Influence of Pelleting Whole Cottonseed on Ration Digestibility and Milk Production and Composition

Two trials were conducted to determine the effect of pelleting whole cottonseed on milk production and composition and ration digestibility. In trial 1, four multiparous Holstein cows were paired by production and used in a 2 × 2 reversal design with 37-d experimental periods. Cow receiving pelleted cottonseed produced 35.12 kg/d milk and 31.74 kg/d of 4% fat corrected milk as compared with 33.41 and 29.83 for cows receiving whole cottonseed. There were no significant differences in dry matter intake or milk composition between treatments. Yield of total solids and lactose was greater for cows receiving pelleted cottonseed as compared with whole cottonseed. Apparent digestibility coefficients for dry matter, gross energy, and crude protein were not different due to pelleting.In trial 2, four ruminal and abomasally cannulated Holstein steers were paired in a 2 × 2 reversal design and fed either pelleted on whole cottonseed for 10 d followed by a 7-d collection. Steers receiving the pelleted cottonseed had higher intakes of gross energy and crude protein. There were greater amounts of total crude protein and crude protein in the particulate phase of abomasal digesta from steers receiving pelleted cottonseed as compared with whole cottonseed. Apparent digestibility for crude protein for the whole tract was not different due to treatment.     

离心除菌UHT乳贮藏期内乳蛋白组成的变化

通过凯氏定氮法、高效液相色谱法和氨基酸分析仪研究了离心预除菌的UHT乳（C-UHT）和常规UHT乳（N-UHT）在常温6个月贮藏过程中乳蛋白和氨基酸成分的变化。热处理和贮藏过程中乳清蛋白质量浓度逐渐降低,非蛋白氮（NPN）质量分数逐渐增加,N-UHT和C-UHT的NPN质量分数从4.2%分别增加到8.7%和7.9%。热处理导致部分酪蛋白胶束解聚和酪蛋白组分进入了乳清相,乳清蛋白聚合进入胶束相,贮藏过程中这种作用持续进行。N-UHT和C-UHT中酪蛋白的解聚量分别为28.6%和22.6%,乳清蛋白的聚合量分别为8.5%和11.3%。热处理导致所有的乳蛋白组分发生了降解,贮藏过程中乳蛋白继续降解。N-UHT和C-UHT中总蛋白由39.81 g/L分别降解到29.57 g/L和31.42 g/L;游离氨基酸总量由原乳的31.4 mg/L增加到35.1～35.7 mg/L。C-UHT乳的乳蛋白降解和乳蛋白相转移程度显著低于N-UHT乳。     

乳蛋白中乳清蛋白与酪蛋白组成、特性及应用的研究进展

乳清蛋白和酪蛋白是乳蛋白的主要组成成分,具有很高的营养价值。本文从乳中的乳清蛋白与酪蛋白出发,阐述了牛、羊等乳中乳清蛋白和酪蛋白的组成,并分别分析了乳清蛋白和酪蛋白的功能及其相关应用,综述了有关乳清蛋白和酪蛋白的新产品开发及综合利用,以期对乳中蛋白营养价值综合利用提供相应依据,为乳业相关企业及相关专业研究人员提供参考。     

乳蛋白浓缩物生产中食品安全管理体系应用研究

本文依据ISO22000,研究食品安全管理体系在乳蛋白浓缩物生产中的应用。建立前提方案,并对乳蛋白浓缩物(MPC)生产流程进行危害分析和危害风险评估,有预见性的预测潜在危害和显著危害,最后分析确定了2个CCP点与2个CP点,分别制定HACCP计划与操作性前提方案对显著危害和潜在危害进行控制。乳蛋白浓缩物生产中食品安全管理体系的建立,可以有效控制和降低可能引入危害的风险,使预防措施系统化,保证了乳蛋白浓缩物的质量与安全。     

水解乳蛋白产生肽及降低蛋白过敏性研究

以蛋白酶水解后的肽含量为评定指标,考察不同温度、pH、加酶量对酶解乳蛋白产生肽的影响。先通过单因素试验初步得到水解工艺条件,再根据Box-Benhnken中心组合实验设计原理,采用三因素三水平响应面分析法,建立多肽含量与各影响因子的回归方程,得出酶水解乳蛋白产生多肽的最佳工艺条件是:温度55.83℃,pH7.08,加酶量0.17%。在此条件下,肽含量达到2.3773mg/mL。通过ELISA试剂盒检测最佳工艺条件水解前、后的主要致敏蛋白,其中α-乳白蛋白、β-乳球蛋白致敏性分别下降70.2%、89.8%。     

羊乳乳清蛋白组成和功能及其与人乳、牛乳的对比分析

本研究将羊乳、牛乳、人乳中乳清蛋白进行分离并结合液质联用技术鉴定,在羊乳、牛乳、人乳乳清蛋白中分别鉴定出156、278、454种蛋白质。与牛乳与人乳乳清蛋白对比显示,羊乳含有99种特异性表达蛋白质,与牛乳和人乳分别有31种和15种相同表达蛋白质。通过分析基因本体(gene ontology,GO)功能注释发现,羊乳乳清蛋白在生物过程中主要发挥生物调节作用;在分子功能上,主要体现在结合作用方面;在细胞组成上,参与的细胞组成主要为细胞器区和胞外区。羊乳乳清蛋白在以上三种功能上与人乳有较大差距,但与牛乳相近。通过分析京都基因与基因组百科全书系统(Kyoto Encyclopedia of Genes and Genomes,KEGG)代谢通路可知,羊乳主要参与补体和凝血级联反应以及吞噬作用,对人体免疫能力有积极影响。对羊乳与人乳、牛乳乳清蛋白组成及功能区别的研究,为羊乳的进一步研究和开发提供一定的理论参考。     

乳清蛋白组分及其对骨代谢的影响

乳清蛋白是干酪加工过程中产生的副产品,由于其组成成分的异质性和丰富性,成就了其在生物学功能上的多样性。乳清蛋白中的成分主要分为两大类：骨桥蛋白、酪蛋白磷酸肽和糖巨肽属活性蛋白等乳清酸性蛋白,及IGF-I、TGF-β和EGF等生长因子、半胱氨酸蛋白酶抑制剂C、HMG样蛋白和激肽原片断等乳清碱性蛋白。它们通过参与破骨细胞介导的骨吸收和成骨细胞介导的骨形成或者改变钙离子的溶解状态等方式影响骨代谢,在延缓由于年龄增长或雌激素减退引起的骨丢失、增强骨骼生物力度等方面发挥积极作用。     

Influence of Intake of Rumen Undegradable Protein on Milk Production of Late Lactation Holstein Cows

Twenty Holstein cows, in late lactation, were assigned to five equal groups in an orthogonal design to determine effects of a rapidly rumen degraded protein source (canola meal) low in estimated rumen undegradable protein substituted for a slowly rumen degraded protein source (corn gluten meal) high in rumen undegradable protein on feed intake, milk production, and milk composition. Cows were fed total mixed rations based upon barley silage, haycrop silage, barley grain, and supplemental protein in three 4-wk periods, subsequent to a 4-wk covariate period. In situ rumen incubation of extreme diets and estimation of intermediate diets indicated that all diets exceeded Agricultural Research Council (United Kingdom) recommendations for rumen degradable and undegradable protein as well as NRC recommendations for rumen degradable protein. However, two to four diets, dependent upon assumed ruminal turnover rates, did not meet NRC recommendations for undegradable protein. Dry matter intake and milk yield were not influenced by substitution of canola meal with corn gluten meal to increase dietary undegradable protein content. Daily yield and milk percent of lactose, fat, and protein were not influenced by substitution. Results do not support NRC recommendations to supplement diets based upon these ensiled forages and barley grain for late lactation cows with protein sources resistent to rumen degradation. Results broadly support lower amounts of rumen undegraded protein recommended by the Agricultural Research Council.     

Effects of Altering Milk Production and Composition by Feeding on Multiple Component Milk Pricing Systems

Data representing 1105 cows were obtained from published scientific reports to estimate the extent to which changes in feeding may affect the composition of milk and the production of milk protein and milk fat. Changes in milk pricing systems were also related to dairy cattle feeding practices that dairy producers may profitably implement. Regression equations were derived to estimate the transfer of gross energy in feed and gross energy in crude protein of feed into milk fat and milk protein. Feeding rations that contained 59% concentrate increased dry matter and crude protein intakes compared to feeding rations that contained 49% concentrate. Feeding higher energy rations also resulted in increased production of milk, milk fat, and milk protein and returned a greater profit over feed costs when milk was priced using each of four milk pricing systems. An increase in milk production, rather than a change in composition of milk components, accounted for most of the economic gain.     

驴乳粉蛋白的特性、结构与组成分析

采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、圆二色谱和基质辅助激光解析电离-飞行时间质谱法研究德州驴乳粉蛋白质的性质、结构和组成,为德州驴乳的深层次开发提供依据。结果表明,驴乳粉蛋白质量分数为16.10%,等电点均匀分布在4.5～6.5之间,分子质量主要集中在10～20 kDa和53～78 kDa的乳清蛋白区域,以及28～36 kDa酪蛋白区域。通过与马科蛋白图库进行对比,检索出386种可识别的蛋白,其中有139种蛋白首次在驴乳中发现,为揭示驴乳的生理功效提供理论基础。     

Effects of Environmental Factors and Milk Protein Polymorphism on Composition of Casein Fraction in Bovine Milk

Test-day samples were collected from individual Holstein cows in 62 herds enrolled in the Quebec Dairy Herd Analysis Service. Samples were analyzed for protein, fat, casein, and serum protein content, somatic cell count, and relative percentages of α-, β-, and κ-casein and a-lactalbumin. Cows included in the study were phenotyped for the genetic variants of α_s1-, β-, and κ-casein. Unadjusted means for relative percentages of α_s-, β-, and κ-casein were 59.85, 31.23, and 8.93%, respectively. Least-squares analyses showed that month of test, stage of lactation, age of the cow, somatic cell count, and phenotype of the cow for β-casein contributed to variations in the relative percentages of α_s- and β-casein. Month of test, somatic cell count, and phenotype of the cow for κ-casein also had a significant effect on the relative percentage of κ-casein. When test-day milk yield; percentages of fat, protein, casein, and serum protein; casein to protein ratio; and relative percentage of α-lactalbumin were included in the model as covariates, only casein percentage did not have a significant effect on the relative percentages of α_s- and β- casein. For κ-casein, only fat percent was significant.     

九龙牦牛奶渣氨基酸含量和蛋白质组成分析

本研究的目的是分析家庭自制的九龙牦牛奶渣中氨基酸含量和蛋白组成特点。结果显示,九龙牦牛奶渣中总氨基酸含量约为36.5%,含量高的氨基酸主要包括谷氨酸、脯氨酸、亮氨酸、天冬氨酸、赖氨酸。必需氨基酸占总氨基酸的比例约为36%。电泳分析显示,牦牛奶渣蛋白质组分以酪蛋白为主,其比例约为82%。实验观察到牦牛酪蛋白的初步降解。研究结果表明,九龙牦牛奶渣的生化组成与普通牦牛奶渣接近。     

河南奶山羊乳酶活力和乳蛋白组分的研究

测定河南奶山羊乳的4种酶酶活力,并采用SDS-PAGE方法对乳中主要蛋白组分进行分析。结果表明：在初乳和常乳中4种酶酶活力分别为：γ-谷胺酰转肽酶(γ-GT)为322.46U/100mL和247.71U/100mL,碱性磷酸酶(AKP)为248.62U/100mL和200.14U/100mL,过氧化物酶(LP)为281.76U/mL和205.07U/mL,淀粉酶(AMY)为71.20U/100mL和22.15U/100mL。初乳中AKP活力显著高于常乳(0.01＜P＜0.05),γ-GT、LP、AMY的活力极显著高于常乳(P＜0.01)。主要乳蛋白按分子质量由小到大均依次显示出乳清蛋白(α-La)、β-乳球蛋白(β-LG)、IgG-L(轻链)、酪蛋白(CN)、IgG-H(重链)、血清白蛋白(SA)等区带。在初乳和常乳中的含量分别为：α-La为4.52%和4.51%,β-LG为18.78%和9.59%,IgG-L为7.52%和3.95%,CN为11.29%和11.49%,IgG-H为6.95%和4.07%,SA为5.48%和5.39%。乳中β-LG相对含量较高,达到20.96%,α-La含量较低。初乳中的免疫球蛋白IgG(IgG-L、IgG-H)相对含量显著高于常乳(P＜0.01或0.01＜P＜0.05),β-LG极显著高于常乳(P＜0.01)。乳球蛋白和免疫球蛋白随着泌乳天数的增加呈现明显的下降趋势,而其他蛋白变化不显著。乳蛋白组分的相对含量在山羊个体间存在差异。     

牛奶蛋白纤维混纺织物的生产实践

阐述了牛奶蛋白纤维的特性以及其混纺织物在纺纱、织造、染色工艺中的技术要点。     

速溶黄粉蛋白乳粉的研制

黄粉蛋白不溶于水，因而限制了它在食品中的应用，依次用碱性蛋白酶、复合酶A和风味酶水解黄粉蛋白，喷雾干燥，并用乙酸乙酯浸提后，通过与大豆蛋白等其他配料混合，可以得到溶解和风味良好的速溶黄粉蛋白乳粉。     

牛奶蛋白纤维氨纶包芯纱的生产

为了顺利生产牛奶蛋白纤维氨纶包芯纱,对各工序纺纱工艺参数进行了优选.生产前对牛奶蛋白纤维进行预处理,清梳工序采用低速度、大隔距、多梳少打、均匀混和、快转移、小张力的工艺原则,并条采用顺牵伸,粗纱适当加大捻度、减少后区牵伸倍数,细纱采用重加压、大后区隔距、小后区牵伸、小钳口隔距等技术措施.措施实施后,成纱质量好,条干均匀.     

水飞蓟粕蛋白氨基酸组成及加工功能特性研究

以水飞蓟粕为原料,研究其蛋白质和氨基酸的组成及其蛋白的功能特性。结果表明,水飞蓟粕中粗蛋白的质量分数为47.23%,其中主要以清蛋白为主。17种氨基酸中谷氨酸、天冬氨酸和精氨酸含量丰富,蛋氨酸含量较少。必需氨基酸和总氨基酸质量分数分别为14.28%和41.70%。氨基酸评分(AAS)表明赖氨酸和含硫氨基酸分别是第1和第2限制性氨基酸。水飞蓟蛋白加工特性良好,有较好的溶解性,乳化性及乳化稳定性和发泡性及泡沫稳定性均优于大豆分离蛋白,是一种值得开发的优质植物蛋白。     

牛奶蛋白纤维与棉纤维混纺纱的生产

为了提高牛奶蛋白纤维棉混纺纱的成纱质量,在精梳棉、牛奶蛋白纤维中混入5%成熟度好、杂质少的原棉共同纺纱,以增强纱线强力,清棉、梳棉工序要注意减少纤维损伤和降低落棉;并条、粗纱、细纱工序要防止纤维缠绕和意外牵伸;通过一系列措施的实施,成纱质量达到客户要求.     

食盐质量浓度对传统自然发酵圆白菜的菌系结构和代谢的影响

以2、5、8 g/100 mL食盐添加量的传统自然发酵泡菜为研究对象,比较了3 种不同食盐质量浓度的传统自然发酵泡菜中优势菌系结构、卤水pH值和总酸、底物和代谢产物、亚硝酸盐含量的变化。结果表明：乳酸菌主导整个泡菜发酵过程,蔗糖一直被代谢利用,葡萄糖和果糖含量逐步增加,发酵结束时乳酸大量积累。食盐质量浓度对泡菜发酵前期有显著影响,2 g/100 mL食盐质量浓度的泡菜中乳酸菌的繁殖代谢最快,发酵结束时pH值最低,总酸含量最高;5 g/100 mL食盐质量浓度能较好地抑制有害微生物的繁殖,最快通过亚硝峰,产生的乙醇量最高;8 g/100 mL食盐质量浓度抑制了泡菜中乳酸菌的繁殖代谢,使泡菜的成熟期延迟,对蔗糖的利用率最低。