体细胞数过高对乳制品品质的影响

本文主要阐述了体细胞数过高对乳制品营养价值、风味、加工特性以及贮藏特性等方面的不利影响。体细胞数过高,则乳脂率和酪蛋白含量降低;牛乳中盐类比例失调,牛乳热稳定性降低,凝固型酸奶的凝乳松散易碎裂,乳清易析出;过氧化物酶含量升高,乳品风味欠佳;脂肪氧化酶增加,其氧化产物游离脂肪酸含量上升,乳易酸败,缩短乳品保质期;蛋白水解酶尤其是血纤维蛋白溶酶含量和活性增加,造成乳蛋白大量水解,降低干酪产量;牛乳中有害微生物含量增加,抗生素残留的风险增加,降低乳制品食用安全。     

奶牛酪蛋白和β-乳球蛋白基因多态及其对泌乳性状的影响

牛乳蛋白主要包括酪蛋白和乳清蛋白,其中酪蛋白基因和β-乳球蛋白基因是对奶牛产奶性能有较大影响的两种基因。牛乳蛋白基因多态性与泌乳性状,如泌乳量、乳脂率、乳蛋白量及乳蛋白率有很强的相关性。本文主要对酪蛋白和β-乳球蛋白基     

牛乳β-酪蛋白遗传多态性及A2型乳制品研究进展

酪蛋白是牛乳酪蛋白的主要组成部分,具有重要的生理功能,与人体健康密切相关。牛乳β-酪蛋白具有多种遗传变异体,最常见的是A1型和A2型,其中A2型为天然原型。本文从β-酪蛋白的遗传多态性、β-酪蛋白消化特性与人体健康、A2型牛群选种选育及A2型乳制品研究进展等方面进行综述,旨在阐述牛乳β-酪蛋白遗传多态性研究现状及其与人体健康的相关性,为今后A2型乳制品行业的研究开发提供参考。     

牦牛乳营养价值的研究进展

近年来,对于牦牛乳营养成分的研究显著增多,牦牛乳作为一种浓缩乳,是营养价值很高且珍稀的乳制品,高原地区牧民经常把它当作食物,相比普通牛乳,牦牛乳蛋白含量更高。牦牛乳蛋白构成成分和其他哺乳动物乳相差不多,除了常规营养成分外,还含有酪蛋白、乳清蛋白及一些生物活性因子。本文主要总结分析了牦牛乳的营养成分和功能,为牦牛乳及其乳制品的开发利用提供理论参考。     

A2型β-酪蛋白牛奶及A2乳制品开发现状

酪蛋白占牛奶总蛋白80%,具有很高的营养价值和重要的生理功能。A1和A2型β-酪蛋白是牛奶中两种主要的β-酪蛋白遗传变异体。牛奶A2型β-酪蛋白和人乳中的β-酪蛋白结构和消化特点相似,对人体更亲和,也更容易被消化吸收。开发A2型牛奶对增加乳制品品种、细分乳制品市场、提高乳制品档次具有积极意义。本文介绍了牛奶β-酪蛋白基因多态性、中国荷斯坦牛群β-酪蛋白基因型频率和等位基因频率、A2奶牛和A2牛奶的检测、以及A2乳制品开发现状,并对新疆开发A2牛奶及乳制品提出意见和建议。     

水牛奶干酪消费潜力分析

干酪是一种具有极高营养价值的乳制品，是牛乳多种营养成分的浓缩精华。水牛奶干物质含量高，其酪蛋白的生物特性证明其最适宜用于加工干酪。本文概述了干酪的营养功能，水牛奶的特点及其国内外开发现，并得出水牛奶产品开发应从干酪产品做起，水牛奶干酪将成为最具消费潜力的乳制品的结论。     

信息广场

乳制品国家标准全面更新国家质量技术监督局日前批准、发布了６项修订后的乳和乳制品标准，至此１９８５年制定的原标准几乎全部被更新，这对乳制品生产和消费将会产生积极影响。 新发布的６项标准中，５项是修订标准，１项是新定标准。修订标准是《酸牛乳》、《巴氏杀菌乳》、《全脂乳粉、脱脂乳粉、全脂加糖乳粉和调味乳粉》、《奶油》、《全脂无糖炼乳和全脂加糖炼乳》；新制定的标准是《灭菌乳》。标准中，“食品添加剂和食品营养强化剂”、“净含量”、“卫生指标”、“标签”等为强制性条文；“原料要求”、“感官特性”、“理化指标…     

牛奶中乳脂乳蛋白快速测定方法的建立与比较

在各类食物中，乳及乳制品以其较高的营养价值成为大众化食品。牛乳中含有丰富的蛋白质、脂肪、碳水化合物、矿物质及维生素，成分齐全，容易消化，风味香甜，其所含营养素比率更适合于幼小动物发育。因此牛乳不仅是人们所喜食的高营养价值食品，而且可作为最重要的母乳代用品，倍受人们的青睐。     

牛乳热稳定性影响因素的研究进展

牛乳的热稳定性是评定乳制品生产工艺合理性和生产质量的重要指标,主要影响因素来自乳成分的改变,如pH、无机盐、乳蛋白及其多态性、非蛋白氮、乳脂、乳糖和体细胞等.本文详细概述了影响牛乳热稳定性的相关因素以及作用机理,以期为乳制品加工中有效控制影响牛乳热稳定性的因素,提高生产效率提供依据和参考.     

生鲜牛乳的质量要求

牛乳、各种乳制品及牛乳食品。已经是人们日常生活中重要的食品之一。生产各种优质的乳制品和牛乳食品。其首要条件是乳牛场要提供卫生、优质的原料乳．即生鲜牛乳（简称生乳）。     

后疫情时代乳制品结构的转变

我国乳制品消费结构发展不平衡,液态奶产销量占比过重,大量干乳制品需要进口。本文基于2016—2020年乳制品的消费结构占比,分析了我国目前乳制品的发展阶段、各乳制品的进口量对比,并结合乳制品新产业政策及理化性质分析预测乳制品市场的新走向;利用主成分分析法建立关于食物营养的评价模型,计算各乳制品得分以评估其营养素含量高低。研究结果表明,我国乳制品消费结构正从第二阶段向第三阶段过渡,我国奶酪制品的市场需求前景大;目前,我国大部分奶酪制品依靠进口,但国外奶酪制品的口味不被我国大部分消费人群接受。因此,具有较高营养价值和口感好的干乳制品在中国有着较大的发展潜力,同时,我国消费者正从“喝奶”向“吃奶”转变;对乳制品的现状及营养成分进行分析,可指导适合我国消费者的新产品研发。     

乳酸菌发酵青贮玉米饲料对奶牛机体健康和生产性能的影响

乳酸菌作为一种应用广泛的微生物制剂,有着改善奶牛机体胃肠道健康、增加产奶量、提高免疫力和改善乳品质的作用,可直接与奶牛饲料搭配进食或用于青贮玉米饲料的制备。玉米作为青贮饲料的优质原料之一,可全株发酵,营养价值丰富,适于奶牛饲喂。本文总结了乳酸菌制剂的作用原理和应用、青贮玉米饲料的制备要点以及青贮玉米饲料添加乳酸菌后对奶牛生产性能、机体健康的影响,旨在为奶牛优质饲料的制备及应用提供参考,促进奶牛养殖业的发展。     

Trends in the quality and hygiene parameters of bulk Italian Mediterranean buffalo (Bubalus bubalis) milk: A three year study

Buffalo milk represents an indispensable source of nourishment in many parts of the world and it is the second most consumed milk worldwide. Buffalo milk is actually used for the production of many dairy products such as pasteurized or concentrated milk, butter, yogurt, ice‐cream, dehydrated milk products and cheeses. Due to its high nutritional value and the presence of natural bioactive substances, buffalo milk can also provide health benefits to consumers. In Italy, buffalo milk is used mainly for cheese making, mozzarella PDO (Protected Designation of Origin), which is a highly valued dairy product. This 3‐year study, carried out between 2011 and 2013, was aimed at evaluating the quality of bulk Italian Mediterranean buffalo milk by monitoring physico‐chemical parameters, somatic cell and total bacterial counts. A total of 51 samples of bulk milk were collected from one herd throughout the monitored period. Analysis of variance, carried out to test month, season and year main effects, highlighted remarkable seasonal effects for fat, protein and lactose content, as well as for predicted mozzarella cheese yield, and somatic cell counts. The calculation of simple correlations allowed the identification of positive correlations between estimated cheese yield and fat and protein content.     

Parameters for the determination and evaluation of heat stress in dairy cattle in South Africa

Not all parameters are trustworthy and practical to use as parameters to determine heat stress in dairy cattle. The temperature-humidity index (THI) is still the best, simplest and most practical index (parameter) for measurement of environmental warmth which cause heat stress in dairy cattle. It is practical, easy to determine and relatively trustworthy to use body temperature and respiratory rate as parameters to determine heat stress in dairy cattle. These physiological parameters must always be used together with THI values to determine and evaluate heat stress in dairy cattle. For practical purposes, plasma cortisol concentration and milk composition cannot be used as parameters to determine heat stress in dairy cattle although good indications of acute or chronic heat stress can be obtained. Vanillic acid is a break-down product of adrenalin found in milk, but before its concentration in milk can be used as an indicator/parameter of heat stress in dairy cows, more about the pharmacodynamics of adrenaline in the milk has to be known. Selection and breeding of dairy cows on the basis of their adaptibility to heat stress using the most practical heat stress parameters will ensure that their offspring will have superior performance in the prevailing environmental conditions.     

保护性蛋氨酸与赖氨酸在奶牛生产中的应用

乳蛋白是体现牛奶质量的重要指标,乳蛋白氨基酸来源于日粮氨基酸。乳蛋白中酪蛋白、乳白蛋白和乳球蛋白除了满足人体基本营养需求,还对人体生长、发育和健康发挥重要作用,是动物源优质蛋白质来源。蛋氨酸与赖氨酸是奶牛日粮限制性氨基酸,不仅是乳蛋白合成的重要底物,同时还作为信号分子调控乳蛋白基因表达。本文综述了奶牛氨基酸需要与来源、必需氨基酸、限制性氨基酸、保护性蛋氨酸和赖氨酸在日粮中的应用,阐述了氨基酸营养在蛋白质合成代谢中的核心作用,为指导奶牛日粮配方提供参考。     

葡萄糖代谢与利用对奶牛生产的影响

葡萄糖是脑细胞等中枢神经系统和胚胎的主要供能物质,也是泌乳奶牛合成乳糖的前体物质,并且与乳脂、乳蛋白合成密切相关,对泌乳奶牛具有重要的营养生理功能。为了提高奶牛泌乳性能以及生理健康,有必要深入研究奶牛葡萄糖的营养与生理功能。本文从葡萄糖的生成、乳腺中葡萄糖代谢与调节、葡萄糖代谢对奶牛生产影响等几个方面对泌乳奶牛葡萄糖的代谢与利用进行综述,为进一步揭示奶牛葡萄糖的代谢机制、提高奶牛对葡萄糖利用、促进奶牛生产提供参考依据。     

牛乳杀菌技术研究进展

乳及乳制品是营养价值极高的食品，为保证充足的安全性、较长的货架期及稳定的营养价值，乳杀菌技术得到研究人员的重点关注。本文综述乳品工业的杀菌技术研究进展，阐明热处理技术和非热处理技术的杀菌机制，介绍巴氏杀菌、超高温瞬时灭菌、超高压处理、超声波、脉冲电场等不同杀菌技术对微生物、营养活性物质、风味物质、质构及化学反应等方面的影响，为其在高生物活性乳制品中的开发应用提供参考。     

奶牛乳脂合成及其关键基因的调控作用

牛奶是提高身体抵抗力、抵抗疾病的最佳营养品。我国奶牛养殖业蓬勃发展的同时,牛奶品质的提高已成为奶业发展的重大课题与挑战。乳脂,作为牛奶主要营养成分之一,不仅为人们提供高质量的天然脂肪,还成为衡量奶牛产奶性能的重要指标,消费者所追求的优质牛奶(营养品)就是乳脂≥3.2%的牛奶。大量的研究报道证明,除了饲养管理与营养因素外,关键基因在奶牛乳腺发育、血液中脂肪酸(fatty acid, FA)摄取、从头合成与转录、三酰甘油的合成、脂滴的形成等起着重要的调控作用。此文就乳脂合成过程中相关蛋白、酶的协同作用,以及一些关键基因对奶牛乳脂生成的研究进展进行综述分析,旨在为后期奶牛乳脂的理论研究奠定基础。     

奶用后备牛不同生理阶段乳腺发育特点及营养调控作用

后备牛阶段的乳腺发育决定成年后的产奶性能,而不同生理阶段的乳腺发育有其不同的特点。奶牛出生、初情期和妊娠期营养水平对乳腺生长发育和优质奶牛培育至关重要。通过日粮营养素调控乳腺发育是提高奶牛产奶性能的重要环节。本文就奶用牛后备牛阶段的乳腺发育特点及规律,乳腺发育对成年泌乳性能的影响,乳腺发育的评价指标及后备牛乳腺发育营养调控做一综述。     

Genetics and physiology of leptin in periparturient dairy cows

In dairy cattle, the increase in milk yield has been accompanied by a more negative energy balance (EB) during early lactation and a decrease in fertility. As the hormone leptin is involved in regulation of nutritional status and reproductive function this hormone is an interesting protein to investigate during the periparturient period in dairy cattle. This study was performed to get insight into the function of leptin during the periparturient period and to perform an association study between polymorphisms in the bovine leptin gene and leptin receptor gene and fertility as well as production traits. Leptin concentrations in the periparturient cow undergo remarkable changes; leptin concentrations were high during late pregnancy and declined to a nadir at parturition. Genetic analysis of the leptin gene indicated that a combination of three polymorphisms located at a 135 bp region of the leptin promoter explained most of the variance in prepartum leptin concentrations. The two extreme genotype combinations could be used to investigate the function of leptin concentrations in pregnant cows. A polymorphism located on intron 2 of the leptin gene explained a significant part of the variation in milk yield. On the promoter region of the leptin gene an SNP was detected that was associated with first postpartum luteal activity (FPLA). This SNP could be a candidate marker for fertility in dairy cows. Another SNP on the leptin promoter was associated with energy balance and dry matter intake (DMI) where a higher dry matter intake occurred together with a higher energy balance. Two genotype combinations of the aforementioned three associated SNPs were defined which had a good milk yield together with a good energy balance and fertility. Calculations of an economical value per trait have to validate if one of these genotype combinations would be a possible candidate to be used in selection.