Effects Of Serine Supplementation On Selenium Content And Selenoprotein Expression Or Activity Of Sows And Piglets

Serine(Ser)can provide the carbon skeleton of selenocysteine(Sec)residues on selenoprotein peptide chain to promote selenoprotein synthesis and expression in vivo.The level of dietary serine is correlated with selenium content and selenoprotein expression,suggesting that serine and selenium have synergistic effects,which can improve the utilization rate of selenium in animals and positively affect their growth performance.This study consisted of two experiments,one with pregnant sows and the other with weaned piglets.The effects of dietary serine supplementation on selenium content and selenoprotein expression or activity in pigs were investigated in terms of growth performance,selenium content in serum and tissues,gene expression of selenoprotein and selenoprotein concentration or activity by Enzyme-linked Immunosorbent Assay(ELISA),Real Time Quantitative PCR(RT-q PCR)and other methods.Experiment 1: A total of 72 healthy and productive sows(Landrace × Yorkshire)were selected and randomly assigned into four treatment groups.During late gestation(from 85 day of gestation to delivery),the sows were fed either a basal diet(CON)or a basal diet supplemented with 0.1375%(L-SER),0.275%(M-SER),or 0.55%(H-SER)serine.The serine content of basal diet was 0.55%;During lactation(from delivery to day 21 of lactation),the sows were fed either a basal diet(CON)or a basal diet supplemented with0.165%(L-SER),0.33%(M-SER),or 0.66%(H-SER)serine.The serine content of basal diet was 0.66%.Experiment 2 : A total of 35 crossbred barrows(Duroc × Landrace × Yorkshire)were used in the experiment.After weanling at the age of 21 days,the piglets were fed a basal diet for 1 week.Then,the piglets were randomly assigned into five treatment groups with seven replicates in each group.During the growth experiment,piglets were fed either a basal diet with no supplemented serine(CONT)or diets supplemented with 0.25%,0.5%,0.75%,or1% serine,respectively.The experiment period lasted for 42 days.The main results of Experiment 1 were as follows:(1)Dietary serine supplementation from late pregnancy to lactation had no effect on the Se content in the serum of sows and their offspring(P>0.05),whereas it significantly increased the Se content in the liver of piglets at the age of 21 days(P<0.05);(2)Dietary serine supplementation from late pregnancy to lactation significantly increased selenium content and Sepp1 content in milk of sows and Sepp1 content in milk of sows at at 24 h post-farrowing and the day 11 of lactation from sows(P<0.05);(3)Dietary serine supplementation from late pregnancy to lactation significantly increased litter weight(P<0.05)and the average body weight(P<0.05)of piglets at the age of 11 days and a Pearson’s r correlation coefficients was found between the average body weight of piglets at the age of 11 days and serum selenoprotein P(Sepp1)content in piglets,at the age of either 3 days or 7 days;(4)Dietary serine supplementation from late pregnancy to lactation significantly increased Sepp1 content(P<0.05),either in the serum of sows or that in their offspring at the ages of 3 days,7 days,and 21 days;The main results of Experiment 2 were as follows:(1)Dietary serine supplementation had no significant effect on selenium content in the serum,longissimus dorsi muscle,and kidney of weaned piglets(P>0.05).However,dietary supplementation with 0.5% serine significantly increased the selenium content in the liver(P<0.05);(2)Dietary serine supplementation significantly increased the gene expression of glutathione peroxidase 1(Gpx1),Gpx2,thioredoxin reductase 1(Txnrd1)、Txnrd2,and Sepp1 in the longissimus dorsi muscle and liver of weaned piglets(P<0.05);(3)Dietary serine supplementation with 0.5%serine had the highest Sepp1 concentration and glutathione peroxidase(Gpx)and thioredoxin reductase(Trx R)activities in the longissimus dorsi muscle of weaned piglets,which were significantly higher than those in the control piglets(P<0.05);(4)Dietary serine supplementation with 0.25% serine had the highest Gpx and Trx R activities in the liver of weaned piglets,which were significantly higher than those in the control piglets(P<0.05).In conclusion,dietary serine supplementation in sows diet could increase the serum Sepp1 content of sows and their piglets.In addition,this study also found a significantly positively correlation between serum Sepp1 content and growth performance of piglets,suggested that serum Sepp1 content is correlated with the growth performance of piglets.It suggested that serum Sepp1 content may be a potential factor affecting the growth performance of piglets.Dietary serine supplementation in weaned piglets could improve the gene expression of selenoprotein and the activities of selenoprotein enzyme in piglets,and alleviated the oxidative stress of piglets,with the appropriate concentrations of serine to be included in the diet being 0.25% and 0.5%.These results indicated that serine is beneficial to the biological function of selenium and promote the healthy growth of pigs.