Phytanic acid concentrations and diastereomer ratios in milk fat during changes in the cow’s feed from concentrate to hay and back

Cow's Milk Bioactive Molecules in the Regulation of Glucose Homeostasis in Human and Animal Studies

Obesity disrupts glucose metabolism, leading to insulin resistance (IR) and cardiometabolic diseases. Consumption of cow's milk and other dairy products may influence glucose metabolism. Within the complex matrix of cow's milk, various carbohydrates, lipids, and peptides act as bioactive molecules to alter human metabolism. Here, we summarize data from human studies and rodent experiments illustrating how these bioactive molecules regulate insulin and glucose homeostasis, supplemented with in vitro studies of the mechanisms behind their effects. Bioactive carbohydrates, including lactose, galactose, and oligosaccharides, generally reduce hyperglycemia, possibly by preventing gut microbiota dysbiosis. Milk-derived lipids of the milk fat globular membrane improve activation of insulin signaling pathways in animal trials but seem to have little impact on glycemia in human studies. However, other lipids produced by ruminants, including polar lipids, odd-chain, trans-, and branched-chain fatty acids, produce neutral or contradictory effects on glucose metabolism. Bioactive peptides derived from whey and casein may exert their effects both directly through their insulinotropic effects or renin-angiotensin-aldosterone system inhibition and indirectly by the regulation of incretin hormones. Overall, the results bolster many observational studies in humans and suggest that cow's milk intake reduces the risk of, and can perhaps be used in treating, metabolic disorders. However, the mechanisms of action for most bioactive compounds in milk are still largely undiscovered.

Amelioration of Phytanic Acid-Induced Neurotoxicity by Nutraceuticals: Mechanistic Insights

Phytanic acid (PA) (3,7,11,15-tetramethylhexadecanoic acid) is a methyl-branched fatty acid that enters the body through food consumption, primarily through red meat, dairy products, and fatty marine foods. The metabolic byproduct of phytol is PA, which is then oxidized by the ruminal microbiota and some marine species. The first methyl group at the 3-position prevents the β-oxidation of branched-chain fatty acid (BCFA). Instead, α-oxidation of PA results in the production of pristanic acid (2,10,14-tetramethylpentadecanoic acid) with CO2. This fatty acid (FA) builds up in individuals with certain peroxisomal disorders and is historically linked to neurological impairment. It also causes oxidative stress in synaptosomes, as demonstrated by an increase in the production of reactive oxygen species (ROS), which is a sign of oxidative stress. This review concludes that the nutraceuticals (melatonin, piperine, quercetin, curcumin, resveratrol, epigallocatechin-3-gallate (EGCG), coenzyme Q10, ω-3 FA) can reduce oxidative stress and enhanced the activity of mitochondria. Furthermore, the use of nutraceuticals completely reversed the neurotoxic effects of PA on NO level and membrane potential. Additionally, the review further emphasizes the urgent need for more research into dairy-derived BCFAs and their impact on human health.

Seasonal Variation in Raw Milk VOC Profile within Intensive Feeding Systems

The study aimed to assess the seasonal variation in raw milk volatile organic compounds (VOCs) from three indoor feeding systems based on maize silage (n = 31), silages/hay (n = 19) or hay (n = 16). After headspace solid-phase microextraction (HS-SPME), VOC profiles were determined by gas chromatography (GC). Chemical and VOC (log₁₀ transformations of the peak areas) data were submitted to a two-way ANOVA to assess the feeding system (FS) and season (S) effects; an interactive principal component analysis (iPCA) was also performed. The interaction FS × S was never significant. The FS showed the highest (p < 0.05) protein and casein content for hay-milk samples, while it did not affect any VOCs. Winter milk had higher (p < 0.05) proportions of protein, casein, fat and some carboxylic acids, while summer milk was higher (p < 0.05) in urea and 2-pentanol and methyl aldehydes. The iPCA confirmed a seasonal spatial separation. Carboxylic acids might generate from incomplete esterification in the mammary gland and/or milk lipolytic activity, while aldehydes seemed to be correlated with endogenous lipid or amino acid oxidation and/or feed transfer. The outcomes suggested that VOCs could be an operative support to trace raw milk for further mild processing.

Effect of phytol in forage on phytanic acid content in cow's milk

Objective

Bioactive compounds in the ruminant products are related to functional compounds in diets. Therefore, this study aimed to explore the effect of forage sources, Italian ryegrass (IR) silage vs corn silage (CS) in the total mixed ration (TMR), on milk production, milk composition, and phytanic acid content in milk, as well as on the extent of conversion of dietary phytol to milk phytanic acid.

Methods

Phytanic acid content in milk was investigated for cows fed a TMR containing either IR silage or corn silage using 17 cows over three periods of 21 days each. In periods 1 and 3, cows were fed corn silage-based TMR (30% corn silage), while in period 2, cows were fed IR silage-based TMR (20% IR silage and10% corn silage).

Results

The results showed that there were no differences in fat, protein, lactose, solids-not-fat, somatic cell count, and fatty acid composition of milk among the three experimental periods. There were no differences in the plasma concentration of glucose, triglycerides, total cholesterol, and nonesterified fatty acids among the three experimental periods, while the blood urea nitrogen was higher (p<0.05) in period 2. The milk phytanic acid content was higher (p<0.05) in period 2 (13.9 mg/kg) compared with period 1 (9.30 mg/kg) and 3 (8.80 mg/kg). Also, the phytanic acid content in the feces was higher (p<0.05) in period 2 (1.65 mg/kg DM) compared with period1 (1.15 mg/kg DM) and 3 (1.17 mg/kg DM). Although the phytol contents in feces did not differ among the three feeding periods, the conversion ratio from dietary phytol to milk phytanic acid was estimated to be only 2.6%.

Conclusion

Phytanic acid content in cow's milk increases with increasing phytol content in diets. However, phytol might not be completely metabolized in the rumen and phytanic acid, in turn, might not be completely recovered into cow's milk. The change of phytanic acid content in milk may be positively correlated with the change of phytol in the diet within a short time.

Branched-Chain Fatty Acids-An Underexplored Class of Dairy-Derived Fatty Acids

Dairy fat and its fatty acids (FAs) have been shown to possess pro-health properties that can support health maintenance and disease prevention. In particular, branched-chain FAs (BCFAs), comprising approximately 2% of dairy fat, have recently been proposed as bioactive molecules contributing to the positive health effects associated with the consumption of full-fat dairy products. This narrative review evaluates human trials assessing the relationship between BCFAs and metabolic risk factors, while potential underlying biological mechanisms of BCFAs are explored through discussion of studies in animals and cell lines. In addition, this review details the biosynthetic pathway of BCFAs as well as the content and composition of BCFAs in common retail dairy products. Research performed with in vitro models demonstrates the potent, structure-specific properties of BCFAs to protect against inflammation, cancers, and metabolic disorders. Yet, human trials assessing the effect of BCFAs on disease risk are surprisingly scarce, and to our knowledge, no research has investigated the specific role of dietary BCFAs. Thus, our review highlights the critical need for scientific inquiry regarding dairy-derived BCFAs, and the influence of this overlooked FA class on human health.

Fatty Acid Profiles of Cow's Milk and Cheese as Affected by Mountain Pasture Type and Concentrate Supplementation

The aim of this trial was to assess the effect of pasture type and concentrate supplementation on the fatty acids (FA) composition of milk and cheese obtained during summer grazing on mountain pasture. Seventy-two Italian Simmental dairy cows were assigned to two groups that differed by the amount of concentrate supplementation: 3.0 kg/head/d (HIGH) vs. 1.5 kg/head/d (LOW). The dairy cows grazed on a Poion alpinae alliance pasture (PAST1), and subsequently they grazed on a Seslerion caeruleae alliance pasture (PAST2) for 10 d each. In the last three days of each experimental period, milk samples were collected immediately before each cheese-making event. Cheese samples were collected from each cheese loaf after 60 d of ripening. LOW showed higher isoFA, FA intermediates of the ruminal biohydrogenation, C18:3 c9,c12,c15, and total polyunsaturated fatty acid (PUFA) levels than HIGH. The pasture type had a more limited effect on FA composition of milk than concentrate level and was mainly related to monounsaturated fatty acids (MUFA), which were higher in PAST1 than PAST2 (p < 0.05). In cheeses, these differences were reduced. The phytanic acid and phytanic isomer ratio (SRR/RRR) in milk were not affected either by supplement level (p > 0.05) or by type of pasture (p > 0.05). Increasing the concentrate offered to dairy cows from 1.5 to 3.0 kg/d did not markedly influence the level of PUFA in cheeses produced during summer grazing on high mountain pasture.

Methodologies for the Characterization of the Quality of Dairy Products

The growing interest of consumers in food quality and safety issues has contributed to the increasing demand for sensitive and rapid analytical technologies. Physicochemical, textural, sensory, etc., methods have been used to evaluate the quality and authenticity of milk and dairy products. Despite the importance of these standard methods, they are expensive and time consuming. Recently, spectroscopic methods have shown great potential due to speed of analysis, minimal sample preparation, high repeatability, low cost, and, most of all, the fact that these techniques are noninvasive and nondestructive and, therefore, could be applied to any on-line monitoring system. This chapter gave examples of the application of the most commonly traditional methods for the determination of the quality of milk and dairy products. A special focus is devoted to the use of infrared and fluorescence spectroscopies for the evaluation of the quality of dairy products.

Content and distribution of phytanic acid diastereomers in organic milk as affected by feed composition

Phytanic acid (PA) is a bioactive compound found in milk that is derived from the phytol chain of chlorophyll, and the content of PA in milk fat depends on the availability of phytol from feed. In this study, the content of PA diastereomers was analyzed in milk sampled from five organic herds twice during the grazing season (May and September). The total content of PA was higher in September compared to May, but was not affected by breed (Danish Holstein or Danish Jersey). Total PA could not be directly related to intake of green feed items. The distribution between diastereomers was closely related to the amount of grazed clovers, where a higher intake resulted in a higher share of the RRR isomer.