不同油料籽实对奶牛瘤胃液、血浆脂肪酸组成及乳脂CLA含量的影响

 【目的】研究不同脂肪酸构成的油料籽实对奶牛瘤胃液和血浆中脂肪酸的组成及乳脂CLA含量的影响,初步探讨乳脂CLA合成机制,为改善牛奶脂肪酸构成,提高乳脂中CLA含量寻找合适途径。【方法】以3头装有永久性瘤胃瘘管的经产荷斯坦奶牛为试验动物,采用3×3拉丁方设计,在日粮中添加不同油料籽实（葵花籽、亚麻籽、菜籽）,3种日粮的粗脂肪含量基本相同,测定采食后不同时间点瘤胃液、血浆及乳脂中脂肪酸含量。【结果】葵花籽组奶牛乳脂中CLA、t11-C18﹕1、PUFA及LCFA比例均显著高于菜籽组和亚麻籽组（P＜0.05）;葵花籽组奶牛血浆中t11-C18﹕1的比例显著高于菜籽组和亚麻籽组（P＜0.05）;瘤胃液中各种脂肪酸含量在3组之间差异不显著（P＞0.05）,随采食后时间的延长,饱和脂肪酸含量逐渐增加,不饱和脂肪酸含量逐渐减少,不同时间点瘤胃液中CLA的比例均较低;瘤胃液、血浆中的t11-C18﹕1含量对乳脂中CLA含量的决定系数（R2）分别为0.841和0.766。【结论】富含亚油酸的葵花籽在优化奶牛乳脂肪酸构成、提高CLA含量方面效果最好。     

日粮添加植物油籽对乳脂脂肪酸的影响

 【目的】 研究日粮中添加国内广泛种植的几种植物油籽对中国荷斯坦奶牛乳脂脂肪酸组成影响，为改变牛奶脂肪酸组成，提高乳品质寻找合适的途径。【方法】 选用40头泌乳中期（150±25d）、胎次（3±1胎）的中国荷斯坦奶牛，采用完全随机试验（对照组、全脂整粒大豆组、混合油籽组以及全脂膨化大豆组）设计。试验期6周，牛奶样品于试验第4、5和6周采集，利用气相色谱仪分析样品脂肪酸组成。【结果】与对照组相比，日粮添加膨化大豆后乳脂中共轭亚油酸（CLA）含量提高了83.33%(P<0.05）。全脂整粒大豆组、混合油籽组以及全脂膨化大豆组乳脂中月桂酸（C12﹕0）和豆蔻酸(C14﹕0)含量分别比对照组降低了35.73%和35.51%、38.65%和23.83%、24.85%和31.48%。【结论】日粮添加植物油籽可以改变乳脂脂肪酸组成，增加CLA含量，降低月桂酸（C12﹕0）和豆蔻酸(C14﹕0)含量，从而提高乳品质。     

日粮不饱和脂肪酸对乳脂CLA合成的影响研究进展

CLA是一组18碳二烯酸结构和位置异构体的总称,反刍动物产品(尤其乳制品)中CLA含量丰富,是人类天然食物中CLA主要来源,是唯一具有抗癌作用的动物源脂肪酸,已成为最近几年的研究热点。在此,从日粮不饱和脂肪酸对乳脂CLA的生物合成的影响及调节机理方面作了概述。     

气相色谱-质谱法测定食品中的反式脂肪酸

[目的]采用气相色谱-质谱联用技术定性定量分析食品中的反棕榈油酸、反油酸和反异油酸3种反式脂肪酸。[方法]从食品中提取的脂肪在碱性条件下甲酯化;Hp-INNOW ax（30 m×0.25 mm×0.25μm）毛细管柱上分离,经质谱检测器检测;通过标准品的保留时间、与标准谱库对照的方法定性;采用外标法定量;通过相关公式计算出样品反式脂肪酸含量。[结果]反式脂肪酸甲酯及其异构体分离效果较好;在0.001~0.010 mg/m l浓度范围内线性良好（r〉0.999 5）,相对标准偏差为0.648%~2.430%,方法回收率为89.1%~102.0%,3种反式脂肪酸甲酯的检出限分别为0.800、0.875、0.840μg/m。l[结论]该方法准确、可靠、简捷,适用于食品中主要反式脂肪酸的测定。     

3种生理调节剂对山羊瘤胃液中脂肪酸组成的影响

研究3种生理调节剂对山羊瘤胃液中共轭亚油酸(CLA)前体反式油酸的积累与CLA含量的影响,选用8只装有永久性瘤胃瘘管的山羊,采用4×4拉丁方设计,试验设对照、葵花油、海南霉素和丙酮酸钙4个处理,每只山羊每天添喂剂量分别为0、0.3、0.05、0.05 g/kg体重。每两周采集瘤胃液样品,采用毛细管气相色谱法分析瘤胃液中反式油酸、CLA含量及其他脂肪酸组成,并对CLA与反式油酸含量进行了相关性分析。结果表明,3种生理调节剂都能在不同程度上提高C18∶1 trans-11(TVA)和CLA含量,其作用效果依次为葵花油>海南霉素>丙酮酸钙。瘤胃中TVA和CLA含量呈极显著正相关(P<0.01)。     

不同烟丝中非挥发性有机酸和高级脂肪酸含量比较

[目的]研究不同卷烟非挥发性有机酸和高级脂肪酸含量差异,为研究卷烟风格差异提供参考.[方法]选取国内外52种不同产地卷烟,采用气相色谱方法分别对烟丝中非挥发性有机酸和高级脂肪酸、烟碱含量进行分析.[结果]试验表明,烤烟型卷烟非挥发性有机酸低于混合型卷烟,而高级脂肪酸含量高于混合型卷烟;国内混合型卷烟草酸、柠檬酸、高级脂肪酸含量高于国外混合型卷烟;不同产地卷烟非挥发性有机酸和高级脂肪酸含量呈现差异分布;利用SPC归类发现,草酸、丙二酸、苹果酸和柠檬酸对样品区分具有显著性作用.[结论]通过对不同卷烟烟丝中的非挥发性有机酸和高级脂肪酸含量以及其指标间的相关性分析,可为研究不同类卷烟的风格特征提供参考.     

纳豆芽孢杆菌对泌乳期奶牛产奶量、牛奶品质的影响

文章旨在研究纳豆芽孢杆菌(Bacillus subtilis Natto)对泌乳期奶牛生产性能、牛奶品质与机体免疫的影响。选用泌乳期、胎次、产奶量、体重相似的荷斯坦奶牛36头,采用完全随机分组原则分成3组,每组12头。试验期为60d,预饲期10d,分别在试验期的0、30、60d采集奶样,每周测定1次产奶量。试验结果表明,添加芽孢杆菌能显著提高产奶量(P<0.05)、改善乳脂率、提高乳蛋白率(P<0.05)、增加牛奶中干物质含量和降低牛奶中体细胞数。     

不同饱和度脂肪酸对泌乳早期奶牛生产性能和乳成分的影响

本试验旨在研究日粮中添加含有不同饱和度脂肪酸的过瘤胃脂肪对泌乳早期高产奶牛生产性能和乳成分的影响。选用泌乳期、胎次、产奶量、体重相似的荷斯坦奶牛105头,采用完全随机分组原则,分成3组,每组35头。试验期为90d,分别在试验期的27、48、69和90d采集奶样,每周测定1次产奶量。结果表明,高饱和度脂肪酸组(High Saturated Fatty Acid,HSFA)能够显著提高产奶量(P<0.05)、4%乳脂校正乳产量,显著(P<0.05)提高乳脂率、改善乳蛋白率。低饱和度脂肪酸组(Low Saturated Fatty Acid,LSFA)能够提高产奶量、4%乳脂校正乳产量,差异不显著;LSFA与对照组相比乳脂率和DMI降低。     

氢化物发生－原子荧光法同时测定土壤样品中 As 和 Se

[目的]研究采用氢化物发生–原子荧光法同时测定土壤样品中As和Se含量的可行性。[方法]研究炉高、负高压、灯电流、载气流速、屏蔽气流速、还原剂种类、酸度浓度、硼氢化钾浓度对原子荧光法同时测定As和Se含量的影响,采用氢化物原子荧光光谱法同时测定土壤样品As和Se含量。[结果]氢化物发生–原子荧光法测定As的检出限为0.370 ng/m L,Se的检出限为0.430 ng/m L,As和Se的相对标准偏差分别为1.28%和2.73%。[结论]氢化物发生–原子荧光法用于同时测定土壤样品中As和Se含量可行,能完全满足土壤样中As、Se的测定要求。     

西宁市市售鲜牛乳质量状况的检测

[目的]了解西宁市市售鲜牛乳的质量状况。[方法]从西宁市随机抽取45份市售鲜牛乳,对奶样的比重、脂肪、固形物、杂质度、酸度、尿素和抗生素含量进行检测。[结果]在45份奶样中,检测出2份掺尿素乳、12份掺盐乳7、份掺碱乳、5份抗生素残留奶、12份酸度超标样品2、8份比重不达标样品3、7份脂肪含量不合格样品4、2份固型物不合格样品。抗生素阳性率为11.11%,比往年高得多,呈逐年增长的趋势。西宁市售鲜牛乳存在较大的质量问题,如普遍掺水现象导致了比重、固型物含量和脂肪含量不达标。[结论]应采取实施牛奶产量配额制度、加强牛奶质量定点检测和通过宣传培训提高奶农素质等措施,以避免牛奶掺假现象。     

夏季高原牧草脂肪酸与牦牛乳脂脂肪酸特征及相关性研究

通过测定青海省海北藏族自治州和甘肃省甘南藏族自治州的新鲜牦牛乳脂脂肪酸与当地牧草脂肪酸情况,探索和揭示牧草和牦牛乳脂脂肪酸组成特征及其相关性.采取两地区夏季牧场新鲜牧草和牦牛乳酥油,利用GC-MS进行脂肪酸分析.结果表明:海北牧草中共检测出28种脂肪酸,甘南牧草中检出33种脂肪酸,两地区牧草中PUFA含量差异大(72....     

DHA制品脂肪酸组成分析

运用ＧＣ和ＧＣ／ＭＳ分析了鱼油、多烯脂肪酸（ＰＵＦＡ）和ＤＨＡ奶粉中脂肪酸组成。结果表明以鱿鱼油制备的ＰＵＦＡ中主要脂肪酸是十六碳烯酸、十六碳酸、十八碳三烯酸、十八碳一烯酸、二十碳五烯酸、二十碳四烯酸、二十二碳六烯酸和二十二碳五烯酸；采用ＳＮＳ法制备的ＰＵＦＡ，（ＤＨＡ＋ＥＰＡ）含量可达９７．８０％，采用不同试剂组合处理，可使ＰＵＦＡ中ＤＨＡ，ＥＰＡ含量分别达到７７．７６％，７６．７１％；ＤＨＡ奶     

The Effects of Graded Abomasal Glucose Infusion on Milk Yield and Composition in Lactating Goats

Four non-pregnant multiparous lactating goats were used in a 4 × 4 latin square experiment in the present study. The four treatments were abomasal infusion of 0, 50, 100, and 150 g d^-1 glucose. The results showed that graded glucose infusion increased milk yield （P 〈 0.01）. The highest milk yield was observed when 50 g d^-1 glucose was infused. An infusion of glucose at 100 or 150 g d^-1 failed to increase milk yield further and milk yield of the 100 g d ^-1 glucose infusion treatment was even significantly lower than that of the 50 g d^-1 treatment （P 〈 0.01）. Though milk fat content was gradually decreased by graded glucose infusions and milk fat yield of the 100 and 150 g d 1 treatments were lower than that of the control （P 〈 0.01）; milk fat yield of the 50 g d i treatment was not depressed and was higher than that of the control （P 〈 0.01）. Graded glucose infusion did not change the contents of milk protein and non-fatty solids. Yields of milk protein （P 〈 0.05）, lactose （P 〈 0.01）, non-fat solids （P 〈 0.01）, and lactose content （P 〈 0.01） of the 50 g d^-1 treatment were higher than those of the control but had no difference among the other three treatments. Contents of those de novo synthesized fatty acids in milk fat remained unchanged or increased and those preformed fatty acids remained unchanged or decreased by graded glucose infusion. Glucose infusion decreased the total yields of C16 ＋ C16：1 and 〉 C16 fatty acids and had no influence on the yield of C4-C14：1 fatty acids （P 〈 0.05）. Results of the present study implied that increased glucose supply had positive effects on the production of milk, milk protein, milk fat, and lactose only when glucose was a limiting factor for milk synthesis. Excessive glucose supply had no further beneficial effects and might depress milk fat synthesis.     

骆驼奶中脂肪酸含量的测定与分析

采用气相色谱和气相质谱测定了骆驼奶、牛奶、羊奶、人奶中的脂肪酸组成和含量.结果表明:在骆驼奶中共检测出11种脂肪酸,其中,不饱和脂肪酸在总脂肪酸中的比例(65.02%)极显著高于牛奶(40.76%)、羊奶(40.23%)、人奶(58.17%)(P＜0.01),尤其是骆驼奶中的亚麻酸(C18∶3)含量(5.09%)极显著...     

关中马奶营养成分分析

经分析研究表明,马奶总的营养成分最接近人奶,属白蛋白奶类。它有着低酸度(4.72°T),高乳糖(7.655％),合宜的钙磷比例(2.45:1),钾钠比例(4.07:1),铜锌比例(6.8:1),含镁(98.6ppm),铁(0.863ppm)高的特点。马奶属高度不饱和脂肪酸奶,短链的多(C和C4组分为28.74％),人体必需脂肪酸含量高,尤其是能抵消饱脂肪酸影响的亚油酸C18:2组分特高(15.5％)。马奶中易被人体吸收的游离氨基酸质和量均优。V_c含量高达12.27mg/100ml。V_A,V_(B1)含量与人奶相近。     

中国荷斯坦牛乳中体细胞评分与脂肪酸含量和组成的相关分析

 【目的】探索中国荷斯坦牛乳中体细胞评分（SCS）与脂肪酸含量和组成的相关性。【方法】采集121头无临床乳房炎、胎次为2—3胎、泌乳期在100—300 d的中国荷斯坦牛早、中、晚共3次的混合奶样,用气相色谱法测定乳中脂肪酸含量,并用多因素方差分析法分析季节、胎次、泌乳阶段、乳中体细胞评分对乳脂率和脂肪酸含量的影响,同时对乳脂率和脂肪酸含量与乳中体细胞评分进行了相关和回归分析。【结果】乳中共检出21种脂肪酸,季节对脂肪酸含量和组成有显著影响（P＜0.05）,泌乳阶段对脂肪酸含量和组成影响较小;除十四碳一烯酸（C14：1）、棕榈油酸（C16：1）、十七酸（C17：0）、硬脂酸（C18：0）、亚油酸（C18：2n6c）、二十酸（C20：0）、二十碳三烯酸（C20：3）、花生四烯酸（C20：4）和多不饱和脂肪酸（PUFA）等8种脂肪酸外,SCS显著影响乳脂率和其它脂肪酸绝对含量（P＜0.05）。乳脂率、脂肪酸总含量、饱和脂肪酸（SFA）、单不饱和脂肪酸（MUFA）及短、中和长链等19类脂肪酸的绝对含量随着乳SCS的逐渐增加而降低。除4种相对含量较低的脂肪酸（十一酸（C11：0）、二十酸（C20：0）、二十碳三烯酸（C20：3）和二十二碳六烯酸（DHA,C22：6）外,SCS对乳中其它脂肪酸及饱和SFA、MUFA、多不饱和脂肪酸（PUFA）及短、中和长链等23类脂肪酸的相对含量均无显著影响。相关分析表明,SCS与SFA、MUFA及短、中和长链脂肪酸绝对含量均呈显著负相关（P＜0.05）,与PUFA和长链脂肪酸的相对含量呈显著正相关（P＜0.05）,与SFA、中、短链脂肪酸的相对含量呈显著负相关（P＜0.05）。回归分析表明,SCS与脂肪酸总量、SFA、MUFA及短、中和长链脂肪酸绝对含量的最佳回归方程均为对数函数,拟合度均在0.9以上;与SFA相对含量的最佳回归方程为指数函数,拟合度达到0.9以上,而与其它各种类脂肪酸相对含量的回归方程拟合度均低于0.9。【结论】该结果为通过SCS来预测和评估乳脂肪酸含量和组成提供了科学依据。     

Artificial neural network models of the rumen fermentation pattern in dairy cattle

The objectives of this study were: (1) to predict the rumen fermentation pattern from milk fatty acids using a machine learning technique, i.e. artificial neural networks (ANN) combined with feature selection and (2) to compare the prediction accuracy of the resulting model to that of a statistical multi-linear regression model, based on odd and branched chain milk fatty acids. Data were collected from 10 experiments with rumen fistulated dairy cows, resulting in a dataset of 138 observations. Feature selection was based on correlation and principal component analysis, and background physiological knowledge. Different ANN architectures and training algorithms were assessed. The evaluation of the model performance, based on the test dataset, showed a root mean square prediction error, expressed relative to the observed mean, of 2.65%, 7.67% and 7.61% of the observed mean for acetate, propionate and butyrate, respectively. Compared to a multi-linear regression model, the ANN revealed not to perform significantly better. However, the results confirm that milk fatty acids have great potential to predict molar proportions of individual volatile fatty acids in the rumen.     

Effects of supplemental energy sources and <Emphasis Type="Italic">trans</Emphasis>-10, <Emphasis Type="Italic">cis</Emphasis>-12 conjugated linoleic acids (CLA) on milk yield and composition in lactating Holstein cows

The effects of supplemental energy sources (corn or saturated fatty acids) and trans-10, cis-12CLA on milk yield and composition were investigated in the present study. Four multiparous Holstein cows (560±31 kg BW, 98±10.5 DIM) were designated to a 2×2 factorial 4×4 Latin Square experiment. Treatments were isoenergetic supplementation of corn or calcium salt of saturated fatty acids (CaFA) with or without calcium salt of CLA. Both milk yield and composition were affected by sources of supplemental energy. Compared to CaFA supplementation, corn supplementation increased the milk yield, the lactose yield, and the content and yield of milk protein but decreased the yield and content of milk fat. Plasma insulin was higher, plasma glucose tended to be higher, and plasma non-esterified fatty acid (NEFA) was lower when corn rather than CaFA was supplemented. CaCLA supplementation did not affect milk yield and the yield of measured milk components, but increased the content of milk protein and decreased the content of total solids. Plasma glucose was decreased by CaCLA supplementation. Content and yield of short and medium chain fatty acids (⩽16 carbon atoms) in milk fat increased or remained unchanged while those of long chain fatty acids (> 16 carbon atoms) decreased or remained unchanged by corn supplementation. CaCLA supplementation failed to increase the content and yield of trans-10, cis-12CLA in milk fat, which explained the unobserved depression of milk fat synthesis by CaCLA supplementation. Yields of de novo synthesized fatty acids in the mammary gland were increased rather than decreased by corn supplementation. The decreased milk fat yield by corn supplementation could be exclusively attributed to reductions in preformed fatty acids, which might be a result of depressed lipolysis by stimulated insulin secretion.