The concentration of free glycerol in goat milk increases during feed restrictions.

This Research Communication introduces a novel enzymatic-fluorometric analytical procedure for glycerol and glycerol 3-phosphate in milk. Milk from thirty-seven goats was analysed during 9 consecutive days during which a two-day feed restriction was introduced. Fractional milk triacylglyceride and free glycerol increased significantly while glycerol 3-phosphate reacted more moderately. The energy status of the mammary cell is discussed.

Zearalenone Triggers Programmed Cell Death and Impairs Milk Fat Synthesis via the AKT-mTOR-PPARγ-ACSL4 Pathway in Bovine Mammary Epithelial Cells.

Zearalenone (ZEN), a mycotoxin from Fusarium fungi, impairs fertility and milk production in female animals, however, the mechanisms remain poorly understood. Using the bovine mammary epithelial cells (MAC-T) as the model, this study investigated the impacts of ZEN on programmed cell death (PCD) and milk fat synthesis, and explored the underlying mechanism. We found that 10 ng/mL prolactin (PRL) notably enhanced the differentiation of MAC-T cells, promoting the expression of genes related to the synthesis of milk fat, protein, and lactose. Next, the toxic effects of different doses of ZEN on the differentiated MAC-T with PRL treatment were determined. 10 µM and 20 µM ZEN significantly reduced cell viability, induced oxidative stress, and triggered PCD (e.g. apoptosis and necrosis). Notably, ZEN exposure downregulated the mRNA/protein levels of critical factors involving in milk fat synthesis by disrupting the AKT-mTOR-PPARγ-ACSL4 pathway. Interestingly, melatonin (MT), known for its antioxidant properties, protected against the above ZEN-induced effects by enhancing the binding of PPARγ to the promoter regions of ACSL4, which led to the upregulated expression of ACSL4 gene. These results underscored the potential of MT to mitigate the adverse effects of ZEN on mammary cells, highlighting a way for potential therapeutic intervention.

Influences of lauric acid addition on performance, nutrient digestibility and proteins related to mammary gland development in dairy cows.

Lauric acid (LA) has the possibility to improve milk production in dairy cows by improving mammary gland development, however, the mechanism by which it might regulate mammary gland development is unclear. The influence of LA on milk production, nutrient digestibility and the expression of proteins related to mammary gland development in dairy cows were evaluated. Forty primiparous Holstein dairy cows were divided into 4 groups in a randomized block design. Four treatments included the control (0 g/d LA per cow), low-LA (100 g/d LA per cow), medium-LA (200 g/d LA per cow), and high-LA (300 g/d LA per cow). Yields of milk, fat-corrected milk, and energy-corrected milk quadratically increased (P < 0.05), and yield and content of milk fat linearly increased (P < 0.05) with LA supplementation. Percentages of C12:0, C18:1 and C20:1 fatty acids in milk fat linearly increased (P < 0.05), but that of C16:0 fatty acid linearly decreased (P = 0.046). Supplementation of LA led to a linear and quadratical increase (P < 0.05) in digestibility of dry matter, organic matter, neutral detergent fibre and acid detergent fibre, and ruminal total volatile fatty acid concentration but a linear reduction (P = 0.018) in the ratio of acetate to propionate. The enzymatic activities of ruminal pectinase, xylanase, and α-amylase, and populations of total bacteria and anaerobic fungi increased linearly (P < 0.05), while populations of total protozoa and methanogens decreased linearly (P < 0.05) with increased LA addition. Following LA addition, blood glucose, triglyceride, estradiol, prolactin, and insulin-like growth factor 1 concentrations increased linearly (P < 0.05) and albumin and total protein concentrations increased quadratically (P < 0.05). Moreover, addition of 200 g/d LA promoted (P < 0.05) the expression of protein involved in mammary gland development and fatty acids synthesis. These results suggested that LA addition enhanced milk production and fatty acids synthesis by stimulating nutrient digestion, the expression of proteins associated with milk fat synthesis and mammary gland development.

In silico analysis of polyphenols modulate bovine PPARγ to increase milk fat synthesis in dairy cattle via the MAPK signalling pathways.

This study investigates the potential phytochemicals that modulate bovine peroxisome proliferator-activated receptor gamma (PPARγ) and the Mitogen-Activated Protein Kinase (MAPK) pathways to enhance milk fat production in dairy animals. Bovine PPARγ, a key member of nuclear hormone receptor superfamily, plays a vital role in regulating metabolic, cellular differentiation, apoptosis, and anti-inflammatory responses in livestock, while the MAPK pathway is contributory in cellular processes that impact milk fat synthesis. This approach involved an all-inclusive molecular docking analysis of 10,000 polyphenols to identify potential PPARγ ligands. From this extensive screening, top 10 compounds were selected that exhibited the highest binding affinities to bovine PPARγ. Particularly, Curcumin sulphate, Isoflavone and Quercetin emerged as the most promising candidates. These compounds demonstrated superior docking scores (-9.28 kcal/mol, -9.27 kcal/mol and -7.31 kcal/mol respectively) and lower RMSD values compared to the synthetic bovine PPARγ agonist, 2,4-Thiazolidinedione (-4.12 kcal/mol), indicating a strong potential for modulating the receptor. Molecular dynamics simulations (MDS) further affirmed the stability of these polyphenols-bovine PPARγ complexes, suggesting their effective and sustained interactions. These polyphenols, known as fatty acid synthase inhibitors, are suggested to influence lipid metabolism pathways crucial to milk fat production, possibly through the downregulation of the MAPK pathway. The screened compounds showed favorable pharmacokinetic profiles, including non-toxicity, carcinogenicity, and high gastrointestinal absorption, positioning them as viable candidates for enhancing dairy cattle health and milk production. These findings may open new possibilities for the use of phytochemicals as feed additives in dairy animals, suggesting a novel approach to improve milk fat synthesis through the dual modulation of bovine PPARγ and MAPK pathways.

L-leucine promotes the synthesis of milk protein and milk fat in bovine mammary epithelial cells through the AKT/mTOR signaling pathway under hypoxic conditions.

Hypoxia stress has been demonstrated to impede animal embryonic development, spermatogenesis, and lactation, leading to decreased animal production performance. However, the impact of hypoxia-induced activation of hypoxia inducible factor-1 (HIF-1) signaling on milk protein and fat synthesis remains unclear. L-leucine, a branched-chain amino acid, is known to modulate milk protein and fat synthesis. Therefore, our study aimed to evaluate the effect of L-leucine on milk protein and fat synthesis under hypoxic conditions and shed light on the molecular mechanism using an in vitro model. The results indicated that hypoxia treatment significantly decreased the synthesis of α-casein and ß-casein, as well as inhibited factors related to milk fat synthesis in bovine mammary epithelial cells (MAC-T). Additionally, hypoxia stress suppressed the activities of the mammalian target of rapamycin (mTOR) and protein kinase B (AKT). Interfering with HIF-1α significantly reversed the expression of AKT, mTOR and factors related to milk synthesis. Importantly, supplementation with L-leucine activated AKT/mTOR signaling, thereby enhancing milk protein and fat synthesis in MAC-T cells to some extent. In conclusion, these findings suggest that HIF-1 signaling plays an important role in milk synthesis and that L-leucine may stimulate the synthesis of milk protein and fat by activating the AKT/mTOR signaling pathway under hypoxic conditions, making it a potential additive for promoting milk synthesis inhibited by hypoxia.

LEP Gene Promotes Milk Fat Synthesis via the JAK2-STAT3 and mTOR Signaling Pathways in Buffalo Mammary Epithelial Cells.

Leptin (LEP), a protein hormone well-known for its role in metabolic regulation, has recently been linked to lipid metabolism in cattle. However, its function in buffalo mammary glands remains unclear. To address this issue, we isolated and identified the LEP gene and conducted experiments to investigate its function in buffalo mammary epithelial cells (BuMECs). In this study, two transcript variants of LEP, designated as LEP_X1 and LEP_X2, were identified. The coding sequences (CDS) of LEP_X1 and LEP_X2 are 504 bp and 579 bp in length, encoding 167 and 192 amino acid residues, respectively. Bioinformatics analysis revealed that LEP_X2 is a hydrophobic protein with an isoelectric point below 7 and contains a signal peptide, while LEP_X1 is hydrophilic and lacks a signal peptide. Our study found that LEP gene expression in lactating BuMECs was significantly higher than in non-lactating cells, with LEP_X2 expression remarkably higher than LEP_X1 in lactating BuMECs. Overexpression of both LEP_X1 and LEP_X2 significantly promoted the expression of genes related to milk fat synthesis in lactating BuMECs, including STAT3, PI3K, mTOR, SCD, and SREBF1, accompanied by an increase in cellular triglycerides (TG). Interestingly, LEP_X2 overexpression significantly suppressed LEP_X1 expression while increasing intracellular TG concentration by 12.10-fold compared to LEP_X1 overexpression, suggesting an antagonistic relationship between the two variants and supposing LEP_X2 plays a dominant role in milk fat synthesis in lactating BuMECs. Additionally, four nucleotide substitutions were identified in the buffalo LEP CDS, including a nonsynonymous substitution c.148C>T (p.Arg50Cys), which was predicted to decrease the stability of the LEP protein without affecting its function. These results collectively underscore the significant role of LEP in milk fat synthesis and can provide a basis for molecular breeding strategies of buffalo.

Bet-hedging in parasitoids: when optimization is not the best strategy to cope with climatic extremes.

Bet-hedging occurs when unreliable environments select for genotypes exhibiting a lower variance in fitness at the cost of a lower mean fitness for each batch of progeny. This means that at the level of the genotype, the production of mostly non-optimal phenotypes may be favored when at least some phenotypes are successful. As extreme unreliable climatic events are increasing because of climate change, it is pertinent to investigate the potential of bet-hedging strategies that allow insects to cope with climate change. Evidence for bet-hedging is scarce in most insects, including parasitoids, but the unique lifestyle and biology of parasitoids leads to the expectation that bet-hedging may occur frequently. Here, we evaluate a range of parasitoid traits for which a bet-hedging strategy could be envisioned even if bet-hedging has not been identified as such yet. Under-identification of bet-hedging in nature could have resulted from a major focus of studies on parasitoid life history evolution and foraging behavior on optimality models, predicting how mean fitness can be maximized. Most environmental factors, however, vary unpredictably. Life history and behavioral adaptations are thus expected to be affected by environmental stochasticity. In this paper, we review different aspects of parasitoid behavior, physiology, and life histories and ask the question whether parasitoid traits could have evolved under selection by environmental stochasticity.

ALG5 Regulates STF-62247-Induced Milk Fat Synthesis via the mTOR Signaling Pathway.

Milk fat content is a critical indicator of milk quality. Exploring the key regulatory genes involved in milk fat synthesis is essential for enhancing milk fat content. STF-62247 (STF), a thiazolamide compound, has the potential to bind with ALG5 and upregulate lipid droplets in fat synthesis. However, the effect of STF on the process of milk fat synthesis and whether it acts through ALG5 remains unknown. In this study, the impact of ALG5 on milk fat synthesis and its underlying mechanism were investigated using bovine mammary epithelial cells (BMECs) and mouse models through real-time PCR, western blotting, Oil Red O staining, and triglyceride analysis. Experimental findings revealed a positive correlation between STF and ALG5 with the ability to synthesize milk fat. Silencing ALG5 led to decreased expression of FASN, SREBP1, and PPARγ in BMECs, as well as reduced phosphorylation levels in the PI3K/AKT/mTOR signaling pathway. Moreover, the phosphorylation levels of the PI3K/AKT/mTOR signaling pathway were restored when ALG5 silencing was followed by the addition of STF. These results suggest that STF regulates fatty acid synthesis in BMECs by affecting the PI3K/AKT/mTOR signaling pathway through ALG5. ALG5 is possibly a new factor in milk fat synthesis.

Stored alcohol and fatty acid intermediates and the biosynthesis of sex pheromone aldehyde in the moth Chloridea virescens.

In most species of moths, the female produces and releases a volatile sex pheromone from a specific gland to attract a mate. Biosynthesis of the most common type of moth sex pheromone component (Type 1) involves de novo synthesis of hexadecanoate (16:Acyl), followed by modification to various fatty acyl intermediates, then reduction to a primary alcohol, which may be acetylated or oxidized to produce an acetate ester or aldehyde, respectively. Our previous work on the moth Chloridea virescens (Noctuidae) showed that females produce 90% of the major pheromone component, (Z)-11-hexadecenal (Z11-16:Ald), via a direct and rapid route of de novo biosynthesis with highly labile intermediates, and ca. 10% from an indirect route that likely mobilizes a pre-synthesized 16-carbon skeleton, possibly, (Z)-11-hexadecenoate (Z11-16:Acyl) or hexadecanoate (16:Acyl). In this paper, we use stable isotope tracer/tracee techniques to study the dynamics of the precursor alcohol (Z)-11-hexadecenol (Z11-16:OH) and stores of Z11-16:Acyl and 16:Acyl to determine their roles in biosynthesis of Z11-16:Ald. We found: (i) that intracellular Z11-16:OH is synthesized at roughly the same rate as Z11-16:Ald, indicating that translocation and oxidation of this moiety does not rate limit biosynthesis of Z11-16:Ald, (ii) intracellular Z11-16:OH consists of two pools, a highly labile one rapidly translocated out of the cell and converted to Z11-16:Ald, and a less labile one that mostly remains in gland cells, (iii) during pheromone biosynthesis, net stores of Z11-16:Acyl increase, suggesting it is not the source of Z11-16:Ald produced by the indirect route, and (iv) no evidence for the gland synthesizing stored 16:Acyl prior to (up to 2 days before eclosion), or after, synthesis of pheromone commenced, suggesting the bulk of this stored moiety is synthesized elsewhere and transported to the gland prior to gland maturation. Thus, the pheromone gland of C. virescens produces very little stored fat over its functional lifetime, being optimized to produce sex pheromone.

Effects of nanoselenium supplementation on lactation performance, nutrient digestion and mammary gland development in dairy cows.

The objective of this experiment was to evaluate the influence of nanoselenium (NANO-Se) addition on milk production, milk fatty acid synthesis, the development and metabolism regulation of mammary gland in dairy cows. Forty-eight Holstein dairy cows averaging 720 ± 16.8 kg of body weight, 66.9 ± 3.84 d in milk (dry matter intake [DIM]) and 35.2 ± 1.66 kg/d of milk production were divided into four treatments blocked by DIM and milk yields. Treatments were control group, low-Se (LSe), medium-Se (MSe) and high-Se (HSe) with 0, 0.1, 0.2 and 0.3 mg Se, respectively, from NANO-Se per kg dietary dry matter (DM). Production of energy- and fat-corrected milk (FCM) and milk fat quadratically increased (p < 0.05), while milk lactose yields linearly increased (p < 0.05) with increasing NANO-Se addition. The proportion of saturated fatty acids (SFAs) linearly decreased (p < 0.05), while proportions of monounsaturated fatty acids (MUFAs) linearly increased and polyunsaturated fatty acids (PUFAs) quadratically increased. The digestibility of dietary DM, organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) quadratically increased (p < 0.05). Ruminal pH quadratically decreased (p < 0.01), while total VFA linearly increased (p < 0.05) with increasing NANO-Se addition. The acetic to propionic ratio decreased (p < 0.05) linearly due to the unaltered acetic molar percentage and a quadratical increase in propionic molar percentage. The activity of CMCase, xylanase, cellobiase and pectinase increased linearly (p < 0.05) following NANO-Se addition. The activity of α-amylase increased linearly (p < 0.01) with an increase in NANO-Se dosage. Blood glucose, total protein, estradiol, prolactin, IGF-1 and Se linearly increased (p < 0.05), while urea nitrogen concentration quadratically decreased (p = 0.04). Moreover, the addition of Se at 0.3 mg/kg from NANO-Se promoted (p < 0.05) mRNA and protein expression of PPARγ, SREBP1, ACACA, FASN, SCD, CCNA2, CCND1, PCNA, Bcl-2 and the ratios of p-ACACA/ACACA and BCL2/BAX4, but decreased (p < 0.05) mRNA and protein expressions of Bax, Caspase-3 and Caspase-9. The results suggest that milk production and milk fat synthesis increased by NANO-Se addition by stimulating rumen fermentation, nutrients digestion, gene and protein expressions concerned with milk fat synthesis and mammary gland development.

MSI2 Modulates Unsaturated Fatty Acid Metabolism by Binding FASN in Bovine Mammary Epithelial Cells.

The regulation of fatty acid metabolism is crucial for milk flavor and quality. Therefore, it is important to explore the genes that play a role in fatty acid metabolism and their mechanisms of action. The RNA-binding protein Musashi2 (MSI2) is involved in the regulation of numerous biological processes and plays a regulatory role in post-transcriptional translation. However, its role in the mammary glands of dairy cows has not been reported. The present study examined MSI2 expression in mammary glands from lactating and dry milk cows. Experimental results in bovine mammary epithelial cells (BMECs) showed that MSI2 was negatively correlated with the ability to synthesize milk fat and that MSI2 decreased the content of unsaturated fatty acids (UFAs) in BMECs. Silencing of Msi2 increased triglyceride accumulation in BMECs and increased the proportion of UFAs. MSI2 affects TAG synthesis and milk fat synthesis by regulating fatty acid synthase (FASN). In addition, RNA immunoprecipitation experiments in BMECs demonstrated for the first time that MSI2 can bind to the 3'-UTR of FASN mRNA to exert a regulatory effect. In conclusion, MSI2 affects milk fat synthesis and fatty acid metabolism by regulating the triglyceride synthesis and UFA content through binding FASN.

Dietary supplementation of sodium butyrate enhances lactation performance by promoting nutrient digestion and mammary gland development in dairy cows.

This experiment was to evaluate the influence of sodium butyrate (SB) addition on milk production, ruminal fermentation, nutrient digestion, and the development and metabolism regulation of the mammary gland in dairy cows. Forty Holstein dairy cows averaging 710 ± 18.5 kg body weight, 72.8 ± 3.66 d in milk (DIM), and 41.4 ± 1.42 kg/d milk production were divided into four treatments blocked by DIM and milk production. Treatments were control group, low SB, medium SB, and high SB with 0, 100, 200 and 300 g/d of SB addition per cow, respectively. The study lasted for 105 d. Production of milk, milk protein and lactose quadratically increased (P < 0.05), while fat-corrected milk, energy-corrected milk and milk fat yields linearly increased (P < 0.05) with increasing SB addition. The digestibility of dietary dry matter, organic matter, and crude protein linearly increased (P < 0.05), whereas the digestibility of ether extract, neutral detergent fibre, and acid detergent fibre quadratically increased (P < 0.05). Ruminal pH quadratically decreased (P = 0.04), while total volatile fatty acids (VFA) quadratically increased (P = 0.03) with increasing SB addition. The acetic acid to propionic acid ratio increased (P = 0.03) linearly due to the unaltered acetic acid molar percentage and a linear decrease in propionic acid molar percentage. Ruminal enzymatic activity of carboxymethyl-cellulase and α-amylase, populations of total bacteria, total anaerobic fungi, total protozoa, Ruminococcus albus, R. flavefaciens, Butyrivibrio fibrisolvens, Fibrobacter succinogenes, and Ruminobacter amylophilus linearly increased (P < 0.05). Blood glucose, urea nitrogen, and non-esterified fatty acids linearly decreased (P < 0.05), while total protein concentration linearly increased (P = 0.04). Moreover, the addition of SB at 200 g/d promoted (P < 0.05) mRNA and protein expression of PPARγ, SREBF1, ACACA, FASN, SCD, CCNA2, CCND1, PCNA, Bcl-2, GPR41, and the ratios of p-Akt/Akt and p-mTOR/mTOR, but decreased (P < 0.05) mRNA and protein expressions of Bax, caspase-3, and caspase-9. The results suggest that milk production and milk fat synthesis increased with SB addition by stimulating rumen fermentation, nutrient digestion, gene and protein expressions concerned with milk fat synthesis and mammary gland development.

Molecular Characteristics and Polymorphisms of Buffalo (Bubalus bubalis) ABCG2 Gene and Its Role in Milk Fat Synthesis.

The ATP-binding cassette subfamily G member 2 (ABCG2) serves crucial roles in secreting riboflavin and biotin vitamins into the milk of cattle, mice, and humans, as well as in the transportation of xenotoxic and cytostatic drugs across the plasma membrane. However, the specific role of the ABCG2 gene in water buffaloes (Bubalus bubalis), especially its effect on milk fat synthesis in buffalo mammary epithelial cells (BuMECs), remains inadequately understood. In this study, the full-length CDS of the buffalo ABCG2 gene was isolated and identified from the mammary gland in buffaloes. A bioinformatics analysis showed a high degree of similarity in the transcriptional region, motifs, and conservative domains of the buffalo ABCG2 with those observed in other Bovidae species. The functional role of buffalo ABCG2 was associated with the transportation of solutes across lipid bilayers within cell membranes. Among the 11 buffalo tissues detected, the expression levels of ABCG2 were the highest in the liver and brain, followed by the mammary gland, adipose tissue, heart, and kidney. Notably, its expression in the mammary gland was significantly higher during peak lactation than during non-lactation. The ABCG2 gene was identified with five SNPs in river buffaloes, while it was monomorphic in swamp buffaloes. Functional experiments revealed that ABCG2 increased the triglyceride (TAG) content by affecting the expression of liposynthesis-related genes in BuMECs. The results of this study underscore the pivotal role of the ABCG2 gene in influencing the milk fat synthesis in BuMECs.

Sodium acetate promotes fat synthesis by suppressing TATA element modulatory factor 1 in bovine mammary epithelial cells.

Short-chain fatty acids are important nutrients that regulate milk fat synthesis. They regulate milk synthesis via the sterol regulatory element binding protein 1 (SREBP1) pathway; however, the details are still unknown. Here, the regulation and mechanism of sodium acetate (SA) in milk fat synthesis in bovine mammary epithelial cells (BMECs) were assessed. BMECs were treated with SA supplementation (SA+) or without SA supplementation (SA-), and milk fat synthesis and activation of the SREBP1 pathway were increased (P = 0.0045; P = 0.0042) by SA+ and decreased (P = 0.0068; P = 0.0031) by SA-, respectively. Overexpression or inhibition of SREBP1 demonstrated that SA promoted milk fat synthesis (P = 0.0045) via the SREBP1 pathway. Overexpression or inhibition of TATA element modulatory factor 1 (TMF1) demonstrated that TMF1 suppressed activation of the SREBP1 pathway (P = 0.0001) and milk fat synthesis (P = 0.0022) activated by SA+. Overexpression or inhibition of TMF1 and SREBP1 showed that TMF1 suppressed milk fat synthesis (P = 0.0073) through the SREBP1 pathway. Coimmunoprecipitation analysis revealed that TMF1 interacted with SREBP1 in the cytoplasm and suppressed the nuclear localization of SREBP1 (P = 0.0066). The absence or presence of SA demonstrated that SA inhibited the expression of TMF1 (P = 0.0002) and the interaction between TMF1 and SREBP1 (P = 0.0001). Collectively, our research suggested that TMF1 was a new negative regulator of milk fat synthesis. In BMECs, SA promoted the SREBP1 pathway and milk fat synthesis by suppressing TMF1. This study enhances the current understanding of the regulation of milk fat synthesis and provides new scientific data for the regulation of milk fat synthesis.

Impact of dietary fat levels and fatty acid composition on milk fat synthesis in sows at peak lactation.

BACKGROUND: Dietary fat is important for energy provision and immune function of lactating sows and their progeny. However, knowledge on the impact of fat on mammary transcription of lipogenic genes, de novo fat synthesis, and milk fatty acid (FA) output is sparse in sows. This study aimed to evaluate impacts of dietary fat levels and FA composition on these traits in sows. Forty second-parity sows (Danish Landrace × Yorkshire) were assigned to 1 of 5 dietary treatments from d 108 of gestation until weaning (d 28 of lactation): low-fat control diet (3% added animal fat); or 1 of 4 high-fat diets with 8% added fat: coconut oil (CO), fish oil (FO), sunflower oil (SO), or 4% octanoic acid plus 4% FO (OFO). Three approaches were taken to estimate de novo milk fat synthesis from glucose and body fat. RESULTS: Daily intake of FA was lowest in low-fat sows within fat levels (P < 0.01) and in OFO and FO sows within high-fat diets (P < 0.01). Daily milk outputs of fat, FA, energy, and FA-derived carbon reflected to a large extent the intake of those. On average, estimates for de novo fat synthesis were 82 or 194 g/d from glucose according to method 1 or 2 and 255 g de novo + mobilized FA/d according to method 3. The low-fat diet increased mammary FAS expression (P < 0.05) and de novo fat synthesis (method 1; P = 0.13) within fat levels. The OFO diet increased de novo fat synthesis (method 1; P < 0.05) and numerically upregulated mammary FAS expression compared to the other high-fat diets. Across diets, a daily intake of 440 g digestible FA minimized milk fat originating from glucose and mobilized body fat. CONCLUSIONS: Sows fed diets with low-fat or octanoic acid, through upregulating FAS expression, increased mammary de novo fat synthesis whereas the milk FA output remained low in sows fed the low-fat diet or high-fat OFO or FO diets, indicating that dietary FA intake, dietary fat level, and body fat mobilization in concert determine de novo fat synthesis, amount and profiles of FA in milk.

Comparative transcriptomic analysis of mammary gland tissues reveals the critical role of GPR110 in palmitic acid-stimulated milk protein and fat synthesis.

The G protein-coupled receptors (GPCR) sensing nutritional signals (amino acids, fatty acids, glucose, etc.) are not fully understood. In this research, we used transcriptome sequencing to analyse differentially expressed genes (DEG) in mouse mammary gland tissues at puberty, lactation and involution stages, in which eight GPCR were selected out and verified by qRT-PCR assay. It was further identified the role of GPR110-mediating nutrients including palmitic acid (PA) and methionine (Met) to improve milk synthesis using mouse mammary epithelial cell line HC11. PA but not Met affected GPR110 expression in a dose-dependent manner. GPR110 knockdown decreased milk protein and fat synthesis and cell proliferation and blocked the stimulation of PA on mechanistic target of rapamycin (mTOR) phosphorylation and sterol-regulatory element binding protein 1c (SREBP-1c) expression. In summary, these experimental results disclose DEG related to lactation and reveal that GPR110 mediates PA to activate the mTOR and SREBP-1c pathways to promote milk protein and fat synthesis.

Milk triglycerides from dairy cows abomasally infused with increasing amounts of high-oleic sunflower fatty acids.

The triglyceride composition of milk fat largely determines the manufacturing characteristics of products containing milk fat. Increasing oleic acid content of milk fat might be desirable for human nutrition and also for butter and whipping cream, among other product applications. The objective of this research was to determine the effects of increasing intestinally available oleic acid (provided via abomasal infusion) on the profile of milk triglycerides. A control and 4 increasing doses of free fatty acids from high oleic sunflower oil (HOSFA) were infused into the abomasum of 4 lactating dairy cows in a changeover experimental design with periods of 7 d. Treatments were (1) control (no fatty acids infused), (2) HOSFA (250 g/d), (3) HOSFA (500 g/d), (4) HOSFA (750 g/d), and (5) HOSFA (1,000 g/d). All treatments included meat solubles and Tween 80 as emulsifiers. Infusion of HOSFA increased oleic acid and decreased short- and medium-chain fatty acids in milk fat. Statistical analysis of results showed linear changes in most of the milk triglycerides analyzed. The most significant changes as the result of increasing HOSFA infusion were a decrease in triglycerides with saturated fatty acids (butyrin-caprylin-palmitin, butyrin-laurin-olein, butyrin-myristin-palmitin, butyrin-palmitin-palmitin, caproin-myristin-palmitin, butyrin-palmitin-stearin, caproin-palmitin-palmitin) and an increase in dioleyl triglycerides (with butyric, lauric, myristic and palmitic acids) and triolein. The synthesis of triglyceride is position-specific and does not follow a random distribution model.

Lian-Qu formula treats metabolic syndrome via reducing fat synthesis, insulin resistance and inflammation.

ETHNOPHARMACOLOGICAL RELEVANCE: Metabolic syndrome (MetS) is a pathological condition characterized by obesity, hyperglycemia, hypertension and hyperlipidemia that increases the risk of cardiovascular disease, type 2 diabetes and non-alcoholic fatty liver disease. The traditional Chinese medicine Lian-Qu formula (LQF) is modified from Xiaoxianxiong decoction, which has been used for coronary heart disease or metabolic disease in clinical for a long time. However, the pharmacological mechanism of LQF on MetS is unclear. AIM OF THE STUDY: Here, we explored the actions of LQF on MetS via network pharmacology and validated the mechanism in the MetS mice. MATERIALS AND METHODS: The chemical components of LQF were searched in the traditional Chinese medicine systems pharmacology database and the natural product activity & species source database. The related targets of MetS disease were gathered from genes cluster with literature profiles database. The protein-protein interaction network was constructed to obtain the key target genes. The Gene Ontology analysis and Kyoto Encyclopedia of Genes and Genomes pathway enrichment of the key targets were performed to predict the potential mechanisms of LQF action on MetS. And then, the high-fat diet-induced MetS mice were used to validate its therapeutic effect and molecular targets. Insulin tolerance test and oral glucose tolerance test were used to assess insulin sensitivity. Body weight and visceral fat index were measured to assess obesity. Liver metabolism was detected by H&E section, oil red O staining and untargeted lipid metabolomics experiments. Finally, the key targets of LQF action on MetS were verified by PCR and ELISA kits. RESULTS: A total of 466 components in LQF were obtained, among which 71 were active. These components correspond to 74 targets associated with MetS. The predicted targets of LQF worked on MetS were AKT1, INSR, PPARs, FASN, LDLR, TNF, CRP, IL-6, IL-1ß and so on. Furthermore, these targets were related to pathways in cellular response to lipid, inflammatory response, glucose transmembrane transport and insulin resistance. Finally, the animal experiments validated that LQF inhibited lipids accumulation by inhibiting the gene expression of FASN and increasing ADPN, and it relieved insulin resistance by increasing GLUT-4 expression. Moreover, LQF alleviated inflammation by reducing IL-6 and CRP levels. CONCLUSION: LQF exerted anti-MetS effects through improving insulin sensitivity, ameliorating hyperlipidemia and obesity, reducing liver injury, and inhibiting inflammatory response.

The impact of environmental and nutritional stresses on milk fat synthesis in dairy cows.

Stress reduces milk and milk components synthesis and increases maintenance requirements of cows. The major stress-related alterations involve enhanced secretion of glucocorticoids and increased sympathetic nervous system activity, which results in biochemical and physiologic changes. In dairy cows exposed to social (ie housing conditions, overstocking, regrouping, feed delivery), physiological (ie initiation of lactation and parturition), or physical (ie heat or cold stress) stressors, responses involve alterations in energy balance and nutrient partitioning. The capacity of the animal to synthesize milk fat largely depends on the availability of substrates for lipid synthesis from the diet, ruminal fermentation or adipose tissue stores, all of which can be altered under stress conditions. Indeed, milk fat concentration is particularly responsive to diet and environment modifications, where a wide range of nutritional and non-nutritional factors influence milk fat output. Milk fat synthesis is an energy demanding process, and extremely sensitive to stress factors during lactation and the involvement of multiple organs. Recent studies examining social, physical, and physiological stressors have provided important insights into how differences in milk yield and milk components may be associated with biological responses to stress factors in dairy cows. This review focuses primarily on the role of stress sources and indicators to which the dairy cow is exposed in regulating milk fat synthesis. We will review the role of nutritional and non-nutritional factors on milk fat synthesis in dairy cows under stress conditions.

Multi-omics analyses reveal that the gut microbiome and its metabolites promote milk fat synthesis in Zhongdian yak cows.

Background: Yak cows produce higher quality milk with higher concentrations of milk fat than dairy cows. Recently, studies have found the yak milk yield and milk fat percentage have decreased significantly over the past decade, highlighting the urgency for yak milk improvement. Therefore, we aimed to analyze how the gut microbiome impacts milk fat synthesis in Zhongdian yak cows. Methods: We collected milk samples from Zhongdian yak cows and analyzed the milk fat percentage, selecting five Zhongdian yak cows with a very high milk fat percentage (>7%, 8.70 ± 1.89%, H group) and five Zhongdian yak cows with a very low milk fat percentage (<5%, 4.12 ± 0.43%, L group), and then obtained gut samples of these ten Zhongdian yak cows through rectal palpation. Gut metagenomics, metabolomics, and conjoint metagenomics and metabolomics analyses were performed on these samples, identifying taxonomic changes, functional changes, and changes in gut microbes-metabolite interactions within the milk fat synthesis-associated Zhongdian yak cows gut microbiome, to identify potential regulatory mechanisms of milk fat at the gut microbiome level in Zhongdian yak cows. Results: The metagenomics analysis revealed Firmicutes and Proteobacteria were significantly more abundant in the gut of the high-milk fat Zhongdian yak cows. These bacteria are involved in the biosynthesis of unsaturated fatty acids and amino acids, leading to greater efficiency in converting energy to milk fat. The metabolomics analysis showed that the elevated gut metabolites in high milk fat percentage Zhongdian yak cows were mainly enriched in lipid and amino acid metabolism. Using a combined metagenomic and metabolomics analysis, positive correlations between Firmicutes (Desulfocucumis, Anaerotignum, Dolosiccus) and myristic acid, and Proteobacteria (Catenovulum, Comamonas, Rubrivivax, Marivita, Succinimouas) and choline were found in the gut of Zhongdian yak cows. These interactions may be the main contributors to methanogen inhibition, producing less methane leading to higher-efficient milk fat production. Conclusions: A study of the gut microbe, gut metabolites, and milk fat percentage of Zhongdian yak cows revealed that the variations in milk fat percentage between yak cows may be caused by the gut microbes and their metabolites, especially Firmicutes-myristic acid and Proteobacteria-choline interactions, which are important to milk fat synthesis. Our study provides new insights into the functional roles of the gut microbiome in producing small molecule metabolites and contributing to milk performance traits in yak cows.