Invited review: The effect of milk feeding practices on dairy calf behavior,health, and performance—A systematic review

The aim of this systematic review was to summarize the literature assessing the effects of milk feeding practices on behavior, health, and performance on dairy calves. Peer-reviewed, published articles, written in English, directly comparing the effects of milk allowance, milk feeding methods, or milk feeding frequency on dairy calves were eligible for inclusion. Outcome measures could include sucking behavior, sucking on a teat (nutritive sucking, non-nutritive sucking on a teat), abnormal sucking behavior (non-nutritive sucking on pen fixtures, other oral behaviors, or cross-sucking), signs of hunger (vocalizations or unrewarded visits at the milk feeder), activity (lying time or locomotor play), feeding behavior (milk intake, starter intake, milk meal duration, or starter meal duration), growth (body weight or average daily gain), and health (occurrence of diarrhea, respiratory disease, or mortality). We conducted 2 targeted searches using Web of Science and PubMed to identify key literature. The resulting articles underwent a 2-step screening process. This process resulted in a final sample of 94 studies. The majority of studies investigated milk allowance (n = 69). Feeding higher milk allowances had a positive or desirable effect on growth, reduced signs of hunger, and increased locomotor play behavior during the preweaning period, whereas starter intake was reduced. Studies addressing health pointed to no effect of milk allowance, with no consistent evidence indicating that higher milk allowances result in diarrhea. Studies addressing milk feeding methods (n = 14) found that feeding milk by teat reduced cross-sucking and other abnormal oral behaviors. However, results on the effect of access to a dry teat were few and mixed. Milk feeding frequency (n = 14 studies) appeared to have little effect on feed intakes and growth; however, there is some evidence that calves with lower feeding frequency experience hunger. Overall, findings strongly suggest feeding higher volumes of milk using a teat; however, further work is needed to determine the optimal feeding frequency for dairy calves.     

Calcium bioavailability in human milk,cow milk and infant formulas—comparison between dialysis and solubility methods

The percentages of total, soluble and dialysable calcium of human milk, cow milk and milk and soy based infant formulas were determined in order to detect possible differences in the calcium bioavailability of the samples. For this purpose an in vitro method was applied to these four calcium sources. The ranking of the analysed samples in terms of calcium bioavailability depends on the criteria applied. Calcium ranked dialysis percentage was: cow milk>human milk>soy based formula>milk based formulas. Calcium ranked solubility percentage was: human milk>cow milk>soy-based formula>milk-based formulas. Comparison of the results of the in vitro assay with the information available on in vivo calcium absorption showed that the total soluble calcium contents agree with the in vivo absorption values better than with calcium dialysis percentages.     

Invited review: The role of the blood–milk barrier and its manipulation for the efficacy of the mammary immune response and milk production

The intact blood–milk barrier (BMB) prevents an uncontrolled exchange of soluble and cellular components between blood and milk in the mammary gland. It enables the sustainability of the optimal milk composition for the nourishment of the offspring. Endothelial cells, connective tissue, the basal membrane, and mainly the epithelial cells provide the semipermeability of this barrier, allowing only a selective transfer of components necessary for milk production. The epithelial cells are closely connected to each other by different formations, in which the tight junctions are the most critical for separating the milk-containing compartments from the surrounding extracellular fluid and vasculature. During mastitis, the integrity of the BMB is reduced. This facilitates the transfer of immune cells and immune factors such as antibodies from blood into milk. Simultaneously, the transfer of soluble blood constituents without an obvious immune function into milk is promoted. Furthermore, a reduced BMB integrity causes a loss of milk constituents into the blood circulation. Different mechanisms are responsible for the barrier impairment including tight junction opening, but also cell degradation. To promote the cure of mastitis, the targeted manipulation of the BMB permeability may be a tool to optimize the immune function of the mammary gland. An intensified opening of the BMB supports the antibody transfer from blood into milk, which is supposed to increase the contribution of the specific immune system in the immune defense. On the contrary, a fast closure of the BMB during the recovery from mastitis can accelerate the normalization of milk composition and milk yield. Various agents have been experimentally shown to either open (e.g., pathogens and pathogen-associated molecular patterns, several nonsteroidal anti-inflammatory drugs, oxytocin, calcium chelators) or close (e.g., glucocorticoids, nonsteroidal anti-inflammatory drugs, natural anti-inflammatory drugs) the BMB.     

Effect of heating on the distribution of transforming growth factor-��2 in bovine milk

The objective of this study was to characterize the impact of heat treatments on the distribution of transforming growth factor-beta (TGF-??2) between cream and skim milk and between the casein and whey fractions of skim milk. Skimming removed 45% and 62% of the TGF-??2 from raw and pasteurized milks and only 8% of the total TGF-??2 in skimmed pasteurized milk was found in whey, compared to 37% in whey from raw skimmed milk. The TGF-??2 content of whey decreased as the heat treatment of the milk increased in intensity (thermization > pasteurization > UHT sterilization). Using milk held for 1 or 2 min at temperatures ranging from 57 to 84 °C, it was shown that TGF-??2 in the whey portion decreases at temperatures above 66 °C and becomes undetectable at temperatures higher than 76 °C. Altogether, these data on the heat-induced changes in TGF-??2 content of cream, skim milk, casein and whey reveal a potentially negative impact of certain heat treatments in developing TGF-??2-enriched fractions from milk.     

The β-lactoglobulin content of bovine milk: Development and application of a biosensor immunoassay

An optical biosensor immunoassay exploiting surface plasmon resonance is described for the quantification of β-lactoglobulin in milk. Samples were diluted with buffer, and the protein estimated from binding with a polyclonal antibody immobilised on the sensor surface. Analytical method performance characteristics including range, detection limit, precision and accuracy were determined and reported. The temporal variability in the β-lactoglobulin content of milk from pasture-fed cows during early lactation and across a production season was investigated. The content of β-lactoglobulin decreased from >10 mg mL⁻¹ in early colostrum to <5 mg mL⁻¹ in mature milk, and the β-lactoglobulin content of skim milk powder trended from 25 to 60 mg g⁻¹ across a season. In view of its allergenicity, these data will improve understanding of the expression of innate β-lactoglobulin in the milk of pasture-grazed dairy herds, thereby providing information that is applicable to the formulation of bovine milk-based products.     

Assessment of cadmium levels in human breast milk and the affecting factors: A systematic review, 1971–2014

Background: This is a first systematic review summarizing 43 years of research from 36 countries for the assessment of cadmium in breast milk, a suitable matrix in human biomonitoring. Objectives: To report from the published literature the levels of cadmium in breast milk, and the affecting factors causing increase in cadmium concentrations. In addition, to gather several quantitative data that might be useful to evaluate the international degrees of maternal and infant exposure. Methods: We reviewed the literature published between 1971 and 2014, available on Pubmed, Science Direct, and Google Scholar, reporting quantitative data about cadmium levels in human breast milk. Information about the aim of the study, name of the country, period of collection of samples, size of samples, sampling method, time of lactation, mother's age, area of residence, cadmium concentration, and other data were extracted. Results: Sixty-seven studies were selected and included in this systematic review. Some concentrations greatly exceed the limit set by the World Health Organization (WHO); however, about 50% of the studies had less than 1 µg/L cadmium concentration (recommended by the WHO); as well as many factors have shown their implication in breast milk contamination. Conclusions: Breast milk is a pathway of maternal excretion of cadmium. It is also a biological indicator of the degree of environmental pollution and cadmium exposure of the lactating woman and the nourished infant. Therefore, preventive measures and continuous monitoring are necessary.     

Genetic polymorphism of ovine milk proteins: its influence on technological properties of milk — a review

Current knowledge of the genetic polymorphism in ovine milk proteins including heterogeneity detected and their relationships with the technological properties of milk is reviewed. In the casein fraction a great heterogeneity has been determined either by the presence of genetic variants or other factors such as a discrete phosphorylation level and the coexistence of protein forms of different chain length. In the whey fractions, three genetic variants (A, B, and C) are described for β-lactoglobulin (β-LG), and two for α-lactalbumin (α-LA). The topics discussed include the rennetability of ovine milk, cheese yield and susceptibility of β-LG genetic variants to heat denaturation as well as the findings concerning the relationships between ovine milk protein polymorphism and milk production and composition. However, further investigation is needed in order to better outline the relevant features of polymorphism and technological properties of ovine milk.     

The effect of ionic strength on the rheology of pH-induced bovine serum albumin/κ-carrageenan coacervates

Protein/polysaccharide coacervates are frequently applied to food products to control the rheology. This study investigated the effect of ionic strength (I) on the rheology of pH-induced protein/polysaccharide coacervates. Bovine serum albumin (BSA) and κ-carrageenan were used as a model protein and a polysaccharide, respectively. As the formation of BSA/κ-carrageenan coacervates increased the turbidity of an aqueous mixture, pH_c, pH_?, and pH_max values were identified corresponding to the pH of the formation of soluble coacervates, insoluble coacervates, and large insoluble coacervates respectively. Based on pH_c, pH_?, and pH_max, a state diagram of BSA/κ-carrageenan coacervation versus pH and I was constructed. Involvement of salt in coacervation screened out the electrostatic interaction between BSA and κ-carrageenan coacervation, resulting in the shift of pH_c, pH_?, and pH_max to lower pH. The shift was linearly changed to 1/I^1/2 that corresponded to the Debye length. BSA/κ-carrageenan coacervates were more elastic than viscous. The transition from insoluble coacervates to large insoluble coacervates contributed to enhancement of the rheology, especially in elasticity. An increase in the I of a BSA/κ-carrageenan mixture reduced the degree of coacervation and the elasticity, and the viscosity of BSA/κ-carrageenan coacervates.     

The combined effect of front-of-pack nutrition labels and health claims on consumers’ evaluation of food products

The majority of studies examining the effect of nutrition information on food packets (such as the nutrition information panel (NIP), front-of-pack labels (FoPLs) and health claims) have examined each in isolation, even though they often occur together. This study investigated the relationship between FoPLs and health claims since (i) they both appear on the front of packs and typically receive more attention from consumers than the NIP, (ii) they can convey contradictory messages (i.e., health claims provide information on nutrients that are beneficial to health while FoPLs provide information on nutrients associated with increased health risks) and (iii) there is currently scant research on how consumers trade off between these two sources of information. Ten focus groups (n = 85) explored adults’ and children’s reactions when presented with both a FoPL (the Daily Intake Guide, Multiple Traffic Lights, or the Health Star Rating) and a health claim (nutrient content, general-level-, or high-level). A particular focus was participants’ processing of discrepant information. Participants reported that health claims were more likely to be considered during product evaluations if they were perceived to be trustworthy, relevant and informative. Trust and ease of interpretation were most important for FoPLs, which were more likely than health claims to meet criteria and be considered during product evaluation (especially the Health Star Rating and Multiple Traffic Lights). Results indicate that consumers generally find FoPLs more useful than health claims.     

Total antioxidant activity and trace elements in human milk: the first 4 months of breast-feeding

The content of many nutrients in breast milk are dependent on the nutritional status of the lactating woman. This is particularly true for fat and water-soluble vitamins, some of which have antioxidant properties. The aim of the study entertained herein was to evaluate the changes in total antioxidant status of human milk during the first 4 months of lactation, and to correlate such changes with the contents in specific antioxidant oligoelements (Cu, Zn, Mn and Se). Milk samples were collected from (31) lactating women recruited at the Service of Obstetrics of the Hospital de São João in Porto, after 1, 4, 8, 12 and 16 weeks after birth. The total antioxidant status (TAS) of human milk was measured by the Randox^® commercial kit and trace metals by ICP-MS (inductively coupled plasma-mass spectrometry). The results found for TAS and oligoelements under study show a decrease in the concentration of these parameters from 7 days to 4 months of breast-feeding and significant correlations (p < 0.05) were found between TAS and Cu, Zn and Se (not Mn). The decreases of Cu, Zn and Se were also correlated, but not proportional between them, suggesting diverse excretion mechanisms for all. Between primipara and multipara women, a significant difference was found only for Cu and Zn concentrations at 7 days of lactation, but not for the other metals or TAS. With respect to the mother’s age, no correlation was found, either for trace metal concentrations or TAS.     

Towards improving the nutrition and health of the aged: the role of sprouted grains and encapsulation of bioactive compounds in functional bread – a review

Aging reduces the absorption of nutrients. Literature related to functional bread processing techniques including sprouting of grains and the application of encapsulation technology and the bioavailability of bioactives was reviewed. Functional ingredients including sprouted/germinated grain particularly brown rice and wheat flours enhance the bioactive properties of functional bread. Ingredients with high polyphenol content such as lavender and melissa by-products, tea-extracts and aronia powder enhance the bioactive content and appear to have a favourable effect on the shelf-life of bread and antioxidant status of consumers. Incorporation of encapsulated bioactive compounds into bread have a huge potential to improve the bread quality and increase the bioavailability and bioaccessibility of bioactive compounds including polyphenols. More investigations and new areas of research should focus on sprouted grain flours and the application of encapsulation technologies especially nanoencapsulation to optimize the bioactivity, storage, bioavailability and nutritional profile of bread to improve nutrition and health with aging.     

Technological solutions and adaptive processing tools to mitigate the impact of seasonal variations in milk composition on Cheddar cheese production—A review

Variability in milk composition and physicochemical properties impact both manufacturing process performance and the end-use functionality of cheese. Such variability may be attributed to seasonal calving patterns, production systems, breed, weather patterns, and feed type and significantly impacts concentrations of macro- and microconstituents and ultimately cheese composition and quality. This article reviews technological approaches (e.g., milk standardisation protocols and calcium addition), and predictive strategies (e.g., predictive models for coagulation and curd cutting time, in-line sensors), used to mitigate the effects of seasonal changes in milk composition and their impact on process efficacy and functionality in Cheddar cheese manufacturing.     

Effects of the circadian rhythm on milk composition in dairy cows: Does day milk differ from night milk?

Metabolism in most organisms can show variations between the day and night. These variations may also affect the composition of products derived from livestock. The aim of the present study was to investigate the difference in composition between the day milk and night milk of dairy cows. Ten multiparous Holstein cows (milk yield = 25.2 ± 5.00 kg/d) were randomly selected during mid lactation. Milk samples were collected at 0500 h (“night milk”) and 1500 h (“day milk”) and analyzed to determine their composition. Mid-infrared spectroscopy was used to analyze macronutrient content of milk. Metabolomics and lipidomics were used to detect and analyze small molecules and fatty acids, respectively. An automatic biochemical analyzer and ELISA kits were used to determine biochemical indicators, as well as antioxidant and immune parameters in the milk. Though milk fat, protein, lactose, and total milk solids were not different between day milk and night milk, small molecules, metabolites and lipids, and hormones and cytokines differed between day milk and night milk. Regarding biochemical and immune-related indicators, the concentrations of malondialdehyde, HSP70, and HSP90 in night milk were lower than that in day milk. However, interferon-γ levels were higher in night milk. Additionally, night milk was naturally rich in melatonin. Lipidomics analyses showed that the levels of some lipids in night milk were higher than those in day milk. Metabolomics analyses identified 36 different metabolites between day milk and night milk. Higher concentrations of N-acetyl-d-glucosamine, cis-aconitate, and d-sorbitol were observed in day milk. However, the other 33 metabolites analyzed, including carbohydrates, lipids, AA, and aromatic compounds, showed lower concentrations in day milk than in night milk. The present findings show that the composition of night milk differs considerably from that of day milk. Notable changes in the circadian rhythm also altered milk composition. These results provide evidence to support the strategic use and classification of day milk and night milk.     

Multiclass and multi-residue determination of antibiotics in bovine milk by liquid chromatography–tandem mass spectrometry: Combining efficiency of milk control and simplicity of routine analysis

Antibiotics are widely used in veterinary medicine and incorrect practices may lead to drug residues in food, including milk. Fast and simple sample preparation methods have been developed for determination of quinolones, fluoroquinolones, tetracyclines, sulphonamides, trimethoprim and bromexine using liquid chromatography–tandem mass spectrometry. Small volumes of sample (0.5 mL) were extracted using organic solvent followed by centrifugation and evaporation and/or dilution. Validation took into account the maximum residue limits (MRLs). Recoveries of 62–108% were obtained. Linearity (r²) above 0.96 was achieved for all compounds using concentrations in the range 0.25–2.0 × MRL. Intraday precision with coefficients of variation (n = 6) lower than 15.0% and inter-day precision lower than 17.3% were obtained for three concentration levels in the range 0.5–1.5 × MRL. Accuracy was 87–108%. Limits of detection and quantitation, as well as decision limit, detection capability, robustness and applicability, were evaluated using >600 real milk samples.     

Addition of milk to tea infusions: Helpful or harmful? Evidence from in vitro and in vivo studies on antioxidant properties

Tea consumption is practised as a tradition, and has shown potential to improve human health. Maximal uptake of tea antioxidants and milk proteins without a negative impact on tea flavor is highly desired by consumers. There is a conflicting evidence of the effect of milk addition to tea on antioxidant activity. Differences in the type of tea, the composition, type and amount of milk, preparation method of tea–milk infusions, the assays used to measure antioxidant activity, and sampling size likely account for different findings. Interactions between tea polyphenols and milk proteins, especially between catechins and caseins, could account for a decrease in antioxidant activity, although other mechanisms are also possible, given the similar effects between soy and bovine milk. The role of milk fat globules and the milk fat globule membrane surface is also important when considering interactions and loss of polyphenolic antioxidant activity, which has not been addressed in the literature.     

A review of the current situation of aflatoxin M1 in cow’s milk in Serbia: risk assessment and regulatory aspects

ABSTRACT

The aim of this systematic review is to provide information regarding the incidence and levels of aflatoxin M₁ (AFM₁) in raw and heat processed cow’s milk in Serbia during 2015–16 and to compare these with collected data on the occurrence of AFM₁ in raw milk and dairy products during the last decade in our region. Estimation of dietary exposure (EDI) and hazard index (HI) calculations for different age groups of the population were also carried out, based on the AFM₁ content of milk samples and on available food consumption data in Serbia. AFM₁ was detected in 69.9% (984/1408) of raw milk samples in 2015 versus 84.9% (3094/3646) in 2016, while in heat-processed milk, AFM₁ was detected in 77.8% (364/468) in 2015 versus 98.5% (753/765) in 2016. On the basis of the obtained results, 450 (9%) of raw and 14 (1.1%) of heat-processed milk samples were contaminated with AFM₁ levels above the maximum permitted level in Serbia (0.25 μg kg^?1). However, a large percentage of raw and heat processed milk in Serbia (30.1% and 17.3%, respectively) was contaminated with AFM₁ levels above the maximum permitted level regulated in the European Union (0.05 μg kg^?1). Therefore, in order to protect consumer health, it is extremely important to further control the level of aflatoxins in milk, and this should be considered as a high priority for risk management actions.     

Effect of milk protein composition and amount of β-casein on growth performance,gut hormones,and inflammatory cytokines in an in vivo piglet model

The objective of this work was to better understand the effect of differences in milk protein composition, and specifically, a change in β-casein to total casein in a milk-based matrix, on growth performance and metabolic and inflammatory responses using a piglet model. Three formulas were optimized for piglets, with similar metabolizable energy, total protein content, and other essential nutrients. Only the protein type and ratio varied between the treatments: the protein fraction of the control diet contained only whey proteins, whereas 2 other matrices contained a whey protein to casein ratio of 60:40, and differed in the amount of β-casein (12.5 and 17.1% of total protein). Piglets fed formula containing whey proteins and caseins, regardless of the concentration of β-casein, showed a significantly higher average daily gain, average daily feed intake, and feed efficiency compared with piglets consuming the formula with only whey protein. Consumption of the formula containing only whey protein showed higher levels of plasma glucagon-like peptide-1 and ghrelin compared with the consumption of formula containing casein and whey protein. A positive correlation was observed between postprandial time and glucagon-like peptide-1 response. The intestinal pro-inflammatory cytokine tumor necrosis factor α increased significantly in piglets fed the whey protein/casein diet compared with those fed whey protein formula. All formula-fed piglets showed a lower level of IL-6 cytokine compared with the ad libitum sow-fed piglets, regardless of composition. No significant differences in the anti-inflammatory IL-10 concentration were observed between treatment groups. Milk protein composition contributed to the regulation of piglets‘ metabolic and physiological responses, with whey protein/casein formula promoting growth performance and a different immune regulatory balance compared with a formula containing only whey protein. Results indicated no differences between treatments containing different levels of β-casein.