Antimicrobial and antidiabetic potential of synbiotic fermented milk: A functional dairy product

The current study was based on evaluation of the therapeutic potential (antimicrobial and antidiabetic) of a synbiotic fermented milk product developed by optimising levels of the prebiotic ingredients (fructooligosaccharide and isomaltooligosaccharide). The maximum growth rate (0.27 ± 0.21a cfu/mL) of Lactobacillus acidophilus ATCC^® 4357? was observed with 2.345–2.445% of fructooligosaccharide and 2.53–2.62% of isomaltooligosaccharide. Significant antimicrobial potential of the synbiotic fermented milk was observed against Escherichia coli and Staphylococcus aureus due to the addition of prebiotics. Similarly, the final product also showed 62.9%, 71.5% and 57.0% reduction in blood glucose, urea and creatinine levels, respectively, of diabetic rabbits, when supplemented with 6% of the synbiotic fermented milk. A synbiotic fermented milk product with significant therapeutic potential could be developed using fructooligosaccharide and isomaltooligosaccharide as prebiotic ingredients.     

Mining data from milk infrared spectroscopy to improve feed intake predictions in lactating dairy cows

Feed intake is one of the most important components of feed efficiency in dairy systems. However, it is a difficult trait to measure in commercial operations for individual cows. Milk spectrum from mid-infrared spectroscopy has been previously used to predict milk traits, and could be an alternative to predict dry matter intake (DMI). The objectives of this study were (1) to evaluate if milk spectra can improve DMI predictions based only on cow variables; (2) to compare artificial neural network (ANN) and partial least squares (PLS) predictions; and (3) to evaluate if wavelength (WL) selection through Bayesian network (BN) improves prediction quality. Milk samples (n = 1,279) from 308 mid-lactation dairy cows [127 ± 27 d in milk (DIM)] were collected between 2014 and 2016. For each milk spectra time point, DMI (kg/d), body weight (BW, kg), milk yield (MY, kg/d), fat (%), protein (%), lactose (%), and actual DIM were recorded. The DMI was predicted with ANN and PLS using different combinations of explanatory variables. Such combinations, called covariate sets, were as follows: set 1 (MY, BW^0.75, DIM, and 361 WL); set 2 [MY, BW^0.75, DIM, and 33 WL (WL selected by BN)]; set 3 (MY, BW^0.75, DIM, and fat, protein, and lactose concentrations); set 4 (MY, BW^0.75, DIM, 33 WL, fat, protein, and lactose); set 5 (MY, BW^0.75, DIM, 33 WL, and visit duration in the feed bunk); set 6 (MY, DIM, and 33 WL); set 7 (MY, BW^0.75, and DIM); set-WL (included 361 WL); and set-BN (included just 33 selected WL). All models (i.e., each combination of covariate set and fitting approach, ANN or PLS) were validated with an external data set. The use of ANN improved the performance of models 2, 5, 6, and BN. The use of BN combined with ANN yielded the highest accuracy and precision. The addition of individual WL compared with milk components (set 2 vs. set 3) did not improve prediction quality when using PLS. However, when ANN was employed, the model prediction with the inclusion of 33 WL was improved over the model containing only milk components (set 2 vs. set 3; concordance correlation coefficient = 0.80 vs. 0.72; coefficient of determination = 0.67 vs. 0.53; root mean square error of prediction 2.36 vs. 2.81 kg/d). The use of ANN and the inclusion of a behavior parameter, set 5, resulted in the best predictions compared with all other models (coefficient of determination = 0.70, concordance correlation coefficient = 0.83, root mean square error of prediction = 2.15 kg/d). The addition of milk spectra information to models containing cow variables improved the accuracy and precision of DMI predictions in lactating dairy cows when ANN was used. The use of BN to select more informative WL improved the model prediction when combined with cow variables, with further improvement when combined with ANN.     

Output of selenium in milk, urine, and feces is proportional to selenium intake in dairy cows fed a total mixed ration supplemented with selenium yeast

Fifteen rumen fistulated Holstein cows in late lactation and fed a total mixed ration offered ad libitum were supplemented with Se yeast to provide 0, 11, 20, 30, or 42 mg of supplemental Se/day to test the hypothesis that amounts of Se secreted in milk, excreted in urine and feces, and apparently retained in tissues would increase in direct proportion to Se intake. One-half of the yeast supplement was placed directly into the rumen through the fistula of each cow just before milking in the morning and again in the evening, and estimates of average daily excretion of Se were made using total collections of urine and feces from 25 to 31 d after treatments commenced. Amounts of Se secreted daily in milk and apparently retained in tissues increased linearly with average daily intake of Se. The amount of Se excreted in feces and total excretion of Se in urine plus feces increased curvilinearly with Se intake, such that proportionately less Se was excreted as the amount of Se fed increased. On average, total Se excretion accounted for 66%, Se secretion in milk accounted for 17%, and Se apparently retained in tissues accounted for 17% of total Se intake by cows. Thus, in herds fed large amounts of Se yeast, most of the Se will be excreted and retained on-farm. High concentrations of Se will be found where urine and feces accumulate (e.g., yards and effluent ponds), and effluent management practices must be tailored to avoid environmental issues.     

Biogenic amine content of kefir: a fermented dairy product

Kefir is a fermented dairy product. Ten samples of kefir supplied from different manufacturers in Turkey were analyzed for the first time to determine biogenic amine contents using HPLC with benzoyl derivatization. Of the 10 biogenic amines under study, putrescine, cadaverine and spermidine were detected in all samples. Tyramine was detected in all kefir samples except one. Tyramine was the prevailing biogenic amine. Tyramine concentrations of kefir samples changed from non detectable values to 12.8 mg/l. Total biogenic amine contents of kefir samples were between 2.4 and 35.2 mg/l. Concentrations of biogenic amines were far below the allowable limits. pH values of kefir samples were in the range from 4.11 to 4.53; acidities were in the range from 0.652 to 1.047% (as lactic acid, w/v); total dry matters were from 8.88 to 12.00% (w/w); total free amino acid contents were from 0.0070 to 0.0206% (as leucine, w/v). No significant correlations were detected between biogenic amine concentrations and pHs and total dry matter contents. Significant correlations were obtained between biogenic amine concentrations and acidities and total free amino acid contents of kefir samples.     

国际食品法典委员会动物源性食品中农药最大残留限量制定现状

将固相支撑液液萃取与超高效液相色谱串联质谱法结合,建立生乳中32种农药残留的快速检测方法,为保障生乳食品安全提供技术支持。样品加入乙腈沉淀蛋白,高速离心分离,上清液用固相支撑液液萃取小柱净化,C₁₈色谱柱梯度洗脱分离后,经串联质谱电喷雾模式扫描,多反应监测模式检测,以基质匹配校准曲线外标法定量。结果表明,32种目标物在一定范围内线性关系良好,相关系数大于0.9962,检出限为0.1~2.5 μg/kg,定量限为0.3~7.5 μg/kg,平均回收率为69.4%~113.8%,相对标准偏差（n=6）小于8.2%。该方法简单、快速、可靠,适用于生乳中32种农药残留的测定。     

发酵豆奶的生产工艺和营养

<正> 大豆是我国的传统食品,蛋白质含量达45％左右,为一般食物含量的3～5倍。现代营养学认为,蛋白质的营养价值主要取决于其氨基酸成分,如果各种氨基酸比例接近人体的氨基酸模式,即符合FAO/WHO建议的氨基酸模式,则该种食物的营养价值高。大豆中蛋白质的必需氨基酸模式不但接近FAO/WHO的建议模式,也与动物蛋白质的氨基酸模式相近,是一种完整的蛋白质。另一方面,大豆蛋白质与奶类或谷类食物搭配,具有蛋白质互补的作用。而且大豆中的脂肪含量达     

Use of milk urea nitrogen to improve dairy cow diets

The hypothesis of this field study was that providing farmers with information regarding their herd's milk urea nitrogen (MUN) would result in more accurate feed management and a change in MUN toward target values. All dairy herd bulk tanks (n = 1156) in the Maryland and Virginia Milk Producers' Cooperative were tested for MUN each month for six months ending in May 1999. Farmers (n = 454) who returned a survey were provided with the results of their MUN analysis each month along with interpretive information. Survey results indicated that most (89.5%) dairy farmers did not routinely use MUN prior to participating in the project, but most (88%) extension agents and nutritionists in the region recommended it. The average MUN across all farms in the study increased in the spring, but the increase was 0.52 mg/dl lower for farmers receiving MUN results than for those who did not participate in the program. Farmers who indicated they increased dietary crude protein (CP) due to low MUN started with MUN values that were 3 mg/dl below target but ended with target values. Farmers who indicated that they decreased CP due to high MUN began the project with high MUN but decreased it by 1 mg/dl compared to non-participating farmers. At the end of the project, 30% of farmers responding to a follow-up survey indicated they would use MUN analysis in the future. Providing MUN results and interpretive information to farmers was documented to change feeding practices and subsequent MUN results.     

Effects of selenium form on blood and milk selenium concentrations,milk component and milk fatty acid composition in dairy cows

BACKGROUND: Human health may be improved if milk with a favorable fatty acid composition and Se concentration is ingested. The present study is to determine how a basal diet supplemented with daily 5 mg Se as Se‐enriched yeast (SY) or sodium selenite (SS) affects the fatty acid composition and Se concentration of bovine milk. The effects of Se form on blood Se concentration, erythrocyte glutathione peroxidase 1 (GPx1) activity, serum GPx3 activity and milk yield and component were also studied. RESULTS: Both Se forms, when compared to control group, increased Se concentrations of blood (P < 0.01) and milk (P < 0.01), erythrocyte GPx1 activity (P < 0.05) and milk percentages of polyunsaturated fatty acids (PUFA) (P < 0.05) and cis‐9,cis‐12 linoleic acid (P < 0.05). Cows supplemented with SY had higher Se levels in blood (P < 0.01) and milk (P < 0.01) and percentage of PUFA in milk (P < 0.05) when compared with those supplemented with SS. Milk yield, milk component and serum GPx3 activity were not significantly affected by Se form. CONCLUSION: Supplementation of diet with SY appears to be of more benefit than SS in producing favorable milk with high PUFA and Se concentrations. Copyright © 2010 Society of Chemical Industry     

Influence of various selenium sources on selenium concentration in the milk of dairy cows

Selenium (Se) as essential trace element is supplemented in various compounds to rations of food producing animals. In human nutrition the range between Se requirement and upper level is very small (1:3–5). Hence, food of animal origin may contribute to Se supply of humans, but can also offer high amounts of Se and exceed the Se upper level for humans. Therefore the transfer into the milk of inorganic (0.2 and 0.4 mg Se from sodium-selenite) or organic (Se methionine) Se-compounds was tested. Fifteen lactating German Holstein cows were fed diets without supplementation (0.1 mg Se/kg dry matter, DM) or supplemented with inorganic or an organic Se-compound over 3 weeks. Se-supplementation did not significantly influence feed intake, milk yield and composition as well as animal health. Se-concentration of milk increased from 13.3 over 17.6 to 19.7 μg/L in the case of inorganic Se supplementation and from 13.9 over 24.6 to 54.8 μg/L after Se-yeast addition.     

A method to quantify changes in supply of metabolizable methionine to dairy cows using concentrations of selenium in milk

A method that accurately quantifies changes in the supply of metabolizable Met following a dietary change will allow accurate economic comparisons of various Met sources. This paper describes a novel method of estimating the relative supply of metabolizable Met based on changes in the concentration of Se in milk. Selenized yeast (Se-yeast) contains selenomethionine (Se-met) and because Se-met and Met are indistinguishable by cells, Se-met can be used as a tracer of Met. We hypothesized that if the size of the Met pool was increased but intake of Se-met was constant, the concentration of Se in milk relative to milk Met would decrease. To test this hypothesis, 6 Holstein cows were fed a diet that contained 0.3 mg of Se from Se-yeast/kg of diet DM and then in a 2-period crossover experiment, were abomasally infused with water (control) or an aqueous solution that provided 9 g of Met/d. Milk was sampled during the infusion and the specific activity (SA) of milk (Se concentration divided by Met concentration) was calculated for each treatment. The SA in milk from Met-infused cows was divided by SA in milk from control cows to calculate the change in supply of metabolizable Met. As hypothesized, infusing Met reduced the SA of milk (84.7 vs. 72.5 μg of Se/mg of Met). The calculated flow of metabolizable Met was 17% greater when cows were infused with 9 g of Met/d compared with cows infused with water (essentially the same difference was measured using SA calculated with N concentrations of milk). Assuming the infused Met was 100% absorbed, the flow of metabolizable Met for control cows was 9/0.17 = 53 g of Met/d, which agreed well with literature data and estimates derived from common nutritional models.     

Hydroxy-selenomethionine: A novel organic selenium source that improves antioxidant status and selenium concentrations in milk and plasma of mid-lactation dairy cows

This study aimed to evaluate the effect of hydroxy-selenomethionine (HMSeBA), a novel organic selenium (Se) source, on milk performance, antioxidative status, and Se concentrations in the milk and plasma of mid-lactation dairy cows compared with that of sodium selenite (SS). Fifty mid-lactation dairy cows with similar days in milk, milk yield, and parity received the same basal diet containing 0.06 mg of Se/kg of DM. They were assigned to 1 of 5 treatments according to a randomized complete block design: negative control (without Se supplementation), SS supplementation (0.3 mg of Se/kg of DM; SS-0.3) or HMSeBA supplementation (0.1, 0.3, or 0.5 mg of Se/kg of DM: SO-0.1, SO-0.3, and SO-0.5, respectively). The experiment lasted for 10 wk, including a pretrial period of 2 wk. The results indicated that neither Se supplementation nor Se source affected dry matter intake, milk yield, milk composition, or blood biochemical parameters, except for milk fat percentage. Simultaneously, milk fat percentage and milk fat yield increased linearly as the quantity of HMSeBA supplementation was increased. Production of 4% FCM and ECM was elevated linearly as dietary HMSeBA increased. The SO-0.3 group showed higher serum activity of glutathione peroxidase, total antioxidant capacity, and superoxide dismutase than the SS-0.3 group, but malondialdehyde content was not affected by Se source. Furthermore, HMSeBA supplementation linearly increased the activities of serum glutathione peroxidase and superoxide dismutase, but decreased malondialdehyde content. Compared with the SS-0.3 group, the SO-0.3 group showed augmented concentrations of total Se in milk and plasma, and total Se milk-to-plasma concentration ratio. In addition, increasing doses of HMSeBA linearly increased the concentrations of total Se in the milk and plasma. This study demonstrates that HMSeBA improves antioxidant status and increases milk and plasma Se concentrations more effectively than SS, indicating that HMSeBA could replace SS as an effective organic Se source for lactating dairy cows.     

传统发酵酸驼乳中乳酸菌的分离及鉴定

对新疆和蒙古国牧民家庭制作的传统发酵酸驼乳中的乳酸菌和酵母菌进行了计数和分离。4份酸驼乳中乳酸菌和酵母菌的数量分别为6.45×107～1.13×109mL-1和7.75×102～4.6×107mL-1。从4份酸驼乳中分离到13株乳酸菌和7株酵母菌。采用传统分类鉴定方法对乳酸菌进行鉴定,鉴定结果为L.helveticus4株(占总分离株的30.8%),L.caseisubsp.pseudoplantarum和L.dellbrueckiisubsp.bulgaricu各2株(15.4%),L.curvatus、Ped.acidilactici、Ped.urinaeequi和Enterococcusfaecalis各1株(7.7%)。此外,还有1株乳酸菌按目前的鉴定方法无法准确判断其归属。     

Use of gases to improve survival of Bifidobacterium bifidum by modifying redox potential in fermented milk

The aim of this work was to study the effect of the oxidoreduction potential, modified using gas, on the growth and survival of a probiotic strain, Bifidobacterium bifidum, and 2 yogurt strains, Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus. Three fermented milks were manufactured with an initial oxidoreduction potential value adjusted to +440 mV (control milk), +350 mV (milk gassed with N₂), and −300 mV [milk gassed with N₂ plus 4% (vol/vol) H₂ (N₂-H₂)]. Acidification profiles, growth during milk fermentation and survival during storage at 4°C for 28 d were determined. This study showed that fermented probiotic dairy products made from milk gassed with N₂ and, more particularly, those made from milk gassed with N₂H₂ were characterized by a significant increase in B. bifidum survival during storage without affecting the fermentation kinetics and the survival of Strep. thermophilus and L. delbrueckii ssp. bulgaricus.     

Biodiversity and origin of the microbial populations isolated from Masske,a traditional Iranian dairy product made from fermented Ewe's milk

Masske is a traditional Iranian dairy product containing 50% butterfat made from fermented ewe's milk. Overall, 672 bacterial isolates were collected from ewe's milk, fermented milk (FM) and Masske samples that were produced in households located in southern regions of the Khorasan Province in Iran. To identify lactic acid bacteria in these samples, a total of 79 Gram‐positive and catalase‐negative isolates were analysed. The identification of isolates was achieved by phenotypic and sequential analysis of the 16S rRNA gene. Enterococcus faecium and Aerococcus viridans were the most frequently isolated species in the samples, but the most commonly present bacteria in Masske were Streptococcus thermophilus.     

Effect of inulin as prebiotic and synbiotic interactions between probiotics to improve fermented milk firmness

Inulin behaved as a prebiotic to improve firmness of skim milk fermented by (a) pure cultures of Lactobacillus acidophilus (La), Lactobacillus rhamnosus (Lr), Lactobacillus bulgaricus (Lb) and Bifidobacterium lactis (Bl), (b) binary co-cultures of them with Streptococcus thermophilus (St), or (c) a cocktail containing all them. Inulin addition to co-cultures and cocktail enhanced products firmness, either after 1 day (D1) or 7 days (D7) of cold storage, likely due to the increase in microbial growth induced by metabolic interactions among lactic acid bacteria and partial inulin metabolization. Co-culture firmness did in fact range from 0.33 N without inulin (St-Lb) after D1 and 0.55 N with inulin (St-Lr) after D7. Also cocktail cultures exhibited high values of firmness, ranging, as an average, from 0.43 N (D1) to 0.46 N (D7), which suggests that they could have been potentiated by the reciprocal synergistic effects of microorganisms in complex mixture.     

Efficacy of feeding hydroxy-selenomethionine on plasma and milk selenium in mid-lactation dairy cows

In this study, we aimed to determine the amount of Se transferred to milk and blood of mid- to late-lactation dairy cows when supplemental Se from hydroxy-selenomethionine (OH-SeMet) was fed compared with an unsupplemented group and a group supplemented with a seleno-yeast (SY). Twenty-four lactating Holstein cows (178 ± 43 d in milk) were used in a complete randomized block design for 91 d (7-d covariate period and 84-d treatment period). Treatments were (1) basal diet with an analyzed Se background of 0.2 mg of Se per kg as-fed (control); (2) basal diet + 0.3 mg of Se/kg as-fed from SY (SY-0.3); (3) basal diet + 0.1 mg of Se/kg as-fed from OH-SeMet (OH-SeMet-0.1); and (4) basal diet + 0.3 mg of Se/kg as-fed from OH-SeMet (OH-SeMet-0.3). During the trial, plasma and milk were analyzed for total Se, and plasma was analyzed for glutathione peroxidase activity. The mean plasma and milk Se concentrations exhibited the same relationship, where OH-SeMet-0.3 resulted in the highest values (142 µg/L of plasma and 104 µg/kg of milk), followed by SY-0.3 (134 µg/L and 85 µg/kg), OH-SeMet-0.1 (122 µg/L and 67 µg/kg), and the control group had the lowest values (120 µg/L and 50 µg/kg). The increment of Se in milk induced by OH-SeMet-0.3 (+54 µg/kg) was 54% higher than that induced by SY-0.3 (+35 µg/kg). Additionally, dietary supplementation of 0.2 mg/kg Se from OH-SeMet in the total mixed ration was estimated to be similar to 0.3 mg/kg Se from SY in the total mixed ration when considering the level of Se in the milk. There was no difference in plasma glutathione peroxidase activity between groups; however, OH-SeMet-0.3 significantly decreased somatic cell count. The results confirmed that supplementation with organic Se increases milk and plasma Se concentrations. Moreover, when administered at the same level of supplementation, OH-SeMet was shown to be more efficient than SY in improving milk quality by increasing Se content and decreasing milk somatic cell count.     

Mycotoxins in cattle feeds and carry-over to dairy milk: A review

The complex diet of ruminants, consisting of forages, concentrates, and preserved feeds, can be a source of very diverse mycotoxins that contaminate individual feed components. A number of mycotoxins are successfully inactivated by the rumen flora, whereas others pass unchanged or are converted into metabolites that retain biological activity. Hence, the barrier function of the rumen largely determines the susceptibility of dairy cows and other ruminant species towards individual mycotoxins. An impairment of this barrier function due to diseases or the direct antimicrobial effect of certain mycotoxins may increase absorption rates. The rate of absorption determines not only the internal dose and risk for adverse health effects, but also the excretion of mycotoxins and the biologically active metabolites into milk.     

Invited review: Proteomics of milk and bacteria used in fermented dairy products: From qualitative to quantitative advances

Proteomics is a powerful tool that can simultaneously analyze several hundred proteins in complex mixtures, either through the use of high-resolution 2-dimensional gel electrophoresis or by mono- and multi-dimensional liquid chromatography coupled with mass spectrometry. Since the last review in 2005, proteomics has mainly been applied to describe minor proteins in the bovine milk fat globule membrane and soluble proteins in human colostrum. At least 130 new minor proteins have been identified. These proteins play roles in cell signaling, host defense, and transport as suggested by sequence homology. Proteomic approaches have also been applied to milk of other species such as donkey, horse, and marsupial. Peptides produced in food matrices that can exhibit functional or bioactive properties have been identified as have the proteases leading to their release in situ. However, the most spectacular proteomic development has been in the field of bacteria used in dairy products. Proteomics has resulted in the establishment of reference maps to detect strain-to-strain variations and to elucidate the mechanisms of in vitro and in vivo adaptation to environmental conditions. Proteomic analysis of bacteria entrapped in cheese has been achieved and revealed which predominant metabolic pathways are active depending on the strain. Proteomic approaches are often evoked as time-consuming procedures that provide a list of identified proteins without efficient quantification of each one. New quantitative proteomic methods have emerged and the most promising ones and their application to dairy products and bacteria will be presented.