A cell transcriptomic profile p ovides insights into adipocytes of porcine mammary gland across development

Background Studying the composition and developmental mechanisms in mammary gland is crucial for healthy growth of newborns. The mammary gland is inherently heterogeneous, and its physiological function dependents on the gene expression of multiple cell types. Most studies focused on epithelial cells, disregarding the role of neighboring adipocytes.Results Here, we constructed the largest transcriptomic dataset of porcine mammary gland cells thus far. The dataset captured 126,829 high-quality nuclei from physiological mammary glands across five developmental stages(d 90 of gestation, G90;d 0 after lactation, L0;d 20 after lactation, L20;2 d post natural involution, PI2;7 d post natural involution, PI7). Seven cell types were identified, including epithelial cells, adipocytes, endothelial cells, fibroblasts cells, immune cells, myoepithelial cells and precursor cells. Our data indicate that mammary glands at different developmental stages have distinct phenotypic and transcriptional signatures. During late gestation(G90), the differentiation and proliferation of adipocytes were inhibited. Meanwhile, partly epithelial cells were completely differentiated. Pseudo-time analysis showed that epithelial cells undergo three stages to achieve lactation, including cellular differentiation, hormone sensing, and metabolic activation. During lactation(L0 and L20), adipocytes area accounts for less than 0.5% of mammary glands. To maintain their own survival, the adipocyte exhibited a poorly differentiated state and a proliferative capacity. Epithelial cells initiate lactation upon hormonal stimulation. After fulfilling lactation mission, their undergo physiological death under high intensity lactation. Interestingly, the physiological dead cells seem to be actively cleared by immune cells via CCL21-ACKR4 pathway. This biological process may be an important mechanism for maintaining homeostasis of the mammary gland. During natural involution(PI2 and PI7), epithelial cell populations dedifferentiate into mesenchymal stem cells to maintain the lactation potential of mammary glands for the next lactation cycle.Conclusion The molecular mechanisms of dedifferentiation, proliferation and redifferentiation of adipocytes and epithelial cells were revealed from late pregnancy to natural involution. This cell transcriptomic profile constitutes an essential reference for future studies in the development and remodeling of the mammary gland at different stages.

Current status of outcome reporting in randomized controlled trials of traditional Chinese medicine for mammary gland hyperplasia: A systematic review

Objective:To assess outcome indicators in clinical trials and provide a reference for establishing a core outcome set to treat hyperplasia of mammary gland(HMG)with traditional Chinese medicine(TCM).Methods:Eight online databases were searched from their inception to December 31,2022,to assess outcomes reported in randomized controlled trials(RCTs)of HMG treated with TCM.The quality of the included studies was assessed according to the Cochrane Risk of Bias Assessment Tool.All outcomes were extracted,classified,and described.Results:A total of 8249 articles were initially retrieved.Of these,70 articles were eligible and involved 10618 participants with HMG.A total of 17 outcome indicators with a frequency of 271 times were involved and were collected according to six outcome domains.Conclusions:The core outcomes of RCTs of HMG treated with TCM are large and divergent.There are problems in evaluation standards,primary and secondary outcomes,TCM characteristic indicators,long-term prognosis,and standardization of reporting.It is recommended to strengthen the trial design and actively construct the core outcome sets with TCM characteristics for HMG.

The Effect of Administration of Rutin on Plasma Levels of Estrogen, Prolactin, Growth Hormone and Gene Expression of Their Receptors in Mammary Glands in Ovariectomized Rats

The development of mammary glands, endocrine hormone concentrations and the gene expression of related receptors were measured in ovariectomized virgin rats after adminstration of an estrogen-like plant extract, rutin. Thirty-two ovariectomized virgin Wistar rats were randomly assigned to 4 treatments with 8 animals each： gastric infusion of 2 mL normal saline per unovariectomized rat per day （Sham）, gastric infusion of 2 mL normal saline per ovariectomized rat per day （Ova）, gastric infusion of 60 mg rutin kg-1 body weight （BW） per ovariectomized rat per day （Ova＋Rut）, or intramuscular injection of 60 ug estradiol kg-1 BW per ovariectomized rat weekly （Ova＋Est）. Samples of blood and mammary glands were harvested to determine the levels of estrogen （E2）, prolactin （PRL） and growth hormone （GH）, and the gene expression of estrogen receptors （ER）, prolactin receptors （PRLR） and growth hormone receptors （GHR） with radioimmunoassy （RIA） and RT-PCR technology, respectively. The E2 concentration in plasma and gland tissues from the rats of Ovx＋Rut or Ovx＋Est was higher than that of Ovx （P〈0.05）, but the plasma E2 concentration from the rats of Ovx＋Rut was lower than that of Sham （P〈0.05）. The order of the PRL concentration in plasma and gland tissues was Ovx〈Ovx＋Rut〈Ovx＋Est 〈Sham, and the difference in each treatment （P〈0.05）. The plasma GH concentration was lower in Ovx than in Ovx＋Rut or Ovx＋Est, and lower in Ovx＋Rut than in Sham （P〈0.05）. The GH concentration in gland tissues was lower in Ovx than in Ovx＋Rut or Ovx＋Est （P〈0.05）, and lower in Ovx＋Rut than in Sham （P〈0.05）. The gene expression of ER in gland tissues was increased in an order as Ovx〈Ovx＋Rut〈Ovx＋Est〈Sham （P〈0.05）, and PRLR, GHR showed the same trend. In conclusion, adminstration of rutin increased the E2 concentration in plasma and mammary glands, promoted pituitary PRL and GH release, up-regulated the gene expression of ER, PRLR and GHR, and stimulated mammary development in ovariectomized virgin rats.

AMPK-mTOR pathway is involved in glucose-modulated amino acid sensing and utilization in the mammary glands of lactating goats

Background:The local supply of energy-yielding nutrients such as glucose seems to affect the synthesis of milk components in the mammary gland(MG).Thus,our study was conducted to investigate the effects of locally available MG glucose supply(LMGS)on amino acid(AA)sensing and utilization in the MG of lactating dairy goats.Six dosages of glucose(0,20,40,60,80,and 100 g/d)were infused into the MG through the external pudendal artery to investigate the dose-dependent changes in mammary AA uptake and utilization(Exp.1)and the changes in mRNA and protein expression of the AMPK-mTOR pathway(Expt.2).Results:In Exp.1,total milk AA concentration was highest when goats were infused with 60 g/d glucose,but lower when goats were infused with 0 and 100 g/d glucose.Increasing LMGS quadratically changed the percentages ofαS2-casein andα-lactalbumin in milk protein,which increased with infusions from 0 to 60 g/d glucose and then decreased with infusions between 60 and 100 g/d glucose.The LMGS changed the AA availability and intramammary gland AA utilization,as reflected by the mammary AA flux indexes.In Exp.2,the mRNA expression of LALBA in the MG increased quadratically with increasing LMGS,with the highest expression at dose of 60 g/d glucose.A high glucose dosage(100 g/d)activated the general control nonderepressible 2 kinase,an intracellular sensor of AA status,resulting in a reduced total milk AA concentration.Conclusions:Our new findings suggest that the lactating MG in dairy goats may be affected by LMGS through regulation of the AA sensory pathway,AA utilization and protein synthesis,all being driven by the AMPK-mTOR pathway.

Differential Acupuncture Treatment of Hyperplasia of Mammary Glands

Hyperplasia of mammary glands is a common disease in the middle-aged women, and it is a precancerous lesion of mammary glands. For many years, the author has used Rugen (ST 18) of the Stomach Meridian of Foot-Yangming as the main point withcertain auxiliary points chosen on basis of the differentiation types to treat the disease and obtained satisfactory therapeutic effects. A report follows. ……

Detection of Progesterone Receptor as a Method of Diagnosing Mammary Cancer in Female Dogs

Introduction: Canine mammary gland tumor is the most common type of neoplasia in non-ovariectomized bitches. Approximately 50% of tumors are malignant. Neoplasms originating from the mammary gland represent the most common neoplastic disease in canines in Veterinary Medicine. Aim: Relate the expression of the receptor to progesterone (PR) with the tumor stage of canine mammary carcinoma. Material and Methods: Analytical-cross-sectional study, samples of paraffinized tumor tissue obtained from 30 canine patients with breast cancer were used. The expression of PR was performed by immunohistochemical labeling, using murine anti-PR (anti-PR Biocare brand). A descriptive analysis was carried out with the results using the SPSS program. Results: The predominant histological subtype of breast cancer was tubular carcinoma with 12 patients, followed by papillary cystic carcinoma with 6 patients, solid carcinoma 5, carcinosarcoma 4 and comedocarcinoma 3. There was a significant trend between breast cancer subtypes, histological grade G1. Among the histopathological findings, the degree of invasion is related to the presence of tumor cells in adjacent lymph nodes, which is why it is a prognostic indicator. The expression of PR in the tumor tissue samples it was 42.8% positive versus 57.14% negative, of which 75% correspond to G1, 8.3% to G2 and 16.6% to G3. With respect to the relationship of the expression of PR vs type of tumor, it was found that 50% correspond to tubular carcinoma, 33.3% to papillary cystic carcinoma, 8.3% to solid carcinoma and 8.3% to comedocarcinoma. Conclusion: The hormone receptor was negative in more than half of the patients and histological grade is significantly associated with tumor subtypes, this study emphasizes the need to introduce receptor testing into our routine clinical practice to offer the best treatment for breast cancer.

ELECTROACUPUNCTURE TREATMENT OF 30 CASES OF HYPERPLASIA OF MAMMARY GLANDS

In the present paper,30 cases of hyperplasia of mammary glands were treated withelectroacupuncture in different times following menstruation,showing satisfactory results.The totaleffective rate was up to 96.67％.In addition,the symptom of mastalgla abated abviously after treat-ment.

Comparative Expression Profiling of Lactogenic Hormone Receptor and It’s Signaling Molecules of Bovine Mammary Glands during lactation

Milk synthesis is known to be modulated by peptide hormones such as prolactin (PRL), growth hormone (GH), and insulin-like growth factor I (IGF-I). Previous studies suggested that PRL and IGF-I acted directly on mammary epithelial cells and were involved in lactation. Meanwhile, GH is thought to be indirectly involved in lactation by stimulating the secretion of IGF-I. It is controversial as growth hormone receptors (GHR) is expressed in the mammary epithelial cells. In order to clarify whether GH acted directly on mammary gland tissue, we investigated the prolactin receptors (PRLR), IGF-I receptors (IGF-IR), and GHR as well as the gene expression levels of the downstream signaling molecule for each receptor in the mammary gland tissue of Holstein cows during different stages of lactation. The results revealed that the mRNA expressions of PRLR and IGF-IR were highest during early lactation, and the mRNA expression of the GHR was highest during mid-lactation. We also found that the expression profiling of the signal transducer and activator of transcription 5 (STAT5) genes was similar to that of the GHR gene. On the other hand, the expression profiling of the PRLR gene was similar to that of the SHP2 gene. These results suggest that GH acts on the mammary glands directly, milk synthesis and secretion are chiefly stimulated in mid-lactation, and the timing of the action is different for PRL and IGF-I.

300 CASES OF HYPERPLASIA OF MAMMARY GLANDS TREATED WITH RED-HOT NEEDLE PLUS FILIFORM NEEDLE

Clinical observations on 300 cases of hyperplasia of mammary glands (group A) treated by red hot needle plus filiform needle are reported in the present study. "Ashi" points were used as the main acupoints. For comparison, other 300 cases (group B) were treated with routine acupuncture method, and Rugen (ST 18) was used as the main acupoint. In addition, other auxiliary acupoints were supplemented in the light of the concrete syndromes in these two groups. The treatment was given once daily, with 10 sessions being a therapeutic course. Of the 300 cases in group A, 240 were clinically cured, amounting to 80%; 58 were effective, amounting to 19.3%; 2 were failed, with a total effective rate of 99.3%. Of the 300 cases in group B, 113 were clinically cured, 165 effective, 22 were failed, with a total effective rate of 92.7%. The therapeutic effect of group A is significantly superior to that of group B (P<0.05).

CLINICAL OBSERVATION ON THE ACUPOINT INTRADERMAL EMBEDDING OF RINGHEADED THUMBTACK-NEEDLE THERAPY FOR HYPERPLASIA OF MAMMARY GLANDS

In the present paper, the author used acupoint intradermal embedding of ringheaded thumbtack-needle therapy combined with herbal medicine therapy to treat 110 cases of hyperplasia of mammary glands, and compared its therapeutic effect with that of herbal therapy alone. The observed indexes of the treatment were pain relief degree, the size of hyperplasic glands and the time of occurrence of marked effect. Following 3 courses of treatment,the results showed the therapeutic effect of the ringheaded thumbtack-needle needle plus herbal medicine therapy was superior to that of herbal medicine therapy alone in the above-mentioned 3 indexes (P ＜ 0.01 ).

ACUPUNCTURE FOR TRERTING 120 CASES OF HYPERPLASIA OF MAMMARY GLANDS

Objective: To observe the therapeutic effect of acupuncture therapy for 120 cases of hyperplasia of mammary glands. Methods: These patients were classified into liver-qi-stagnation type (n=53), phlegm-coagulation type (n=30) and Thoroughfare-Conception vessel maladjustment type (n=37). Acupoints used were Qimen (期门 LR 14), Wuyi (屋翳 ST 15), Weishu (胃俞 BL 21), etc.. Acupuncture treatment was conducted once daily and 30 treatments constituted one therapeutic course. Results: After 3 courses of treatment, of the 53, 30 and 37 cases of the liver-qi-stagnation, phlegm-coagulation and Thoroughfare-Conception vessel maladjustment types, 43 (81.1%), 24 (80.0%) and 29 (78.4%) were cured, 7 (13.2%), 5 (16.7%)and 5 (13.5%) markedly improved, 3 (5.7%), 1 (3.3%) and 2 (5.4%) improved respectively, and 1 (2.7%) of Thoroughfare-Conception vessel maladjustment type failed. A two-years’ follow-up showed that 3 of the cured 92 cases had a relapse, and after 2 more courses of treatment, they were cured again. Conclusion: Acupuncture therapy is effective for the treatment of hyperplasia of mammary glands.

Research Progress on Classical Prescriptions in Treating Mammary Glands Hyperplasia

According to Zhongjing Zhang's academic thought,gynecological diseases mostly result from deficiency,accumulated cold,and qi stagnation,so the treatment of gynecological miscellaneous diseases should take qi and blood as the general principle,and focus on the liver.The pathogenesis of mammary glands hyperplasia(MGH)is liver and kidney deficiency,disharmony of the thoroughfare vessel and the conception vessel,the causes of which are emotional imbalance,liver qi depression,and failure of transportation due to spleen deficiency.The superficial causes include qi stagnation,phlegm coagulation,and blood stasis,which are mainly related to the liver,spleen,kidney,the thoroughfare vessel,and the conception vessel.In clinical treatment of MGH,Xiaochaihu Decoction or Sini Powder can be used for qi stagnation syndrome,Xiao Xianxiong Decoction for phlegm coagulation syndrome,Guizhi Fuling Pill or Dahuang Zhechong Pill for spleen deficiency syndrome,and Wenjing Decoction for the deficiency-cold syndrome.

Expression of Human GCSF in Mammary Gland of Mice by Injection of Plasmid DNA

The vectors carrying the genes coding for the proteins of interest are of unpredictable efficiency in transgenic animals. The expression vector of mammary gland (pINGG) containing GCSF genomic DNA was injected into mouse mammary gland, and expression was detected in the milk of mice. The result showed that mammary gland injection method could provide a convenient transient system to confirm vector validity.

Amino acids and mammary gland development:nutritional implications for milk production and neonatal growth

Milk is synthesized by mammary epithelial cells of lactating mammals. The synthetic capacity of the mammary gland depends largely on the number and efficiency of functional mammary epithelial cells. Structural development of the mammary gland occurs during fetal growth, prepubertal and post-pubertal periods, pregnancy, and lactation under the control of various hormones （particularly estrogen, growth hormone, insulin-like growth factor-I, progesterone, placental lactogen, and prolactin） in a species- and stage-dependent manner. Milk is essential for the growth, development, and health of neonates. Amino acids （AA）, present in both free and peptide-bound forms, are the most abundant organic nutrients in the milk of farm animals. Uptake of AA from the arterial blood of the lactating dam is the ultimate source of proteins （primarily 13-casein and a-lactalbumin） and bioactive nitrogenous metabolites in milk. Results of recent studies indicate extensive catabolism of branched-chain AA （leucine, isoleucine and valine） and arginine to synthesize glutamate, glutamine, alanine, aspartate, asparagine, proline, and polyamines. The formation of polypeptides from AA is regulated not only by hormones （e.g., prolactin, insulin and glucocorticoids） and the rate of blood flow across the lactating mammary gland, but also by concentrations of AA, lipids, glucose, vitamins and minerals in the maternal plasma, as well as the activation of the mechanistic （mammalian） target rapamycin signaling by certain AA （e.g., arginine, branched-chain AA, and glutamine）. Knowledge of AA utilization （including metabolism） by mammary epithelial cells will enhance our fundamental understanding of lactation biology and has important implications for improving the efficiency of livestock production worldwide.

Influence on Cellular Signal Transduction Pathway in Dairy Cow Mammary Gland Epithelial Cells by Galactopoietic Compound Isolated from Vaccariae segetalis

The galactopoietic mechanism of Vaccaria segetalis is still unknown. Understanding dibutyl phthalate （DBP） separated from Vaccaria segetalis on the expression of lactation signal transduction genes of mammary gland epithelial cells, including prlr, erα, akt1, socs2, pparγ and elf5, will be helpful to reveal the molecular mechanism. Western blot and qRT- PCR were used to study the change of prlr, erα, akt, socs2, pparγ, and elf5 expression at mRNA and protein level. Co- localization expression of prolactin receptor （PRLR） and estrogen receptor α （ERα） was observed by immunofluorescence; the expression changes of miRNAs （21, 125b, 143, and 195） and the secretion of β-casein and lactose were detected by qRT-PCR and RP-HPLC. The results showed that Vaccaria segetalis active compound had similar fuctions as estrogen and/or prolactin （PRL） in dairy cow mammary gland epithelial cells （DCMECs）, increased the expressions of prlr, erα, akt1, and elf5 genes, while repressed pparγ expressions. DBP promoted socs2 mRNA expression, but its protein expressions were repressed. Furthermore, both DBP and PRL could repress the expressions of miRNA-125b, miRNA-143 and miRNA- 195 in DCMECs. DBP could repress the expression of miRNA-21, while the influence of PRL on miRNA-21 was not certain. DBP could promote the lactation ability of DCMECs by regulating the ER and PRLR cellular signal transduction pathway.

Milk production and composition and metabolic alterations in the mammary gland of heat-stressed lactating dairy cows

This experiment was conducted to investigate the effects of heat stress(HS) on the feed intake, milk production and composition and metabolic alterations in the mammary gland of dairy cows. Twenty Holstein cows were randomly assigned to one of two treatments according to a completely randomized design. Half of the cows were allocated to the HS group in August(summer season), and the other half were assigned to the HS-free group in November(autumn season). HS reduced(P<0.01) dry matter intake(DMI), milk yield, milk protein and milk urea nitrogen(MUN) of cows compared with HSfree control, but increased(P<0.01) milk somatic cell counts(SCC). We determined the HS-induced metabolic alterations and the relevant mechanisms in dairy cows using liquid chromatography mass spectrometry combined with multivariate analyses. Thirty-four metabolites were identified as potential biomarkers for the diagnosis of HS in dairy cows. Ten of these metabolites, glucose, lactate, pyruvate, lactose, β-hydroxybutyrate, citric acid, α-ketoglutarate, urea, creatine, and orotic acid, had high sensitivity and specificity for HS diagnoses, and seven metabolites were also identified as potential biomarkers of HS in plasma, milk, and liver. These substances are involved in glycolysis, lactose, ketone, tricarboxylic acid(TCA), amino acid and nucleotide metabolism, indicating that HS mainly affects lactose, energy and nucleotide metabolism in the mammary gland of lactating dairy cows. This study suggested that HS might affect milk production and composition by affecting the feed intake and substance metabolisms in the mammary gland tissue of lactating dairy cows.

Metabolic Regulation of Mammary Gland Epithelial Cells of Dairy Cow by Galactopoietic Compound Isolated from Vaccariae segetalis

In previous experiment, we isolated a compound dibutyl phthalate （DBP） from Vaccaria segetalis which had galactopoietic function on mammary gland epithelial cells of dairy cow （DCMECs）. In this experiment, we ascertained the metabolic regulation function of DBP on DCMECs. Many genes related to lactation including Stat5, AMPK, b-casein, Glut1, SREBP-1, PEPCK, and ACC were detected by real-time PCR. Furthermore, Stat5 and AMPK were detected by Western blot and immunofluorescence co-localization, respectively. The results showed that DBP stimulates the expression of Stat5 and p-Stat5, thus activates Stat5 cell signal transduction pathway and stimulates b-casein synthesis. DBP also raises the activities of Glut1 and AMPK to stimulate glucose uptake and glycometabolism and activates the expression of AMPK downstream target genes PEPCK and ACC and expression of SREBP-1 to stimulate milk fat synthesis. In addition, the activities of HK, G-6-PDH, ICDH, ATPase, and energy charges were stimulated by DBP to increase the energy metabolism level of DCMECs. The results showed DBP stimulates energy metabolism related to galactopoietic function in DCMECs.

Recent progress of porcine milk components and mammary gland function

As the only nutritional source for newborn piglets,porcine colostrum and milk contain critical nutritional and immunological components including carbohydrates,lipids,and proteins(immunoglobulins).However,porcine milk composition is more complex than these three components.Recently,scientists identified additional and novel components of sow colostrum and milk,including exosomes,oligosaccharides,and bacteria,which possibly act as biological signals and modulate the intestinal environment and immune status in piglets and later in life.Evaluation of these nutritional and non-nutritional components in porcine milk will help better understand the nutritional and biological function of porcine colostrum and milk.Furthermore,some important functions of the porcine mammary gland have been reported in recent published literature.These preliminary studies hypothesized how glucose,amino acids,and fatty acids are transported from maternal blood to the porcine mammary gland for milk synthesis.Therefore,we summarized recent reports on sow milk composition and porcine mammary gland function in this review,with particular emphasis on macronutrient transfer and synthesis mechanisms,which might offer a possible approach for regulation of milk synthesis in the future.

Mammary gland growth and vascularity at parturition and during lactation in primiparous ewes fed differing levels of selenium and nutritional plane during gestation

Background： Objectives were to examine the effects of selenium （Se） supply and maternal nutritional plane during gestation on mammary gland growth, cellular proliferation, and vascularity at parturition and d 20 of lactation. Rambouillet primiparous ewes （n = 84） were allocated to treatments in a 2 x 3 factorial. Factors were dietary Se （adequate Se [ASe, 11.5 μg/kg BW] or high Se [HSe, 77.0 μg/kg BVV]） and nutritional plane （60% IRES], 100% [CON], or 140% [EXC]）. At parturition, lambs were removed and 42 ewes （7/treatment） were necropsied. Remaining ewes were fed a common diet meeting requirements for lactation and mechanically milked twice daily until necropsy on d 20. At both necropsy periods, mammary glands were dissected and tissues harvested. Samples were analyzed for RNA, DNA, and protein content, cell proliferation, and vascularity. Where interactions were present （P 〈 0.05）, least squares means from the highest-order interaction are presented. Results： Final body weight of ewes was least （P 〈 0.002） in RES, intermediate for CON, and greatest for EXC, regardless of stage of the ewe at necropsy （parturition or d 20 of lactation）. In ewes necropsied at parturition, mammary glands were heavier （P = 0.02） in EXC compared to RES, with CON intermediate. Concentration of RNA （rag/g） was decreased （P= 0.01） in EXC compared to CON at parturition. There was a tendency （P= 0.07） for a Se by nutrition interaction in percentage of cells proliferating where ASe-EXC ewes had greater （P_〈 0.02） number of proliferating cells then all other treatments. Mammary vascular area tended （P = 0.08） to be affected by a Se by nutrition interaction where ASe-CON had less （P= 0.007） vascular area than HSe-CON ewes. In ewes necropsied at d 20 of lactation, the number of alveoli per area was decreased （P 〈- 0.05） in RES compared to CON and EXC-fed ewes. Conclusions： Results of this study indicate that proper maternal nutritional plane during gestation is important for mammary gland development, even out to d 20 of lactation.

Effects of dietary valine supplementation during late gestation on the reproductive performance and mammary gland development of gilts

Background:Mammary gland development during late gestation in gilts is a major factor that alters the composition of colostrum and growth performance of piglets.Plasma valine is taken up and metabolized extensively by the mammary gland;however,the effects of valine on mammary gland development during late gestation are still unclear.Thirty primiparous gilts were divided into three treatment groups(n=10)and received one of the three diets starting on day 75 of gestation until the day of farrowing.The total dietary valine to lysine ratio of the three diets was 0.63(LV),0.73(MV),and 0.93(HV),respectively.Results:Dietary valine supplementation during late gestation did not affect(P>0.05)the litter size and weight at farrowing;however,the piglet weight and average daily gain at weaning were linearly increased(P<0.05)as the dietary valine increased.The highest piglet weight at weaning was observed when the gilts were provided the HV diet.Dietary valine supplementation linearly elevated(P<0.05)protein,fat and solids-not-fat and some free amino acids content in colostrum.The concentration of prolactin in plasma of gilts was linearly increased in response to valine supplementation at days 1 and 10 of lactation(P<0.05).Furthermore,with increasing dietary valine allowance,a linear increase(P<0.05)was observed in the area of the lumen of alveolus and the content of DNA,RNA,and total protein in the mammary tissues at day 1 of lactation.Moreover,the protein expression of cyclin D1,p-mTOR,p-S6,and p-4EBP1 was also linearly increased(P<0.05)in the mammary tissue at day 1 of lactation.However,no difference(P>0.05)was observed in the indices related to mammary development and the mTOR signaling pathway at day 21 of lactation.Conclusion:The results revealed that increasing the total dietary valine to lysine ratio to 0.93 during late gestation significantly enhances the piglet weight and average daily gain at weaning probably due to improved development of mammary gland.