Effects of selenium supplementation on chemical composition and aromatic profiles of cow milk and its derived cheese

Selenomethionine Promotes Milk Protein and Fat Synthesis and Proliferation of Mammary Epithelial Cells through the GPR37-mTOR-S6K1 Signaling

Selenomethionine (SeMet) is an important nutrient, but its role in milk synthesis and the GPCR related to SeMet sensing is still largely unknown. Here, we determined the dose-dependent role of SeMet on milk protein and fat synthesis and proliferation of mammary epithelial cells (MECs), and we also uncovered the GPCR-mediating SeMet function. At 24 h postdelivery, lactating mother mice were fed a maintenance diet supplemented with 0, 5, 10, 20, 40, and 80 mg/kg SeMet, and the feeding process lasted for 18 days. The 10 mg/kg group had the best increase in milk production, weight gain of offspring mice, and mammary gland weight and acinar size, whereas a higher concentration of SeMet gradually decreased the weight gain of the offspring mice and showed toxic effects. Transcriptome sequencing was performed to find the differentially expressed genes (DEGs) between the mammary gland tissues of mother mice in the 10 mg/kg SeMet treatment group and the control group. A total of 258 DEGs were screened out, including 82 highly expressed genes including GPR37 and 176 lowly expressed genes. SeMet increased milk protein and fat synthesis in HC11 cells and cell proliferation, mTOR and S6K1 phosphorylation, and expression of GPR37 in a dose-dependent manner. GPR37 knockdown decreased milk protein and fat synthesis in HC11 cells and cell proliferation and blocked SeMet stimulation on mTOR and S6K1 phosphorylation. Taken together, our data demonstrate that SeMet can promote milk protein and fat synthesis and proliferation of MECs and functions through the GPR37-mTOR-S6K1 signaling pathway.

Combined Supplementation of Two Selenium Forms (Organic and Inorganic) and Iodine in Dairy Cows' Diet to Obtain Enriched Milk, Cheese, and Yogurt

This study evaluated the effects of dietary supplementation in dairy cows with two Se forms (organic and inorganic) and I at the maximum levels permitted in the European Union, with the aim to obtain naturally enriched milk and derived products. A total of 20 Holstein Friesian cows in lactation were fed 2 diets for 64 days: a control diet with a supply of 0.57 mg of inorganic Se and 0.57 mg of I per kg of ration in dry matter (DM), and an experimental diet (SeI) with a supply of 0.34 mg of inorganic Se, 0.23 mg of organic Se, and 5.68 mg of I per kg of ration in DM. The SeI diet did not modify the performance or, in general, the metabolic profile of cows. Se and I levels in milk were affected by diet type and time of measurement (p < 0.01). Thus, a marked increase of both microminerals was evident between the beginning and the end of the test, when the SeI diet was administered. For Se, this increase ranged from 1.95 to 3.29 μg/100 g of milk; and for I, from 19.69 to 110.06 μg/100 g of milk. The SeI diet increased (p < 0.01) the Se and I content in the cheese, reaching levels of 16.4 μg/100 g for Se and 269.7 μg/100 g for I. An increase in I was observed in yogurt from the SeI diet (p < 0.001). The supplementation of two forms of Se and I in the cows' ration, at the levels evaluated, produced milk and dairy products enriched in these microelements without altering their quality parameters. However, a responsible intake of these products is necessary to avoid risks of deficiencies or excesses that could negatively affect the health of consumers.

The use of olive cake in the diet of dairy cows improves the mineral elements of Provola cheese

Mineral elements (Ca, Na, K, Mg, Zn, Ti, Sr, Fe, Ni, Ba, Cr, Mn, Cu, Se, Cd, Mo, B, V, As, Pb and Hg) in Provola cheeses obtained from dairy cows fed with two different integrated diets (Biotrak) and without olive cake (Control) were determined to discriminate between the two different cheeses. The results showed that cheeses from the Biotrak group presented higher values of essential elements. Selenium (Se) was found to be the most interesting: in Biotrak cheeses the content of Se was in the range of 0.112 to 0.281 mg/kg, about twice the content of Se in cheeses from the Control group. Among the toxic elements, only Cd was found in the samples, but at low levels (in average lower than 0.11 mg/kg). Therefore, the use of olive cake in animal feed is a good strategy to improve the mineral profile of the product obtained.

Effects of reduced levels of organic trace minerals in proteinate forms and selenium yeast in the mineral mix on lactation performance, milk fatty acid composition, nutrient digestibility, and antioxidant status in dairy goats

The objective was to evaluate the effects of replacing inorganic trace minerals (ITM) with reduced levels of organic trace minerals (OTM) in proteinate forms and selenium yeast (Se-yeast) in the mineral premix of prepartal and lactating dairy goats on lactation performance, milk fatty acid (FA) composition, nutrient digestibility, and antioxidant status. Xinong Saanen dairy goats (n = 40) were blocked by parity and body weight, and randomly assigned to either ITM or OTM treatments from 4 wk prepartum to 8 mo of lactation. Both groups received the same basal diet except for the trace mineral supplement. The ITM supplement included Fe, Cu, Zn, and Mn as sulfates, and Se as selenite to meet the recommendations. The OTM supplement included Fe, Cu, Zn, and Mn as proteinates at 50% of ITM supplement levels, and Se as Se-yeast at 100% of ITM supplement level. Sampling and measurements were performed in the first, second, fourth, and eighth month of lactation. Data were summarized by month and treatment, and analyzed using the Mixed Model of SPSS with repeated measures. OTM group showed lower milk fat (P = 0.02) and higher milk Se (P = 0.03) with no compromised effects on milk yield and milk protein compared to ITM group. Furthermore, OTM decreased the content of C6:0, C8:0, and C10:0 (P < 0.05) and increased the content of odd- and branched-chain FAs in milk fat due to greater content of C15:0 (P = 0.01) and anteiso C15:0 (P = 0.07). OTM led to greater total tract digestibility of dry matter (P = 0.03), crude protein (P = 0.07), ether extract (P = 0.03), and acid detergent fiber (P = 0.05). OTM goats showed less fecal excretion of Fe (P = 0.01), Cu (P < 0.01), and Zn (P = 0.08) compared to ITM goats. There was a tendency for greater serum GSH-Px activity (P = 0.09) with OTM. Overall, the long-term substitution of reduced levels of OTM for ITM can change milk fat and FA composition while maintaining milk yield, digestibility, and antioxidant status.

Selenomethionine alleviates NF-κB-mediated inflammation in bovine mammary epithelial cells induced by Escherichia coli by enhancing autophagy

Autophagy is crucial for the maintenance of homeostasis under stimuli related to infection. Selenium (Se) plays variable roles in defence against infection and Selenomethionine (Se-Met) is a common Se supplementation. This study aimed to understand whether Se-Met could regulate the nuclear factor-kappa B (NF-κB) signaling pathway through autophagy. Mammary alveolar cell-T (MAC-T) was challenged with Escherichia coli (E. coli). Western blotting and real-time quantitative PCR (RT-qPCR) were used to detect the protein expression and mRNA expression of cytokines. Immunofluorescence assays were performed to observe the expression of intracellular LC3. The results showed that E. coli inhibited autophagy by decreasing the LC3-Ⅱ protein levels, and the Atg5 and Beclin1 protein levels were increased after 4 h. Infection also decreased the number of LC3 puncta. E. coli increased the phosphorylation of p65 and IκBα protein. Concomitantly, the levels of interleukin (IL)-1β, IL-6, IL-8 and tumour necrosis factor (TNF)-α mRNA increased at 3 and 4 h post-infection. We further explored the regulatory role of autophagy on NF-κB-mediated inflammation with autophagy modulators and shAtg5. The results indicated that the autophagy activator reduced the phosphorylation of p65 and IκBα and the mRNA expression of IL-1β, IL-6, IL-8 and TNF-α. Additionally, activating autophagy weakened the adhesion to MAC-T of E. coli. Autophagy inhibitors exacerbated NF-κB-mediated inflammation and strengthened the adhesion of E. coli to cells. We then examined the effects of Se-Met on NF-κB-mediated inflammation through autophagy. The data suggested that Se-Met enhanced LC3-II expression, inhibited the E. coli-induced phosphorylation of p65 and IκBα, and suppressed the adhesion ability of E. coli to MAC-T and that the effects of Se-Met in attenuating NF-κB-mediated inflammation were partially blocked by an autophagy inhibitor. In summary, Se-Met alleviated NF-κB-mediated inflammation induced by E. coli by enhancing autophagy in bovine mammary epithelial cells.

Effects of dietary iodine supplement on sheep milk and cheese

The work reported in this paper addresses the iodine nutritional deficiency that still affects a large number of people. For this purpose, we analyzed the possibility to use, as iodine vehicle, a hard typical ewe cheese, called Canestrato d'Abruzzo, derived from milk of ewes fed with an iodine-fortified diet. Both in the milk and the cheese of these animals, the iodine level was higher than that measured in sheep with a normal diet. An increase in the lactoferrin and iron content was evident in the whey derived from milk of the iodine group. Furthermore, in derived cheese, the caseins seemed more efficiently transformed in small peptides making the product more digestible and, for this reason, particularly suitable for feeding the elderly. In conclusion, the dairy products obtained from ewes fed with iodine diet contain more bioactive compounds so that they represent a useful food to prevent iodine and iron deficiency in lamb and humans.

Graduate Student Literature Review: Current understanding of the influence of on-farm factors on bovine raw milk and its suitability for cheesemaking

Relationships between dairy farm practices, the composition and properties of raw milk, and the quality of the resulting cheese are complex. In this review, we assess the effect of farm factors on the quality of bovine raw milk intended for cheesemaking. The literature reports several prominent farm-related factors that are closely associated with milk quality characteristics. We describe their effects on the composition and technological properties of raw milk and on the quality of the resulting cheese. Cow breed, composite genotype, and protein polymorphism all have noticeable effects on milk coagulation, cheese yield, and cheese composition. Feed and feeding strategy, dietary supplementation, housing and milking system, and seasonality of milk production also influence the composition and properties of raw milk, and the resulting cheese. The microbiota in raw milk is influenced by on-farm factors and by the production environment, and may influence the technological properties of the milk and the sensory profile of certain cheese types. Advances in research dealing with the technological properties of raw milk have undoubtedly improved understanding of how on-farm factors affect milk quality attributes, and have refuted the concept of one milk for all purposes. The specific conditions for milk production should be considered when the milk is intended for the production of cheese with unique characteristics. The scientific identification of these conditions would improve the current understanding of the complex associations between raw milk quality and farm and management factors. Future research that considers dairy landscapes within broader perspectives and develops multidimensional approaches to control the quality of raw milk intended for long-ripening cheese production is recommended.

Can Moderate Levels of Organic Selenium in Dairy Cow Feed Naturally Enrich Dairy Products?

Simple Summary

Milk and dairy products, such as cheese and yogurt, can be useful sources of selenium-enriched products to increase human Se intake. We studied the effect of dairy cow feed supplementation with inorganic plus organic Se on milk yield, and on the Se enrichment of milk and dairy products to obtain naturally enriched products. Two groups of lactating cows were assigned to two feeding treatments, both with 0.240 mg Se/kg of ration dry matter: One was supplemented with inorganic Se, the other with a 60/40 ratio of inorganic Se/organic Se. The results showed that the inclusion of inorganic plus organic Se did not affect the yield or basic chemical composition of milk; however, the Se content of milk was higher with inorganic plus organic Se supplementation. Cheese from cows fed inorganic plus organic Se had a higher Se content, although this effect was not observed for yogurt. At a moderate level in the diet, sodium selenite plus Se yeast may be more effective than only inorganic Se, increasing the Se concentration in milk and cheese.

Abstract

This work studied the effect of dairy cow ration supplementation with inorganic plus organic Se on metabolic status, milk yield, and the quality of milk and dairy products, especially its Se content. Twenty multiparous Holstein Friesian lactating cows were assigned to two feeding treatments. The cows were fed with 22.5 kg dry matter (DM) of total mixed ration (11.75 kg DM of forage plus 10.75 kg DM of concentrate) by head. There were two different concentrates with the same Se content (0.240 mg/kg of ration DM) but with different Se sources: The control (CON) was supplemented with inorganic Se (sodium selenite); and the other (IOSe) was supplemented with sodium selenite plus organic Se (Sel-Plex^®), at 0.144 and 0.096 mg Se/kg of ration DM, respectively. The results indicated that, in general, the IOSe treatment did not modify the metabolic profile, and even decreased the total oxidant status (p < 0.05) and did not lead to a deterioration of quality and yield of milk. However, milk and cheese from IOSe had higher Se content (an increase of 29.7% and 38.2%, respectively) than CON (p < 0.01), but this effect was not observed in yogurt. In general, physical or sensorial parameters of cheeses did not show differences between treatments. Moderate inorganic plus organic Se supplementation may be more effective than inorganic Se, increasing the Se content in milk and cheese, without causing a deterioration in quality or productive parameters.

Physical, Nutritional, and Sensory Properties of Cheese Obtained from Goats Fed a Dietary Supplementation with Olive Leaves

Simple Summary

This study aims to investigate the effects of cheese obtained from goats fed a dietary supplementation with olive leaves. Thirty Saanen goats were allocated into two groups, (1) a control group that received a standard diet, and (2) an experimental group whose diet was supplemented with olive leaves. The results suggest a positive role of olive leaves in improving the cheese fatty acids composition and oxidative stability during ripening. Moreover, there were several variations in the development of volatile flavor compounds, even if no changes were evidenced in the sensory properties.

Abstract

The aim of this study is to evaluate the physical, nutritional, and sensory properties of cheese obtained from goats fed a dietary supplementation with olive leaves (OL). Thirty Saanen goats were randomly allocated into two groups of 15 goats each, (1) a control group fed with a standard diet (CG), and (2) an experimental group (EG) fed an OL-enriched diet. The trial lasted for 30 days. The milk of each group was then collected and used to produce Caciotta cheese, which was analyzed at the beginning and at the end of the ripening period (60 days). The results showed a positive effect of dietary OL supplementation in improving the fatty acid profiles due to the significant increase of unsaturated fatty acids, mostly α-linolenic acid (C18:3 n-3), with the consequent reduction of the ω-6/ω-3 ratio, a condition commonly associated with an increased health functionality of food products. Moreover, improved oxidative stability was observed in cheese during ripening, a presumable consequence of the transfer into the milk of dietary bioactive compounds, mainly polyphenols of high biological value, and credited as a marked antioxidant potential. Furthermore, reduced lipolytic action was observed in 60-day ripened cheese, even if no significant changes in sensory properties were evidenced.

Volatile Profile in Yogurt Obtained from Saanen Goats Fed with Olive Leaves

The aim of this study was to evaluate the development of volatile compounds in yogurt samples obtained from goats fed a dietary supplementation with olive leaves (OL). For this purpose, thirty Saanen goats were divided into two homogeneous groups of 15 goats each: a control group that received a standard diet (CG) and an experimental group whose diet was supplemented with olive leaves (OLG). The trial lasted 28 days, at the end of which the milk of each group was collected and used for yogurt production. Immediately after production, and after 7 days of storage at 4 °C in the absence of light, the yogurt samples were characterized in terms of fatty acid profile, oxidative stability and volatile compounds by the solid-phase microextraction (SPME)-GC/MS technique. Dietary OL supplementation positively affected the fatty acid composition, inducing a significant increase in the relative proportion of unsaturated fatty acids, mainly oleic acid (C18:1 cis9) and linolenic acid (C18:3). With regard to the volatile profile, both in fresh and yogurt samples stored for 7 days, the OL supplementation induced an increase in free fatty acids, probably due to an increase in lipolysis carried out by microbial and endogenous milk enzymes. Specifically, the largest variations were found for C6, C7, C8 and C10 free fatty acids. In the same samples, a significant decrease in aldehydes, mainly heptanal and nonanal, was also detected, supporting-at least in part-an improvement in the oxidative stability. Moreover, alcohols, esters and ketones appeared lower in OLG samples, while no significant variations were observed for lactones. These findings suggest the positive role of dietary OL supplementation in the production of goats' milk yogurt, with characteristics potentially indicative of an improvement in nutritional properties and flavor.

Proteolytic Volatile Profile and Electrophoretic Analysis of Casein Composition in Milk and Cheese Derived from Mironutrient-Fed Cows

The aim of the study was to evaluate the proteolytic process in Caciocavallo cheese obtained from Friesian cows fed zinc, selenium, and iodine supplementation. Thirty-six Friesian cows, balanced for parity, milk production, and days in milk, were randomly assigned to four groups. The control group (CG) was fed with a conventional feeding strategy, while the three remaining groups received a diet enriched with three different trace elements, respectively zinc (ZG), selenium (SG), and iodine (IG). At the end of the experimental period, samples of milk were collected and used to produce Caciocavallo cheese from each experimental group. Cheese samples were then analyzed after 7 and 120 days from the cheese making in order to obtain information on chemical composition and extent of the proteolytic process, evaluated through the electrophoretic analysis of caseins and the determination of volatiles profile. Both milk and cheese samples were richer in the amount of the microelement respectively used for the integration of the cattle’s diet. The zymographic approach was helpful in evaluating, in milk, the proteolytic function performed by endogenous metalloenzymes specifically able to degrade gelatin and casein; this evaluation did not highlight significant differences among the analyzed samples. In cheese, the electrophoretic analysis in reducing and denaturing condition showed the marked ability of β-casein to resist the proteolytic action during ripening, whereas the dietary selenium supplementation was shown to perform a protective action against the degradation of S1 and S2 isoforms of α-casein. The analysis of the volatile profile evidenced the presence of compounds associated with proteolysis of phenylalanine and leucine. This approach showed that selenium was able to negatively influence the biochemical processes that lead to the formation of 3-methyl butanol, although the identification of the specific mechanism needs further investigation.

Metagenomic and volatile profiles of ripened cheese obtained from dairy ewes fed a dietary hemp seed supplementation

Chemical and organoleptic properties of dairy products largely depend on the action of microorganisms that tend to be selected in cheese during ripening in response to the availability of specific substrates. The aim of this work was to evaluate the effects of a diet enriched with hemp seeds on the microbiota composition of fresh and ripened cheese produced from milk of lactating ewes. Thirty-two half-bred ewes were involved in the study, in which half (control group) received a standard diet, and the other half (experimental group) took a diet enriched with 5% hemp seeds (on a DM basis) for 35 d. The dietary supplementation significantly increased the lactose in milk, but no variations in total fat, proteins, caseins, and urea were observed. Likewise, no changes in total fat, proteins, or ash were detected in the derived cheeses. The metagenomic approach was used to characterize the microbiota of raw milk and cheese. The phyla Proteobacteria and Firmicutes were in equally high abundance in both control and experimental raw milk samples, whereas Bacteroidetes was less abundant. The scenario changed when considering the dairy products. In all cheese samples, Firmicutes was clearly predominant, with Streptococcaceae being the most abundant family in the experimental group. The reduction of taxa observed during ripening was in accordance with the increment (relative abundance) of the starter culture Lactococcus lactis and Streptococcus thermophilus, which together dominate the microbial community. The analysis of the volatile profile in ripened cheeses led to the identification of 3 major classes of compounds: free fatty acids, ketones, and aldehydes, which indicate a prevalence of lipolysis compared with the other biochemical mechanisms that characterize the cheese ripening.

Dietary Grape Pomace Supplementation in Dairy Cows: Effect on Nutritional Quality of Milk and Its Derived Dairy Products

Grape pomace (GP) is the main solid by-product of winemaking and represents a rich source of potent bioactive compounds which could display a wide range of beneficial effects in human health for their association with reduced risk of several chronic diseases. Several studies have proposed the use of GP as a macro-ingredient to obtain economically worthwhile animal feedstuffs naturally enriched by polyphenols and dietary fibers. Moreover, the research carried out in this field in the last two decades evidences the ability of GP to induce beneficial effects in cow milk and its derived dairy products. First of all, a general increase in concentration of polyunsaturated fatty acids (PUFA) was observed, and this could be considered the reflection of the high content of these compounds in the by-product. Furthermore, an improvement in the oxidative stability of dairy products was observed, presumably as a direct consequence of the high content of bioactive compounds in GP that are credited with high and well-characterized antioxidant functions. Last but not least, particularly in ripened cheeses, volatile compounds (VOCs) were identified, arising both from lipolytic and proteolytic processes and commonly associated with pleasant aromatic notes. In conclusion, the GP introduction in the diet of lactating cows made it possible to obtain dairy products characterized by improved nutritional properties and high health functionality. Furthermore, the presumable improvement of organoleptic properties seems to be effective in contributing to an increase in the consumer acceptability of the novel products. This review aims to evaluate the effect of the dietary GP supplementation on the quality of milk and dairy products deriving from lactating dairy cows.

Volatile Flavor Compounds in Cheese as Affected by Ruminant Diet

Extensive research has been conducted concerning the determination and characterization of volatile compounds contributing to aroma and flavor in cheese. Considerable knowledge has been accumulated on the understanding of the mechanisms through which these compounds are formed during ripening, as well as on the optimization of the methodological approaches which lead to their detection. More recently, particular attention has been given to the aromatic properties of milk and cheeses obtained from lactating dairy ruminants fed experimental diets, characterized, for instance, by the addition of trace elements, natural supplements, or agricultural by-products rich in bioactive compounds. The purpose of this review is to summarize the major families of volatile compounds most commonly found in these types of dairy products at various ripening stages, describing in greater detail the role of animal diet in influencing the synthesis mechanisms most commonly responsible for cheese flavor determination. A large number of volatile compounds, including carboxylic acids, lactones, ketones, alcohols, and aldehydes, can be detected in cheese. The relative percentage of each compound depends on the biochemical processes that occur during ripening, and these are mainly mediated by endogenous enzymes and factors of bacterial origin whose function can be strongly influenced by the bioactive compounds taken by animals with the diet and released in milk through the mammary gland. Further evaluations on the interactions between volatile compounds and cheese matrix would be necessary in order to improve the knowledge on the synthesis mechanisms of such compounds; in addition to this, more should be done with respect to the determination of synergistic effects of flavor compounds, correlating such compounds to the aroma of dairy products.

Influence of Licorice Root Feeding on Chemical-Nutritional Quality of Cow Milk and Stracciata Cheese, an Italian Traditional Fresh Dairy Product

Simple Summary

The aim of this study was to investigate the effects of dietary licorice root supplementation on chemical and nutritional characteristics of cow milk and Stracciata cheese, an Italian traditional fresh dairy product. Our results suggest a positive role of licorice in improving the nutritional and organoleptic properties of dairy cow products, influencing various parameters such as fatty acid and volatile profiles.

Abstract

The aim of this study was to evaluate the effect of dietary licorice root supplementation on chemical and nutritional characteristics of cow milk and Stracciata cheese. Licorice did not influence milk and Stracciata fat content but induced modifications in fatty acid profile. Both in milk and Stracciata, a decrease in saturated fatty acids was detected and in cheeses an increase of monounsaturated and polyunsaturated fatty acids was observed. Stracciata obtained from the experimental group showed an improved oxidative stability after six days of ripening, a finding partly justifiable by the well-known richness of antioxidant compounds in the licorice root. The volatile profile of Stracciata was also affected by dietary licorice intake, with an increase in esters and a reduction of aldehydes and ketones. These results suggest a positive role of licorice in modifying chemical and physical properties of cow cheeses, reducing lipid oxidation and inducing changes in color and flavor with a presumable improvement in consumer acceptability.