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锌是奶牛营养必需的微量元素。它广泛分布于动物机体的各种组织中，已知体内与锌有关的酶类和功能蛋白有300余种。Renner（1984）综述牛奶中的平均锌含量（umol／L）为55．07，变动范围22．95-107．1。汪玉松等（1995）归纳牛奶中的锌含量平均为53．54（30．60—91．79）umol／L。 相似文献
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奶牛的好坏．不仅体现在产奶量上．还体现在牛奶的品质上。牛奶中主要成分是水、脂肪、蛋白质、乳糖、盐类及微量元素。其中脂肪和蛋白质含量是牛奶两个最重要的质量指标。正常的牛乳各成分含量都有一定的变动范围．但变化最大的是脂肪．其次是蛋白质。牛奶的检验就是根据奶中各主要成分的含量来鉴定等级的。牛奶中脂肪和蛋白质的增加． 相似文献
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以PAL材料为主要成分研制的矿物质饲料添加剂应用于奶牛生产，经过5个月的饲喂试验后．测定结果为：试验组与对照组在产奶量、耗料量及牛奶营养成分等方面均无差异，但试验组牛奶中微量元素碘、硒、锌的含量大幅度提高，其中碘提高了97％，硒提高了117．2％，锌提高了15．95％。表明应用PAL材料是生产特质营养保健牛奶的一种有效途径。 相似文献
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稻草经过液氨处理后，粗蛋白质由４．５７％提高到８．８５％。在补充矿物质微量元素和维生素的基础上，作为唯一的粗饲料饲喂奶牛，与东北羊草相对比。结果两组的平均日产奶量（１３．２对１３．４ｋｇ）、平均体重变化（＋１４．６对十２．８ｋｇ）以及常规乳成分分析，均无显著差异。测定血清及牛奶中无机磷、钙、尿素氮的含量发现，两组经２４天试验，血清中各成分变化不显著，但牛奶中各成分变化差异显著，分别为磷（－１０．６５对－５．５ｍｇ％），钙（－９．８对２．９ｍｇ％）．氮（－４．４９对－０．０８ｍｇ％）。说明用氨化稻草饲喂奶牛，对奶牛的体重、产奶量以及血液中的某些理化指标无明显影响，但能引起牛奶中无机磷、钙、尿素氮相对减少。 相似文献
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随着人们生活水平不断提高,对奶的需求也在逐步增加,乳牛饲养在辽宁省迅速发展起来.为满足市场需求解决供求之间的矛盾,在大力发展乳牛数量的同时,要不断改进乳牛的培育方法. 相似文献
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对10份鲜牛乳以98℃煮沸5 min消毒后用乳酸杆菌发酵制作酸乳,测定了发酵前后乳中SOD的活性和T-AOC的变化.结果发酵前SOD活性和T-AOC分别为54.44 U/mL±10.37 U/mL,4.86 U/mL±2.06 U/mL;发酵后SOD活性和T-AOC分别为:66.96 U/mL±6.45 U/mL,7.97 U/mL±3.51 U/mL.发酵乳SOD活性升高了23%,T-AOC升高了64%(均P《0.01). 相似文献
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《畜牧与兽医》2017,(3):39-42
本研究旨在探讨复合微生态制剂对奶牛泌乳性能和乳品质的影响,为微生态制剂在奶牛养殖中的推广应用提供参考依据。将90头荷斯坦奶牛随机分成3组(对照组、试验Ⅰ组、试验Ⅱ组),对照组饲喂基础日粮,试验Ⅰ组、Ⅱ组分别在基础日粮中添加0.5 g·kg~(-1)、1.0 g·kg~(-1)的复合微生态制剂。通过测定各处理组的产奶量、采食量、料奶比等泌乳性能指标和乳脂率、乳蛋白率、乳糖率、乳干物质率、体细胞数等乳品质指标,比较分析复合微生态制剂不同添加水平对奶牛泌乳性能和乳品质的影响。结果显示,试验Ⅱ组与对照组相比,日产奶量显著提高(P0.05),料奶比显著降低(P0.05),乳脂率、乳蛋白率均显著提高(P0.05),体细胞数显著降低(P0.05)。该结果表明奶牛基础日粮中添加1.0 g·kg~(-1)的复合微生态制剂能显著改善奶牛的泌乳性能和乳品质。 相似文献
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A negative relationship of glutamic acid content and milk yield over the first 100 days of lactation was found in a set of 20 cows. In some free amino acids, large differences exist between the cows with the higher milk yield and those with the lower milk yield, the largest difference being recorded in the content of glutamic acid (in favour of the cows with the lower milk output). The group of cows with the higher milk output per day or per first 100 days of lactation showed no dependence on any of the free amino acids in milk. The group of cows with the lower milk yield showed a significant negative relation of glutamic acid content to milk yield over the first 100 days of lactation and a significant to highly significant positive relation between serine, threonine and alanine contents on the one hand and daily milk yield on the other. 相似文献
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The two possible pathways contaminating milk and milk products with mycotoxins are either the secretory or post-secretory route. The latter is of only little importance due to cooling conditions in production and storage. A secretory contamination can only occur with such mycotoxins, which undergo no complete degradation through their passage into the milk. From the mycotoxins, present in cow's feed; virtually only aflatoxin B1 yields a milkborne metabolite, the aflatoxin M1. The carry over rate is low (2 +/- 1%), but can be enhanced by polyhalogenated biphenyls, also present in the forage. Under normal conditions, however, this enhancement will not be measurable due to low equimolar concentrations of both reactants. The aflatoxin M1 content in herd's bulk milk depends exclusively on the content of the precursor aflatoxin B1 in the ration of the cow and is with less than 10 ng/kg fairly low at present in the Federal Republic of Germany. A careful supervision of the imported feed ingredients for mixed feed, however, will ensure to keep those batches out of dairy cow feeding which exceed a certain level of aflatoxin. The legal threshold is 10 micrograms/kg, being even too high to ensure a milk containing less than 10 ng/kg under high energy feeding conditions. The discussed thresholds for aflatoxin M1 in milk are 50 and 10 ng/kg resp., the latter value is scheduled for milk used in infant nutrition. To keep this low concentration the intake of aflatoxin B1 must be less than 2 micrograms/kg of the daily ration. 相似文献
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用气相色谱 质谱联用仪(GC MS)对牦牛乳、黑白花奶牛乳、犏牛乳及牦牛乳制品（奶油、酥油、曲拉、酸奶）中的脂肪酸组成进行了测定。结果表明,牦牛乳中功能性脂肪酸,如共轭亚油酸（CLA）、亚油酸（LA）、α 亚麻酸（ALA）、γ 亚麻酸（GLA）占总脂肪酸的比重均显著高于犏牛乳和黑白花奶牛乳（P＜0.05）;犏牛乳中ω 6/ω 3 PUFA的比值（1.55）略高于牦牛乳（1.54）,差异不显著（P＞0.05）,但都在最佳膳食平衡比值范围内,黑白花奶牛乳中ω 6/ω 3多不饱和脂肪酸（PUFA）的比值（11.33）超过了推荐最佳比值。加工处理能够改变乳制品脂肪酸的构成,如牦牛乳奶油中检测出原奶中所不含的一种亚油酸（18:2Δ8c,11c）。酥油主要以不饱和脂肪酸（UFA）为主,而曲拉主要以饱和脂肪酸（SFA）为主,牦牛酸奶中没有检测到GLA。 相似文献
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Milk immunoglobulins were extracted from the stained cream layer of positive milk ring tests from experimentally inoculated or naturally infected cows. IgA was always found, associated with IgM in most cases (15/17) and with IgG in a smaller number of cases (11/17). An additional incubation at 20 degrees C for 18 h gave clearer positive and negative results and a lower limit of detection than that of the usual milk ring test. 相似文献
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For food evaluation the determination of the number of Staphylococcus aureus (hereinafter S. aureus) colonies is insufficient in view of present scientific knowledge. The results, advantages and shortcomings of diagnostic methods are demonstrated on an example of three methods of detection of staphylococcal enterotoxins in milk and milk products. 133 strains were investigated by the method of biotyping of S. aureus strains. Four strains of S. aureus were included in biotype A, seven xin-producing strains were isolated seventeen times by detection of 96 S. aureus strains were not included in any biotype, the other strains belonged to biotypes C and E. This method can be used as an auxiliary method of evaluation of foods containing S. aureus bacteria. The agar-gel precipitation method of enterotoxin detection in isolated strains of S. aureus has just restricted validity. The enteroto-strains. The main shortcoming of this method is a fact that the result concerning the isolated strains need not be identical with the result of enterotoxin detection in food. Direct assays of staphylococcal enterotoxins in milk and milk products using an enzymoimmunological method seem to be the most promising, mainly due to their high sensitivity (0.0001-0.001 micrograms.ml1-) and other advantages. Positive and negative results are presented on an example of two model trials with winter sheep milk cheese. 相似文献