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以24株人肠道病原菌(包括病原性大肠杆菌12株、沙门氏菌8株、志贺氏菌3株、小肠结肠炎耶尔森氏菌1株)作为抗原,对乳牛进行系统免疫,免疫乳与非免疫乳乳中IgG含量无显著差异。系统免疫并不增加乳中IgG的含量,但IgG的抗体特异性大大增强,所得的免疫初乳中乳抗体对24种不同病原菌的凝集价为2^8-2^12,为普通初乳中乳抗体凝集价的32—256倍。采用硫酸胺盐析从免疫初乳中分离乳抗体,免疫初乳中的特异性IgG乳抗体较普通初乳中的IgG可显著抑制大肠杆菌和沙门氏菌的生长。动物试验表明,免疫乳中特异性的IgG对大肠杆菌和沙门氏菌所致小鼠腹泻具有很好的保护作用,而普通乳中非特异性的IgG则无此作用,这是由于IgG的特异性所决定。 相似文献
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免疫婴儿乳粉的安全毒理学评定 总被引:1,自引:0,他引:1
以24株人肠道病原菌(包括病原性大肠杆菌12株、沙门氏菌8株、志贺氏菌3株、小肠结肠炎耶尔森氏菌1株)作为抗原,对乳牛进行系统免疫,免疫乳与非免疫乳乳中IgG含量无显著差异。系统免疫并不增加乳中IgG的含量,但IgG的抗体特异性大大增强,所得的免疫初乳中乳抗体对24种不同病原菌的凝集价为28~212,为普通初乳中乳抗体凝集价的32~256倍。以免疫初乳作为原料制备免疫初乳粉并添加到婴儿乳粉中制成免疫婴儿乳粉。婴儿免疫乳粉LD50>10g/kg;Ames试验及小鼠骨髓微核试验和小鼠精子畸变试验表明婴儿免疫乳粉无致畸变作用。大鼠30d喂养试验表明,婴儿免疫乳粉对大鼠生长无不良影响,大鼠血液指标正常,病理学检查未见任何病变。 相似文献
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舍饲新疆褐牛初乳产量及乳成分测定 总被引:2,自引:0,他引:2
测定10头全舍饲新疆褐牛母牛分娩后2,24,48,72,96,120h的初乳产量、常规营养成分、IgG和矿物元素含量。结果表明,母牛分娩后2h(第1次)所挤初乳产量平均为4.73kg,72h内初乳平均总产量为46.6kg,占成母牛305d平均产奶量的0.9%;120h内初乳平均总产量为85.1kg,占305d平均产奶量的1.65%。2h挤出的初乳其蛋白质、脂肪、乳糖、灰分的含量分别为12.59,6.5,2.87,1.11g/100g,是常乳的3.93,1.76,0.57,1.48倍;IgG质量浓度为60.56g/L,是常乳的108.14倍;Ca,P,Na,Mg,Fe,Zn的含量分别为186.03,167.10,89.65,23.31,0.30,2.25mg/100g,是常乳的1.66,2.01,1.81,2.05,2.14,6.43倍。随泌乳期的延长,初乳中除乳糖以外的各种成份均迅速下降,在48h以内,以蛋白质和IgG的下降幅度最大,分别达62.27%和93.40%。至第120h,除蛋白质及矿物元素的Zn以外,各种成分已和常乳相接近。新疆褐牛分娩后不同时间段初乳成分的变化规律和荷斯坦牛相似。 相似文献
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一株肠出血性大肠杆菌O157H7免疫奶牛实验即抗EHEC O157H7免疫乳的试制 总被引:1,自引:1,他引:0
用1株O157H7菌株和另外11株人类肠道主要病原细菌配制O157H7单菌疫苗和多菌联合多价疫苗,对荷斯坦牛进行免疫实验。对免疫常乳中抗EHEC O157H7特异性抗体凝集价进行了长期监测,并对受试奶牛的免疫反应、应激反应及疫苗对奶牛可能产生的毒性作用进行了观察。结果证明,疫苗免疫效果很好,所有奶牛在整个泌乳期一直保持较高的特异性抗体效价(滴度),均在27以上,下个泌乳期开始阶段也未见明显下降的迹象。本次实验意外发现约有30%的未进行过免疫注射的对照组乳样有较高的O157H7特异性抗体滴度,个别乳样凝集价高达27,这可能说明这些牛群中有较高的O157H7感染率或携带率。O157H7是人类近二十余年来才开始认识到的出血性结肠炎(HC)的主要致病菌,能造成出血性腹泻和其它严重并发症。是值得研究和重点防范的病原细菌。 相似文献
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为得到兔血清中纯度较高的特异性抗体,通过将纯化的水牛乳β-乳球蛋白耦联到免疫亲和梓上,用3mol/L氯化镁将特异性的IgG洗脱,得到了SDS-PAGE纯的IgG,其蛋白含量为5.8mg/ml,经ELISA榆测滴度为1:109。本实验所建立的方法可用于纯化兔血清中特异性的IgG。 相似文献
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Kaylegian KE Houghton GE Lynch JM Fleming JR Barbano DM 《Journal of dairy science》2006,89(8):2817-2832
Mid-infrared (MIR) milk analyzers are traditionally calibrated using sets of preserved raw individual producer milk samples. The goal of this study was to determine if the use of sets of preserved pasteurized modified milks improved calibration performance of MIR milk analyzers compared with calibration sets of producer milks. The preserved pasteurized modified milk sets exhibited more consistent day-to-day and set-to-set calibration slope and intercept values for all components compared with the preserved raw producer milk calibration sets. Pasteurized modified milk calibration samples achieved smaller confidence interval (CI) around the regression line (i.e., calibration uncertainty). Use of modified milk calibration sets with a larger component range, more even distribution of component concentrations within the ranges, and the lower correlation of fat and protein concentrations than producer milk calibration sets produced a smaller 95% CI for the regression line due to the elimination of moderate and high leverage samples. The CI for the producer calibration sets were about 2 to 12 times greater than the CI for the modified milk calibration sets, depending on the component. Modified milk calibration samples have the potential to produce MIR milk analyzer calibrations that will perform better in validation checks than producer milk-based calibrations by reducing the mean difference and standard deviation of the difference between instrument values and reference chemistry. 相似文献
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To determine whether individual cow milking vacuum (within the short milk tube and the liner mouthpiece) could be substituted for milk flow technology to identify delayed (bimodal) milk ejection, and the possible relationship between bimodal milk flow and milk yield, we recorded milking data from 663 Holstein cows on a 3,600-cow Michigan dairy that milked 3 times per day. Overall, delayed milk ejection occurred in 45.6% of the milkings, and 98% of the cows with delayed milk ejection also had bimodal flow. Multivariable analysis revealed that milk yield during each individual cow milking was positively associated with increasing lactation number but negatively associated with increasing days in milk and delayed milk ejection. As the time between unit attachment and the estimated milk letdown (the lag period) increased, milk yield decreased; relative to a lag of <30 s, milk yield decreased by 1.8 and 3.1 kg for lags of 30–59 and ≥60 s, respectively. The final multivariate model had an adjusted coefficient of determination of 0.27. The negative association between delayed milk ejection and decreased milk yield in this study suggested that milking vacuum parameters from individual cows could serve as a useful tool to qualitatively estimate milk flow within a herd and that this information may be used to enhance herd productivity. 相似文献
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免疫学检测羊乳中掺入牛乳成分 总被引:2,自引:0,他引:2
由于营养、价格和原料等原因,市场上在羊乳中掺入牛乳的现象常有发生。针对这种乳源性掺假陆续产生了多种检测方法,本文主要综述了以ELISA为主的免疫学快速检测方法。 相似文献
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The physical characteristics of milk powders used in chocolate can have significant impact on the processing conditions needed to make that chocolate and the physical and organoleptic properties of the finished product. Four milk powders with different particle characteristics (size, shape, density) and "free" milk fat levels (easily extracted with organic solvent) were evaluated for their effect on the processing conditions and characteristics of chocolates in which they were used. Many aspects of chocolate manufacture and storage (tempering conditions, melt rheology, hardness, bloom stability) were dependent on the level of free milk fat in the milk powder. However, particle characteristics of the milk powder also influenced the physical and sensory properties of the final products. 相似文献
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The US Pasteurized Milk Ordinance (PMO) allows milk tanker trucks to be used repeatedly for 24 h before mandatory clean-in-place cleaning, but no specifications are given for the length of time a tanker can be empty between loads. We defined a worst-case hauling scenario as a hauling vessel left empty and dirty (idle) for extended periods between loads, especially in warm weather. Initial studies were conducted using 5-gallon milk cans (pilot-scale) as a proof-of-concept and to demonstrate that extended idle time intervals could contribute to compromised raw milk quality. Based on pilot-scale results, a commercial hauling study was conducted through partnership with a Pacific Northwest dairy co-op to verify that extended idle times of 6 h between loads have minimal influence on the microbiological populations and enzyme activity in subsequent loads of milk. Milk cans were used to haul raw milk (load 1), emptied, incubated at 30°C for 3, 6, 10, and 20 h, and refilled with commercially pasteurized whole milk (load 2) to measure cross-contamination. For the commercial-scale study, a single tanker was filled with milk from a farm known to have poorer quality milk (farm A, load 1), emptied, and refilled immediately (0 h) or after a delay (6 h) with milk from a farm known to have superior quality milk (farm B, load 2). In both experiments, milk samples were obtained from each farm's bulk tank and from the milk can or tanker before unloading. Each sample was microbiologically assessed for standard plate count (SPC), lactic acid bacteria (LAB), and coliform counts. Selected isolates were assessed for lipolytic and proteolytic activity using spirit blue agar and skim milk agar, respectively. The pilot-scale experiment effectively demonstrated that extended periods of idle (>3 h) of soiled hauling vessels can significantly affect the microbiological quality of raw milk in subsequent loads; however, extended idle times of 6 h or less would not measurably compromise milk quality in subsequent loads in commercial tankers. Current tanker sanitation practices appear to be sufficient for maintaining raw milk SPC, LAB, and coliform levels, which are important measures of milk quality. 相似文献
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《Journal of dairy science》2023,106(4):2230-2246
Corrected milk equations were developed in attempts to bring milk weights to a standardized basis for comparison by expressing the weight and composition of milk as corrected to the energy content of milk of a specific composition. Expressed as milk weights familiar on farm and in commerce, this approach integrates energy contributions of the dissimilar components to make the mass units more comparable. Such values are applied in evaluating feed efficiency, lactation performance, and global milk production, as functional units for lifecycle assessments, and in translation of research results. Corrected milk equations are derived from equations relating milk gross energy to milk composition. First, a milk energy equation is used to calculate the energy value of the milk composition to correct to (e.g., 0.695 Mcal/kg for milk with 3.5% fat, 3.05% true protein, and 4.85% lactose). That energy value is divided into the energy equation to give the corrected milk equation. Confusion has arisen, as different equations purport to correct to the same milk composition; their differences are based on uses of different energy equations or divisors. Accuracy of corrected milk equations depends on the accuracy of the energy equations used to create them. Energy equations have evolved over time as different milk component analyses have become more available. Inclusion of multiple milk components more accurately predicts milk energy content than does fat content alone. Omission of components from an equation requires the assumption that their content in milk is constant or highly correlated with an included component. Neither of these assumptions is true. Milk energy equations evaluated on a small data set of measured milk values have demonstrated that equations that incorporate protein, fat, and lactose contents multiplied by the gross energy of each component more closely predict milk energy than equations containing fewer components or regression-derived equations. This provides a tentative recommendation for using energy equations that include the 3 main milk components and their gross energy multipliers for predicting milk energy and deriving corrected milk equations. Accuracy of energy equations is affected by the accuracy of gross energy values of individual components and variability of milk composition. Lactose has consistent reported gross energy values. In contrast, gross energy of milk fat and protein vary as their compositional profiles change. Future refinements could assess accuracy of milk fat and protein gross energy and whether that appreciably improves milk energy predictions. Fat gross energy has potential to be calculated using the milk fatty acid profile, although the influence on gross energy may be small. For research, direct reporting of milk energy values, rather than corrected milk, provides the most explicit, least manipulated form of the data. However, provision of corrected milk values in addition to information on components can serve to translate the energy information to a form familiar to and widely used in the field. When reporting corrected milk data, the corrected milk equation, citation for the energy equation used, and composition and energy contents of the corrected milk must be described to make clear what the values represent. 相似文献
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毛细管电泳法对乳及乳制品中乳源蛋白的研究 总被引:2,自引:0,他引:2
采用毛细管电泳方法对原料乳、市售鲜奶、不同厂家的巴氏灭菌乳、不同厂家和产地超高温灭菌乳(UHT)、调味乳、乳酸饮料、复原乳、酸奶、奶粉中蛋白成分进行检测。选择聚乙烯醇涂层毛细管,采用柠檬酸缓冲体系,在紫外检测214nm、分离电压20kV条件下对乳及乳制品中的α一乳白蛋白(α-La)、β一乳球蛋白(β-Lg)、α-酪蛋白(α-CN)、β-酪蛋白(β-CN)和k-酪蛋白(k-CN)进行分离测定。结果表明:五种蛋白的含量在原料乳(巴氏灭菌乳、市售鲜奶)、UHT乳、酸奶、调味乳、乳酸饮料、复原乳中依次降低,而UHT乳含量随保质期的增加而减少,奶粉中蛋白质含量因其适应人群而有差异。乳及乳制品中蛋白质的含量与其存在形式、产地及加工工艺相关。 相似文献