭病毒性肠炎病毒(DEV)增殖过程中的影响.本研究通过已获得的鸭源cofilin2全基因序列(GenBank登录号:MF434775),设计出4对shRNA序列,插入载体中,并转染到鸭胚成纤维细胞中,经FQ-PCR方法和荧光显微镜观察筛选出具有较高干扰效率的shRNA序列,用干扰效率...     

4种蛋白酶制备水溶性蜂王浆

通过水溶性蛋白质的提取率,比较了4种蛋白酶制备水溶性蜂王浆的效果,结果显示,木瓜蛋白酶、无花果蛋白酶、中性蛋白酶、菠萝蛋白酶的水溶性蛋白质提取率分别为14.10%、13.97%、24.91%、7.20%,酶解产物在热、酸、碱环境中具有较强的稳定性。采用中性蛋白酶制备水溶性蜂王浆明显优于其他3种酶,同时中性蛋白酶反应条件简易,可用于水溶性蜂王浆的生产。     

钼对大鼠肝微粒体苯胺羟化酶活力的影响

为研究钼对大鼠肝微粒体中苯胺羟化酶的影响,将50只大鼠随机分为5个组,4个试验组每天分别灌服剂量为8.325、16.65、33.3、66.6 mg/kg的钼酸胺,对照组每天灌服三重蒸馏水,持续灌服2周,然后处死5个组所有大鼠,采用钙沉淀法制备大鼠肝微粒体,再用对氨基酚量法测定苯胺羟化酶的活力.结果显示,4个试验组的苯胺羟化酶的活力分别为2.724 4±0.037 5、2.681 8±0.187 8、2.347 4±0.095 3、2.304 6±0.110 9 nmol/(mg·min),对照组为1.921 0±0.074 3 nmol/(mg·min).与对照组相比,4个试验组苯胺羟化酶的活力都极显著升高(P＜0.01),并且随着剂量增大而逐渐上升.由此证明,钼酸胺口服剂量在8.325 mg/kg～66.6 mg/kg范围内能使大鼠苯胺羟化酶的活力增强.     

Estimation of transmission parameters of a fluoroquinolone-resistant Escherichia coli strain between pigs in experimental conditions

Antimicrobial resistance is of primary importance regarding public and animal health issues. Persistence and spread of resistant strains within a population contribute to the maintenance of a reservoir and lead to treatment failure. An experimental trial was carried out to study the horizontal transmission of a fluoroquinolone-resistant Escherichia coli strain from inoculated to naïve pigs. All naïve contact pigs had positive counts of fluoroquinolone-resistant E. coli after only two days of contact. Moreover, re-infections of inoculated pigs caused by newly contaminated animals were suspected. A maximum likelihood method, based on a susceptible-infectious-susceptible (SIS) model, was used to determine the transmission parameters. Two transmission levels were identified depending on the quantity of bacteria shed by infected individuals: (i) low-shedders with bacterial counts of resistant E. coli in the faeces between 5*10³ and 10⁶ CFU/g (β_L = 0.41 [0.27; 0.62]), (ii) high shedders with bacterial counts above 10⁶ CFU/g (β_H = 0.98 [0.59; 1.62]). Hence, transmission between animals could be pivotal in explaining the persistence of resistant bacteria within pig herds.     

Interaction between energy level in the diet and environmental temperature on the utilization of energy in growing pigs

Thirty-two pigs weighing approximately 50 kg were maintained in respiration chambers to measure their heat production and the partition of energy retention between protein and fat deposition at two environmental temperatures (23 and 13 C) and with two energy levels in the diet: 3.39 (HE) and 2.92 (LE) Mcal ME/kg. From energy balance data, maintenance requirements (MEm) and the efficiency (k) of energy (ME) utilization for energy deposition were calculated for each treatment. For both diets, MEm averaged 122 kcal ME/kg.75 at 23 C, the rate of increase of MEm being 3.7 kcal ME/kg.75 for each 1 C decrease in the environmental temperature. At 23 C, k was higher with the HE diet (.81 vs .55) and similar for both diets (.78) at 13 C. At comparable ME intakes, heat production was higher with the LE diet at 23 C, and the rate of increase of heat production between 23 and 13 C was lower with the LE diet (1 kcal/kg.75) than with the HE diet (3 kcal/kg.75), resulting in similar heat production at 13 C for both diets. This resulted in an interaction (P less than .01) between temperature and diet on heat production. Protein retention was lower (P less than .01) at 13 C but unaffected by diet at both temperatures. This resulted in an interaction (P less than .01) between temperature and diet on fat retention. Consequently, energy of LE and HE diets was similarly utilized at 13 C, while at 23 C, the HE diet was better utilized. The comparison between these results and those obtained in growth experiments is discussed.     

Effectiveness of morantel tartrate and naphthalophos against levamisole resistantOstertagia in sheep

Adult worms from a levamisole resistant population ofOstertagia consisting ofO. circumcincta andO. trifurcata showed no dose response to morantel tartrate. The lowest dose rate of 2.2 mg/kg removed 30.8% of worms while the highest dose rate of 17.6 mg/kg removed 39.2%. A dose response was obtained against naphthalophos and the LD₅₀ and LD₉₅ were determined as 12.54 mg/kg and 23.25 mg/kg respectively. It was concluded that the strain was cross resistant to morantel tartrate but not to naphthalophos.     

载畜率对荒漠草原植物群落影响的研究

对不同载畜率下短花针茅荒漠草原植物群落特征进行比较,结果表明:不同植物种群的盖度对载畜率的响应不同,无芒隐子草盖度在轻度放牧区最大,栉叶蒿盖度在7月份、8月份分别以中度放牧区和轻度放牧区最大;短花针茅、冷蒿、阿氏旋花、细叶葱、木地肤随载畜率增大高度下降明显,猪毛菜高度在四个载畜率下差异均不显著;随着载畜率的增大,植物群落生物量呈下降趋势,且重度放牧与不放牧、轻度放牧有显著差异;随着载畜率的增大,建群种、优势种地位改变不明显,但一年生的猪毛菜重要值增大,在重度放牧区达到最大并占据优势地位;Shannon-wiener指数、Simpson指数、Pielou均匀度指数均以轻度放牧区最大,Shannon-wiener指数、Simpson指数均为轻度放牧>中度放牧>重度放牧>不放牧,且不放牧与轻度放牧差异显著。     

酒糟和醋糟营养成分差异及其瘤胃降解特性分析

本试验旨在评价酒糟、醋糟等非常规饲料资源的饲用价值,为酒糟醋糟资源应用于肉牛养殖提供数据参考.试验选用山西不同地区酒糟、醋糟试样5个,试样编号分别为白酒糟、啤酒糟、醋糟1、醋糟2、醋糟3,发酵原料分别为白酒糟(高粱)、啤酒糟(大麦+大米)、醋糟1(高粱+大麦)、醋糟2(大麦+玉米)、醋糟3(高粱+玉米).通过实验室常规...