Regulatory role for amino acids in mammary gland growth and milk synthesis

Impacts of Maternal Nutrition on Sow Performance and Potential Positive Effects on Piglet Performance

The objectives of this review are to identify the nutritional challenges faced by modern sows and present potential solutions to mitigate excessive maternal tissue loss and reproductive failure as it relates to recent genetic improvements. Current feeding programs have limitations to support the rapid genetic improvements in reproductive performance for modern sows. Since 2012, both litter size at birth and fetal weight have increased by 2.26 pigs per litter and 0.22 kg per piglet, respectively, thereby increasing the nutrient needs for sows during gestation and lactation. Prediction models generated in this review predict that modern sows would need 31% more lysine during gestation when compared with current feeding programs. Physiological challenges facing modern sows are also addressed in this review. High oxidative stress, pelvic organ prolapse, and lameness can directly affect the sow, whereas these physiological challenges can have negative impacts on colostrum and milk quality. In response, there is growing interest in investigating the functional roles of select bioactive compounds as feed additives to mitigate the severity of these challenges. Selenium sources, catechins, and select plant extracts have been utilized to reduce oxidative stress, calcium chloride and phytase have been used to mitigate pelvic organ prolapse and lameness, algae and yeast derivatives have been used to improve colostrum and milk quality, and fiber sources and probiotics have been commonly utilized to improve sow intestinal health. Collectively, this review demonstrates the unique challenges associated with managing the feeding programs for modern sows and the opportunities for revision of the amino acid requirements as well as the use of select bioactive compounds to improve reproductive performance.

Dietary CP and digestion kinetics influence BW loss, litter weight gain, and reproduction by affecting postprandial amino acid metabolism in lactating sows

To avoid a high body protein mobilization in modern lean sows during lactation, an adequate dietary amino acid (AA) supply and an efficient AA utilization are crucial. This study evaluated the effects of dietary CP and in vitro protein digestion kinetics on changes in sow body condition, litter weight gain, milk composition, blood metabolites, protein utilization efficiency and subsequent reproductive performance. We hypothesized that a slower digestion of dietary protein would improve AA availability and utilization. In total, 110 multiparous sows were fed one of four lactation diets in a 2 × 2 factorial design, with two CP concentrations: 140 g/kg vs 180 g/kg, and two protein digestion kinetics, expressed as a percentage of slow protein (in vitro degradation between 30 and 240 min): 8 vs 16% of total protein. Feeding sows the high CP diets reduced sow weight loss (Δ = 7.6 kg, P < 0.01), estimated body fat loss (Δ = 2.6 kg, P = 0.02), and estimated body protein loss (Δ = 1.0 kg, P = 0.08), but only at a high percentage of slow protein. A higher percentage of slow protein increased litter weight gain throughout lactation (Δ = 2.6 kg, P = 0.04) regardless of CP concentrations, whereas a higher CP only increased litter weight gain during week 3 of lactation (Δ = 1.2 kg, P = 0.01). On Day 15 postfarrowing, serial blood samples were taken from a subsample of sows fed with the high CP diets. In these sows, a high percentage of slow protein resulted in higher plasma AA concentrations at 150 and 180 min after feeding (Δ = 0.89, P = 0.02, Δ = 0.78, P = 0.03, mmol/L, respectively) and lower increases in urea at 90 and 120 min after feeding (Δ = 0.67, P = 0.04, Δ = 0.70, P = 0.03, mmol/L, respectively). The higher dietary CP concentration increased total nitrogen loss to the environment (Δ = 604 g, P < 0.01) with a reduction of protein efficiency (Δ = 14.8%, P < 0.01). In the next farrowing, a higher percentage of slow protein increased subsequent liveborn litter size (Δ = 0.7, P < 0.05). In conclusion, feeding sows with a high dietary CP concentration alleviated maternal weight loss during lactation when the dietary protein digestion rate was slower, but lowered protein efficiency. A slower protein digestion improved litter weight gain, possibly by reducing AA oxidation and improving plasma AA availability, thus, improving protein efficiency.

Effects of dietary folic acid supplementation on lactation performance and mammary epithelial cell development of dairy cows and its regulatory mechanism

The experiment investigated the impacts of FA on the proliferation of bovine mammary gland epithelial cells (BMECs) and to investigate the underlying mechanisms. Supplementation of 10 µM FA elevated the mRNA expression of proliferating cell nuclear antigen (PCNA), cyclin A2 and cyclin D1, and protein expression of PCNA and Cyclin A1. The mRNA and protein expression of B-cell lymphoma-2 (BCL2) and the BCL2 to BCL2 associated X 4 (BAX4) ratio elevated, while that of BAX, Caspase-3 and Caspase-9 reduced by FA. Both Akt and mTOR signaling pathways were activated by FA. Moreover, the stimulation of BMECs proliferation, the alteration of proliferative genes and protein expression, the change of apoptotic genes and protein expression, and the activation of mTOR signaling pathway caused by FA were obstructed by Akt inhibitor. Suppression of mTOR with Rapamycin reversed the FA-modulated promotion of BMECs proliferation and change of proliferous genes and protein expression, with no impact on mRNA or proteins expression related to apoptosis and FA-activated Akt signaling pathway. Supplementation of rumen-protected FA in cow diets evaluated milk yields and serum insulin-like growth factor-1 and estradiol levels. The results implied that the proliferation of BMECs was stimulated by FA through the Akt-mTOR signaling pathway.

Optimizing hormonal and amino acid combinations for enhanced cell proliferation and cell cycle progression in bovine mammary epithelial cells

OBJECTIVE

The number of bovine mammary epithelial cells (BMECs) is closely associated with the quantity of milk production in dairy cows; however, the optimal levels and the combined effects of hormones and essential amino acids (EAAs) on cell proliferation are not completely understood. Thus, the purpose of this study was to determine the optimal combination of individual hormones and EAAs for cell proliferation and related signaling pathways in BMECs.

METHODS

Immortalized BMECs (MAC-T) were treated with six hormones (insulin, cortisol, progesterone, estrone, 17β-estradiol, and epidermal growth factor) and ten EAAs (arginine, histidine, leucine, isoleucine, threonine, tryptophan, lysine, methionine, phenylalanine, and valine) for 24 h.

RESULTS

Cells were cultured in a medium containing 10% fetal bovine serum (FBS) as FBS supplemented at a concentration of 10% to 50% showed a comparable increase in cell proliferation rate. The optimized combination of four hormones (insulin, cortisol, progesterone, and 17β-estradiol) and 20% of a mixture of ten EAAs led to the highest cell proliferation rate, which led to a significant increase in cell cycle progression at the S and G2/M phases, in the protein levels of proliferating cell nuclear antigen and cyclin B1, cell nucleus staining, and in cell numbers.

CONCLUSION

The optimal combination of hormones and EAAs increased BMEC proliferation by enhancing cell cycle progression in the S and G/2M phases. Our findings indicate that optimizing hormone and amino acid levels has the potential to enhance milk production, both in cell culture settings by promoting increased cell numbers, and in dairy cows by regulating feed intake.

Leucine and arginine enhance milk fat and milk protein synthesis via the CaSR/Gi/mTORC1 and CaSR/Gq/mTORC1 pathways

BACKGROUND AND AIMS

Amino acids (AAs) not only constitute milk protein but also stimulate milk synthesis through the activation of mTORC1 signaling, but which amino acids that have the greatest impact on milk fat and protein synthesis is still very limited. In this study, we aimed to identify the most critical AAs involved in the regulation of milk synthesis and clarify how these AAs regulate milk synthesis through the G-protein-coupled receptors (GPCRs) signaling pathway.

METHODS

In this study, a mouse mammary epithelial cell line (HC11) and porcine mammary epithelial cells (PMECs) were selected as study subjects. After treatment with different AAs, the amount of milk protein and milk fat synthesis were detected. Activation of mTORC1 and GPCRs signaling induced by AAs was also investigated.

RESULTS

In this study, we demonstrate that essential amino acids (EAAs) are crucial to promote lactation by increasing the expression of genes and proteins related to milk synthesis, such as ACACA, FABP4, DGAT1, SREBP1, α-casein, β-casein, and WAP in HC11 cells and PMECs. In addition to activating mTORC1, EAAs uniquely regulate the expression of calcium-sensing receptor (CaSR) among all amino-acid-responsive GPCRs, which indicates a potential link between CaSR and the mTORC1 pathway in mammary gland epithelial cells. Compared with other EAAs, leucine and arginine had the greatest capacity to trigger GPCRs (p-ERK) and mTORC1 (p-S6K1) signaling in HC11 cells. In addition, CaSR and its downstream G proteins Gi, Gq, and Gβγ are involved in the regulation of leucine- and arginine-induced milk synthesis and mTORC1 activation. Taken together, our data suggest that leucine and arginine can efficiently trigger milk synthesis through the CaSR/Gi/mTORC1 and CaSR/Gq/mTORC1 pathways.

CONCLUSION

We found that the G-protein-coupled receptor CaSR is an important amino acid sensor in mammary epithelial cells. Leucine and arginine promote milk synthesis partially through the CaSR/Gi/mTORC1 and CaSR/Gq/mTORC1 signaling systems in mammary gland epithelial cells. Although this mechanism needs further verification, it is foreseeable that this mechanism may provide new insights into the regulation of milk synthesis.

The Peptide Fractions of Cheddar Cheese Made with Lactobacillus helveticus 1.0612 Play Protective Effects in H2O2-Induced Oxidative-Damaged Caco-2 Cells Models

In this study, water-soluble peptide (WSP) fractions of cheddar cheese made with Lactobacillus helveticus 1.0612 were purified into WSP-Ⅰ (<3 kDa), WSP-Ⅱ (3-10 kDa), and WSP-Ⅲ (>10 kDa). The protective effects of WSP, WSP-Ⅰ, WSP-Ⅱ, and WSP-Ⅲ fractions against oxidative stress in Caco-2 cells were assayed, and the cytoprotective mechanism of WSP-Ⅰ on cells oxidative damage was elucidated via metabolomics. The results showed that all four peptide fractions were able to attenuate the decrease in cell viability caused by oxidative stress and also could reduce the production of reactive oxygen species and malondialdehyde caused by oxidative stress, and increased cellular catalase and superoxide dismutase activities, thereby enhancing cellular antioxidant capacity. The WSP-Ⅰ fraction with the highest protective effect was used for metabolomics analysis, and 15 significantly different metabolites were screened. Functional pathway analysis revealed that the protective effect of the WSP-I fraction was related with nine metabolic pathways and weakened the metabolic disorders caused by H₂O₂ via regulating energy metabolism and amino acid metabolism. All in all, peptide fractions of cheddar cheese showed a cytoprotective effect through improved cellular metabolism.

Serum metabolic profiling of rats infected with Clonorchis sinensis using LC-MS/MS method

Background

Clonorchiasis is an important foodborne parasitic disease. The omics-based-techniques could illuminate parasite biology and further make innovations in the research for parasitic diseases. However, knowledge about the serum metabolic profiles and related metabolic pathways in clonorchiasis is very limited.

Methods

A untargeted ultra-high performance liquid tandem chromatography quadrupole time of flight mass spectrometry (UHPLC-QTOF-MS) was used to profile the serum metabolites of rats at both 4 and 8 weeks post infection (wpi) with Clonorchis sinensis (C. sinensis). Additionally, multivariate statistical analysis methods were employed to identify differential metabolites. Next, serum amino acids and phosphatidylcholines (PCs) levels were determined by targeted metabolomics analysis.

Result

A total of 10530 and 6560 ions were identified in ESI+ and ESI- modes. The levels of phosphatidylcholines, glycerophosphocholine and choline were significantly changed, with the shift in lipid metabolism. Significant changes were also observed in amino acids (isoleucine, valine, leucine, threonine, glutamate and glutamine). Targeted analysis showed that BCAAs (isoleucine, valine, leucine) levels significantly increased at 4 wpi and decreased at 8 wpi; threonine was increased at 8 wpi, whereas glutamate and glutamine showed a decreasing trend at 8 wpi. Additionally, the level of 17 PCs were significantly changed in infected rats. Marked metabolic pathways were involved in clonorchiasis, including glycerophospholipid metabolism, alanine, aspartate and glutamate metabolism, histidine metabolism and pyrimidine metabolism.

Conclusion

These results show that C. sinensis infection can cause significant changes in the rat serum metabolism, especially in amino acids and lipids. The metabolic signature together with perturbations in metabolic pathways could provide more in depth understanding of clonorchiasis and further make potential therapeutic interventions.

The effect of moderate energy and protein restriction during gilt development on changes in body weight and backfat depth and subsequent lactation performance

Eighty-eight gilts [initial body weight (BW) 49.8 ± 0.8 kg] were recruited to determine the effects of moderate energy and protein restriction during the development period on changes in BW and backfat depth (BF) and subsequent lactation performance. Gilts were randomly assigned to one of four feeding programs: 1) standard commercial diet fed ad libitum (CON), 2) standard commercial diet fed 10% or 3) 20% below ad libitum, or 4) a high-fiber diet fed ad libitum [2.5 times more fiber (neutral detergent fiber) than the commercial diet to dilute net energy and crude protein by approximately 20% and 13%, respectively; FIB]. The gilts were housed individually and received the feeding programs between 90 and 190 (breeding) d of age and standard gestation and lactation diets thereafter. Litters were standardized to 12 ± 1 pigs within 48 h of farrowing; weaning occurred at 20.0 ± 0.4 d of age. Gilts that received the 20% restricted program had lower overall average daily feed intake (ADFI) during the development period (2.64 ± 0.04 kg; P < 0.05) versus all other feeding programs and gilts that received the 10% restricted program had lower ADFI than FIB and CON, which were not different (2.96 vs. 3.44 and 3.47 ± 0.04 kg for 10%, FIB and CON, respectively; P < 0.05). Plasma free fatty acid (FFA) concentrations on day 180 of age were lower for gilts that received the 10% and 20% restricted programs compared to gilts that received the FIB and CON programs, which were not different (97 and 86 vs. 220 and 149 ± 29 µEq/L, respectively; P < 0.05). Plasma concentrations of glucose, urea, prolactin, and IGF-1 were not different among feeding programs on day 180 of age. At breeding, gilts that received the FIB and 10% programs had lower BW and BF versus CON (145.7 and 144.8 vs. 155.2 ± 0.9 kg and 14.4 and 14.8 vs. 16.5 ± 0.2 mm for BW and BF, respectively; P < 0.05) but greater BW than gilts that received the 20% restricted program (137.9 kg; P < 0.05). The BW and BF of gilts did not differ at the end of gestation or at weaning. The ADFI of sows during lactation and offspring birth weight and growth rate during lactation and the 5-wk nursery period were not influenced by gilt development feeding program. Therefore, a high-fiber feeding program could be used in group-housing gilt-development scenarios, where feed is offered ad libitum, to control BW and BF prior to breeding without influencing milk production in the subsequent lactation period.

Impact of dietary supplementation of l-Arginine, l-Glutamine, and the combination of both on nursing performance of multiparous sows

Dietary supplementation with arginine (Arg) or glutamine (Gln) has been considered as an option to improve nursing performance in reproductive sows. This study investigated whether a low-level supplementation of Arg or Gln or a blend of both could modify milk nutrients and improve piglets' growth beyond weaning. Seventy-two multiparous sows were assigned to four groups: one group fed a control diet, three treatment groups fed the control diet supplemented with either 0.35% Arg, 0.35% Gln, or both, from day 108 of gestation until weaning at day 26 of lactation. Immediately after birth, the litters were cross fostered to 13 piglets and monitored until 2 wk after weaning. Sows body condition and litter growth were assessed. Colostrum and milk samples were collected for nutrient analyses. Plasma concentrations of insulin-like growth factor 1 (IGF-1) around weaning were determined in sows and two representative piglets per litter. Supplementing Gln or the combination of Arg and Gln had no effect on the parameters studied. Arg supplementation increased weaning weight, while decreasing the variation of piglet weights 2 wk after weaning. There was no correlation with plasma IGF-1 since the hormone was not altered in sows or piglets. The colostral concentration of fat tended to increase in the Arg-group, whereas protein, lactose, energy, and polyamine concentrations remained unaffected. Milk samples obtained on day 12 and 25 of lactation were not influenced by dietary treatment. The data indicate that there might be a window of opportunity, explicitly at the onset of lactation, for dietary intervention by maternal dietary Arg supplementation.

Maternal Amino Acid Mixtures Supplementation during Late Gestation and Lactation Improved Growth Performance of Piglets through Improving Colostrum Composition and Antioxidant Capacity

During late gestation and lactation, oxidative stress in sows can affect their health and reproductive performance. Supplemental amino acid contributes to the antioxidant capacity of pigs. This study was conducted to evaluate the effects of different combinations of Gln, Leu and γ-GABA (amino acid mixtures, AAMs) during late gestation and lactation on the performance of the sows and their offspring. Fifty large white × landrace sows were randomly assigned to 5 groups (n = 10), including a control group and four AAMs groups (AAMs1, Gln + Leu; AAMs2 (Gln + GABA; AAMs3, Leu + GABA; AAMs4, Gln + Leu + GABA). AAMs supplementation improved the antioxidant capacity of sows, including significantly enhanced total antioxidant capacity in AAMs2, 3 and 4 groups and reduced malonaldehyde concentration in AAMs1, 3 and 4 groups. Additionally, all AAMs significantly increased lactoprotein, total solid and IgA levels of colostrum in sows during lactation. Average body weight of piglets on day 21 after birth in all AAMs groups were significantly increased. Furthermore, the significantly increased total antioxidant capacity was observed in the piglets of every AAMs group. In conclusion, supplementing AAMs during late gestation and lactation improved the antioxidant capacity of sows and colostrum composition, thereby enhancing antioxidant status and the growth performance of piglets. This study provides the possibility of maternal amino acid mixtures to improve the productivity of the swine industry.

Dietary supplementation with branched-chain amino acids enhances milk production by lactating sows and the growth of suckling piglets

Background

Under current dietary regimens, milk production by lactating sows is insufficient to sustain the maximal growth of their piglets. As precursors of glutamate and glutamine as well as substrates and activators of protein synthesis, branched-chain amino acids (BCAAs) have great potential for enhancing milk production by sows.

Methods

Thirty multiparous sows were assigned randomly into one of three groups: control (a corn- and soybean meal-based diet), the basal diet + 1.535% BCAAs; and the basal diet + 3.07% BCAAs. The ratio (g/g) among the supplemental L-isoleucine, L-leucine and L-valine was 1.00:2.56:1.23. Diets were made isonitrogenous by the addition of appropriate amounts of L-alanine. Lactating sows had free access to drinking water and their respective diets. The number of live-born piglets was standardized to 9 per sow at d 0 of lactation (the day of parturition). On d 3, 15 and 29 of lactation, body weights and milk consumption of piglets were measured, and blood samples were obtained from sows and piglets 2 h and 1 h after feeding and nursing, respectively.

Results

Feed intake did not differ among the three groups of sows. Concentrations of asparagine, glutamate, glutamine, citrulline, arginine, proline,  BCAAs, and many other amino acids  were greater (P < 0.05) in the plasma of BCAA-supplemented sows and their piglets than those in the control group. Compared with the control, dietary supplementation with 1.535% and 3.07% BCAAs increased (P < 0.05) concentrations of free and protein-bound BCAAs, glutamate plus glutamine, aspartate plus asparagine, and many other amino acids in milk; milk production by 14% and 21%, respectively; daily weight gains of piglets by 19% and 28%, respectively, while reducing preweaning mortality rates by 50% and 70%, respectively.

Conclusion

Dietary supplementation with up to 3.07% BCAAs enhanced milk production by lactating sows, and the growth and survival of their piglets.

A Whole Genome Sequencing-Based Genome-Wide Association Study Reveals the Potential Associations of Teat Number in Qingping Pigs

Teat number plays an important role in the reproductive performance of sows and the growth of piglets. However, the quantitative trait loci (QTLs) and candidate genes for the teat number-related traits in Qingping pigs remain unknown. In this study, we performed GWAS based on whole-genome single-nucleotide polymorphisms (SNPs) and insertions/deletions (Indels) for the total number of teats and five other related traits in 100 Qingping pigs. SNPs and Indels of all 100 pigs were genotyped using 10× whole genome resequencing. GWAS using General Linear Models (GLM) detected a total of 28 SNPs and 45 Indels as peak markers for these six traits. We also performed GWAS for the absolute difference between left and right teat number (ADIFF) using Fixed and random model Circulating Probability Unification (FarmCPU). The most strongly associated SNP and Indel with a distance of 562,788 bp were significantly associated with ADIFF in both GLM and FarmCPU models. In the 1-Mb regions of the most strongly associated SNP and Indel, there were five annotated genes, including TRIML1, TRIML2, ZFP42, FAT1 and MTNR1A. We also highlighted TBX3 as an interesting candidate gene for SSC14. Enrichment analysis of candidate genes suggested the Wnt signaling pathway may contribute to teat number-related traits. This study expanded significant marker-trait associations for teat number and provided useful molecular markers and candidate genes for teat number improvement in the breeding of sows.

Metabolic profiling of serum and urine in lactating dairy cows affected by subclinical ketosis using proton nuclear magnetic resonance spectroscopy

Ketosis is associated with high milk yield during lactating or insufficient feed intake in lactating dairy cows. However, few studies have been conducted on the metabolomics of ketosis in Korean lactating dairy cows. The present study aimed to investigate the serum and urine metabolites profiling of lactating dairy cows through proton nuclear magnetic resonance (¹H-NMR) spectroscopy and comparing those between healthy (CON) and subclinical ketosis (SCK) groups. Six lactating dairy cows were categorized into CON and SCK groups. All experimental Holstein cows were fed total mixed ration. Serum and urine samples were collected from the jugular vein of the neck and by hand sweeping the perineum, respectively. The metabolites in the serum and urine were determined using ¹H-NMR spectroscopy. Identification and quantification of metabolites was performed by Chenomx NMR Suite 8.4 software. Metabolites statistical analysis was performed by Metaboanalyst version 5.0 program. In the serum, the acetoacetate level was significantly (p < 0.05) higher in the SCK group than in the CON group, and whereas acetate, galactose and pyruvate levels tended to be higher. CON group had significantly (p < 0.05) higher levels of 5-aminolevulinate and betaine. Indole-3-acetate, theophylline, p-cresol, 3-hydroxymandelate, gentisate, N-acetylglucosamine, N-nitrosodimethylamine, xanthine and pyridoxine levels were significantly (p < 0.05) higher in the urine of the SCK group than that in the CON group, which had higher levels of homogentisate, ribose, gluconate, ethylene glycol, maltose, 3-methyl-2-oxovalerate and glycocholate. Some significantly (p < 0.05) different metabolites in the serum and urine were associated with ketosis diseases, inflammation, energy balance and body weight. This study will be contributed useful a future ketosis metabolomics studies in Korea.

Effects of Phenolic Phytogenic Feed Additives on Certain Oxidative Damage Biomarkers and the Performance of Primiparous Sows Exposed to Heat Stress under Field Conditions

The aim of this study was to investigate the effects of two commercial phenolic phytogenic feed additives (PFAs) on sows under heat stress conditions of high summer temperatures for seven days before and seven days after the farrowing. The PFA-1 product was a mixture based on the plants Emblica officinalis, Foeniculum vulgare, Citrus sinensis and nut fiber, while the PFA-2 product was a mixture based on plants Andrographis paniculata, Glycyrrhizia glabra, Tinospora cordifolia and nut fiber. A total of 48 primiparous sows were divided into three groups: T1-control group: regular gestation (GF) and lactation feed (LF); T2 group: regular GF and LF supplemented with PFA-1; T3 group: regular GF and LF supplemented with PFA-2. Each sow in the T2 and T3 groups received 5 g daily of the PFA-1 and PFA-2 product, respectively, for seven days before and seven days after the farrowing. Blood samples were collected from all groups 24 h after farrowing. Thiobarbituric acid-–reactive substances (TBARS) and protein carbonyl (CARB) concentrations were determined in the sow plasma. The body condition scoring (BCS) and the backfat of sows on the farrowing and weaning days along with reproductive parameters and litter characteristics were recorded. The highest number of stillborn piglets and the largest interval from weaning to estrus were observed in the T1 group. The lowest number of alive 24 h after birth and weaning piglets and the lowest BCS and backfat at weaning were also recorded in the T1 group. TBARS and CARB concentrations were significant higher in the T1 group compared to all other groups. In conclusion, the use of phenolic PFAs seems to reduce oxidative damage caused by heat stress and ameliorate performance in primiparous sows.

Dietary supplementation with monosodium glutamate enhances milk production by lactating sows and the growth of suckling piglets

This study was conducted to test the hypothesis that increasing dietary content of glutamate through addition of monosodium glutamate (MSG) enhances milk production by lactating sows and the growth of their offspring. Thirty multiparous sows (Landrace × Large White) were assigned randomly into one of three dietary groups: control (a corn- and soybean meal-based diet), the basal diet + 1% MSG, and the basal diet + 2% MSG. Diets were made isonitrogenous by the addition of appropriate amounts of L-alanine. Lactating sows had free access to drinking water and were fed twice daily their respective diets. The number of live-born piglets was standardized to 9 per sow at day 0 of lactation (the day of farrowing). On days 3, 15, and 29 of lactation, body weight and milk consumption of piglets were measured, and blood samples obtained from sows and piglets at 2 h and 1 h after feeding, respectively. Feed intake of sows did not differ (P > 0.05) among the three groups of sows. Concentrations of aspartate, glutamine, citrulline, arginine, tryptophan, proline, branched-chain amino acids, and glutamate were greater (P < 0.05) in the plasma of MSG-supplemented sows and their piglets than for controls. When compared with the control, dietary supplementation with 1-2% MSG increased (P < 0.05): concentrations of many free amino acids (including glutamate plus glutamine) and all protein-bound amino acids in milk; the milk intake of piglets by 14-25%; and daily weight gains of piglets by 23-44%. These results indicate that dietary supplementation with 1-2% MSG to lactating sows enhances milk production to support the growth of sow-reared piglets.

Activation of whole body by high levels of polyamine intake in rats

Polyamines are important to the survival and activation of organs and tissues via a homeostatic cell-metabolic process, and the polyamine content in cytoplasm decreases with aging. Decreases in cellular polyamine have been known to augment mutagenesis and cell death. Thus, supplementary polyamine in food is important to the prevention of aging. Here we show the anti-aging effects of oral intake of polyamine using luciferase-transgenic rats. Healthy rats, 10–12 weeks old, were given foods containing 0.01% and 0.1% (w/w) of polyamine, as compared a control food without polyamine, for 4 weeks. Using a bioimaging system, the photon intensities seen in the whole bodies and livers of rats consuming 0.1% of polyamine in food were stronger than those in rats consuming 0.01% and 0% of polyamine. However, there were no differences between groups in other characteristics, such as liver damage and body weight. In conclusion, we found that polyamine intake can activate cells throughout the whole body, providing an anti-aging effect.

Identifying Suitable Supplements to Improve Piglet Survival during Farrowing and Lactation

Piglet mortality during parturition and prior to weaning is an ongoing economic and welfare issue. This review collates the current literature describing the effects of specific dietary supplements on key parameters affecting piglet survival. Four distinct parameters were identified as having a direct impact on the survival of piglets to weaning: stillbirth rate, birth weight and weight variation, daily gain and weaning weight, and colostrum and milk quality. In the primary stage, relevant literature from the past 5 years was reviewed, followed by a secondary review of literature older than 5 years. The focal parameters benefitted from different supplements. For example, stillbirth may be reduced by supplements in late gestation, including forms of arginine, alpha-tocopherol-selenium, uridine, and Saccharomyces cerevisiae yeast culture, whereas average daily gain and weaning weight were related closely to supplements which improved colostrum and milk quality, most commonly fats and fatty acids in the form of n-3 polyunsaturated fatty acids, soybean oil, and fish oil, and polysaccharides, such as ginseng polysaccharide. Therefore, an effective supplement plan for piglet mortality reduction must consider the circumstances of the individual system and target one or more of the highlighted parameters.

Identifying Suitable Supplements to Improve Piglet Survival during Farrowing and Lactation

Piglet mortality during parturition and prior to weaning is an ongoing economic and welfare issue. This review collates the current literature describing the effects of specific dietary supplements on key parameters affecting piglet survival. Four distinct parameters were identified as having a direct impact on the survival of piglets to weaning: stillbirth rate, birth weight and weight variation, daily gain and weaning weight, and colostrum and milk quality. In the primary stage, relevant literature from the past 5 years was reviewed, followed by a secondary review of literature older than 5 years. The focal parameters benefitted from different supplements. For example, stillbirth may be reduced by supplements in late gestation, including forms of arginine, alpha-tocopherol-selenium, uridine, and Saccharomyces cerevisiae yeast culture, whereas average daily gain and weaning weight were related closely to supplements which improved colostrum and milk quality, most commonly fats and fatty acids in the form of n-3 polyunsaturated fatty acids, soybean oil, and fish oil, and polysaccharides, such as ginseng polysaccharide. Therefore, an effective supplement plan for piglet mortality reduction must consider the circumstances of the individual system and target one or more of the highlighted parameters.

Loss of Nitric Oxide Induces Fibrogenic Response in Organotypic 3D Co-Culture of Mammary Epithelia and Fibroblasts-An Indicator for Breast Carcinogenesis

Simple Summary

Fibrosis, which is often caused by chronic diseases and environmental substances, is closely associated with cancer. Thus, the development of a robust method allowing for deep studies of the linkage between fibrosis and cancer is essential. Here, we tested whether our novel three-dimensional (3D) co-culture of breast epithelia and fibroblasts would be a suitable model for that purpose. We compared the phenotypic effects of L-NAME, an inhibitor of nitric oxide (NO) production, on 3D mono- and co-cultures. We previously reported that prolonged NO depletion with L-NAME caused fibrosis and tumorigenesis in mouse mammary glands. Such in vivo effects of L-NAME were well recapitulated in 3D co-cultures, but not in 3D mono-cultures of epithelia and fibroblasts. These results support not only the essential roles of the presence of the stroma in cancer development, but also the utility of this co-culture in studying the causal relationship between fibrosis and cancer.

Abstract

Excessive myofibroblast activation, which leads to dysregulated collagen deposition and the stiffening of the extracellular matrix (ECM), plays pivotal roles in cancer initiation and progression. Cumulative evidence attests to the cancer-causing effects of a number of fibrogenic factors found in the environment, diseases and drugs. While identifying such factors largely depends on epidemiological studies, it would be of great importance to develop a robust in vitro method to demonstrate the causal relationship between fibrosis and cancer. Here, we tested whether our recently developed organotypic three-dimensional (3D) co-culture would be suitable for that purpose. This co-culture system utilizes the discontinuous ECM to separately culture mammary epithelia and fibroblasts in the discrete matrices to model the complexity of the mammary gland. We observed that pharmaceutical deprivation of nitric oxide (NO) in 3D co-cultures induced myofibroblast differentiation of the stroma as well as the occurrence of epithelial–mesenchymal transition (EMT) of the parenchyma. Such in vitro response to NO deprivation was unique to co-cultures and closely mimicked the phenotype of NO-depleted mammary glands exhibiting stromal desmoplasia and precancerous lesions undergoing EMT. These results suggest that this novel 3D co-culture system could be utilized in the deep mechanistic studies of the linkage between fibrosis and cancer.

Arginine Alters miRNA Expression Involved in Development and Proliferation of Rat Mammary Tissue

Simple Summary

MiRNAs are small noncoding RNAs that regulate a variety of developmental and physiological processes, with many having well-defined developmental and cell-type specific expression patterns. Aspects of the cell cycle such as cell differentiation, proliferation and apoptosis can be regulated by miRNA, underscoring an unexplored link between arginine supply and mammary tissue function during lactation. The specific objective of the present study was to determine miRNA profiles in mammary tissue at the end of lactation in response to enhanced dietary supply of arginine. Our results indicate that arginine may potentially be involved in the development of rat mammary glands through miRNA.

Abstract

This study was designed to determine the effects of dietary arginine on development and proliferation in rat mammary tissue through changes in miRNA profiles. Twelve pregnant Wistar rats were allocated randomly to two groups. A basal diet containing arginine or the control diet containing glutamate on an equal nitrogen basis as the arginine supplemented diet were used. The experiment included a pre-experimental period of four days before parturition and an experimental period of 17 days after parturition. Mammary tissue was collected for histology, RNA extraction and high-throughput sequencing analysis. The greater mammary acinar area indicated that arginine supplementation enhanced mammary tissue development (p < 0.01). MicroRNA profiling indicated that seven miRNA (miR-206-3p, miR-133a-5p, miR-133b-3p, miR-1-3p, miR-133a-3p, miR-1b and miR-486) were differentially expressed in response to Arginine when compared with the glutamate-based control group. In silico gene ontology enrichment and KEGG pathway analysis revealed between 240 and 535 putative target genes among the miRNA. Further verification by qPCR revealed concordance with the differential expression from the sequencing results: 17 of 28 target genes were differentially expressed (15 were highly expressed in arginine and 2 in control) and 11 target genes did not have significant difference in expression. In conclusion, our study suggests that arginine may potentially regulate the development of rat mammary glands through regulating miRNAs.

Interorgan Metabolism of Amino Acids in Human Health and Disease

Amino acids are integral for human health, influencing an array of physiological processes from gene expression to vasodilation to the immune response. In accordance with this expansive range of unique functions, the tissues of the body engage in a complex interplay of amino acid exchange and metabolism to respond to the organism's dynamic needs for a range of nitrogenous products. Interorgan amino acid metabolism is required for numerous metabolic pathways, including the synthesis of functional amino acids like arginine, glutamate, glutamine, and glycine. This physiological process requires the cooperative handling of amino acids by organs (e.g., the small intestine, skeletal muscle, kidneys, and liver), as well as the complete catabolism of nutritionally essential amino acids such as the BCAAs, with their α-ketoacids shuttled from muscle to liver. These exchanges are made possible by several mechanisms, including organ location, as well as the functional zonation of enzymes and the cell-specific expression of amino acid transporters. The cooperative handling of amino acids between the various organs does not appear to be under the control of any centralized regulation, but is instead influenced by factors such as fluctuations in nutrient availability, hormones, changes associated with development, and altered environmental factors. While the normal function of these pathways is associated with health and homeostasis, affected by physical activity, diet and body composition, dysregulation is observed in numerous disease states, including cardiovascular disease and cancer cachexia, presenting potential avenues for the manipulation of amino acid consumption as part of the therapeutic approach to these conditions in individuals.

Effects of mineral methionine hydroxy analog chelate in sow diets on epigenetic modification and growth of progeny

The study was conducted to determine the effects of mineral methionine hydroxy analog chelate (MMHAC) partially replacing inorganic trace minerals in sow diets on epigenetic and transcriptional changes in the muscle and jejunum of progeny. The MMHAC is zinc (Zn), manganese (Mn), and copper (Cu) chelated with methionine hydroxy analog (Zn-, Mn-, and Cu-methionine hydroxy analog chelate [MHAC]). On day 35 of gestation, 60 pregnant sows were allotted to two dietary treatments in a randomized completed block design using parity as a block: 1) ITM: inorganic trace minerals with zinc sulfate (ZnSO₄), manganese oxide (MnO), and copper sulfate (CuSO₄) and 2) CTM: 50% of ITM was replaced with MMHAC (MINTREX trace minerals, Novus International Inc., St Charles, MO). Gestation and lactation diets were formulated to meet or exceed NRC requirements. On days 1 and 18 of lactation, milk samples from 16 sows per treatment were collected to measure immunoglobulins (immunoglobulin G, immunoglobulin A, and immunoglobulin M) and micromineral concentrations. Two pigs per litter were selected to collect blood to measure the concentration of immunoglobulins in the serum, and then euthanized to collect jejunal mucosa, jejunum tissues, and longissimus muscle to measure global deoxyribonucleic acid methylation, histone acetylation, cytokines, and jejunal histomorphology at birth and day 18 of lactation. Data were analyzed using Proc MIXED of SAS. Supplementation of MMHAC tended to decrease (P = 0.059) body weight (BW) loss of sows during lactation and tended to increase (P = 0.098) piglet BW on day 18 of lactation. Supplementation of MMHAC increased (P < 0.05) global histone acetylation and tended to decrease myogenic regulatory factor 4 messenger ribonucleic acid (mRNA; P = 0.068) and delta 4-desaturase sphingolipid1 (DEGS1) mRNA (P = 0.086) in longissimus muscle of piglets at birth. Supplementation of MMHAC decreased (P < 0.05) nuclear factor kappa B mRNA in the jejunum and DEGS1 mRNA in longissimus muscle and tended to decrease mucin-2 (MUC2) mRNA (P = 0.057) and transforming growth factor-beta 1 (TGF-β1) mRNA (P = 0.057) in the jejunum of piglets on day 18 of lactation. There were, however, no changes in the amounts of tumor necrosis factor-alpha, interleukin-8, TGF-β, MUC2, and myogenic factor 6 in the tissues by MMHAC. In conclusion, maternal supplementation of MMHAC could contribute to histone acetylation and programming in the fetus, which potentially regulates intestinal health and skeletal muscle development of piglets at birth and weaning, possibly leading to enhanced growth of their piglets.

Distinct maternal amino acids and oxylipins predict infant fat mass and fat-free mass indices

Interested in maternal determinants of infant fat mass index (FMI) and fat-free mass index (FFMI), considered as predictors for later development of obesity, we analysed amino acids (AA) and oxylipins in maternal serum and breast milk (BM). FMI and FFMI were calculated in 47 term infants aged 4 months (T4). Serum AA were analysed in pregnancy (T1, T2) and 6-8 weeks postpartum (T3). At T3, AA and oxylipins were analysed in BM. Biomarker-index-associations were identified by regression analysis. Infant FMI (4.1 ± 1.31 kg/m²; MW ± SD) was predicted by T2 proline (R² adj.: 7.6%, p = .036) and T3 BM 11-hydroxy-eicosatetraenoic-acid (11-HETE) and 13-hydroxy-docosahexaenoic-acid (13-HDHA; together:35.5% R² adj., p < .001). Maternal peripartum antibiotics (AB) emerged as confounders (+AB: 23.5% higher FMI; p = .025). Infant FFMI (12.1 ± 1.19 kg/m²; MW ± SD) was predicted by histidine (R² adj.: 14.5%, p < .001) and 17-HDHA (BM, R² adj.:19.3%, p < .001), determined at T3. Confirmed in a larger cohort, the parameters could elucidate connections between maternal metabolic status, nutrition, and infant body development.

Transcriptome Analysis Reveals the Potential Role of Long Non-coding RNAs in Mammary Gland of Yak During Lactation and Dry Period

The mammary gland is a remarkably dynamic organ of milk synthesis and secretion, and it experiences drastic structural and metabolic changes during the transition from dry periods to lactation, which involves the expression and regulation of numerous genes and regulatory factors. Long non-coding RNA (lncRNA) has considered as a novel type of regulatory factors involved in a variety of biological processes. However, their role in the lactation cycle of yak is still poorly understood. To reveal the involved mechanism, Ribo-zero RNA sequencing was employed to profile the lncRNA transcriptome in mammary tissue samples from yak at two physiological stages, namely lactation (LP) and dry period (DP). Notably, 1,599 lncRNA transcripts were identified through four rigorous steps and filtered through protein-coding ability. A total of 59 lncRNAs showed significantly different expression between two stages. Accordingly, the results of qRT-PCR were consistent with that of the transcriptome data. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated that target genes of differentially expressed lncRNAs (DELs) were involved in pathways related to lactation, such as ECM-receptor interaction, PI3K-Akt signaling pathway, biosynthesis of amino acids and focal adhesion etc. Finally, we constructed a lncRNA-gene regulatory network containing some well known candidate genes for milk yield and quality traits. This is the first study to demonstrate a global profile of lncRNA expression in the mammary gland of yak. These results contribute to a valuable resource for future genetic and molecular studies on improving milk yield and quality, and help us to gain a better understanding of the molecular mechanisms underlying lactogenesis and mammary gland development of yak.

Transcriptomic study of yak mammary gland tissue during lactation

Yak milk, a high-quality milk, is one of the best raw materials for dairy products and economically important to pastoral herdsmen. To make a further understanding of the molecular differences in mammary tissues of the yaks with different milk production during lactation, in this study, we took the use of RNA-seq to perform high-throughput sequencing and analysis of the mammary gland transcriptomes of both high-yielding yak and low-yielding yaks during lactation. By the comparison and analysis of the transcriptome data for the mammary gland tissue of high-yielding yak and low-yield yak, 144 differential genes were screened out, of which 49 were upregulated and 95 were downregulated. Further functional analysis indicated that these differential genes involved in multiple classes based on Gene Ontology (GO) and multiple Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The GO analysis showed that the functions of the differential genes are closely related to the carbohydrate metabolism and other biological processes. KEGG pathway analysis revealed that these genes are mostly enriched in the pathway of antigen processing and presentation, phagosome pathway and type I diabetes pathway and enriched followed by extracellular matrix receptor interaction pathway. Moreover, several other pathways related to amino acid metabolism also showed significant enrichment. Here, the mammary gland transcriptomes of high-yielding yak and low-yielding yaks during lactation have for the first time been compared, and the related differential genes have been screened out and analyzed. Our study paves a way for the further elucidation of the basic molecular mechanism of yak mammary gland tissue, and at the same time provides new ideas for improving the milk production of yaks.

Arginine Supply Impacts the Expression of Candidate microRNA Controlling Milk Casein Yield in Bovine Mammary Tissue

Arginine, a semi-essential functional amino acid, has been found to promote the synthesis of casein in mammary epithelial cells to some extent. Data from mouse indicated that microRNA (miRNA) are important in regulating the development of mammary gland and milk protein synthesis. Whether there are potential links among arginine, miRNA and casein synthesis in bovine mammary gland is uncertain. The objective of the present work was to detect the effects of arginine supplementation on the expression of miRNA associated with casein synthesis in mammary tissue and mammary epithelial cells (BMEC). The first study with bovine mammary epithelial cells (BMEC) focused on screening for miRNA candidates associated with the regulation of casein production by arginine. The BMEC were cultured with three different media, containing 0, 1.6 and 3.2 mM arginine, for 24 h. The expression of candidate miRNA was evaluated. Subsequently, in an in vivo study, 6 Chinese Holstein dairy cows with similar BW (mean ± SE) (512.0 ± 19.6 kg), parity (3), BCS (4.0) and DIM (190 ± 10.3 d) were randomly assigned to three experimental groups. The experimental cows received an infusion of casein, arginine (casein plus double the concentration of arginine in casein), and alanine (casein plus alanine, i.e., iso-nitrogenous to the arginine group) in a replicated 3 × 3 Latin square design with 22 d for each period (7 d for infusion and 15 d for washout). Mammary gland biopsies were obtained from each cow at the end of each infusion period. Results of the in vitro study showed differences between experimental groups and the control group for the expression of nine miRNA: miR-743a, miR-543, miR-101a, miR-760-3p, miR-1954, miR-712, miR-574-5p, miR-468 and miR-875-3p. The in vivo study showed that arginine infusion promoted milk protein content, casein yield and the expression of CSN1S1 and CSN1S2. Furthermore, the expression of miR-743a, miR-543, miR-101a, miR-760-3p, miR-1954, and miR-712 was also greater in response to arginine injection compared with the control or alanine group. Overall, results both in vivo and in vitro revealed that arginine might partly influence casein yield by altering the expression of 6 miRNAs (miR-743a, miR-543, miR-101a, miR-760-3p, miR-1954, and miR-712).

Estimation of Dietary Amino Acid Intake and Independent Correlates of Skeletal Muscle Mass Index among Korean Adults

The aim of this study was to develop a database to identify dietary amino acid intake levels, and to determine whether any amino acid groups were independently correlated with skeletal muscle mass index (SMI). We used data from the Korea National Health and Nutrition Examination Survey 2008–2011, and a total of 3292 participants aged 50–64 years were included in the analysis. Dietary data were obtained using the 24 h recall method. Data regarding dietary amino acid intake was assessed using the computer-aided nutritional analysis program 4.0 published by the Korean Nutrition Society. Multivariate linear regression analysis was used to identify independent correlates of SMI. The major food group that contributed the highest essential amino acid intake was grain and grain products (histidine 25.5%, isoleucine 43.9%, leucine 44.2%, methionine 31.0%, phenylalanine 44.8%, tryptophan 26.4%, and valine 50.8%). Higher SMI was independently associated with sex (men), lower age and body mass index, higher levels of physical activity, and a higher intake of energy and branched-chain amino acids. These results are expected to be used as a basis for developing dietary amino acid intake guidelines for Koreans.

Dynamic changes in circulating levels of metabolites in the portal-drained viscera of finishing pigs receiving acute administration of l-arginine

In this study, we examined the effects of acute intravenous administration of l-arginine on circulating levels of metabolites in the portal-drained viscera (PDV) of 12 barrows surgically fitted with chronic catheters in the portal vein. At day 14 post-surgery, the pigs were fasted for 12 hr and then randomly allocated to one of three groups to receive administration of normal saline, l-alanine [103 mg/kg body weight (BW), isonitrogenous control] or l-arginine-HCl (61 mg/kg BW), via the portal vein. Blood samples were obtained from the carotid artery before and at 30-min intervals for 5 hr after the administration of saline or amino acid in order to determine metabolic profiles. The results showed that, compared with the saline treatment, arginine infusion increased plasma concentrations of insulin-like growth factor-I, arginine and cystine in the portal vein plasma, whereas plasma concentrations of threonine, serine, leucine and methionine were reduced. These findings indicate that increasing arginine concentrations in the portal vein alters the metabolic profile in swine, an established animal model for studying human nutrition and metabolism.

Amino acid transportation, sensing and signal transduction in the mammary gland: key molecular signalling pathways in the regulation of milk synthesis

The mammary gland, a unique exocrine organ, is responsible for milk synthesis in mammals. Neonatal growth and health are predominantly determined by quality and quantity of milk production. Amino acids are crucial maternal nutrients that are the building blocks for milk protein and are potential energy sources for neonates. Recent advances made regarding the mammary gland further demonstrate that some functional amino acids also regulate milk protein and fat synthesis through distinct intracellular and extracellular pathways. In the present study, we discuss recent advances in the role of amino acids (especially branched-chain amino acids, methionine, arginine and lysine) in the regulation of milk synthesis. The present review also addresses the crucial questions of how amino acids are transported, sensed and transduced in the mammary gland.

Relationship between energy balance and metabolic profiles in plasma and milk of dairy cows in early lactation

Negative energy balance in dairy cows in early lactation is related to alteration of metabolic status. However, the relationships among energy balance, metabolic profile in plasma, and metabolic profile in milk have not been reported. In this study our aims were: (1) to reveal the metabolic profiles of plasma and milk by integrating results from nuclear magnetic resonance (NMR) with data from liquid chromatography triple quadrupole mass spectrometry (LC-MS); and (2) to investigate the relationship between energy balance and the metabolic profiles of plasma and milk. For this study 24 individual dairy cows (parity 2.5 ± 0.5; mean ± standard deviation) were studied in lactation wk 2. Body weight (mean ± standard deviation; 627.4 ± 56.4 kg) and milk yield (28.1 ± 6.7 kg/d; mean ± standard deviation) were monitored daily. Milk composition (fat, protein, and lactose) and net energy balance were calculated. Plasma and milk samples were collected and analyzed using LC-MS and NMR. From all plasma metabolites measured, 27 were correlated with energy balance. These plasma metabolites were related to body reserve mobilization from body fat, muscle, and bone; increased blood flow; and gluconeogenesis. From all milk metabolites measured, 30 were correlated with energy balance. These milk metabolites were related to cell apoptosis and cell proliferation. Nine metabolites detected in both plasma and milk were correlated with each other and with energy balance. These metabolites were mainly related to hyperketonemia; β-oxidation of fatty acids; and one-carbon metabolism. The metabolic profiles of plasma and milk provide an in-depth insight into the physiological pathways of dairy cows in negative energy balance in early lactation. In addition to the classical indicators for energy balance (e.g., β-hydroxybutyrate, acetone, and glucose), the current study presents some new metabolites (e.g., glycine in plasma and milk; kynurenine, panthothenate, or arginine in plasma) in lactating dairy cows that are related to energy balance and may be of interest as new indicators for energy balance.

Valine supplementation during late pregnancy in gilts increases colostral protein synthesis through stimulating mTOR signaling pathway in mammary cells

Mammary gland development during late pregnancy in sows is a major factor affecting the composition of colostrum and milk and the pre-weaning growth of piglets, while valine is essential for protein and nitrogen metabolism in mammary gland of sow. However, the effects of valine and its underlying mechanism on mammary gland development during late pregnancy are still unclear. Here, we hypothesized that dosage of dietary valine during late pregnancy will affect protein synthesis of colostrum in gilts. The results showed that supplementation of valine during late pregnancy significantly increased content of protein (P < 0.01), fat (P = 0.02) and solids-non-fat (P = 0.04) in colostrum. Our in vitro study also confirmed that valine supplementation increased protein synthesis and cell proliferation in porcine mammary epithelial cells (PMEC). Furthermore, these changes were associated with elevated phosphorylation levels of mammalian target of rapamycin (mTOR), and ribosomal protein S6 kinase (S6) and eukaryotic initiation factor 4E-binding protein-1 (4EBP1) in valine-supplemented cells, which could be effectively blocked by the antagonists of mTOR. These findings indicated that valine enhanced mammary gland development and protein synthesis in colostrum via the mTOR signaling pathway. These results, using an in vivo and in vitro model, helped to understand the beneficial effects of dietary valine supplementation on gilts.

Oxidative stress status and reproductive performance of sows during gestation and lactation under different thermal environments

Objective

Two experiments were conducted using 28 healthy multiparous sows to evaluate the oxidative stress status and reproductive performance of sows during gestation and lactation under different thermal environments.

Methods

Fourteen multiparous sows were used in Exp. 1 under a high thermal environment, and the other 14 multiparous sows were used in Exp. 2 under a moderate thermal environment. In both experiments, reproductive performances of sows were recorded. Plasma samples were collected on d 35, 60, 90, and 109 of gestation, and d 1 and 18 of lactation for malondialdehyde, protein carbonyls, 8-hydroxy-deoxyguanosine, immunoglobulin g (IgG), and IgM analysis.

Results

For sows in Exp. 1, plasma malondialdehyde concentration on d 109 of gestation tended to be greater (p<0.05) than it on d 18 of lactation. Plasma concentration of protein carbonyl on d 109 of gestation was the greatest (p<0.05) compared with all the other days. Plasma concentrations of 8-hydroxy-deoxyguanosine on d 109 of gestation was greater (p< 0.05) than d 18 of lactation in Exp. 1. For sows in Exp. 2, there was no difference of malondialdehyde and protein carbonyl concentration during gestation and lactation. In both Exp. 1 and 2, litter size and litter weight were found to be negatively correlated with oxidative stress indicators.

Conclusion

Sows under a high thermal environment had increased oxidative stress during late gestation indicating that increased oxidative damage to lipid, protein, and DNA could be one of the contributing factors for reduced reproductive performance of sows in this environment. This study indicates the importance of providing a moderate thermal environment to gestating and lactating sows to minimize the increase of oxidative stress during late gestation which can impair reproductive outcomes.

Profiling solute-carrier transporters in key metabolic tissues during the postpartum evolution of mammary epithelial cells from nonsecretory to secretory

Modifications in the abundance of solute-carrier (SLC) transcripts in tandem with adjustments in genes-associated with energy homeostasis during the postpartum transition of the mammary epithelial cells (MEC) from nonsecretory to secretory is pivotal for supporting milk synthesis. The goal of this study was to identify differentially expressed SLC genes across key metabolic tissues between late pregnancy and onset of lactation. Total RNA was isolated from the mammary, liver, and adipose tissues collected from rat dams on day 20 of pregnancy (P20) and day 1 of lactation (L1) and gene expression was measured with Rat 230 2.0 Affymetrix GeneChips. LIMMA was utilized to identify the differential gene expression patterns between P20 and L1 tissues. Transcripts engaged in conveying anions, cations, carboxylates, sugars, amino acids, metals, nucleosides, vitamins, and fatty acids were significantly increased (P < 0.05) in MEC during the P20 to L1 shift. Downregulated (P < 0.05) genes in the mammary during the physiological transition included GLUT8 and SLC45a3. In the liver, SLC genes encoding for anion, carbonyl, and nucleotide sugar transporters were upregulated (P < 0.05) at L1. while genes facilitating transportation of anions and hexose were increased (P < 0.05), from P20 to L1 in the adipose tissue. GLUT1 and GLUT4 in the liver, along with GLUT4 and SGLT2 in the adipose tissue, were repressed (P < 0.05) at L1. Our results illustrate that MEC exhibit dynamic molecular plasticity during the nonsecretory to secretory transition and increase biosynthetic capacity through a coordinated tissue specific SLC transcriptome modification to facilitate substrate transfer.

Effects of tail docking and/or teeth clipping on behavior, lesions, and physiological indicators of sows and their piglets

To evaluate effects of tail docking and/or teeth clipping on sows and their piglets, a total of 24 sows and their 302 piglets at 3 days of age were randomly allocated to one of four treatments: teeth clipping and tail docking (TCTD), teeth clipping (TC), tail docking (TD), or intact teeth and tail (Intact). Behavior of piglets and sows, lesions on the body and tail of piglets and sows' teats were inspected. Heart rates of processed piglets were increased (p < .01) during the procedures. Teeth clipping decreased body surface temperature (p < .01) of piglets during and after the procedures but tail docking did not (p > .01). Processed piglets spent more (p < .05) time lying alone and playing/fighting than sham-processed piglets. Tail docked piglets spent less (p < .01) time standing than tail sham-docked piglets. Intact teeth increased (p < .05) the avoidance behaviors of sows. Teeth clipping decreased (p < .05) the lesion scores on the anterior, middle, and posterior teats. Taken together, piglet teeth clipping had more impact on sows and their piglets than tail docking did in the lactation period based on our findings.

Identification of the association between FABP4 gene polymorphisms and milk production traits in Sfakia sheep

The aim of this study was to estimate the effect of variation in the fatty acid binding protein 4 gene (FABP4) on milk production traits in Greek Sfakia sheep. Polymerase chain reaction – single-stranded conformational polymorphism (PCR-SSCP) analysis was used to genotype a total of 374 Sfakia ewes for two regions of FABP4 located around exon 2–intron 2 (Region 1) and exon 3–intron 3 (Region 2). Each month, for a period of 6 months, milk samples were collected from the ewes to measure total milk yield, fat content, protein content, lactose content, non-fat solid content, pH, and somatic cell count (SCC). A general linear model was used to test the association between the variation observed in FABP4 and milk production traits. Four gene variants (A1–A4) were found in Region 1 and two variants (C1–C2) were found in Region 2. In the first region, the FABP4 genotype significantly affected (P<0.05) non-fat solid levels, fat content, and SCC. The presence of the A2 variant was significantly associated (P<0.05) with decreased SCC, while the presence of A4 was significantly associated with decreased milk yield (P<0.01), increased non-fat solid content (P<0.05), decreased fat content (P<0.01), increased lactose content (P<0.05), and increased pH (P<0.05). In the second region, FABP4 genotype had an effect (P<0.05) on protein content and the presence of the C2 variant was associated (P<0.05) with increased protein content, decreased SCC, and lower pH. The results suggest an association between variation in ovine FABP4 and milk production traits in Greek Sfakia sheep. Nevertheless, further analyses in independent sheep populations of increased size will strengthen these findings.

Reduced Basal Nitric Oxide Production Induces Precancerous Mammary Lesions via ERBB2 and TGFβ

One third of newly diagnosed breast cancers in the US are early-stage lesions. The etiological understanding and treatment of these lesions have become major clinical challenges. Because breast cancer risk factors are often linked to aberrant nitric oxide (NO) production, we hypothesized that abnormal NO levels might contribute to the formation of early-stage breast lesions. We recently reported that the basal level of NO in the normal breast epithelia plays crucial roles in tissue homeostasis, whereas its reduction contributes to the malignant phenotype of cancer cells. Here, we show that the basal level of NO in breast cells plummets during cancer progression due to reduction of the NO synthase cofactor, BH₄, under oxidative stress. Importantly, pharmacological deprivation of NO in prepubertal to pubertal animals stiffens the extracellular matrix and induces precancerous lesions in the mammary tissues. These lesions overexpress a fibrogenic cytokine, TGFβ, and an oncogene, ERBB2, accompanied by the occurrence of senescence and stem cell-like phenotype. Consistently, normalization of NO levels in precancerous and cancerous breast cells downmodulates TGFβ and ERBB2 and ameliorates their proliferative phenotype. This study sheds new light on the etiological basis of precancerous breast lesions and their potential prevention by manipulating the basal NO level.

Decreased plasma l-arginine levels in organic acidurias (MMA and PA) and decreased plasma branched-chain amino acid levels in urea cycle disorders as a potential cause of growth retardation: Options for treatment

BACKGROUND AND AIM

Patients with methylmalonic acidemia (MMA) and propionic acidemia (PA) and urea cycle disorders (UCD), treated with a protein restricted diet, are prone to growth failure. To obtain optimal growth and thereby efficacious protein incorporation, a diet containing the essential and functional amino acids for growth is necessary. Optimal growth will result in improved protein tolerance and possibly a decrease in the number of decompensations. It thus needs to be determined if amino acid deficiencies are associated with the growth retardation in these patient groups. We studied the correlations between plasma L-arginine levels, plasma branched chain amino acids (BCAA: L-isoleucine, L-leucine and L-valine) levels (amino acids known to influence growth), and height in MMA/PA and UCD patients.

METHODS

We analyzed data from longitudinal visits made in stable metabolic periods by patients registered at the European Registry and Network for Intoxication Type Metabolic Diseases (E-IMD, Chafea no. 2010 12 01).

RESULTS

In total, 263 MMA/PA and 311 UCD patients were included, all aged below 18 years of age. In patients with MMA and PA, height z-score was positively associated with patients' natural-protein-to-energy prescription ratio and their plasma L-valine and L-arginine levels, while negatively associated with the amount of synthetic protein prescription and their age at visit. In all UCDs combined, height z-score was positively associated with the natural-protein-to-energy prescription ratio. In those with carbamylphosphate synthetase 1 deficiency (CPS1-D), those with male ornithine transcarbamylase deficiency (OTC-D), and those in the hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome subgroup, height z-score was positively associated with patients' plasma L-leucine levels. In those with argininosuccinate synthetase deficiency (ASS-D) and argininosuccinate lyase deficiency (ASL-D), height was positively associated with patients' plasma L-valine levels.

CONCLUSION

Plasma L-arginine and L-valine levels in MMA/PA patients and plasma L-leucine and L-valine levels in UCD patients, as well as the protein-to-energy prescription ratio in both groups were positively associated with height. Optimization of these plasma amino acid levels is essential to support normal growth and increase protein tolerance in these disorders. Consequently this could improve the protein-to-energy intake ratio.

Comprehensive Preterm Breast Milk Metabotype Associated with Optimal Infant Early Growth Pattern

Early nutrition impacts preterm infant early growth rate and brain development but can have long lasting effects as well. Although human milk is the gold standard for feeding new born full-term and preterm infants, little is known about the effects of its bioactive compounds on breastfed preterm infants' growth outcomes. This study aims to determine whether breast milk metabolome, glycome, lipidome, and free-amino acids profiles analyzed by liquid chromatography-mass spectrometry had any impact on the early growth pattern of preterm infants. The study population consisted of the top tercile-Z score change in their weight between birth and hospital discharge ("faster grow", n = 11) and lowest tercile ("slower grow", n = 15) from a cohort of 138 premature infants (27⁻34 weeks gestation). This holistic approach combined with stringent clustering or classification statistical methods aims to discriminate groups of milks phenotype and identify specific metabolites associated with early growth of preterm infants. Their predictive reliability as biomarkers of infant growth was assessed using multiple linear regression and taking into account confounding clinical factors. Breast-milk associated with fast growth contained more branched-chain and insulino-trophic amino acid, lacto-N-fucopentaose, choline, and hydroxybutyrate, pointing to the critical role of energy utilization, protein synthesis, oxidative status, and gut epithelial cell maturity in prematurity.

Regulation of protein synthesis in porcine mammary epithelial cells by L-valine

This study was conducted to determine the catabolism of L-valine in porcine mammary epithelial cells (PMECs) and its role in stimulating protein synthesis in these cells. PMECs were incubated with 0.05-, 0.10-, 0.25-, 0.5-, and 1.0-mM L-valine at 37 ^oC for 2 h. Cell viability and expressions of α-lactalbumin and β-casein were measured after culture with L-valine for 3 days. L-[1-¹⁴C]valine was used to study valine catabolism, whereas [³H]phenylalanine was employed as a tracer to determine protein synthesis and degradation in PMECs. The abundances of proteins involved in the mTOR signaling pathway and the mRNA levels for the related key genes were determined using the western blot and RT-PCR techniques, respectively. Cell numbers and the synthesis of proteins (including α-lactalbumin and β-casein) were greater (P < 0.05) in the presence of 0.5-mM L-valine, compared with 0.05- or 0.1-mM L-valine. L-Valine at 0.5 mM also enhanced (P < 0.05) the production of α-lactalbumin by PMECs, in comparison with 0.25 mM L-valine. Increasing the extracellular concentration of L-valine from 0.05 to 0.5 mM stimulated protein synthesis in a concentration-dependent manner without affecting proteolysis. Although L-valine was actively transaminated in PMECs, its α-ketoacid product (α-ketoisovalerate) at 0.05-0.2 mM did not affect protein synthesis or degradation in the cells. Thus, the effect of L-valine on protein synthesis was independent of its metabolism to yield α-ketoisovalerate. At the molecular level, 0.5-mM L-valine increased (P < 0.05) the mRNA levels for Ras, ERK1/2, and p70S6K, and the abundances of mTOR, p-4EBP1, total 4EBP1, p-ERK1/2, and total ERK1/2 proteins. These findings establish the critical role of L-valine in enhancing PMEC growth and milk protein synthesis possibly by regulating the mTOR and Ras/ERK signaling pathways. Further studies are warranted to understand how L-valine regulates gene expression and mTOR activation in PMECs.

BOARD-INVITED REVIEW: Arginine nutrition and metabolism in growing, gestating, and lactating swine

Arginine (Arg) has traditionally not been considered as a deficient nutrient in diets for gestating or lactating swine due to the assumption that these animals can synthesize sufficient amounts of Arg to meet their physiological needs. The lack of full knowledge about Arg nutrition has contributed to suboptimal efficiency of pork production. Over the past 25 yr, there has been growing interest in Arg metabolism in the pig, which is an agriculturally important species and a useful model for studying human biology. Arginine is a highly abundant amino acid in tissues of pigs, a major amino acid in allantoic fluid, and a key regulator of gene expression, cell signaling, and antioxidative reactions. Emerging evidence suggests that dietary supplementation with 0.5% to 1% Arg maintains gut health and prevents intestinal dysfunction in weanling piglets, while enhancing their growth performance and survival. Also, the inclusion of 1% Arg in diets is required to maximize skeletal muscle accretion and feed efficiency in growing pigs, whereas dietary supplementation with 1% Arg reduces muscle loss in endotoxin-challenged pigs. Furthermore, supplementing 0.83% Arg to corn- and soybean meal-based diets promotes embryonic/fetal survival in swine and milk production by lactating sows. Thus, an adequate amount of dietary Arg as a quantitatively major nutrient is necessary to support maximum growth, lactation, and reproduction performance of swine. These results also have important implications for improving the nutrition and health of humans and other animals.

Parenteral administration of l-arginine to twin-bearing Romney ewes during late pregnancy is associated with reduced milk somatic cell count during early lactation

Maternal milk is the primary source of nutrition for suckling mammals, and its yield and composition are important determinants of survival during the early neonatal period. The objective of this study was to examine whether parenteral administration of l-Arg to twin-bearing ewes, during mid to late pregnancy, influenced prepartum maternal mammary gland development and subsequent lactation performance in the early postpartum period (14 d). At 80 d of pregnancy, multiparous Romney ewes were housed indoors in group pens, split into 2 cohorts, and fed a lucerne-based pellet diet, formulated to meet 100% of National Research Council-recommended requirements for twin-bearing pregnant ewes, once a day. Cohort 1 was administered l-Arg (72.7 mg/kg of live weight via i.v, 3 times a day) from d 100 of pregnancy until d 140. At d 140, ewes were euthanized and maternal mammary tissues were collected for analysis of the biochemical indices total DNA, RNA, protein, protein synthetic efficiency (protein:RNA), cell size (protein:DNA), transcriptional efficiency (RNA:DNA), and the abundance of mammalian target of rapamycin (mTOR) and mTOR^Ser2448 protein. Cohort 2 was administered an identical l-Arg regimen as cohort 1, but from d 100 until parturition. Milk was collected over a 14-d period (d 1, 4, 7, 10, and 14) to assess milk yield and composition. In cohort 1, total mammary DNA (cell number) tended to be higher in l-Arg ewes, with no change in total mammary RNA or protein content, biochemical indices of protein synthetic efficiency, cell size or transcriptional efficiency, or mTOR protein abundance or phosphorylation. In cohort 2, milk composition analysis from l-Arg ewes showed lower (d 7-14) milk somatic cell counts, greater crude protein percentage from d 7 to 10 but lower at d 14, and altered absolute concentrations of some free AA (d 7 and 14) compared with controls. We propose that parenteral administration of l-Arg during late pregnancy is associated with increased mammary gland cellular content and decreased somatic cell counts during early lactation.

Metabolism, Nutrition, and Redox Signaling of Hydroxyproline

SIGNIFICANCE

Hydroxyproline is a structurally and physiologically important imino acid in animals. It is provided from diets and endogenous synthesis, and its conversion into glycine enhances the production of glutathione, DNA, heme, and protein. Furthermore, oxidation of hydroxyproline by hydroxyproline oxidase (OH-POX) plays an important role in cell antioxidative reactions, survival, and homeostasis. Understanding the mechanisms whereby hydroxyproline participates in metabolism and cell signaling can improve the nutrition and health of animals and humans. Recent Advances: Hydroxyproline is highly abundant in milk and is utilized for renal synthesis of glycine to support neonatal growth, development, and survival. The oxidation of hydroxyproline by mitochondrial OH-POX generates reactive oxygen species (ROS). Enhanced ROS production contributes to the regulation of oxidative defense, apoptosis, angiogenesis, tumorigenesis, hypoxic responses, and cell survival in animals.

CRITICAL ISSUES

Although dietary hydroxyproline enters the portal circulation, its utilization by the portal-drained viscera is unknown. Pathways for hydroxyproline metabolism and their regulation at the molecular, cellular, and whole-body levels remain to be defined. Furthermore, the mechanisms responsible for hydroxyproline-derived ROS and related metabolites to induce cell survival or apoptosis are unknown.

FUTURE DIRECTIONS

Interorgan metabolism of hydroxyproline (including synthesis, catabolism, and flux) in animals must be quantified using isotope technologies. Efforts should also be directed toward studying dietary, hormonal, and epigenetic regulation of OH-POX expression at transcriptional and translational levels. Another emerging research need is to understand the roles of cellular redox and signaling networks involving both ROS and Δ¹-pyrroline-3-hydroxy-5-carboxylate in nutrition, health, and disease.

Role of Maternal Dietary Protein and Amino Acids on Fetal Programming, Early Neonatal Development, and Lactation in Swine

Simple Summary

Dietary protein is an important nutrient source for sows, necessary for not only growth and production, but also other physiological functions. Protein limitations in maternal diets have the potential to impair fetal myogenesis, while excess maternal dietary protein appears to only have minor effects on early fetal muscle formation. Effects of maternal protein deficiency on increased fat deposition in porcine neonates is inconsistent with gene expressions in the neonates. Sufficient maternal dietary protein can enhance porcine milk protein and fat concentration. Understanding the function of protein and amino acids in sows and the effects on their offspring can provide rational approaches for the regulation of piglet growth and further improvements in meat quality in the future.

Abstract

Maternal nutrition plays a vital role in fetal development, early development of neonates, and lactation and regulates the lifetime productivity of offspring. During pregnancy, maternal nutrition alters expression of the fetal genome and the development of tissues and organs via fetal programming. After parturition, maternal nutrition continues to regulate growth and development of piglets through maternal milk, which contains carbohydrates, lipids, proteins and oligosaccharides. Thus, deficiencies in maternal nutrition are detrimental to development of piglets, which can lead to inefficient growth and decreased carcass merit. Protein is an important nutritional component for sows, which not only functions in muscle development, but also plays a vital role in embryonic and neonatal development and lactation. Although effects of maternal undernutrition on neonatal development have been widely studied in sows, the function of different maternal dietary protein levels on fetal development, neonatal growth and lactation performance of sows is largely unknown. Determination of the effects and underlying mechanisms of maternal dietary protein levels on development of piglets is vital to the pork industry. Therefore, we summarized recent reports regarding mechanisms of effects of maternal protein levels on regulation of conceptus growth and early postnatal development though uterine fetal programming and lactation in swine.

L-Glutamate nutrition and metabolism in swine

L-Glutamate (Glu) has traditionally not been considered as a nutrient needed in diets for humans and other animals (including swine) due to the unsubstantiated assumption that animals can synthesize sufficient amounts of Glu to meet their needs. The lack of knowledge about Glu nutrition has contributed to suboptimal efficiency of global livestock production. Over the past 25 years, there has been growing interest in Glu metabolism in the pig, which is an agriculturally important species and also a useful model for studying human biology. Because of analytical advances in its analysis, Glu is now known to be a highly abundant free amino acid in milk and intracellular fluid, a major constituent of food and tissue proteins, and a key regulator of gene expression, cell signaling, and anti-oxidative reactions. Emerging evidence shows that dietary supplementation with 2% Glu maintains gut health and prevents intestinal dysfunction in weanling piglets, while enhancing their growth performance and survival. In addition, the inclusion of 2% Glu is required for dietary arginine to maximize the growth performance and feed efficiency in growing pigs, whereas dietary supplementation with 2% Glu reduces the loss of skeletal muscle mass in endotoxin-challenged pigs. Furthermore, supplementing 2% Glu to a corn- and soybean-meal-based diet promotes milk production by lactating sows. Thus, an adequate amount of dietary Glu as a quantitatively major nutrient is necessary to support maximum growth, development, and production performance of swine. These results also have important implications for improving the nutrition and health of humans and other animals.

l-arginine supplementation in sow diet during late gestation decrease stillborn piglet, increase piglet birth weight and increase immunoglobulin G concentration in colostrum

The fetal growth is rapid during the last trimester of gestation in sows and hence sow nutrition during this period is important for fetal growth and development. During the last decade, studies reported that l-arginine HCl supplementation during gestation increased sow and piglet performances. However, clinical studies concerning the association between l-arginine HCL supplementation and some neonatal piglet characteristics as well as colostrum and milk yield of sow are still lacking. The present study aims to determine the effect of l-arginine HCl supplementation in sow diet during late gestation on piglet characteristics at birth, colostrum consumption (CC), concentration of immunoglobulin G (IgG) in colostrum, milk yield, average daily gain at d 7 and 21 and piglet mortality at d 7 and 21 of life. In total, 166 sows were allocated into four groups, i.e., CON (n = 66), ARG-0.5 (n = 42), ARG-1.0 (n = 41) and ALA (n = 17). The sows in each group were fed with a conventional gestation diet (CON) or the same diet supplemented with 0.5% l-arginine HCl (ARG-0.5), 1.0% l-arginine HCl (ARG-1.0) or 1.7% l-alanine (ALA, isonitrogenous with ARG-1.0). The feeding protocol was carried out from 85 days of gestation until farrowing. The proportion of live-born piglets, piglet birth weight (BW_B), within-litter variation of BW_B, proportion of piglets with BW_B above 1.35 kg, proportion of growth-restricted piglets (defined as BW_B below 1.0 kg), blood oxygen saturation (SatO₂) and heart rate were determined in 2292 newborn piglets from 166 litters. Colostrum consumption of each individual piglets and the colostral concentration of IgG was determined. The milk yield between d 0-7 and 7-21 and relative backfat loss were estimated in each individual sow. The piglet mortality and body weight was determined at d 7 and 21 of life. On average, the number of piglet born alive per litter was 12.4. The proportion of stillborn piglets, piglets with BW_B above 1.35 kg and growth-restricted piglets were 6.9%, 62.7% and 14.0%, respectively. Piglet preweaning mortality at d 7 and 21 were 8.5% and 12.4%, respectively. Compared to the ALA group, ARG-0.5 increased the proportion of live-born piglets per litter (+9.8%, P < 0.001), reduced stillborn (-8.3%, P < 0.001) and tended to increase the proportion of piglets with BW_B above 1.35 kg (+6.4%, P = 0.08). Compared to the CON group, ARG-0.5 increased BW_B (+7.0%, P < 0.001), increased SatO₂ (+3%, P < 0.001) and reduced heart rate (-20%, P < 0.001) and tended to reduce the relative backfat loss (-4.4%, P = 0.06). No difference between ARG-1.0 and ARG-0.5 was observed among these traits. Other traits including within-litter variation of BW_B, growth-restricted piglets, average daily gain, piglets preweaning mortality and CC and milk yield were not affected by treatment (P > 0.05). The colostral concentration of IgG at 1 h after onset of farrowing in ARG-1.0 sows (116 mg/ml) was higher than CON, ARG-0.5 and ALA sows (85, 74 and 78 mg/ml, respectively; P < 0.05). In conclusions, dietary l-arginine HCl supplementation in late gestating sows favourably increased proportion of live-born piglets, BW_B, SatO₂ and IgG concentration in the sow colostrum.