不同锌源对奶牛产奶量和乳品质的影响

本试验采用3×3拉丁方设计,将9头中国荷斯坦奶牛分为3组,分别饲喂对照组基础日粮,补加蛋氨酸锌日粮(锌含量400mg),补加氧化锌日粮(锌含量400mg),研究补饲不同锌源对奶牛产奶量及乳品质的影响。结果表明,不同来源的锌对奶牛产奶量均有不同程度提高,蛋氨酸锌提高幅度大于氧化锌,但差异不显著(p>0.05);对乳脂率无明显影响;补锌可增加乳中锌的含量,蛋氨酸锌比氧化锌明显(p<0.05)。     

酶制剂对奶牛产奶量和乳品质的影响

根据年龄、胎次、产奶量、乳成分和泌乳期相近的原则选择30头泌乳中期经产荷斯坦奶牛,随机分为3组,分别在精料补充料中添加0、500和1 000 g/t反刍动物专9"1酶制剂.结果表明:添加酶制剂能够显著提高泌乳中期奶牛的产奶量(P＜0.05),提高乳脂率,并起到降低牛奶中的体细胞数的作用(P＜0.05).     

发酵黄芪粉对奶牛产奶量及乳成分的影响研究

研究发酵黄芪粉对奶牛产奶量及乳品质的影响.对照组奶牛饲喂基础日粮,试验Ⅰ、Ⅱ和Ⅲ组奶牛分别饲喂10、20和30 g/(头·d)的发酵黄芪粉基础日粮.结果表明:与对照组相比,试验组奶牛产奶量增加了0.95、1.45和1.58 kg/(头·d),但试验Ⅱ、Ⅲ组组间差异不显著;可显著提高奶牛乳蛋白率,但对奶牛乳脂率、乳糖及非脂固型物均无显著影响;可降低奶牛乳体细胞数,其中试验Ⅱ、Ⅲ组奶牛乳体细胞数显著低于对照组和试验Ⅰ组,但试验Ⅱ、Ⅲ组组间差异不显著;可提高奶牛经济效益,各试验组奶牛经济效益分别高于对照组2.6、3.4和2.72元/(头·d).该试验条件下,发酵黄芪粉以20 g/(头·d)的添加量较好.     

瑞士乳杆菌发酵乳中生物活性小肽的免疫功能特性研究

利用MTT、中性红吞噬、一氧化氮诱生分泌等方法从已获得的瑞士乳杆菌发酵乳来源小肽中筛选出对小鼠腹腔巨噬细胞具有免疫活性的小肽GLPN,并通过ELISA方法检测TNF-Ω,IL-1β,IL-6的细胞因子水平,以对具有的免疫促进作用效果进行评估.结果表明,GLPN在0.1 g/L质量浓度下所有指标上都能表现出显著的促进作用,而在LPS作用下,GLPN质量浓度达到0.5 g/L也未引起炎症因子的过量表达.     

麦蓝菜对奶牛产奶量及乳成分的影响

选用15头体质量、胎次、产奶量均相近中国荷斯坦奶牛,随机分为A、B、C三组(n=5)∶A组(对照组)饲喂基础日粮;B组(试验组1)饲喂基础日粮+50 g麦蓝菜种子;C组(试验组2)饲喂基础日粮+150 g麦蓝菜植株.试验周期24 d,每天测定各组奶牛产奶量及乳成分,研究麦蓝菜对奶牛产奶量及乳成分的影响.结果表明:B组较A组产奶量提高了15.56％ (P＜0.01),牛奶乳蛋白和干物质分别提高了11.9％和5.1％(P＜0.01),乳脂率提高了9.4％(P＜0.05),A、B两组间乳糖含量差异不显著;C组较A组产奶量提高了3.48％(P＜0.01),牛奶乳蛋白和干物质体分别提高了6.3％和4.9％(P＜0.01),乳脂率和乳糖分别提高了9.1％和6.6％(P＜0.05).研究表明,基础日粮中添加麦蓝菜植株和种子均可以显著提高奶牛产奶量和乳品质.     

王不留行增乳单体对牛乳产量和乳品质的影响

研究了对王不留行活性单体进行分离.采用聚酰胺柱层析、硅胶柱层析、制备型HPLC等分离技术对增乳活性单体进行制备,利用增乳单体注射液对奶牛进行注射来验证其增乳效应.结果表明,该增乳单体为邻苯二甲酸二丁酯,注射该增乳单体后提高了奶牛的泌乳性能.其中泌乳量增加了17.82%,乳脂率增加了6.39%,乳糖增加了6.97%,乳蛋白和非脂固形物变化不明显.     

几种酵母菌添加剂对奶牛产奶量及乳成分的影响

将54头高产中国荷斯坦奶牛随机分为6组，1组基础对照组，5组（A，B，C，D，E）试验组，试验组在基础日粮的水平上添加15g不同型号的酵母菌制剂，预试期2周，正试期为6周。结果表明：不同型号的酵母菌对奶牛产奶量和奶成分有不同程度的影响，其中C和E组奶牛的产奶量分别比对照组有所增加，B和D组的产奶量与对照组相比增加显著（P〈0．05），A组则有所下降；不同型号的酵母菌制剂对牛乳成分也有不同程度的影响，试验组B，D，E组乳脂日产量比对照组有增加，并且差异显著（P〈0．05）；E组乳脂率增加，差异显著；蛋白质日产量除A组无显著性差异（P〉0．05），B，C，D，E组相比对照组都有所增加，其中C和E组相比对照组，差异显著（P〈0．05）；试验组的乳糖、非脂固形物产量与对照组没有显著差异（P〉0．05）；各试验组的所生产牛奶的比重、冰点、酸度与对照组无显著差异，但试验组的酸度除D组外均比对照组有所提高，乳中体细胞数均比对照组低，其中酵母菌C和D能显著减少乳中体细胞数（P〈0．05）。     

小肽制品"喂大快"对断奶仔猪生长的影响

选择日龄 ,体重相近的三元杂交仔猪 6 0头 ,随机分为三大组 :即对照组、试验 1组和试验 2组 ,每个大组各设置一重复。经过 2 9d试验 ,试验结果表明 :试验组与对照组增重差异极显著 (P <0 .0 1 ) ,组内差异不显著 (P>0 .0 5 )。试验 1组、试验 2组平均日增重比对照组分别提高 7.85 % ,8.85 % (P <0 .0 1 ) ;饲料转化率分别提高1 0 .0 6 % ,1 1 .0 6 %。从腹泻情况来看 ,饲用“喂大快”组仔猪下痢头数明显少于对照组     

添加火麻仁粕蛋白肽的发酵乳品质特性分析

本实验采用碱溶酸沉法提取火麻仁粕中的蛋白质,经碱性蛋白酶酶解蛋白12h得到水解度为16.62%的火麻仁粕蛋白肽(HSMPP),探究不同添加量的HSMPP对发酵乳凝乳时间、质构及贮藏期间滴定酸度、p H、持水率、活菌数和感官评价的影响。结果表明,添加3%～12%的HSMPP能显著缩短发酵乳的凝乳时间,降低酸度、硬度和胶黏性,提高内聚性和弹性;对发酵乳的贮藏特性研究表明,添加HSMPP能延缓发酵乳在4℃贮藏21 d期间的后酸化程度,提高发酵乳的持水率和活菌数。综合各项指标,HSMPP添加量为6%的发酵乳品质最佳,在贮藏期内稳定性好,活菌数和感官评分较高,在第14 d时持水率达最高值31.24%,第21 d的活菌数为9.23 log(CFU/g),感官评分为86分。说明添加适量的火麻仁粕蛋白肽可以有效改善发酵乳的品质,并提高其贮藏稳定性,本研究为火麻仁粕蛋白肽的应用提供了理论依据。     

成熟温度和时间对牦牛乳硬质干酪中生物活性肽的影响

以不同条件成熟的牦牛乳硬质干酪为研究对象,探究成熟温度和时间对牦牛乳硬质干酪中水溶性多肽的DPPH自由基清除能力、抑菌性以及抑制血管紧张素转换酶（ACE）活性的影响。结果表明,5 ℃、10 ℃、15 ℃成熟4～6个月牦牛乳硬质干酪的水溶性多肽对DPPH自由基均有清除能力。5 ℃、10 ℃成熟5个月、15 ℃成熟4个月牦牛乳硬质干酪的水溶性多肽对DPPH自由基清除率最高,分别为（20.38±1.20）%、（28.70±0.67）%和（30.19±0.32）%。5 ℃、10 ℃、15 ℃成熟的牦牛乳硬质干酪在4～6个月成熟过程中,其水溶性多肽对大肠杆菌、金黄色葡萄球菌的抑制程度分别呈增强趋势。成熟温度从5 ℃提高到15 ℃时,牦牛乳硬质干酪的水溶性多肽对大肠杆菌、金黄色葡萄球菌和血管紧张素转换酶的抑制作用呈加强趋势。     

Effect of rumen-protected methionine on feed intake, milk production, true milk protein concentration, and true milk protein yield, and the factors that influence these effects: A meta-analysis

A meta-analysis of published studies was used to investigate the effect of rumen-protected methionine (RPM) added to the diets of lactating dairy cattle on dry matter intake, milk production, true milk protein (TMP) production, and milk fat yield. Differences in responses between 2 commonly used RPM products, Mepron (Evonik Industries, Hanau, Germany) and Smartamine (Adisseo, Antony, France), were investigated as well as dietary and animal factors that could influence responses. Diets were coded with respect to the amino acid (AA) deficiency of the control diet as predicted by the AminoCow model (version 3.5.2, http://www.makemilknotmanure.com/aminocow.php; 0 = no AA deficiency, 1 = Met deficiency, 2 = Met and Lys deficiency, 3 = Met and Lys plus at least 1 other AA deficiency) to test the effect of AA deficiencies on RPM response. Thirty-five studies were identified, 17 studies evaluating Mepron, 18 studies evaluating Smartamine, and 1 study evaluating both. This permitted 75 dietary comparisons between control and RPM-added diets. Diets were entered into the AminoCow and the 2001 National Research Council models to compare predictions of Met, Lys, and metabolizable protein (MP) flow. Mean Met and Lys in diets where RPM was fed were estimated to be 2.35 and 6.33% of MP, respectively. Predictions of flows between models were similar. Overall, RPM addition to diets increased production of TMP, both as percentage (0.07%) and yield (27 g/d). Dry matter intake and milk fat percentage were slightly decreased, whereas milk production was slightly increased. Differences between products were detected for all production variables, with Mepron-fed cows producing less TMP percentage but greater milk production, resulting in twice as much TMP yield. Milk protein response to RPM was not related to predicted AA deficiency, calculated Met deficiency, or Met as a percentage of MP. Other dietary factors, including Lys flow (g/d), Lys as percentage of MP, neutral detergent fiber percentage, crude protein percentage, or energy balance, had no detectable effects on TMP response. When cows with a predicted positive AA balance were fed RPM, milk production increased, but when AA balance was negative, milk production decreased. Amount of RPM added to the diet was not correlated to TMP response. This study does not support the necessity of a high Lys level as a prerequisite to obtaining a TMP response to feeding RPM or the MP requirement suggested by the National Research Council model (2001). However, more dose-response studies over a wide range of milk production and dietary regimens will be required to more clearly establish AA requirements and to predict responses to RPM supplementation.     

大豆肽制备得率影响条件的研究

以低温脱脂豆粕为原料,采用酸洗、醇洗后酸洗和提取分离蛋白三种不同方式对其进行前处理,选用Alcalase碱性蛋白酶进行水解。考察不同的前处理方式对大豆肽得率、色泽、气味的影响。确定醇洗后酸洗为较好的前处理方式。在此基础上,通过单因素实验研究了底物浓度、酶解pH、酶解温度、加酶量对蛋白水解度DH和大豆肽得率的影响,并通过响应面分析法对酶解条件进行了优化,得出最佳条件为:底物浓度5%(w/w),酶解pH8·77,酶解温度56·53℃,加酶量5400U/g蛋白。此条件下,蛋白水解度为22·56%,大豆肽酶解得率为77·90%。     

Effect of quantitative trait loci for milk protein percentage on milk protein yield and milk yield in Israeli Holstein dairy cattle

Although numerous quantitative trait loci (QTL) mapping studies involving milk protein percent (PP), milk yield (MY), and protein yield (PY) have been carried out, there has not been any systematic evaluation of the effects of individual QTL on these 3 interrelated traits. Consequently, the aim of the present study was to investigate the effects on MY and PY of QTL for PP previously mapped in various laboratories. The study, based on selective DNA pooling of milk samples, included 10 Israeli Holstein artificial insemination bulls, each the sire of 1,800 or more milk-recorded daughters. For each sire-trait combination across the 10 sires, milk samples of the highest and lowest daughters with respect to estimated breeding values for PP, PY, and MY were collected for pooling. A total of 134 dinucleotide microsatellites distributed over 25 bovine autosomes were used. An empirical standard error for marker-QTL linkage testing was calculated based on the variation among split samples within the same tail. Threshold comparison-wise error rate P-values were set to control proportion of false positives at P = 0.10 level for declaring significant effects at the marker-trait level. Estimates of the number of true null hypotheses for each trait were obtained from the histogram of marker comparison-wise error rate P-values. Based on these estimates, effective power of the experiment at the marker-trait level was estimated as 0.75, 0.41, and 0.73 for PP, PY, and MY. The proportion of heterozygosity at the QTL was estimated as 0.46, 0.39, and 0.40, respectively. After correcting for incomplete power and proportion of false positives, it was estimated that 38.7 and 37.5% of the markers affecting PP and MY, respectively, also affected PY. Of the markers affecting PY, 68.9 and 76.5%, respectively, also affected PP and MY. Apparently, none of the significant markers affected PY exclusively, and only 6.5 and 16.0%, respectively, affected PP or MY exclusively. Thus, almost all significant markers, and by inference almost all QTL, had effects on at least 2 of the 3 traits.     

Effects of milk protein genetic variants on milk yield and composition

Effects of genetic variants of the milk proteins, alpha S1-casein, beta-casein, kappa-casein and beta-lactoglobulin (beta-lg), on milk yield and composition, particularly the protein composition, were investigated in milk samples from 289 Jersey and 249 Friesian cows in eight commercial herds. Milk protein genotypes had no significant effect on yields over a complete lactation of milk and fat, but significant differences in fat content were detected for beta-casein (B, A1B, A2 greater than A1A2) and beta-lg (B, AB greater than A) variants. Significant differences between beta-lg variants were also found with total solids (B, AB greater than A), casein (B, AB greater than A), whey protein (A greater than AB greater than B) and beta-lg (A greater than AB, AC greater than B greater than BC) concentrations. Casein genotypes were not significantly different in total protein and casein concentrations but many differences were found in casein composition. alpha S1-Casein variants significantly affected alpha S1-casein (BC greater than B) and kappa-casein (B greater than BC) concentrations. beta-Casein variants affected concentration and proportion of beta-casein (A1B, A2B greater than A1, A1A2, A2, B), alpha S1-casein (A1, A2 greater than B) and kappa-casein (B greater than A2) and concentration of whey protein (A1 greater than most other beta-casein variants). kappa-Casein variants affected concentration and proportion of kappa-casein (B greater than AB greater than A), proportion of alpha S1-casein (A greater than AB greater than B) and concentrations of beta-lg (A greater than AB, B) and alpha-lactalbumin (A, AB greater than B). Differences in milk composition were found between breeds, herds and ages, and with stage of lactation. The potential use of milk protein genotypes as an aid in dairy cattle breeding is discussed.     

Dried milk protein products

The commercial methods of isolation of the main milk proteins marketed in the dried form, casein, caseinates and whey proteins, are described, together with process developments for the production of other types of dried protein. Production statistics and present world markets are discussed in relation to Government policies, and possible market developments based on new types of product are considered.     

Comparison of feed evaluation models on predictions of milk protein yield on Québec commercial dairy farms

Feed evaluation models (FEM) are a core part in dairy cow feeding. As these models are developed using different biological and mathematical approaches mainly tested in a research context, their abilities to predict production in commercial farms need to be validated, even more so when they are used outside the context of their development. Four FEM—National Research Council, 2001 (NRC_2001); Cornell Net Carbohydrate and Protein System, 2015 (CNCPS); NorFor, 2011; and INRA, 2018 (INRA_2018)—were evaluated on their abilities to predict daily milk protein yield (MPY) of 541 cows from 23 dairy herds in the province of Québec, Canada. The effects of cow and diet characteristics were tested on the residuals of MPY. Sensitivity and uncertainty analyses were then performed to evaluate the influence of the uncertainty of the main characteristics of cows and feed ingredients measured on the farm and used in the 4 FEM on the predictions of metabolizable protein (MP) supply and MPY. The 4 models had acceptable predictions of MPY, with concordance correlation coefficients (CCC) ranging from 0.75 to 0.82 and total bias ranging from 12.8% to 19.3% of the observed mean. The Scandinavian model NorFor had the best predictions with a CCC of 0.82, whereas the 3 other models had similar CCC at 0.75 to 0.76. The INRA_2018 and NRC_2001 models presented strong central tendency biases. Removing herd effect put the 4 FEM at the same level of performance, with 11.9 to 12.4% error. Analyzing model behavior within a herd seems to partly negate the effect of using predicted dry matter intake (DMI) in the comparison of models. Diet energy density, days in milk, and MPY estimated breeding value were related to the residual in the 4 models, and Lys and Met (as percent of MP) only in NRC_2001 and NorFor. This suggests that inclusion of these factors in these models would improve MPY predictions. From the sensitivity analysis, for the 4 FEM, DMI and factors affecting its prediction had the greatest influence on the predictions of MP supply and MPY. Of the feed ingredients, forage composition had the greatest effect on these predictions, including a strong effect of legume proportion with NorFor. Diet acid detergent fiber concentration had a very strong effect on MP supply and MPY predictions only in INRA_2018, because of its effect on organic matter digestibility estimation. The range of predictions of MP supply and MPY when combining all these potential uncertainties varied depending on the models. The INRA_2018 model presented the lowest standard deviation (SD) and NorFor the highest SD for the predictions of both MP supply and MPY. Overall, despite the fact that FEM were developed in a research context, their use in a commercial context yields acceptable predictions, with NorFor yielding the best predictions overall, although within-herd responses varied similarly for the 4 tested models.     

Expected effects on protein yield of marker-assisted selection at quantitative trait loci affecting milk yield and milk protein percentage

Protein yield (PY) is currently the major economic product of the dairy herd. Genome-wide scans for quantitative trait loci (QTL) affecting milk yield (MY) and milk protein percentage (PP) suggest that of the loci affecting the 2 traits, about 1/4 exclusively affect MY, 1/4 exclusively affect PP, and half affect both traits. Because PY is the product of MY and PP, it is of interest to evaluate the expected effects on PY of marker-assisted selection (MAS) applied to these 3 classes of QTL. It is clear that selection for the appropriate allele at QTL exclusively affecting MY or PP will have a positive effect on PY. The question arises as to the effect of MAS directed at QTL affecting both MY and PP. Because the observed genetic correlation of about −0.5 between MY and PP must be generated by these loci, and because they comprise about half the total number of loci affecting the 2 traits, it can be inferred that the genetic correlation between MY and PP at loci affecting both traits is close to −1.0. This seems to imply that generally such loci would be neutral in their effects on PY. In the present study, biometrical expressions originally developed to describe the relationships of MY, fat percentage, and fat yield were adapted to describe the relationships of MY, PP, and PY. The resultant expressions were validated by showing that they correctly predicted the observed phenotypic standard deviation and heritability of PY, and the vastly different genetic correlations of PY with MY (very high positive) and of PY with PP (very low positive). Contrary to initial impressions, further biometrical analysis of the projected effects on PY of MAS at the loci affecting both traits, showed that even under the assumption that the genetic correlation between MY and PP at these loci is −1.0, selection for the allele favoring MY will have a strong positive effect on PY, whereas selection for the allele favoring PP will have an equal but opposite negative effect on PY. These diametrically opposed effects are due to the lower genetic coefficient variation of PP compared with MY. It is speculated that the reduced coefficient of variation of PP may be because of more stringent homeostatic buffering of milk composition compared with milk yield.     

乳蛋白活性肽功能性的研究

介绍了乳蛋白肽的来源及国内外发展概况，通过人体试验证明了乳蛋白肽的调节免疫和抗氧化两大生物功效，并就其发展前景进行了讨论。     

Milk protein polymorphism in Danish dairy cattle and the influence of genetic variants on milk yield

In milk samples from 549 cows of the breeds Danish Jersey, Red Danish Dairy Cattle (RDM), and Black and White Danish Dairy Cattle (SDM) the genetic polymorphisms of the alpha-s1, beta and k-casein and beta=lactoglobulin (beta-Lg) loci were determined by isoelectric focusing in agarose gels. The results of the screening were compared with results obtained by Larsen and Thymann. In addition, the genetic linkage of the three casein loci was studied , and the association between milk protein genotypes and yields in first and second lactations of milk, fat and protein were investigated. The distribution of genotypes of all four milk protein systems was different from breed to breed. For Jersey cows, significant differences in the gene frequencies from the results of the 1966 investigation were found for alpha-s1 and k-casein and beta-Lg. For SDM cows a change in the k-casein frequency had occurred whereas for RDM cows no changes were found. Linkage between some of the casein loci was found within all three breeds. For the RDM breed the possible linkage between alpha-s1-casein and the other caseins could not be tested because nearly all the cows were homozygous for the alpha-s1-casein-B genotypes. beta-Casein genotypes were associated with yield parameters in all breeds. The A2A2 genotype of this protein gave higher yields of milk, fat, and protein in the second lactation than the A1A1 genotype.     

Aflatoxins in dairy cow feed,raw milk and milk products from Turkey

This study aims to detect aflatoxins (AFs) in dairy cow feed, milk and milk products using a high-performance liquid chromatography coupled with fluorescence detection (HPLC-FLD) method. All the validation parameters met the method performance criteria of the European Union. The samples comprised 76 dairy cow feeds and 205 milk and milk products (including yoghurt and yoghurt-based beverage, ayran). AFs were present in 26.3% of the feed samples. Two feed samples exceeded the maximum limit (ML) of 5 µg kg^?1 for AFB₁ as established by the EU. Nineteen milk samples (21.1%) contained aflatoxin M₁ (AFM₁) of which three exceeded the EU ML of 0.05 µg l^?1. In addition, only two yoghurt samples and one ayran sample contained AFM₁, but the levels were lower than the EU ML.