ABSTRACT: Due to the high altitude and low oxygen levels, individuals residing or traveling in high-altitude regions often experience hypoxic cardiac dysfunction, which significantly affects their overall well-being and quality of life. Our previous investigations showed that peptide from yak milk residue exhibits notable antioxidant, anti-inflammatory, and anti-apoptotic properties that may have a good regulatory effect on hypoxic cardiac dysfunction. In this study, our results suggest that oral administration of yak milk peptide T3 improves the cardiac dysfunction of mice by the hypoxia-inducible factor 1α (HIF-1α) pathway, and these results may be related to the regulation of T3 on the gut microbiota of mice. Additionally, oral administration T3 enhances the permeability of the intestinal barrier and reduces intestinal inflammation. Further analysis revealed that the genera Oscillospira, Clostridium, and Staphylococcus are associated with aspartate aminotransferase, lactate dehydrogenase, and reactive oxygen species levels in heart tissues, which could ameliorate hypoxia-induced myocardial injury in mice. In vitro cell models have also confirmed that T3 intervention can activate the HIF-1α pathway and inhibit myocardial inflammation and cardiomyocyte apoptosis. These findings suggest that T3 may be a potential candidate for developing functional foods to reduce hypoxia-induced cardiac dysfunction.
Anna Flynn, Wiley Barton, Catherine McAloon
et al.
ABSTRACT: Feeding waste milk, a common practice in dairy farming, exposes calves to subtherapeutic levels of antimicrobials, potentially contributing to antibiotic resistance—a growing concern globally. Many dairy farmers, including those in Ireland, continue this practice, feeding waste milk from antibiotic-treated cows to calves. Although previous studies have linked waste milk feeding to changes in calf growth and health during the preweaning period, its effects postweaning remain unclear. This study examined how the duration of antimicrobial exposure at levels equivalent to those found in waste milk influences health and growth outcomes of dairy heifer calves both before and after weaning. It also assessed the prevalence of extended-spectrum β-lactamase (ESBL)-producing antimicrobial-resistant Escherichia coli in feces and changes in the fecal microbiota over time. To mimic waste milk, as derived from a cow treated with an intramammary suspension of antibiotics, a simulated waste milk (SWM) was prepared by adding amoxicillin (1.68 mg/L) and neomycin (2.28 mg/L) to a conventional milk replacer (MR). The study employed a randomized block design with 87 dairy heifer calves assigned to 1 of 3 treatments: (1) long-term antibiotic (LTA), with calves fed SWM until weaning at 12 wk; (2) short-term antibiotic (STA), with SWM fed from 3 to 5 wk; and (3) control (CONT), with calves fed antibiotic-free MR. Calves were weighed weekly, and health scores, including fecal scores (tail and hindquarters cleanliness as diarrhea indicator), were recorded twice per week. Fecal and blood samples were collected to analyze microbiome changes and the shedding of antimicrobial resistance. Blood samples were taken to measure systemic inflammation, using serum amyloid A as a biomarker. Results indicated that SWM feeding did not affect average daily gains before or after weaning. However, higher fecal scores were observed in the LTA group during weaning and after weaning in the STA group. Antibiotic-resistant isolates were present in all groups, with the highest prevalence in LTA. Fecal microbiota analysis revealed treatment-specific microbial community variations, with an increase of Enterococcus faecium genes resistant to macrolide, aminoglycoside, and tetracycline antibiotics in LTA and STA compared with CONT. In summary, SWM feeding did not significantly affect growth or overall health, but it was associated with increased fecal shedding of resistant bacteria and some changes in the microbiota, indicating potential long-term implications for antimicrobial resistance in dairy herds.
ABSTRACT: The objectives of this study were to determine the range in ruminal degradability of crude protein (CP) and intestinal digestibility of rumen undegradable protein in commercial soybean meal (SBM) and to investigate the range in in situ ruminal AA and phytate (InsP6) degradation and their relationship to CP degradation. An in situ study was conducted using 3 lactating Jersey cows with permanent rumen cannulas. Seventeen SBM variants from Europe, Brazil, Argentina, North America, and India were tested for ruminal CP and AA degradation, and in vitro intestinal digestibility of rumen undegradable protein. Nine variants were used to investigate the ruminal degradation of InsP6. The estimated rapidly degradable fraction (a) of CP showed an average value of 4.5% (range: 0.0%–9.0%), the slowly degradable fraction (b) averaged 95% (91%–100%), and the potential degradation was complete for all 17 SBM variants. The degradation of fraction b started after a mean lag phase of 1.7 h (1.1–2.0 h) at an average rate (c) of 10% per hour, but with a high range from 4.5% to 14% per hour. Differences in the degradation parameters induced a considerable range in CP effective degradation at a rumen passage rate of 6% per hour (CPED6) from 38% to 67%; hence, the concentration of rumen undegradable protein varied widely from 33% to 62%. The range in AA degradation between the SBM variants was high, with Ser showing the widest range, from 28% to 96%, and similar for the other AA. The regression equations showed close relationships between CP and AA degradation after 16 h of in situ incubation. However, the slopes of the linear regressions were significantly different between AA, suggesting that degradation among individual AA differs upon a change in CP degradation. The concentrations of InsP6 and myo-inositol pentakisphosphate in bag residues in the in situ study decreased constantly with longer ruminal incubation times. The ruminal degradation parameters of InsP6 ranged from 11% to 37% for fraction a, 63% to 89% for fraction b, and from 7.7% to 21% per hour for degradation rate c, with average values of 21%, 79%, and 16% per hour, respectively. The calculated InsP6 effective degradation at a rumen passage rate of 6% per hour (InsP6ED6) varied from 61% to 84% among the SBM variants. Significant correlations were detected between InsP6ED6 and CPED6 and between InsP6ED6 and chemical protein fractions A, B1, B2, B3, and C. Linear regression equations were developed to predict ruminal InsP6 degradation using CPED6 and chemical protein fractions B3 and C chosen by a stepwise selection procedure. We concluded that a high range in CP, AA, and InsP6 degradation exists among commercial SBM, suggesting that general degradability values may not be precise enough for diet formulation for dairy cows. Degradation of CP in SBM may be used to predict rumen degradation of AA and InsP6 using linear regression equations. Degradation of CP and InsP6 could also be predicted from the chemical protein fractions.
Vinzent Boerner, Thuy T.T. Nguyen, Gert J. Nieuwhof
ABSTRACT: Interbull's multiple across-country evaluaftion provides national breeding organizations with breeding values for internationally used bulls, which integrate performance data obtained in different breeding populations, environments, and production systems. However, breeding value-based selection decisions on domestic individuals born to foreign sires can only benefit from Interbull breeding values if they are integrated such that their information can contribute to the breeding values of all related domestic animals. For that purpose, several methods have been proposed which either model Interbull breeding values as prior information in a Bayesian approach, as additional pseudo data points, or as correlated traits, where these methods also differ in their software and parameterization requirements. Further, the complexity of integration also depends on the traits and genetic evaluation models. Especially random regression models require attention because of the dimensionality discrepancy between the number of Interbull breeding values and the number of modeled genetic effects. This paper presents the results from integrating 16,063 Interbull breeding values into the domestic single-step random regression test-day model for milk, fat, and protein yield for Australian Red dairy cattle breeds. Interbull breeding values were modeled as pseudo data points with data point-specific residual variances derived within animal across traits, ignoring relationships between integrated animals. Results suggest that the integration was successful with regard to alignment of Interbull breeding values with their domestic equivalent as well as with regard to the individual and population-wide increase in reliabilities. Depending on the relationship structure between integration candidates, further work is required to account for those relationships in a computationally feasible manner. Other traits with separate parity effects nationally could use a similar approach, even if not modeled with a test-day model.
ABSTRACT: The present study aimed to evaluate the effect of continuous butyrate administration in dairy calves' liquid diet considering diarrhea, metabolic profile, gastrointestinal development, and corporal growth. Immediately after birth, calves were randomly allocated into 2 groups of 62 calves (50 females and 12 males), with access to water and a solid feed ad libitum. The butyrate group (BG) received 4 g/d of sodium butyrate (Admix Easy, Adisseo) diluted in the whole milk, and the control group (CG) received whole milk with no supplementation. Sodium butyrate was administered from d 1 of life until the weaning at 90 d. Feces consistency was assessed daily for the first 30 d of life and characterized by scores from 0 to 4 (0 and 1 for normal, and 2, 3, and 4 for abnormal feces). Diarrhea was diagnosed when the animals had abnormal feces and fever. Morbidity, recurrence, mortality, and lethality data were recorded and compared between the groups. Average daily gain (ADG) and corporal growth (body weight, thoracic perimeter, height at the withers, and croup width) were evaluated weekly, from the first day to d 30, and later at 45, 60, and 90 d of life. Blood samples were taken weekly for up to 30 d to determine the circulating levels of total calcium, phosphorus, chloride, bicarbonate, glucose, β-hydroxybutyrate, and nonesterified fatty acids. The males were euthanized at 15 (n = 6 per group) and 30 d (n = 6 per group) for morphometric, histological, and gene expression analysis of the gastrointestinal tract. The results showed that the BG had a lower rate of morbidity (BG = 30% vs. CG = 50%) and recurrence (BG = 26.7% vs. CG = 60%) of diarrhea than the CG. In addition, the BG had abnormal feces for a shorter period (BG = 4.64 ± 0.47 d vs. CG = 8.6 ± 0.65 d). The ADG tended to be higher in BG than CG up to 30 and 60 d. Metabolic evaluations showed the lowest levels of glucose and highest levels of nonesterified fatty acids in BG. On d 30 of life, rumen papillae length, papilla area, duodenum villus length, and crypt depth were higher in BG than in CG. The duodenal gene expression at 30 d showed that animals with diarrhea episodes that did not receive butyrate had the highest levels of transcripts for the LCT and GLP2 genes. In addition, in different ways, both butyrate and neonatal diarrhea affected the gene expression of IGF1, SLC5A1, and AQP3. These results allow us to conclude that continuous supplementation with sodium butyrate improves gastrointestinal development, reduces the occurrence of diarrhea, and makes clinical conditions milder with faster recovery, favoring a higher ADG in the first 30 and 60 d of life. Based on these results, we conclude that sodium butyrate can be indicated for liquid diet supplementation to accelerate gastrointestinal tract development and prevent severe cases of neonatal diarrhea, tending to improve average daily gain until weaning.
ABSTRACT: Bovine colostrum contains a high concentration of immune-related microRNAs (miRNAs) that are packaged in exosomes and are very stable. In this study, 5 immune-related miRNAs (miR-142-5p, miR-150, miR-155, miR-181a, and miR-223) were quantified in dam blood, colostrum, and calf blood using reverse transcription quantitative PCR. Their levels in calf blood after colostrum ingestion were investigated to assess whether miRNAs are transferred from the dam to newborn calves. Three groups of Holstein–Friesian bull calves were bottle-fed 2 L of colostrum or milk from different sources twice per day. The group A calves received colostrum from their own dam and the group B calves were fed foster dam colostrum. Each pair of group A and group B calves were fed identical colostrum from the same milking of the corresponding group A dam for 3 d and then bulk tank milk for 7 d after birth. Group C calves were fed only 2L of “pooled colostrum” from multiple dams d 0 to 4 postpartum, and then fed bulk tank milk thereafter for 7 d after birth. The groups were fed colostrum from different sources and different amounts to assess possible miRNA absorption from the colostrum. All miRNAs were at the highest level in colostrum at d 0 and then decreased rapidly after d 1. The level of miR-150 had the largest decrease from 489 × 106 copies/µL (d 0) to 78 × 106 copies/µL (d 1). MicroRNA-223 and miR-155 were the most abundant in both colostrum and milk. Dam colostrum had significantly higher levels of miR-142-5p, miR-155, and miR-181a than the bulk tank milk. However, only the miR-155 concentration was significantly higher in the dam colostrum than in the pooled colostrum. The concentrations of miRNAs in the colostrum were less than in the cow blood (100- to 1,000-fold less). There was no significant correlation between the level of miRNAs in the dam blood and their colostrum, suggesting that miRNA is synthesized locally by the mammary gland rather than being transferred from the blood. MicroRNA-223 had the highest level in both calf and cow blood compared with the other 4 immune-related miRNAs. Calves were born with high levels of immune-related miRNAs in their blood, and there were no significant differences in miRNA levels between the 3 calf groups at birth or after they were fed different colostrum. This suggests that these miRNAs were not transferred from the colostrum to the newborn calves.
ABSTRACT: This study aimed to investigate the crystal network of bulk milk fat fractions and the partial coalescence, and the rheological properties of their oil-in-water (O/W) emulsions. Different milk fat fraction model systems were compared for their physicochemical properties, crystallization kinetics, and fat crystal networks across a range of temperatures. The extent of partial coalescence and rheological properties of the O/W emulsion prepared by different milk fat fractions were further analyzed. The results demonstrated that the ratio between saturated fatty acids (SFA) and unsaturated fatty acids and triacylglycerides (TAG) influenced the melting thermal behaviors, solid fat contents (SFC), and crystal networks of various milk fat fractions, which in turn influenced the partial coalescence and rheological characteristics of their O/W emulsions. Moreover, an excellent fit of the trend line confirmed that hardness increased exponentially with SFC. Trisaturated TAG in fractions with high melting points (HMF) such as milk fat fraction MF45, whose clarification temperature was 45°C, enriched long-chain SFA (saturated:unsaturated fatty acid = 2.2:1). We found that MF45 achieved higher SFC and hardness in the range of 0 to 40°C and, ultimately, formed a well-defined microstructural network with thick, rod-like crystals. Further, TAG in fractions with low melting points (LMF) such as MF10, whose clarification temperature was 10°C, were enriched with short-chain and unsaturated fatty acids (saturated:unsaturated fatty acid = 1.5:1), and a disordered crystal network in MF10, composed of randomly arranged, translucent platelets, was detected. Although fat globules of HMF and LMF were stabilized against coalescence, this could be attributed to a variety of mechanisms involving SFC, liquid fat, protective film around the fat globule, and minor lipids. According to the rheological profiles, all O/W emulsions exhibited weak viscoelastic “gel-like” structures [storage modulus (G′) > loss modulus (Gʺ)] over most of the measured range. The G′ values and apparent viscosity of HMF were greater than those of other fractions, indicating that the large and rigid crystals strengthen the networks more effectively.
Gunvantsinh Rathod, Steven Beckman, J.K. Amamcharla
ABSTRACT: Commercial manufacturing of dairy products involves the addition of dairy ingredients (such as nonfat dry milk and milk protein concentrates), as well as nondairy additives (such as gums, stabilizers, emulsifiers, and texture modifiers) to get the best product appearance, maintain the product quality, and extend shelf life. Though these nondairy additives are not harmful, consumers do not prefer them in dairy food formulations. Therefore, the dairy industry is working on improving the inherent functionality of dairy ingredients using different processes. Recently, fibrillation emerged as a new technique to convert globular proteins such as whey proteins into fibrils, which provide enhanced viscosity, foaming, and emulsification capacity. Therefore, skim milk was subjected to microfiltration followed by ultrafiltration of microfiltration permeate to fractionate whey proteins. Then, whey proteins were selectively fibrillated and mixed back with other streams of microfiltration and ultrafiltration to get fibrillated skim milk. Fibrillated skim milk was spray-dried to get fibrillated nonfat dry milk (NDM). Visible whey protein fibrils were observed in reconstituted fibrillated NDM, which showed survival of fibrils in fibrillated NDM. Fibrillated NDM showed significantly higher viscosity than control NDM. Fibrillated NDM also showed higher emulsification capacity, foaming capacity, and stability than the control NDM but lower gel strength. Considering the improved functionality of fibrillated NDM, they can be used in product formulations such as ice cream mix, where the thickening of a solution, good emulsification, and foaming properties are required.
Ultrasonic processing of fermented milk products has created much interest in current research on dairy products. This has been employed in cultured milk products to enhance the emulsification of milk fat and to intensify the fermentation process. Benefits including remarkable product stability, reduced processing time and enhanced quality are being recorded. Ultrasound (US) altered the colour and flavour profile of milk; however, the effect of US-induced fermentation on the synthesis of flavour compounds in milk has not been reported in the literature. This review paper presents a comprehensive scenario on the impact of power US on the fermentation profile and quality of ultrasonically processed dairy products. A theoretical background on US and details of its effect on the metabolic performance of lactic acid bacteria are presented. Finally, it describes how the quality attributes of fermented milk gels are modified due to the intensification of the fermentation process with US.
Almudena V. Merchán, Santiago Ruiz-Moyano, María Vázquez Hernández
et al.
ABSTRACT: The yeasts involved in the ripening process of artisanal soft raw ewe milk Protected Designation of Origin (PDO) Torta del Casar and Queso de la Serena cheeses produced in Extremadura, Spain, were isolated throughout their ripening process, strain typed, and characterized for some important technological properties. A total of 508 yeast isolates were obtained and identified by inter-single sequence repeat anchored PCR amplification analysis and subsequent sequencing of the internal transcribed spacer ITS1/ITS2 5.8S rRNA. A total of 19 yeast species representing 8 genera were identified. Debaryomyces hansenii, Pichia kudriavzevii, Kluyveromyces lactis, and Yarrowia lipolytica were the predominant species. We selected 157 isolates, by genotyping and origin, for technological characterization. The evaluation of yeast isolates' growth under stress conditions of cheese ripening showed that 87 presented better performance. Among them, 71 isolates were not able to catabolize tyrosine to produce a brown pigment. Principal component analysis of the biochemical features of these isolates showed that 9 strains stood out, 3 K. lactis strains (2287, 2725, and 1507), 2 Pichia jadinii (1731 and 433), 2 Yarrowia alimentaria (1204 and 2150), Y. lipolytica 2495 and P. kudriavzevii 373. These strains displayed strong extracellular proteolytic activity on skim milk agar as well as an adequate enzymatic profile (strong aminopeptidase and weak protease activity), suggesting their great potential for cheese proteolysis. Extracellular lipolytic activity was mainly restricted to Yarrowia spp. isolates and weakly present in P. kudriavzevii 373 and K. lactis 2725, although enzymatic characterization by API-ZYM (bioMérieux SA) evidenced that all may contribute, at least in part, to the lipolysis process. Moreover, these strains were able to assimilate lactose, galactose, and glucose at NaCl concentrations higher than that usually found in cheese. However, lactate and citrate assimilation were limited to Y. lipolytica 2495, P. kudriavzevii 373, and P. jadinii 433, and may contribute to the alkalinizing process relevant to biochemical processes that take place in the last stages of ripening. By contrast, K. lactis strains showed acidifying capacity and β-galactosidase activity and may take part in the initial stages of ripening, together with lactic acid bacteria. Thus, considering the technological characteristics studied, the 9 selected strains presented biochemical features well suited to their potential use as adjunct cultures, alone or in combination with autochthonous starter bacteria in the cheesemaking process, to overcome the heterogeneity of these PDO cheeses, preserving their unique sensory characteristics.
ABSTRACT: Subacute ruminal acidosis (SARA) is a metabolic disorder in dairy cows that is associated with dysbiosis of rumen and hindgut microbiomes, translocation of immunogenic compounds from the gut lumen into blood circulation, and systemic inflammatory response. In this study we hypothesized that Saccharomyces cerevisiae fermentation products (SCFP) attenuate the increases in ruminal and peripheral bacterial endotoxin concentrations and the inflammation resulting from repeated induction of SARA. Lactating Holstein dairy cows (parity 2 and 3+, n = 32) were fed diets with or without SCFP (all from Diamond V) and subjected to 2 episodes of SARA challenges. Cows received a basal total mixed ration (TMR) containing 34% neutral detergent fiber and 18.6% starch, dry matter (DM) basis. Treatments were randomly assigned to control (basal TMR and 140 g/d of ground corn with no SCFP) or 1 of 3 SCFP treatments: basal TMR and 14 g/d Original XPC (SCFPa), 19 g/d NutriTek (SCFPb-1×), or 38 g/d NutriTek (SCFPb-2×) mixed with 126, 121, or 102 g/d of ground corn, respectively. Treatments were implemented from 4 wk before until 12 wk after parturition. During wk 5 (SARA1) and wk 8 of lactation (SARA2), grain-based SARA challenges were conducted by gradually replacing 20% of DM of the basal TMR over 3 d with pellets containing 50% wheat and 50% barley. Ruminal fluid, fecal, and blood samples were collected weekly during Pre-SARA1 (wk 4, as baseline), Post-SARA1 (wk 7), and Post-SARA2 (wk 10 for blood and wk 12 for rumen and fecal parameters) stages, and twice a week during the challenges SARA1 and SARA2. Rumen papillae samples were taken only during Pre-SARA1 and Post-SARA2. We measured the concentrations of free lipopolysaccharides (LPS) in the rumen fluid and feces; free LPS and lipoteichoic acid (LTA) endotoxins in peripheral plasma; interleukin (IL)-1β and IL-6 in peripheral serum; acute-phase proteins, serum amyloid A (SAA), and LPS-binding protein in peripheral plasma; haptoglobin (Hp) in peripheral serum; and myeloperoxidase (MPO) in rumen papillae. Induction of SARA episodes increased free LPS concentrations in rumen fluid and tended to increase LTA in peripheral plasma. The SARA episodes increased concentration of circulating SAA and tended to increase that of IL-1β compared with Pre-SARA1. Induction of SARA did not affect the concentrations of circulating IL-6, Hp, and MPO. The SCFP supplementation reduced plasma concentrations of LTA and SAA and serum concentration of IL-1β compared with control. Additionally, SCFPb-2× tended to reduce ruminal LPS in second-parity cows compared with control. Overall, SCFP supplementation appeared to stabilize the rumen environment and reduce proinflammatory status, hence attenuating adverse digestive and inflammatory responses associated with SARA episodes.
Haruka Ukita, Takeshi Yamazaki, Satoshi Yamaguchi
et al.
ABSTRACT: Dairy cattle must allocate energy to milk production and reproduction. Therefore, understanding the environmental factors that affect conception rates in nulliparous and primiparous cows is helpful in appropriate feeding management strategies before and after calving. Accordingly, the aim of this study was to investigate the influence of environmental factors before and after the first calving on the conception rate, representing the starting point of milk production. The records of the first artificial insemination (AI) from Holstein nulliparous cows (n = 533,672) and primiparous cows (n = 516,710) in Hokkaido, Japan, were analyzed using separate multivariable logistic regression models. The mean conception rates for nulliparous and primiparous cows from 2012 to 2018 were 55.2 and 39.2%, respectively. In both nulliparous and primiparous cows, the conception rate of crossbreeding using Japanese Black (JB) semen was significantly higher than that for purebred Holstein breeding. The conception rate using sexed semen decreased in the warmer months only in nulliparous cows. Moreover, we grouped primiparous cows according to milk yield during peak lactation (PY; < 25, 25–30, 30–35, ≥35 kg) and the interval from calving to first insemination (CFI; < 60, 60–79, 80–99, ≥100 d), and evaluated their combined effect on the conception rate. Both PY and CFI strongly affected the conception rate in primiparous cows, which decreased with an increase in PY, even for the group with CFI ≥100 d; however, the conception rate increased for a CFI ≥60 d regardless of PY. Taken together, this study demonstrates the long-term effect of PY and an independent effect of CFI on the conception rate of cows. These results provide guidance for management to execute appropriate AI implementation strategies before and after lactation.
Ultrafiltration and microfiltration are 2 types of membrane filtration commonly used by the dairy industry. Filtered milk products are becoming increasingly common, but there is concern that consumers unfamiliar with these processing methods may form negative uninformed perceptions of cheeses made with these milks. There are many studies that address the chemical and physical properties of cheeses made with filtered milk, but, to our knowledge, there are none that address consumer perception of these products. Similarly, ultrapasteurization is becoming more common for US dairy products. Although previous work has characterized consumer liking of ultrapasteurized milks, few have investigated understanding and perception of this process. The objective of this study was to explore consumer understanding of milk processing and constituents, particularly as it relates to milk used as an ingredient in cheese. To achieve this goal, we investigated the following 4 questions: (1) Does the average dairy product consumer understand the basic ingredients and nutrients in fluid milk and cultured dairy products? (2) Does the average dairy product consumer understand the basic processes for fluid milk and cultured dairy products? (3) Do different processes affect consumer perception or purchase intent? (4) Does explaining a process change consumer understanding of, beliefs about, and purchase intent for dairy products? Qualitative interviews (n = 54) and an online survey (n = 1,210) were conducted with dairy product consumers. Survey responses paralleled those from one-on-one interviews. The average dairy product consumer could recall key words related to dairy processing, composition, nutrients, and ingredients, but was largely unfamiliar with these subjects. Highly educated and older consumers were more likely to have a better understanding of dairy composition and nutrition, particularly lactose content of milk and Cheddar cheese and the source of fluid whey and whey protein. Processing-related descriptors (e.g., ultrapasteurized or ultrafiltered) in ingredient statements were likely to be overlooked on labels (especially for familiar products), as just 34% of dairy product consumers read the labels on dairy products often or always before purchase. The majority (>80%) of dairy product consumers were unfamiliar with ultrafiltered or microfiltered milk, but uninformed perceptions were generally positive. Consumers unfamiliar with processing methods were likely to assume those methods increase the price of a dairy product. For the majority of consumers, purchase intent for fluid milk and cultured dairy products was not affected when nonconventional processing terms such as ultrafiltered or microfiltered were included in the ingredients statement. This effect was consistent for fluid milk and Cheddar cheeses but not for cottage cheese, suggesting the possibility of product-specific effects. Providing respondents with a definition of filtration increased consumer understanding of, positive beliefs about, and purchase intent for fluid filtered milk and cheese made with filtered milk. Educating consumers through on-package labeling and other marketing messaging should be investigated for dairy products that incorporate processes such as ultrapasteurization or filtration.
Cow's milk and dairy products derived from this complex food source have long been proposed as beneficial to human health, yet underlying clinical evidence of direct benefit continues to raise controversy. Limited evidence supports positive cardiometabolic effects of a number of dairy macro- and micronutrient components including whey protein and casein, unsaturated fats, milk fat globule membrane (MFGM) and polar phospholipids, vitamin D and calcium, in addition to non-bovine components including bacterial and yeast probiotics. More controversial remain lipid components trans fats, including trans vaccenic acid, trans palmitoleic acid, and conjugated cis trans linoleic acid (CLA), plus medium-chain and odd-chain dairy fats. New evidence is rapidly identifying multiple pathways by which these dairy nutrients may effect health. Processing, including fermentation and homogenization, may also have positive effects. Conversely, the high saturated fat content of dairy has long raised concern, aligned with international guidelines to minimize dietary intake of animal-origin saturated fatty acids (SFA) to achieve better cardiometabolic health. However, led in part by observational studies and meta-analyses showing dairy to have no or even an inverse association with cardiometabolic health, evidence from randomized controlled trials (RCTs) has been scrutinized over the last 5 years, and focus on low-fat dairy has been challenged. Recent evidence supports the hypothesis that adverse effects of SFAs on metabolic health may be ameliorated when these fats are consumed within a complex matrix such as milk, cheese or yogurt, and that dairy food categories may influence outcomes as much as total fat content. For example, yogurt and high-fat, high-SFA cheese have a negative association with risk of type 2 diabetes (T2D) in many, not all, published trials. However, large sample dairy RCTs of long duration with CVD or T2D incidence as primary endpoints are lacking. This is a clear research gap, with these clinical studies required if a causative link between dairy and improved cardiometabolic health is to be confirmed and in turn promoted through dietary guidelines. Current advisories from national guidance groups such as American Heart Association (AHA) and European Society of Cardiology (ESC) continue to promote consumption of low-fat dairy products, whilst liquid milk and yogurt remain part of nutrition guidelines from joint American Diabetes Association (ADA)/European Association for Study of Diabetes (EASD) reports, and as part of a “no-one-size-fits-all” answer to diet and T2D by the ADA in their most recent 2019 Consensus Report.