Exploration of the bovine colostrum proteome and effects of heat treatment time on colostrum protein profile

Heat treatment of colostrum is performed on modern dairy farms to reduce pathogenic contamination before hand-feeding the colostrum to newborn calves; however, limited data are available concerning effects of heat treatment on biologically active proteins in colostrum. The objective of this exploratory study was to investigate effects of heat treatment and length of heat treatment on colostrum protein profile. Colostrum samples were collected from Holstein cows within 12 h after parturition and assigned to the following groups: heat treatment at 60°C for 0 (untreated control), 30, 60, or 90 min. Samples were fractionated using acid precipitation, followed by ultracentrifugation and ProteoMiner (Bio-Rad Laboratories, Hercules, CA) treatment, and tandem-mass tagging was used to comparatively assess the low abundance protein profile. A total of 162 proteins were identified with more than 2 peptides in the low abundance protein enriched fraction. Of these, 62 differed in abundance by more than 2-fold in heat-treated samples compared with the unheated control. The majority of proteins affected by heat treatment were involved in immunity, enzyme function, and transport-related processes; affected proteins included lactadherin, chitinase-3-like protein 1, and complement component C9. These results provide a foundation for further research to determine optimum heat treatment practices to ensure newborn calves are fed colostrum-containing proteins with the highest nutritional and biological value.     

超高压处理对牛初乳中IgG活性的影响

牛初乳中富含营养物质和多种活性成分,尤其是IgG的含量特别高。以产犊后48h内的牛初乳为原料,研究不同的超高压处理条件对牛初乳中IgG活性的影响,采用ELISA方法检测经过超高压处理后样品中IgG的活性。结果显示,在压力500MPa、温度35℃、时间20min条件下处理牛初乳,其IgG活性提高率达到最大。      

Effect of heat treatment of bovine colostrum on bacterial counts, viscosity, and immunoglobulin G concentration

A study was conducted to identify the optimal temperature and time at which heat treatment of bovine colostrum would least change viscosity and IgG concentrations yet reduce bacterial count. First-milking colostrum with >50 g of immunoglobulins/L (measured by colostrometer) was collected from 30 Holstein cows. Aliquots of colostrum were heated for 0, 30, 60, or 90 min at 57, 60, or 63°C in a water bath. Samples were examined for viscosity, IgG₁, and IgG₂ concentrations, standard plate count, coagulase-negative staphylococci, environmental streptococci, coliform, gram-negative noncoliform, Streptococcus agalactiae, and Staphylococcus aureus counts. All heat treatments reduced counts of all bacteria groups measured compared with untreated colostrum samples. Heat treatment at ≥60°C denatured IgG₁ compared with untreated colostrum; however, colostral IgG₂ levels were not reduced when temperature was held at 60°C for <60 min. Viscosity was not affected when temperature was held at 60°C for <60 min. In this study, heat treatment of bovine colostrum at 60°C for 30 or 60 min reduced bacterial count, slightly reduced IgG concentration, and did not affect viscosity.     

Effect of heat treatment on antirotaviral activity of bovine and ovine whey

Rotavirus is the major cause of infectious diarrhoea in infants and children throughout the world. Several studies have indicated that some milk fractions may protect against rotavirus infection. The present study evaluates the effect of some heat treatments on the antirotaviral activity of bovine and ovine whey by an immunofluorescence assay validated in this work. Neutralising activity of diverse proteins present in whey has also been verified individually. Bovine and ovine whey, at 1 mg mL⁻¹ protein, inhibit MA104 cells infection with bovine rotavirus strain WC3, with values of 89.2 and 76.6% inhibition, respectively. Furthermore, the inhibitory activity was influenced by temperature and duration of heat treatment. The ability of bovine and ovine whey to inhibit rotavirus infection was not affected by treatment at 75 °C for 20 s; after 85 °C for 10 min bovine and ovine whey still maintained 16.1 and 32.5%, respectively, of neutralisation activity.     

Effect of heat treatment on the antibacterial activity of bovine lactoferrin against three foodborne pathogens

The effect of different heat treatments on the antimicrobial activity of bovine lactoferrin against Escherichia coli O157:H7, Salmonella enteritidis and Listeria monocytogenes has been studied. We have observed that the heat treatments lower than 85°C for 10 min did not affect the antibacterial activity of the protein. Hydrolysates of bovine lactoferrin were found to be more active than the native protein against the three pathogens. Moreover, the antibacterial effect of bovine lactoferrin was also assayed in milk and whey, and although we found a reduction in the number of viable cells, this reduction was lower than in culture media.     

Absolute quantification of bovine lactadherin to screen the anti-rotavirus activity of dairy ingredients

The anti-rotavirus components in breast milk and infant formulas play an important role in the prevention of rotavirus infection. The present study examined whether the levels of phospholipids and bovine lactadherin, which are the major components and proteins of the milk fat globule membrane complex, are useful indices of the anti-rotavirus activity of dairy ingredients used in infant formulas. We compared the anti-rotavirus activity of 2 types of dairy ingredients enriched in the milk fat globule membrane complex: high-fat whey protein concentrate (high-fat WPC) and butter milk powder (BMP), using 50% inhibition concentration (IC₅₀) and linear inhibition activity to determine levels of solid contents, total proteins, phospholipids, and bovine lactadherin. Here, we developed a quantification method using full-length isotope-labeled proteins to measure bovine lactadherin levels in these dairy ingredients. The evaluation of anti-rotavirus activity showed that the difference in IC₅₀ was the smallest when the 2 dairy ingredients were compared at the bovine lactadherin level, among other indices in this study. Additionally, no significant difference was observed between the inhibition linearity of 2 dairy ingredients when evaluating only bovine lactadherin levels. These results indicated that the level of bovine lactadherin was more strongly associated with anti-rotavirus activity than the level of phospholipids. Our results suggest that bovine lactadherin levels can be used to estimate the anti-rotavirus activity of dairy ingredients and can be a criterion used in selecting ingredients for infant formulas.     

Short communication: The effect of heat treatment of bovine colostrum on the concentration of oligosaccharides in colostrum and in the intestine of neonatal male Holstein calves

The objective of this study was to determine the effect of the heat treatment (HT, 60°C for 60 min) on the concentration of bovine colostrum oligosaccharides (bCO) in pooled bovine colostrum and the intestine of neonatal male Holstein calves after feeding. First-milking colostrum was pooled from both primiparous and multiparous cows, and half of the pooled colostrum was heat-treated at 60°C for 60 min (HC), whereas the other half was not heat-treated and remained fresh (FC). At birth, 32 male Holstein calves were randomly assigned to 1 of 3 treatment groups: (1) control calves that did not receive colostrum for the duration of the experiment and were euthanized at 6 h (NC, n = 4) or 12 h (NC, n = 4), (2) calves fed fresh colostrum (FC) and were euthanized at 6 h (FC, n = 6) or 12 h (FC, n = 6), or (3) calves fed heat-treated colostrum (HC) and euthanized at 6 h (HC, n = 6) or 12 h (HC, n = 6). All calves were fed 2 L of colostrum within 1 h after birth. At dissection, digesta of the distal jejunum, ileum, and colon was collected and analyzed by liquid chromatography-mass spectrometry to determine the concentration of bCO within each intestinal region. The heat-treated colostrum displayed numerically higher concentrations of total bCO (3,511.6 μg/g) when compared with fresh colostrum (1,329.9 μg/g), with 3′-sialyllactose being the most abundant bCO in both fresh and HT colostrum. In contrast, calves fed HT colostrum displayed a lower amount of total bCO in the distal jejunum (221.91 ± 105.3 vs. 611.26 ± 265.1 μg/g), ileum (64.97 ± 48.39 vs. 344.04 ± 216.87 μg/g), and colon (25.60 ± 13.1 vs. 267.04 ± 125.81 μg/g) at 6 h of life when compared with calves fed fresh colostrum. No differences were observed in regard to the concentrations of total bCO in the intestine of FC and HC calves at 12 h of life. It is speculated that lower concentrations of bCO in the gastrointestinal tract of HC calves at 6 h of life could be due to the early establishment of beneficial bacteria, such as Bifidobacterium, in HC calves and their subsequent metabolism of bCO as a carbon source. These findings suggest that the heat treatment of colostrum increases the amount of free bCO, which may serve as prebiotics available to microbiota within the intestine of the neonatal calf.     

牛初乳中IGF-I提取物对肠黏膜修复作用的研究

目的:研究牛初乳中胰岛素生长因子-I（IGF-I）对大鼠受损肠黏膜的修复作用。方法:应用氨甲喋呤制备大鼠小肠炎模型,实验设正常对照组,MTX模型对照组（20μg/kg）,牛初乳IGF-I提取物修复组（75μg/kg）,IGF-I修复组（75μg/kg）。后2组每天灌胃给药1次,给药时间从造模后第2d开始至实验结束,共5d。第6d检测大鼠血浆二氨氧化酶（DAO）活性、血浆D-乳酸水平,光镜下观察小肠组织病理形态学改变。结果:与对照组相比,模型组大鼠血浆DAO活性和血浆D-乳酸水平明显升高（P<0.05）,小肠损伤程度明显高于对照组（P<0.05）,牛初乳中IGF-I提取物组和IGF-I组可降低血浆DAO活性及D-乳酸水平（P<0.05）,减轻小肠损伤程度（P<0.05）。结论:牛初乳中IGF-I提取物能够明显减轻大鼠肠黏膜的损伤,同时可减轻炎细胞的浸润,对实验性大鼠的小肠炎具有修复作用。      

牛初乳低温喷雾干燥技术研究

传统的干燥方法可根据温度高低的不同分为高温热力干燥、低温干燥和冷冻干燥.定义了低温干燥的概念,并分析了低温干燥的机理.将玻璃化转变理论和低温干燥理论应用于牛初乳低温喷雾干燥,通过实验研究提出了低温喷雾干燥装置设计.     

A survey of bovine colostrum composition and colostrum management practices on Pennsylvania dairy farms

Colostrum composition and management were surveyed via sample and data collection from 55 dairy farms in Pennsylvania. Colostrum samples were analyzed for fat, protein, lactose, total solids, ash, Ig, lactoferrin, water- and fat-soluble vitamins, and minerals. Mean percentages of fat, protein, and lactose in colostrum were 6.7, 14.9, and 2.5, respectively. Concentrations of IgG₁, IgG₂, IgA, IgM, and lactoferrin were 35.0, 6.0, 1.7, 4.3, and 0.8 mg/mL, respectively. Mean concentrations of fat-soluble vitamins, including retinol, tocopherol, and β-carotene, were 4.9, 2.9, and 0.7 μg/g, respectively. Mean concentrations of water-soluble vitamins were 0.34, 0.90, 4.55, 0.60, 0.15, 0.21, and 0.04 μg/mL for niacin, thiamine, riboflavin, vitamin B₁₂, pyridoxal, pyridoxamine, and pyridoxine, respectively. Mean concentrations (mg/kg) of selected minerals in colostrum were also determined (Ca 4,716; P 4,452; Mg 733; Na 1,058; K 2,845; Zn 38; Fe 5.3; Cu 0.3; S 2,595; and Mn 0.1). The findings of this study revealed that the mean concentrations of most nutrients in colostrum have increased when compared with values previously reported. Results also showed that management practices have improved over time, particularly with regard to colostrum storage and feeding. Additionally, we observed that herd size influenced colostrum management and quality. It can be inferred, based on these findings, that although improvements have been made with regard to colostrum management and quality, there is still a need to educate producers on issues related to storage and timely feeding of colostrum to increase passive transfer and decrease the rate of calf morbidity and mortality.     

牛初乳营养成分与其免疫球蛋白活性保持技术研究进展

牛初乳由高浓度的生物活性成分组成,具有调节肠道菌群、促进机体生长发育、增强人体免疫力的作用,是一种十分重要的功能性食品原料。免疫球蛋白是牛初乳中最重要的活性成分,但其在加工过程中损失较大。免疫球蛋白活性保持技术能够保护其免于热、酸和碱等不良环境的影响,进而提升牛初乳综合利用价值。文章综述了牛初乳的营养成分和牛初乳中免疫球蛋白主要活性保持技术的研究进展,并对其未来研究前景进行了展望。     

Short communication: Effect of barn climate and management-related factors on bovine colostrum quality

Several factors have been reported to influence colostrum quality (immunoglobulin concentration). To date, knowledge of the influence of climatic factors in association with other potential influencing factors on colostrum quality is scarce. Associated influential factors are parity, body condition score, length of dry period, ration fed ante partum (AP), β-hydroxybutyrate postpartum (PP), milk yield, milk fat and protein, as well as somatic cell counts from previous and current lactation. The objective of the present study was to examine the effect of barn climate and the aforementioned factors on colostrum quality. Data were collected from 1,381 multiparous Holstein Friesian cows kept on one dairy farm over a period of one year (August 2014 to August 2015). Colostrum was harvested on farm within 1 h PP. The quantity and quality of first colostrum (estimated by Brix refractometry) were recorded for each cow. Additional data recorded were parity, body condition score at drying off, length of dry period, ration fed AP, milk yield data from previous and current lactation, milk somatic cell counts, and β-hydroxybutyrate PP. During the study period, temperature and humidity were recorded in the barn every hour, and temperature-humidity-index (THI) was calculated. Linear regression was performed with colostrum quality as the dependent variable. In the final model, colostrum quantity (L), length of dry period, parity, and climatic factors (specifically, median humidity in the 3rd week AP and hours with THI ≥72 in the last 14 and 21 d AP, respectively) were significant. Colostrum quality improved with parity and length of dry period and decreased with colostrum quantity, humidity, and hours with a THI ≥72. A classification and regression tree analysis revealed that colostrum quantity was the most important factor in this model [normalized importance (NI) 100%]. Parity (NI 42.7%), length of dry period (NI 37.1%), and climatic factors (NI 0.4 to 1.9%) followed with decreasing importance. These results indicate that the most important factors for colostrum quality (i.e., colostrum quantity and parity) may not be influenced by management. The 2 factors that can be influenced by management [i.e., length of dry period and THI (e.g., by cooling)], were quantitatively of minor importance compared with the other 2 factors. Further studies are necessary to determine whether changing these factors can improve colostrum quality significantly.     

牛初乳巴氏杀菌工艺的优化研究

热处理是牛初乳加工中必不可少的工艺过程.通过对热处理强度对初乳中IgG保留率、微生物数量以及营养成分损失的影响进行研究,并对巴式杀菌工艺进行优化,得出以下结果:杀菌温度为60℃和63℃,加热时间超过30 min可以将微生物数量降低到安全数量.IgG的保留率随加热温度的升高而降低,随加热时间的延长而降低.加热温度对美拉德反应、脂肪氧化和蛋白质水解反应的影响均显著.通过优化得出,杀菌温度60℃和加热时间30 min,可以既保证微生物安全,同时最大保留IgG的浓度和营养成分损失较低.     

牛初乳免疫球蛋白稳定性研究概述

牛初乳富含很多营养成分,其中含有大量的免疫球蛋白,能够抵抗外界病毒侵害,增强机体自身免疫力,但在加工过程中,其活性受到很多因素影响。文中综述了温度、p H值、蛋白酶、超高压等因素对牛初乳免疫球蛋白稳定性的影响,对提高其稳定性的方法如食品添加剂保护法及微胶囊法的研究现状做出总结,为进一步开展牛初乳免疫球蛋白研究提供了参考。     

牛初乳原料杀菌和酸奶加工研究

通过添加稳定剂提高牛初乳的热稳定性并将其加工成酸奶。牛初乳中按0.5 g/100g添加Na2HPO4,65℃加热,记录凝固时间及评价杀菌效果;确定葡萄糖和蔗糖的添加比例,将杀菌初乳制成酸奶,进行乳酸菌和杂菌计数。结果表明,添加Na2HPO4的牛初乳加热40 min才开始凝固,而未添加组加热6 min完全凝固。65℃加热15 min,牛初乳菌落总数和大肠菌群均合格;当葡萄糖添加量为3 g/100g,蔗糖添加量为4 g/100g时,牛初乳酸奶口感最佳,乳酸菌数为1.26×106 cfu/mL。因此按0.5 g/100g添加Na2HPO4可以显著提高牛初乳的热稳定性,加工制成的初乳酸奶兼具了牛初乳和酸乳的双重功效。     

Effect of temperature on colostrometer readings for estimation of immunoglobulin concentration in bovine colostrum.

Effect of temperature on colostrometer readings for estimation of immunoglobulin concentration in bovine colostrum was investigated. Twenty-five colostrum samples were collected within 24 h postpartum from Holstein cows. Immunoglobulin concentration of colostrum was measured using a colostrometer through 5 degrees C increments from 0 to 40 degrees C. Two technicians measured independently a total of 225 samples. The agreement between technicians' readings was high (r = .98); thus, readings were averaged and used in regression analysis. A final regression model explained 92.5% of the total variation: corrected reading at 20 degrees C = uncorrected reading - 13.2 + .8 x temperature (degrees C). The regression equation was used to develop a conversion chart for practical field use.