Major Milk Components Research Articles

Research Progress on Genomic Regions and Candidate Genes Related to Milk Composition Traits of Dairy Goats Based on Functional Genomics: A Narrative Review.

Goat milk has gained global attention for its unique nutritional properties and potential health benefits. Advancements in functional genomic technologies have significantly progressed genetic research on milk composition traits in dairy goats. This review summarizes various research methodologies applied in this field. Genome-wide association studies (GWAS) have identified genomic regions associated with major milk components, with the diacylglycerol acyltransferase 1 (DGAT1) gene and casein gene cluster consistently linked to milk composition traits. Transcriptomics has revealed gene expression patterns in mammary tissue across lactation stages, while the role of non-coding RNAs (such as miRNAs and circRNAs) in regulating milk composition has been confirmed. Proteomic and metabolomic studies have not only helped us gain a more comprehensive understanding of goat milk composition characteristics but have also provided crucial support for the functional validation of genes related to milk components. The integration of multi-omics data has emerged as an effective strategy for elucidating complex regulatory networks from a systems biology perspective. Despite progress, challenges remain, including refining reference genomes, collecting large-scale phenotypic data, and conducting functional validations. Future research should focus on improving reference genomes, expanding study populations, investigating functional milk components, exploring epigenetic regulation and non-coding RNAs, and studying microbiome-host genome interactions. These efforts will inform more precise genomic and marker-assisted selection strategies, advancing genetic improvements in milk composition traits in dairy goats.

Genetic parameters of milk mid-infrared spectra and their genetic relationships with milk production and feed efficiency traits in French Lacaune dairy sheep

In French dairy sheep, Fourier transform infrared (FTIR) milk spectral data routinely predict the major milk components used in national genetic evaluations. The direct influence of genetic and environmental factors on milk FTIR spectra has been widely studied in dairy cattle, and relatively little in dairy ewes. In this study, 36,873 milk test-day records were available for 4,712 French Lacaune ewes farmed on 8 commercial farms. Our main goals were to provide the first description of spectral data and estimate the genetic parameters of French Lacaune dairy sheep during lactation. Principal component analysis (PCA) results demonstrated the impact of the lactation period on specific wavenumbers, allowing the identification of FTIR spectra collected at early (mo 2-4) and late (mo 5-7) lactation stages. The average estimated heritability (±mean SE) of the FTIR milk spectra from 2,971 to 926 cm-1 (446 wavenumbers) was 0.29 ± 0.02, ranging from 0.13 ± 0.01 to 0.42 ± 0.02. Furthermore, the heritabilities of spectra collected at the beginning or end of lactation changed at each point of the spectrum. However, at each wavenumber, the genomic correlation of transmittance values between these 2 lactation periods was high (>0.77), indicating the absence of a genotype-environment interaction. The genomic correlations between spectral regions and milk production traits (i.e., daily milk yield, fat and protein content, somatic cell score) varied from moderate to high. The results suggested that the most heritable areas of the spectrum were also genetically associated with dairy traits. Finally, the genomic correlations observed between the ewes' feed efficiency traits and the FTIR spectrum were moderate to high, while the genomic correlations between the change in body condition score and spectral data were rather low to moderate. This study confirmed that spectral data from Lacaune ewe milk were heritable, evolved phenotypically and genetically during lactation and were genetically correlated with traits included in breeding goals or traits of interest to the dairy industry.

Digestive Profiles of Human Milk, Recombinant Human and Bovine Lactoferrin: Comparing the Retained Intact Protein and Peptide Release.

Lactoferrin (LF) is a major component of human milk. LF supplementation (currently bovine) supports the immune system and helps maintain iron homeostasis in adults. No recombinant human lactoferrin (rhLF) is available for commercial food use. To determine the extent to which rhLF (Effera™) produced by Komagataella phaffii digests similarly to hmLF, a validated in vitro digestion protocol was carried out. Bovine LF (bLF) was used as an additional control, as it is approved for use in various food categories. This study compared the extent of intact protein retention and the profile of peptides released in hmLF, bLF and rhLF (each with low and high iron saturation) across simulated adult gastric and intestinal digestion using gel electrophoresis, ELISA and LC-MS. Intact LF retention across digestion was similar across LF types, but the highest iron-saturated hmLF had greater retention in the simulated gastric fluid than all other sample types. Peptides identified in digested hmLF samples strongly correlated with digested rhLF samples (0.86 < r < 0.92 in the gastric phase and 0.63 < r < 0.70 in the intestinal phase), whereas digested bLF samples were significantly different. These findings support the potential for rhLF as a food ingredient for human consumption.

Regulatory roles of dopamine D2 receptor in milk protein production and apoptosis in mammary epithelial cells

Dopamine D2 receptors (D2Rs) play crucial roles in regulating diverse physiological functions of the central nervous system and peripheral organs. D2Rs are also expressed in mammary glands. However, which cell types express D2Rs and whether they are involved in milk production remains unclear. The present findings revealed that D2Rs are expressed in the apical regions of the lateral membranes of mammary epithelial cells (MECs) in lactating mice. We also investigated the effects of the D2R agonist bromocriptine and/or antagonist domperidone on intracellular cAMP levels, milk protein production, and apoptosis in a lactation culture model of MECs that produce major milk components like lactating MECs in vivo. We found that bromocriptine decreased intracellular cAMP levels, whereas domperidone dose-dependently neutralized this effect. Bromocriptine also inhibited casein and lactoferrin production and suppressed activities of STAT5 and glucocorticoid receptors (GRs). Domperidone neutralized the inhibition of casein production as well as STAT5 and GR inactivation induced by bromocriptine. Furthermore, D2R activation by bromocriptine induced apoptosis and inactivated ERK, a signaling molecule responsible for promoting cell proliferation and survival. Domperidone attenuated ERK inactivation and apoptosis induced by bromocriptine. These findings suggest that D2Rs play regulatory roles in milk protein production and apoptosis in MECs.

Chemerin Stimulates the Secretory Activity of BME-UV1 Bovine Mammary Epithelial Cells.

Adipose tissue is an active endocrine gland, synthesizing and secreting multiple signaling molecules termed adipokines. Following the detection of adipokines and their receptors in the mammary tissue of various species, it is indicated that adipokines play a role in the development of the mammary gland. The aim of the present study was to determine the concentration-dependent influence of three adipokines, leptin, adiponectin, and chemerin, on the viability, apoptosis, and secretory activity of BME-UV1 bovine mammary epithelial cells. The study confirmed that BME-UV1 cells contain the leptin receptor (Ob-R) protein, and express transcripts of adiponectin (ADIPOR1 and ADIPOR2) and chemerin (CMLKR1 and GPR1) receptors. Regardless of the administered dose, none of the three tested adipokines had an effect on the viability of BME-UV1 cells, and the number of apoptotic cells remained unchanged. However, chemerin (100 ng/mL) stimulated BME-UV1 cells to synthesize and secrete αS1-casein, the major protein component of milk. These results indicate that chemerin may be a potent regulator of the bovine mammary epithelial cells' functional differentiation, contributing, along with the major systemic hormones and local growth factors, to the development of the bovine mammary gland.

The Role of Human Milk Oligosaccharides in Myelination, Socio-Emotional and Language Development: Observational Data from Breast-Fed Infants in the United States of America.

Infancy is a critical period for neurodevelopment, which includes myelination, synaptogenesis, synaptic pruning, and the development of motor, social-emotional, and cognitive functions. Human milk provides essential nutrients to the infant's developing brain, especially during the first postnatal months. Human milk oligosaccharides (HMOs) are a major component of human milk, and there is growing evidence of the association of individual HMOs with cognitive development in early life. However, to our knowledge, no study has explained these associations with a mechanism of action. Here, we investigated possible mediating associations between HMOs in human milk, brain myelination (measured via myelin water fraction), and measures of motor, language (collected via the Bayley Scales of Infant and Toddler Development (Bayley-III)), and socioemotional development (collected via the Ages and Stages Questionnaire: Social-Emotional Version (ASQ-SE)) in healthy term-born breast-fed infants. The results revealed an association between 6'Sialyllactose and social skills that was mediated by myelination. Furthermore, associations of fucosylated HMOs with language outcomes were observed that were not mediated by myelination. These observations indicate the roles of specific HMOs in neurodevelopment and associated functional outcomes, such as social-emotional function and language development.

Effects of Feeding A1 and A2 Cow Milk-based Diet on Hematological Parameters in Diabetic Mice Model

Background: Milk is essential part of diet across the globe and is a rich source of protein and calcium. Major protein component of milk is casein with beta-casein (β-casein) as the second most prevalent protein in cow milk. β-casein has 15 different genetic variants and of these A1 and A2 have gained research focus. All livestock as well as well human have proline at amino acid position 67 of β-casein, which is referred as A2 variant, but in cattle breeds, other genetic variant called A1 with histidine at amino acid position 67 is also present. This A1 type variant of â-casein or A1 type milk has been implicated as a potential etiological factor in several pathologies. Methods: The objective of the present study was to evaluate the A1and A2 β-casein variants of cow milk as factors affecting different hematological parameters and other parameters like glucose and insulin in streptozotocin (STZ)-induced diabetic C57/BL6 mice after the induction of diabetes. Diabetes was induced by injecting STZ intraperitoneally at dose of 45mg per kg of body weight for consecutive 5 days. Milk powder prepared from milk with A1A1 and A2A2 genotypes was used for feeding for three months. Result: After 3 months of feeding trial, it was observed that diabetic mice fed with A1A1 milk (STZ+A1A1) exhibited significantly elevated levels of glucose and insulin. Similarly, the levels of white blood cells, lymphocytes and neutrophils showed significant changes in STZ+A1A1 group compared to control and STZ+A2A2 group indicating the probable association A1A1 milk with inflammatory reaction. However, no significant changes were observed in parameters like red blood cells, hemoglobin, hematocrit or mean cell volume. In the mice group fed with A2A2 milk powder-based diet, no significant change was observed in the observed parameters except lymphocyte percentage which was lower compared to control group. In summary, our results show that A1 form of cow milk might have a proinflammatory effect.

Comparative analysis of fat digestion characteristics in sow milk and piglet formulas based on dynamic in vitro gastrointestinal digestion

Piglet formula is an important substitute for piglets when sow milk is unavailable. Triacylglycerols (TAGs) are the major components of sow milk and formulas. Lipolysis of TAGs in sow milk and five piglet formulas, mainly PF1 containing high similarity of sow milk fat substitute, PF2 containing coconut oil, and PF3-PF5 containing different amounts of 19.7%∼38.5% of medium chain fatty acids, was studied using in vitro dynamic gastrointestinal digestion system of piglets, and to elucidate the mechanism on digestive behaviors affected by different types of fats. The results showed that sow milk exhibited the largest particle size (4.22 μm) and the lowest absolute zeta-potential (12.8 mV) compared with formulas, contributing to its highest lipolysis degree (60.6%). It was followed by PF1 (56.2%), which had a similar fat composition to sow milk, especially the high content of sn-2 C16:0. Similarly, sow milk released the highest level of free fatty acids (56.9%, mainly long-chain species) after digestion, followed by PF1 (54.2%), and the other three formulas (33.8%–50.7%). The releases of diacylglycerides (e.g., L/L, P/L, P/O, O/O, and O/L) and monoacylglyceride-C16:0 were positively correlated with sn-2 C16:0 concentration, and the later will be re-esterified and reutilized for providing energy and essential fatty acids to piglets. It was indicated that the difference of fat digestive behaviors between sow milk and piglet formulas was associated to fat compositions and interfacial properties of their fat droplets. In this regard, digestion of fats for piglet formulas contributes to improving piglet health.

Importance of Mid-Infrared Spectra Regions for the Prediction of Mastitis and Ketosis in Dairy Cows.

Mid-infrared (MIR) spectroscopy is routinely applied to determine major milk components, such as fat and protein. Moreover, it is used to predict fine milk composition and various traits pertinent to animal health. MIR spectra indicate an absorbance value of infrared light at 1060 specific wavenumbers from 926 to 5010 cm-1. According to research, certain parts of the spectrum do not contain sufficient information on traits of dairy cows. Hence, the objective of the present study was to identify specific regions of the MIR spectra of particular importance for the prediction of mastitis and ketosis, performing variable selection analysis. Partial least squares discriminant analysis (PLS-DA) along with three other statistical methods, support vector machine (SVM), least absolute shrinkage and selection operator (LASSO), and random forest (RF), were compared. Data originated from the Austrian milk recording and associated health monitoring system (GMON). Test-day data and corresponding MIR spectra were linked to respective clinical mastitis and ketosis diagnoses. Certain wavenumbers were identified as particularly relevant for the prediction models of clinical mastitis (23) and ketosis (61). Wavenumbers varied across four distinct statistical methods as well as concerning different traits. The results indicate that variable selection analysis could potentially be beneficial in the process of modeling.

Multivariate relationship between major constituents and casein fractions in buffalo milk using canonical correlation analysis

This study explored the multivariate relationship of protein, fat, lactose, minerals, water, and milk urea nitrogen (MUN) with major casein (CN) fractions in buffalo milk using canonical correlation analysis (CCA). Two sets of milk chemical constituents were produced: the first group was composed of variables related to CN fractions (e.g., αS2-CN, αS1-CNB, αS1-CNA, κ-CNX2, κ -CNX1, and β-CN; canonical variate U) and the second group contained variables associated with major milk components (e.g., fat, lactose, protein, minerals, water, and milk urea nitrogen (MUN); canonical variate V). A major canonical correlation (R = 0.946) was obtained by using the CANCOR procedure of SAS, whose significance (P <0.01) was verified by the Wilks' Lambda test. Exploration of the major canonical correlation, revealed for the canonical variate U, the following canonical loadings for CN fractions: β-CN = 0.619, αS2-CN = 0.361, αS1-CNB = 0.314, κ-CNX1 = 0.137, κ-CNX2 = 0.056, and αS1-CNA=0.004. Regarding canonical variate V, the canonical loadings for major milk components were the following: protein = 0.936, water = –0.685, fat = 0.474, lactose = –0.286, minerals = 0.226, and MUN = 0.068. Hence, when buffalo's milk composition is explored from a multivariate approach, an increase in protein, fat, and minerals, as well as a decrease in water and lactose may result in increased CN fractions, mainly β-CN, αS2-CN, and αS1-CNB. A better understanding of the multivariate relationship among milk chemical components may provide insights for designing future efficient animal nutrition models to accurately modulate the milk chemical composition of buffaloes, which may be useful for improving the technological properties of the milk for this species.

Age-dependent associations of human milk oligosaccharides with body size and composition up to 4 years of age

BackgroundHuman milk oligosaccharides (HMOs) are major components of human milk that may mediate its beneficial effects on infant growth. ObjectivesTo investigate relationships between HMO concentrations in milk at 6 wk postpartum and anthropometry to 4 y of age in human milk-fed infants. MethodsMilk samples were collected from 292 mothers at 6 wk (median 6.0 wk; range 3.3, 11.1] postpartum in a longitudinal, population-derived cohort. Of the infants, 171 were exclusively human milk-fed to 3 mo of age and 127 to 6 mo. Concentrations of 19 HMOs were quantified using high-performance liquid chromatography. Maternal secretor status (n = 221 secretors) was determined from 2’-fucosyllactose (2’FL) concentration. We calculated z-scores for child weight, length, head circumference, summed triceps and subscapular skinfold thicknesses, and weight-for-length at 6 wk, 6 mo, 12 mo, and 4 y. We investigated associations of secretor status and each HMO measure with change from birth for each z-score using linear mixed-effects models. ResultsMaternal secretor status was not associated with anthropometric z-scores up to 4 y of age. Several HMOs were associated with z-scores at 6 wk and 6 mo, predominantly within secretor status subgroups. Higher levels of 2’FL were associated with greater weight [β = 0.91 increase in z-score per SD increase log-2’FL, 95% CI (0.17, 1.65)] and length [β = 1.22, (0.25, 2.20)] in children born to secretor mothers, but not body composition measures. Higher lacto-N-tetraose was associated with greater weight [β = 0.22, (0.02, 0.41)] and length (β = 0.30, (0.07, 0.53)] among children born to nonsecretor mothers. Several HMOs were associated with anthropometric measures at 12 mo and 4 y of age. ConclusionsMilk HMO composition at 6 wk postpartum is associated with several anthropometry measures up to 6 mo of age in a potential secretor status-specific manner, with largely different HMOs associating with anthropometry from 12 mo to 4 y of age.

Valine Treatment Enhances Antimicrobial Component Production in Mammary Epithelial Cells and the Milk of Lactating Goats Without Influencing the Tight Junction Barrier

The production of antimicrobial components and the formation of less-permeable tight junctions (TJs) are important in the defense system of lactating mammary glands and for safe dairy production. Valine is a branched-chain amino acid that is actively consumed in the mammary glands and promotes the production of major milk components like β-casein; additionally, branched-chain amino acids stimulate antimicrobial component production in the intestines. Therefore, we hypothesized that valine strengthens the mammary gland defense system without influencing milk production. We investigated the effects of valine in vitro using cultured mammary epithelial cells (MECs) and in vivo using the mammary glands of lactating Tokara goats. Valine treatment at 4 mM increased the secretion of S100A7 and lactoferrin as well as the intracellular concentration of β-defensin 1 and cathelicidin 7 in cultured MECs. In addition, an intravenous injection of valine increased S100A7 levels in the milk of Tokara goats without influencing milk yield and milk components (i.e., fat, protein, lactose, and solids). In contrast, valine treatment did not affect TJ barrier function either in vitro or in vivo. These findings indicate that valine enhances antimicrobial component production without influencing milk production and TJ barrier function in lactating mammary glands; thus, valine contributes to safe dairy production.

Single nucleotide polymorphisms within exon four of the prolactin gene and their effect on milk traits in cattle populations of Ethiopia

Bovine prolactin (PRL) gene is essential for the initiation and maintenance of lactation and exerts multiple effects on mammary alveoli to promote the synthesis and secretion of major components of milk. The objectives of this study were to identify mutations in PRL gene and to evaluate the mutations as potential markers of milk performance traits in cattle populations of Ethiopia. For this purpose, genomic DNA from whole blood was extracted through salting out procedure from 87 animals of five cattle populations of Ethiopia. Accordingly, three single nucleotide polymorphisms (SNPs) were identified of which one SNP g.8323T > A showed missense mutation while the other two SNPs revealed silent mutations. FST values showed statistically significant genetic differentiation among the studied populations. Intermediate polymorphic information content was noted for most SNPs, which indicates the presence of sufficient genetic variation at this locus. Two SNPs showed heterozygote deficiency as a result of positive FIS values. Only g.8398A > G SNP have statistically significant (p < 0.05) effect on average daily milk yield, fat and solid not fat percentage in all studied cattle populations. Therefore, g.8398A > G SNP identified in this study influences cattle milk production and may be used as possible candidate SNP for marker-assisted selection programs in cattle populations of Ethiopia.

Lactic acid bacteria in cow raw milk for cheese production: Which and how many?

Lactic Acid Bacteria (LAB) exert a fundamental activity in cheese production, as starter LAB in curd acidification, or non-starter LAB (NSLAB) during ripening, in particular in flavor formation. NSLAB originate from the farm and dairy environment, becoming natural contaminants of raw milk where they are present in very low concentrations. Afterward, throughout the different cheesemaking processes, they withstand chemical and physical stresses becoming dominant in ripened cheeses. However, despite a great body of knowledge is available in the literature about NSLAB effect on cheese ripening, the investigations regarding their presence and abundance in raw milk are still poor. With the aim to answer the initial question: "which and how many LAB are present in cow raw milk used for cheese production?," this review has been divided in two main parts. The first one gives an overview of LAB presence in the complex microbiota of raw milk through the meta-analysis of recent taxonomic studies. In the second part, we present a collection of data about LAB quantification in raw milk by culture-dependent analysis, retrieved through a systematic review. Essentially, the revision of data obtained by plate counts on selective agar media showed an average higher concentration of coccoid LAB than lactobacilli, which was found to be consistent with meta-taxonomic analysis. The advantages of the impedometric technique applied to the quantification of LAB in raw milk were also briefly discussed with a focus on the statistical significance of the obtainable data. Furthermore, this approach was also found to be more accurate in highlighting that microorganisms other than LAB are the major component of raw milk. Nevertheless, the variability of the results observed in the studies based on the same counting methodology, highlights that different sampling methods, as well as the "history" of milk before analysis, are variables of great importance that need to be considered in raw milk analysis.

2'-Fucosyllactose Inhibits Coxsackievirus Class A Type 9 Infection by Blocking Virus Attachment and Internalisation.

Coxsackieviruses, a genus of enteroviruses in the small RNA virus family, cause fatal infectious diseases in humans. Thus far, there are no approved drugs to prevent these diseases. Human milk contains various biologically active components against pathogens. Currently, the potential activity of breast milk components against the coxsackievirus remains unclear. In our study, the inhibitory effect of 16 major human milk components was tested on coxsackievirus class A type 9 isolate (CV-A9), BUCT01; 2'-Fucosyllactose (2'-FL) was identified to be effective. Time-of-addition, attachment internalisation assays, and the addition of 2'-FL at different time points were applied to investigate its specific role in the viral life cycle. Molecular docking was used to predict 2'-FL's specific cellular targets. The initial screening revealed a significant inhibitory effect (99.97%) against CV-A9 with 10 mg/mL 2'-FL, with no cytotoxicity observed. Compared with the control group, 2'-FL blocked virus entry (85%) as well as inhibited viral attachment (48.4%) and internalisation (51.3%), minimising its infection in rhabdomyosarcoma (RD) cells. The cell pre-incubation with 2'-FL exhibited significant inhibition (73.2-99.9%). Extended incubation between cells with 2'-FL reduced CV-A9 infection (93.9%), suggesting that 2'-FL predominantly targets cells to block infection. Molecular docking results revealed that 2'-FL interacted with the attachment receptor αvβ6 and the internalisation receptor FCGRT and β2M with an affinity of -2.14, -1.87, and -5.43 kcal/mol, respectively. This study lays the foundation for using 2'-FL as a food additive against CV-A9 infections.

Molecular characterization of buffalo αs1-casein gene

The caseins (Alpha s1, Alpha s2, beta and kappa) comprise the major protein component of ruminant milk and are secreted in the form of stable calcium phosphate micelles. The present study was proposed to characterize αs1-casein gene in buffalo at the molecular level to determine complete αs1-casein cDNA sequence. Sequencing results were analyzed and aligned with available mRNA GenBank sequences of other domestic animals (Accession AAB34797, NM_001009795, X72221, AY344966, NM_181029, AY948385 and BC109618). The complete amino acid coding region of the buffalo αs1- casein was deduced from cloned cDNA generated from mammary tissue mRNA. Amino acid sequence comprises of 199 amino acid residues. When aligned with previously reported buffalo sequence (Accession-AY948385) it showed one amino acid (Glutamine) deletion at amino acid position 78.

Biotin, folic acid, and vitamin B12 supplementation given in early lactation to Holstein dairy cows: Their effects on whole-body propionate, glucose, and protein metabolism

Biotin (B8), folic acid (B9), and vitamin B12 (B12) play key roles in energy and protein metabolism. The aim of this study was to evaluate the effects of a B8 supplement, administered alone or combined with B9 and B12 during the transition period on glucose, propionate, and protein metabolism. Thirty-two Holstein multiparous cows were assigned to one of the 4 treatments according to an incomplete block design in a 2 × 2 factorial arrangement: 1) 2-mL of weekly intramuscular injections of saline 9 g/L NaCl (B8 −/B9B12 −); 2) 20 mg/d of dietary B8 (unprotected from ruminal degradation) and 2-mL weekly intramuscular injections of saline 9 g/L NaCl (B8 +/B9B12 −); 3) 2.6 g/d of dietary B9 (unprotected) and 2-mL weekly intramuscular injections of 10 mg of B12 (B8 −/B9B12 +); 4) 20 mg/d of dietary B8, 2.6 g/d of dietary B9 and weekly intramuscular injections of 10 mg of B12 (B8 +/B9B12 +). Treatments were given from − 26–45 days relative to calving date. At 43 (SD:3) days in milk (DIM), D-[6,6-2H2]-glucose (23.9 mmol/h; jugular vein) and [1-13C]-sodium propionate (22.7 mmol/h; ruminal vein) were simultaneously infused for 4 h; the following 2 d, respectively, [13C]-sodium bicarbonate (3.0 mmol/h) and L[1-13C]-Leu (3.7 mmol/h) were infused into a jugular vein for 4 h. Blood samples were collected every 15 min during the last 1.5 h of infusions at 43 DIM and every 20 min at 44 and 45 DIM during the last 2 h of infusions. During the infusion week, there were no treatment effects on milk yield and major milk components, on whole-body propionate (1354 ± 116 mmol/h) and glucose (811 ± 34 mmol/h) rates of appearance, and on the proportion of glucose synthesized from propionate (65.1 ± 4.0%). Nevertheless, plasma glucose concentration during the infusions at 43 DIM for cows receiving the B8 supplement was greater when given in combination with B9 and B12, whereas no effect was noted without B8 supplementation. Whole-body Leu rate of appearance, Leu oxidation, and Leu used for protein synthesis and exportation averaged 133 ± 5, 23 ± 2, 111 ± 4, and 53 ± 2 mmol/h, respectively, and were not different among treatments. The present results might indicate that at the time of infusions between 43 and 45 days in milk under the current conditions, supplies of B8, B9, and B12 were sufficient to meet cow requirements. This reinforces the need to better define under which conditions cows would likely benefit from a supplementation caused by an imbalance between supplies and needs.

Are casein micelles extracellular condensates formed by liquid-liquid phase separation?

Casein micelles are extracellular polydisperse assemblies of unstructured casein proteins. Caseins are the major component of milk. Within casein micelles, casein molecules are stabilised by binding to calcium phosphate nanoclusters and, by acting as molecular chaperones, through multivalent interactions. In the light of such interactions, we discuss whether casein micelles can be considered as extracellular condensates formed by liquid-liquid phase separation. We analyse the sequence, structure and interactions of caseins in comparison with proteins forming intracellular condensates. Furthermore, we review the similarities between caseins and small heat-shock proteins whose chaperone activity is linked to phase separation of proteins. By bringing these observations together, we describe a regulatory mechanism for protein condensates, as exemplified by casein micelles.

Predictive formulas for different measures of cheese yield using milk composition from individual goat samples

The objective of this study was to develop formulas based on milk composition of individual goat samples for predicting cheese yield (%CY) traits (fresh curd, milk solids, and water retained in the curd). The specific aims were to assess and quantify (1) the contribution of major milk components (fat, protein, and casein) and udder health indicators (lactose, somatic cell count, pH, and bacterial count) on %CY traits (fresh curd, milk solids, and water retained in the curd); (2) the cheese-making method; and (3) goat breed effects on prediction accuracy of the %CY formulas. The %CY traits were analyzed in duplicate from 600 goats, using an individual laboratory cheese-making procedure (9-MilCA method; 9 mL of milk per observation) for a total of 1,200 observations. Goats were reared in 36 herds and belonged to 6 breeds (Saanen, Murciano-Granadina, Camosciata delle Alpi, Maltese, Sarda, and Sarda Primitiva). Fresh %CY (%CYCURD), total solids (%CYSOLIDS), and water retained (%CYWATER) in the curd were used as response variables. Single and multiple linear regression models were tested via different combinations of standard milk components (fat, protein, casein) and indirect udder health indicators (UHI; lactose, somatic cell count, pH, and bacterial count). The 2 %CY observations within animal were averaged, and a cross-validation (CrV) scheme was adopted, in which 80% of observations were randomly assigned to the calibration (CAL) set and 20% to the validation (VAL) set. The procedure was repeated 10 times to account for sampling variability. Further, the model presenting the best prediction accuracy in CrV (i.e., comprehensive formula) was used in a secondary analysis to assess the accuracy of the %CY predictive formulas as part of the laboratory cheese-making procedure (within-animal validation, WAV), in which the first %CY observation within animal was assigned to CAL, and the second to the VAL set. Finally, a stratified CrV (SCrV) was adopted to assess the %CY traits prediction accuracy across goat breeds, again using the best model, in which 5 breeds were included in CAL and the remaining one in the VAL set. Fitting statistics of the formulas were assessed by coefficient of determination of validation (R2VAL) and the root mean square error of validation (RMSEVAL). In CrV, the formula with the best prediction accuracy for all %CY traits included fat, casein, and UHI (R2VAL = 0.65, 0.96, and 0.23 for %CYCURD, %CYSOLIDS, and %CYWATER, respectively). The WAV procedure showed R2VAL higher than those obtained in CrV, evidencing a low effect of the 9-MilCA method and, indirectly, its high repeatability. In the SCrV, large differences for %CYCURD and %CYWATER among breeds evidenced that the breed is a fundamental factor to consider in %CY predictive formulas. These results may be useful to monitor milk composition and quantify the influence of milk traits in the composite selection indices of specific breeds, and for the direct genetic improvement of cheese production.

Milk Fermented with Mushrooms Prevents Stroke in the Stroke-Prone Spontaneously Hypertensive Rats Independently of Blood Pressure

ObjectivesIn a previous study, a mushroom was shown to digest milk protein to a mixture of oligopeptides and free amino acids. The aim of this study was to examine effects of this mixture, i.e., mushroom-fermented milk, on blood pressure and stroke susceptibility in the stroke-prone spontaneously hypertensive rats (SHRSP). Materials and MethodsRats were fed mushroom-fermented milk with or without 1 % salt water. Blood pressure was monitored either by the tail-cuff method or the telemetry system. Symptoms of stroke were examined every day to determine the stroke latency. ResultsMushroom-fermented milk at 120 mg/Kg BW/day (estimated as a peptides/amino acids content) did not ameliorate hypertension in SHRSP. In contrast, mushroom-fermented milk significantly improved stroke susceptibility under salt-loading. The effects were replicated using milk fermented with three different mushrooms. To elucidate the effective components in mushroom-fermented milk, spermidine (3 mM), one of major components of mushroom-fermented milk, and a mixture of amino acids (0.8 g/L) was examined, both of which showed no significant effects on stroke susceptibility. Intake of mushroom-fermented milk did not affect sodium content significantly either in feces or in urine of the rats given 1% salt water. This observation indicated sodium absorption by the digestive system was not inhibited by intake of mushroom-fermented milk. ConclusionDespite that the mechanisms were not elucidated, intake of mushroom-fermented milk effectively prevented stroke in SHRSP. Mushroom-fermented milk would be a new candidate for a supplemental nutrient supporting the cardiovascular health.