Background:Methionine or lysine has been reported to influence DNA methylation and fat metabolism,but their combined effects in N6-methyl-adenosine(m^(6)A)RNA methylation remain unclarified.The combined effects of rum...Background:Methionine or lysine has been reported to influence DNA methylation and fat metabolism,but their combined effects in N6-methyl-adenosine(m^(6)A)RNA methylation remain unclarified.The combined effects of rumen-protected methionine and lysine(RML)in a low-protein(LP)diet on lipid metabolism,m^(6)A RNA methylation,and fatty acid(FA)profiles in the liver and muscle of lambs were investigated.Sixty-three male lambs were divided into three treatment groups,three pens per group and seven lambs per pen.The lambs were fed a 14.5%crude protein(CP)diet(adequate protein[NP]),12.5%CP diet(LP),and a LP diet plus RML(LP+RML)for 60 d.Results:The results showed that the addition of RML in a LP diet tended to lower the concentrations of plasma leptin(P=0.07),triglyceride(P=0.05),and non-esterified FA(P=0.08).Feeding a LP diet increased the enzyme activity or m RNA expression of lipogenic enzymes and decreased lipolytic enzymes compared with the NP diet.This effect was reversed by supplementation of RML with a LP diet.The inclusion of RML in a LP diet affected the polyunsaturated fatty acids(PUFA),n-3 PUFA,and n-6 PUFA in the liver but not in the muscle,which might be linked with altered expression of FA desaturase-1(FADS1)and acetyl-Co A carboxylase(ACC).A LP diet supplemented with RML increased(P<0.05)total m^(6)A levels in the liver and muscle and were accompanied by decreased expression of fat mass and obesity-associated protein(FTO)and alk B homologue 5(ALKBH5).The m RNA expressions of methyltransferase-like 3(METTL3)and methyltransferase-like 14(METTL14)in the LP+RML diet group were lower than those in the other two groups.Supplementation of RML with a LP diet affected only liver YTH domain family(YTHDF2)proteins(P<0.05)and muscle YTHDF3(P=0.09),which can be explained by limited m^(6)Abinding proteins that were mediated in m RNA fate.Conclusions:Our findings showed that the inclusion of RML in a LP diet could alter fat deposition through modulations of lipogenesis and lipolysis in the liver and muscle.These changes in fat metabolism may be associated with the modification of m^(6)A RNA methylation.展开更多
Background: Liver has important immune function during fetal development and after birth.However,the effect of maternal malnutrition on immune function of the fetal liver is rarely reported.In this study,twelve pregna...Background: Liver has important immune function during fetal development and after birth.However,the effect of maternal malnutrition on immune function of the fetal liver is rarely reported.In this study,twelve pregnant goats(Xiangdong black goat,at d 45 of gestation) were assigned to the control group(fed 100% of nutritional requirements) and the restriction group(fed 60% of the intake of the control group) during gestation from d 55 to100.Fetal goats were harvested at d 100 of gestation and immune indexes and amino acid profiles of the umbilical cord blood and liver Toll-like receptors(TLRs) signaling pathways were measured.Results: Maternal body weight in the restriction group was lower than the control group(P < 0.05).Maternal feed intake restriction decreased(P < 0.05) heart weight,heart index,alkaline phosphatase and serum amyloid protein A in the umbilical cord blood(UCB).Moreover,only histidine was decreased in the restricted group(P = 0.084),and there were no differences in other amino acids contents in the UCB between the two groups(P > 0.05).The TLR2 and TLR4 mRNA expression in the fetal liver in the restriction group was greater(P < 0.05) than that in the control group.Furthermore,the mRNA expression levels of myeloid differentiation primary response 88(MyD88),TNF receptor associated factor 6,nuclear factor kappa B subunit 1,NFKB inhibitor alpha,IFN-β,TGF-β,TNF-α and IL-1β in the restricted group were upregulated(P < 0.05),and the expression of TLR3(P = 0.099) tended to be higher in the restricted group.However,protein levels of TLR2,TLR4,IκBα,phosphorylated IκBα,phosphorylated IκBα/total IκBα,TRIF and MyD88 were not affected(P > 0.05) by maternal intake restriction.Conclusions: These results revealed that the restriction of maternal feed intake influenced the development of heart and hepatic protein synthesis at the acute phase of fetal goats and upregulated the mRNA expression of genes involved in MyD88-dependent signaling pathways and of target cytokines.展开更多
Macleaya cordata extract(MCE)is a potential replacement for antibiotics.In the current study,effects of MCE on the gastrointestinal health and humoral responses of host animals were explored.A total of 30 weanling goa...Macleaya cordata extract(MCE)is a potential replacement for antibiotics.In the current study,effects of MCE on the gastrointestinal health and humoral responses of host animals were explored.A total of 30 weanling goats with similar body weight of 9.15±1.36 kg were randomly allocated into three groups(n=10 per group):control group(CON group,fed with a basal diet),antibiotic group(Abx group,fed with the basal diet supplemented with 0.18 g/d vancomycin and 0.36 g/d neomycin),and MCE group(fed with the basal diet supplemented with 5 g/d MCE),for three weeks.Results showed that antibiotic addition decreased the height and area of rumen papillae,ruminal mucosa Toll-like receptor 8(TLR8),interleukin-8(IL-8)and interleukin-1β(IL-1β)gene relative expression levels and microbial diversity,altered the volatile fatty acid(VFA)profile in the rumen,and increased monocytes amount and CD4^(+)T cells percentage in the peripheral blood(P<0.05)compared to CON group.MCE addition increased the average daily gain,ileal villus height,villus height/crypt depth,and immunoglobulin M(IgM)content in the peripheral blood(P<0.05)compared to the CON.Additionally,MCE addition decreased the proportion of isobutyric acid in the chyme of the ileum(P=0.005)compared to the CON group.These results suggest that antibiotic supplementation may suppress the epithelial state and microbial diversity and fermentation in goats,but stimulate cellular response to maintain the growth performance of goats.MCE administration improved the epithelial state and humoral response to promote the growth performance in goats.展开更多
Ramie(Boehmeria nivea)is noted for the production of a large biomass that has a high protein content and is rich in antioxidants.It may thus serve as a high-quality forage material to replace alfalfa and improve the m...Ramie(Boehmeria nivea)is noted for the production of a large biomass that has a high protein content and is rich in antioxidants.It may thus serve as a high-quality forage material to replace alfalfa and improve the meat quality of farmed animals.In this study,we evaluated the carcass characteristics and meat quality of goats when 0,35%,75%,and 100%of dietary alfalfa was replaced with ramie.Crude protein content(linear,P<0.0001)and key muscle color values at 24 h after slaughter decreased with increasing ramie levels.The content of most individual amino acids,non-essential amino acids(NEAA),total amino acids(TAA),branched chain amino acids(BCAA),functional amino acids(FAA),and flavor amino acids(DAA)decreased(P<0.05)with increasing dietary ramie.The diet in which 35%of alfalfa was replaced with ramie yielded meat with the highest amino acid content,whereas the fatty acid profile was unaffected by the inclusion of ramie.These results indicate that ramie could be used as a potential dietary forage resource for goats,and that substituting 35%of alfalfa with ramie,which is equivalent to 126 g/kg DM content,would be optimal in terms of goat meat quality.展开更多
Zinc supplementation in the diet of goats affects pancreas development in offspring.However,the impact of maternal inorganic and organic zinc supplementation in offspring is poorly defined.In this study,14 late-pregna...Zinc supplementation in the diet of goats affects pancreas development in offspring.However,the impact of maternal inorganic and organic zinc supplementation in offspring is poorly defined.In this study,14 late-pregnant goats were assigned at random to the zinc sulfate group(ZnSO_(4),n=7)and the zinc-glycine chelate group(Zn-Gly,n=7),respectively.Serum samples and pancreas tissue were collected from kids whose mothers were fed ZnSO_(4)and Zn-Gly at the late pregnancy,respectively.Histologic examination showed no morphologic differences between the 2 groups.Pancreatic zinc content in kids tended to be increased when replacing ZnSO_(4)with Zn-Gly.The serum insulin concentration was greater and glucagon less in the Zn-Gly group when compared to the ZnSO_(4)group.The activities of lipase and chymotrypsin were enhanced when replacing ZnSO_(4)with Zn-Gly.Proteomics results showed that 234 proteins were differentially expressed between the 2 groups,some of which were associated with the secretion of insulin,enzyme activity and signal transduction.The results suggested that supply of dietary Zn-Gly to goats during late pregnancy promoted pancreatic function in offspring compared with dietary ZnSO_(4)supplementation.This provides new information about pancreatic function when supplementing different zinc sources in the diets of late pregnant goats.展开更多
The biological mechanism by which maternal undernutrition increases the metabolic disorder risk of skeletal muscles in offspring is not fully understood.We hypothesize that maternal intake restriction influences metab...The biological mechanism by which maternal undernutrition increases the metabolic disorder risk of skeletal muscles in offspring is not fully understood.We hypothesize that maternal intake restriction influences metabolic signals in the skeletal muscles of offspring via a glucagon-mediated pathway.Twentyfour pregnant goats were assigned to the control group(100%of the nutrients requirement,n=12)and restricted group(60%of the control feed allowance from pregnant days 45 to 100,n=12).Blood and Longissimus thoracis muscle were sampled from dams(100 d of gestation),fetuses(100 d of gestation),and kids(90 d after birth)in each group.The data were analyzed using the linear MIXED model,with the multiple comparison method of SIDAK applied.Intake restriction reduced(P<0.05)the total blood protein of dams and fetuses.Maternal restriction decreased(P<0.05)the cAMP-responsive element-binding protein 1(CREB1),CREB-binding protein(CREBBP),protein kinase A(PKA),aryl hydrocarbon receptor nuclear translocator-like protein 1(BMAL1),protein kinase B(AKT1),mammalian target of rapamycin(mTOR),and regulatory-associated protein of mTOR(RPTOR)mRNA expression in the fetuses,and reduced(P<0.05)the CREBBP,nuclear receptor subfamily 1 group H member 3(NR1 H3),D-box binding PAR bZIP transcription factor(DBP)and PKA mRNA levels in the kids,but increased(P<0.05)the peroxisome proliferator-activated receptor gamma coactivator 1 alpha(PGC1 A)and tuberous sclerosis 2(TSC2)mRNA levels in the fetuses.The mRNA expression of clock circadian regulator(CLOCK)and TSC2 genes was increased(P<0.05)in the restricted kids.The protein expression of total PKA and phosphorylated PKA in the restricted fetuses and kids were downregulated(P<0.05),and the protein expression of total mTOR and phosphorylated mTOR were reduced(P<0.05)in the restricted fetuses and kids.Maternal intake restriction regulated fat oxidation,protein synthesis,and circadian clock expression in the muscles of the offspring probably via the glucagon-mediated PKA-CREB pathway,which reveals a noteworthy molecular pathway that maternal undernutrition leads to metabolic adaptation of skeletal muscle in offspring.展开更多
The purpose of this study was to investigate the effects of dietary L-theanine supplementation on apparent nutrient digestibility,milk yield,milk composition,and blood biochemical indices of dairy cows under heat stre...The purpose of this study was to investigate the effects of dietary L-theanine supplementation on apparent nutrient digestibility,milk yield,milk composition,and blood biochemical indices of dairy cows under heat stress.Thirty Chinese Holstein cows(19.84±2.42 kg milk/d,192.36±40.77 d in milk and2±0.93 parities)were divided into 3 groups of 10 animals each.The control group was fed a basal total mixed ration(TMR)diet,while treatment 1(LTA16)and treatment 2(LTA32)groups were fed a basal TMR diet supplemented with L-theanine at 16 and 32 g/cow per day,respectively.The results showed that feeding the dairy cows with LTA16 treatment decreased(P<0.05)their rectal temperature,whereas feeding with LTA32 treatment decreased(P<0.05)their rumen fluid ammonia nitrogen content.In comparison to the control group,the supplementation of L-theanine had no significant effect(P>0.05)on the dry matter intake,nutrient digestibility,total volatile fatty acid(TVFA)concentration and molar proportion of volatile fatty acid,milk yield,milk composition,feed efficiency and antioxidant capacity of the dairy cows.The triglyceride(TG)content of the LTA32 group was significantly greater(P=0.014)than that of the control group.With the increase in L-theanine dosage,the serum cholesterol(CHOL)content significantly increased(P=0.013).The serum albumin(ALB;P=0.067),low-density lipoprotein cholesterol(LDL-C;P=0.053),and high-density lipoprotein cholesterol(HDL-C;P=0.067)contents showed an upward trend as L-theanine dosage increased.Ultimately,the results of this study show that supplementing dairy cow diet with L-theanine could decrease dairy cow rectal temperature,affect lipid metabolism,and potentially relieve the heat stress of dairy cows to some extent.展开更多
基金funded by Chinese Academy of Sciences(Strategic Priority Research Program Grant NO.XDA26040304,XDA26050102)CAS Science and Technology Service Network Initiative(KFJ-STS-ZDTP-075)Innovation Province Project(2019RS3021)。
文摘Background:Methionine or lysine has been reported to influence DNA methylation and fat metabolism,but their combined effects in N6-methyl-adenosine(m^(6)A)RNA methylation remain unclarified.The combined effects of rumen-protected methionine and lysine(RML)in a low-protein(LP)diet on lipid metabolism,m^(6)A RNA methylation,and fatty acid(FA)profiles in the liver and muscle of lambs were investigated.Sixty-three male lambs were divided into three treatment groups,three pens per group and seven lambs per pen.The lambs were fed a 14.5%crude protein(CP)diet(adequate protein[NP]),12.5%CP diet(LP),and a LP diet plus RML(LP+RML)for 60 d.Results:The results showed that the addition of RML in a LP diet tended to lower the concentrations of plasma leptin(P=0.07),triglyceride(P=0.05),and non-esterified FA(P=0.08).Feeding a LP diet increased the enzyme activity or m RNA expression of lipogenic enzymes and decreased lipolytic enzymes compared with the NP diet.This effect was reversed by supplementation of RML with a LP diet.The inclusion of RML in a LP diet affected the polyunsaturated fatty acids(PUFA),n-3 PUFA,and n-6 PUFA in the liver but not in the muscle,which might be linked with altered expression of FA desaturase-1(FADS1)and acetyl-Co A carboxylase(ACC).A LP diet supplemented with RML increased(P<0.05)total m^(6)A levels in the liver and muscle and were accompanied by decreased expression of fat mass and obesity-associated protein(FTO)and alk B homologue 5(ALKBH5).The m RNA expressions of methyltransferase-like 3(METTL3)and methyltransferase-like 14(METTL14)in the LP+RML diet group were lower than those in the other two groups.Supplementation of RML with a LP diet affected only liver YTH domain family(YTHDF2)proteins(P<0.05)and muscle YTHDF3(P=0.09),which can be explained by limited m^(6)Abinding proteins that were mediated in m RNA fate.Conclusions:Our findings showed that the inclusion of RML in a LP diet could alter fat deposition through modulations of lipogenesis and lipolysis in the liver and muscle.These changes in fat metabolism may be associated with the modification of m^(6)A RNA methylation.
基金jointly supported by the National Natural Science Foundation of China(Grant No.31760678,31730092)Youth Innovation Team Project of ISA,CAS(2017QNCXTD_ZCS)
文摘Background: Liver has important immune function during fetal development and after birth.However,the effect of maternal malnutrition on immune function of the fetal liver is rarely reported.In this study,twelve pregnant goats(Xiangdong black goat,at d 45 of gestation) were assigned to the control group(fed 100% of nutritional requirements) and the restriction group(fed 60% of the intake of the control group) during gestation from d 55 to100.Fetal goats were harvested at d 100 of gestation and immune indexes and amino acid profiles of the umbilical cord blood and liver Toll-like receptors(TLRs) signaling pathways were measured.Results: Maternal body weight in the restriction group was lower than the control group(P < 0.05).Maternal feed intake restriction decreased(P < 0.05) heart weight,heart index,alkaline phosphatase and serum amyloid protein A in the umbilical cord blood(UCB).Moreover,only histidine was decreased in the restricted group(P = 0.084),and there were no differences in other amino acids contents in the UCB between the two groups(P > 0.05).The TLR2 and TLR4 mRNA expression in the fetal liver in the restriction group was greater(P < 0.05) than that in the control group.Furthermore,the mRNA expression levels of myeloid differentiation primary response 88(MyD88),TNF receptor associated factor 6,nuclear factor kappa B subunit 1,NFKB inhibitor alpha,IFN-β,TGF-β,TNF-α and IL-1β in the restricted group were upregulated(P < 0.05),and the expression of TLR3(P = 0.099) tended to be higher in the restricted group.However,protein levels of TLR2,TLR4,IκBα,phosphorylated IκBα,phosphorylated IκBα/total IκBα,TRIF and MyD88 were not affected(P > 0.05) by maternal intake restriction.Conclusions: These results revealed that the restriction of maternal feed intake influenced the development of heart and hepatic protein synthesis at the acute phase of fetal goats and upregulated the mRNA expression of genes involved in MyD88-dependent signaling pathways and of target cytokines.
基金supported by National Key R&D Program of China (2022YFD1301700)Changsha Munic-ipal Natural Science Foundation (kq2208245)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences (XDA26040304)Natural Science Foundation of Hunan Province of China (2022JJ10054).
文摘Macleaya cordata extract(MCE)is a potential replacement for antibiotics.In the current study,effects of MCE on the gastrointestinal health and humoral responses of host animals were explored.A total of 30 weanling goats with similar body weight of 9.15±1.36 kg were randomly allocated into three groups(n=10 per group):control group(CON group,fed with a basal diet),antibiotic group(Abx group,fed with the basal diet supplemented with 0.18 g/d vancomycin and 0.36 g/d neomycin),and MCE group(fed with the basal diet supplemented with 5 g/d MCE),for three weeks.Results showed that antibiotic addition decreased the height and area of rumen papillae,ruminal mucosa Toll-like receptor 8(TLR8),interleukin-8(IL-8)and interleukin-1β(IL-1β)gene relative expression levels and microbial diversity,altered the volatile fatty acid(VFA)profile in the rumen,and increased monocytes amount and CD4^(+)T cells percentage in the peripheral blood(P<0.05)compared to CON group.MCE addition increased the average daily gain,ileal villus height,villus height/crypt depth,and immunoglobulin M(IgM)content in the peripheral blood(P<0.05)compared to the CON.Additionally,MCE addition decreased the proportion of isobutyric acid in the chyme of the ileum(P=0.005)compared to the CON group.These results suggest that antibiotic supplementation may suppress the epithelial state and microbial diversity and fermentation in goats,but stimulate cellular response to maintain the growth performance of goats.MCE administration improved the epithelial state and humoral response to promote the growth performance in goats.
基金financially supported by the National Key Research and Development Program of China(No.2018YFD0501604,2018YFD0501900)China Special Fund for Agro-Scientific Research in the Public Interest(No.201303144)+2 种基金the National Natural Science Foundation of China(No.31501988)Hunan Provincial Major Scientific and Technological Special Project(No.2017NK1020)Key Research and Development Program of Hunan Province(No.2016NK2171)
文摘Ramie(Boehmeria nivea)is noted for the production of a large biomass that has a high protein content and is rich in antioxidants.It may thus serve as a high-quality forage material to replace alfalfa and improve the meat quality of farmed animals.In this study,we evaluated the carcass characteristics and meat quality of goats when 0,35%,75%,and 100%of dietary alfalfa was replaced with ramie.Crude protein content(linear,P<0.0001)and key muscle color values at 24 h after slaughter decreased with increasing ramie levels.The content of most individual amino acids,non-essential amino acids(NEAA),total amino acids(TAA),branched chain amino acids(BCAA),functional amino acids(FAA),and flavor amino acids(DAA)decreased(P<0.05)with increasing dietary ramie.The diet in which 35%of alfalfa was replaced with ramie yielded meat with the highest amino acid content,whereas the fatty acid profile was unaffected by the inclusion of ramie.These results indicate that ramie could be used as a potential dietary forage resource for goats,and that substituting 35%of alfalfa with ramie,which is equivalent to 126 g/kg DM content,would be optimal in terms of goat meat quality.
基金The authors wish to acknowledge the financial support received from the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant NO.XDA 26040304)Natural Science Foundation of Hunan Province(2020JJ5634)National Natural Science Foundation of China(31760678).
文摘Zinc supplementation in the diet of goats affects pancreas development in offspring.However,the impact of maternal inorganic and organic zinc supplementation in offspring is poorly defined.In this study,14 late-pregnant goats were assigned at random to the zinc sulfate group(ZnSO_(4),n=7)and the zinc-glycine chelate group(Zn-Gly,n=7),respectively.Serum samples and pancreas tissue were collected from kids whose mothers were fed ZnSO_(4)and Zn-Gly at the late pregnancy,respectively.Histologic examination showed no morphologic differences between the 2 groups.Pancreatic zinc content in kids tended to be increased when replacing ZnSO_(4)with Zn-Gly.The serum insulin concentration was greater and glucagon less in the Zn-Gly group when compared to the ZnSO_(4)group.The activities of lipase and chymotrypsin were enhanced when replacing ZnSO_(4)with Zn-Gly.Proteomics results showed that 234 proteins were differentially expressed between the 2 groups,some of which were associated with the secretion of insulin,enzyme activity and signal transduction.The results suggested that supply of dietary Zn-Gly to goats during late pregnancy promoted pancreatic function in offspring compared with dietary ZnSO_(4)supplementation.This provides new information about pancreatic function when supplementing different zinc sources in the diets of late pregnant goats.
基金supported by the National Natural Science Foundation of China[31730092,31760678 and 31402105]Hunan innovative Province construction project[2019RS3021]。
文摘The biological mechanism by which maternal undernutrition increases the metabolic disorder risk of skeletal muscles in offspring is not fully understood.We hypothesize that maternal intake restriction influences metabolic signals in the skeletal muscles of offspring via a glucagon-mediated pathway.Twentyfour pregnant goats were assigned to the control group(100%of the nutrients requirement,n=12)and restricted group(60%of the control feed allowance from pregnant days 45 to 100,n=12).Blood and Longissimus thoracis muscle were sampled from dams(100 d of gestation),fetuses(100 d of gestation),and kids(90 d after birth)in each group.The data were analyzed using the linear MIXED model,with the multiple comparison method of SIDAK applied.Intake restriction reduced(P<0.05)the total blood protein of dams and fetuses.Maternal restriction decreased(P<0.05)the cAMP-responsive element-binding protein 1(CREB1),CREB-binding protein(CREBBP),protein kinase A(PKA),aryl hydrocarbon receptor nuclear translocator-like protein 1(BMAL1),protein kinase B(AKT1),mammalian target of rapamycin(mTOR),and regulatory-associated protein of mTOR(RPTOR)mRNA expression in the fetuses,and reduced(P<0.05)the CREBBP,nuclear receptor subfamily 1 group H member 3(NR1 H3),D-box binding PAR bZIP transcription factor(DBP)and PKA mRNA levels in the kids,but increased(P<0.05)the peroxisome proliferator-activated receptor gamma coactivator 1 alpha(PGC1 A)and tuberous sclerosis 2(TSC2)mRNA levels in the fetuses.The mRNA expression of clock circadian regulator(CLOCK)and TSC2 genes was increased(P<0.05)in the restricted kids.The protein expression of total PKA and phosphorylated PKA in the restricted fetuses and kids were downregulated(P<0.05),and the protein expression of total mTOR and phosphorylated mTOR were reduced(P<0.05)in the restricted fetuses and kids.Maternal intake restriction regulated fat oxidation,protein synthesis,and circadian clock expression in the muscles of the offspring probably via the glucagon-mediated PKA-CREB pathway,which reveals a noteworthy molecular pathway that maternal undernutrition leads to metabolic adaptation of skeletal muscle in offspring.
基金financially supported by National Key Research and Development Program(Grant No.2018YFD0501604)Hunan Provincial Science and Technology Major Project(Grant No.2017NK1020)+3 种基金Hunan Provincial Natural Science Foundation(Grant No.2019JJ50279)The Construction of Innovative in Hunan Province(Grant No.2019RS3021)Hunan Agricultural University(Grant No.17QN09)Effect of secondary metabolites of rapeseed meal on methane emission from goats(Grant No.2019ZDSYS01)。
文摘The purpose of this study was to investigate the effects of dietary L-theanine supplementation on apparent nutrient digestibility,milk yield,milk composition,and blood biochemical indices of dairy cows under heat stress.Thirty Chinese Holstein cows(19.84±2.42 kg milk/d,192.36±40.77 d in milk and2±0.93 parities)were divided into 3 groups of 10 animals each.The control group was fed a basal total mixed ration(TMR)diet,while treatment 1(LTA16)and treatment 2(LTA32)groups were fed a basal TMR diet supplemented with L-theanine at 16 and 32 g/cow per day,respectively.The results showed that feeding the dairy cows with LTA16 treatment decreased(P<0.05)their rectal temperature,whereas feeding with LTA32 treatment decreased(P<0.05)their rumen fluid ammonia nitrogen content.In comparison to the control group,the supplementation of L-theanine had no significant effect(P>0.05)on the dry matter intake,nutrient digestibility,total volatile fatty acid(TVFA)concentration and molar proportion of volatile fatty acid,milk yield,milk composition,feed efficiency and antioxidant capacity of the dairy cows.The triglyceride(TG)content of the LTA32 group was significantly greater(P=0.014)than that of the control group.With the increase in L-theanine dosage,the serum cholesterol(CHOL)content significantly increased(P=0.013).The serum albumin(ALB;P=0.067),low-density lipoprotein cholesterol(LDL-C;P=0.053),and high-density lipoprotein cholesterol(HDL-C;P=0.067)contents showed an upward trend as L-theanine dosage increased.Ultimately,the results of this study show that supplementing dairy cow diet with L-theanine could decrease dairy cow rectal temperature,affect lipid metabolism,and potentially relieve the heat stress of dairy cows to some extent.