| Stevia residue is the waste after high temperature extraction of Stevia.The content of crude fiber,neutral washing fiber and acid washing fiber are 22.97%,53.78% and 66.87% respectively in dry matter,and many chlorogenic acids and steviol are also contained.The results showed that Stevia residue not only has rich crude fiber,but also a large number of phenolic acids and derivatives can improve the quality of milk,milk production,anti-inflammatory,antibacterial,prevention of reproductive system diseases,antioxidant and anti stress effects.However,the excessive crude fiber content in feed may reduce the digestibility of pregnant sows.Therefore,the reproductive performance of sows can be improved by adding appropriate Stevia residue to the diets of pregnant sows.This study aimed to investigate the effects of different supplementation levels of stevia residues in high-fiber diets on the reproductive performance,growth performance,fecal microorganisms and expression of nutrient transport genes in placenta of pregnant sows and growth performance of piglets.Forty-eight first farrowing Danish Landrace sows with similar weight,age,and due date were randomly divided into four groups.The control group was fed a normal diet(CON;3.15 % crude fiber content),and the treatment groups were supplemented with 20 %(SRL),30 %(SRM),or40 %(SRH)stevia residue,with crude fiber content of 7.79 %,9.15 %,and 10.68 %,respectively.The results showed that :(1)Compared with the control group,stevia residue addition group could significantly increase the feed intake of lactating sows(P<0.05),and the highest feed intake of 30% level group was 5.96 kg.45 days later,the back fat growth rate o f Stevia group was significantly higher than that of the control group(P<0.05).Compared with the control group,the time of gastrointestinal emptying in the 30% level group was significantly increased(P<0.05).(2)The total milk production of 30% and 40% level group was significantly higher than that of the control group(P<0.05),reaching 222.77 kg.Compared with the control group,the duration of labor in the 30% and 40% level groups was significantly shorter(P<0.05),which was 14.06%and 12.48% shorter respectively.The number of weak offspring in the 40% level group was significantly lower than that in the control group(P<0.05).The number of weak offspring in the20% level group and the 30% level group was significantly lower than that in the control group(P<0.01),decreased by 68.5% and 57% respectively.Compared with the control group,the survival rate of piglets in the 30% level group was significantly improved(P<0.05).(3)The diarrhea rate of Stevia residue group was significantly lower than that of the control group(P<0.05),which decreased by 87.96%,95.10% and 97.06% respectively.(4)Compared with the control group,there was a decreasing trend in nutrient digestibility in the 40% level group(P>0.05).The digestibility of crude protein and crude fiber in the 30% level group was significantly higher than that in the control group(P<0.05).(5)Compared with the control group,the content of conventional components in the 30% and40% level groups was significantly increased(P<0.05).The optimal components in the 30% level group were 8.23% of milk fat,9.91% of milk protein,13.95% of lactose and 19.93% of non fat milk solids.The contents of immunoglobulin A,G,M,growth factor and insulin-like growth factor-Ⅰ in 30% group were significantly increased(P<0.05).(6)The total protein content in cord blood of piglets in 30% level group was 17.19% higher than that in control group(P>0.05).Compared with the control group,the levels of 20%,30% and40% in the control group were significantly lower than tho se in the control group(P<0.05),which were 17.80%,22.96% and 37.34% respectively.(7)Compared to the control group,species diversity was greater in the 30 % stevia residue group.At the phylum level,Firmicutes and Spirochaetes had the greatest relative abundances;Firmicutes was most abundant in the 30% level group,and Spirochaetes was most abundant in the control group.At the genus level,Lactobacillus,Streptococcus,Lachnospiraceae＿XPB1014＿group,and Treponema＿2 had the highest relative abundances in the stevia residue treatments.Among them,Lactobacillus and Treponema＿2 were more abundant in 20% level group,Streptococcus was more abundant in 40% level group,and Lachnospiraceae＿XPB1014＿group was more abundant in 30% level group.Linear discriminant analysis effect size(LEf Se)showed that the bacterial species differed among the stevia residue treatments.20% level group mainly included g＿＿Lactobacillus and g＿＿Romboutsi,30% level group mainly included g＿＿Lachnospiraceae＿XPB1014＿group and g＿＿Ruminococcaceae＿UCG＿014,40% level group mainly included g＿＿Streptococcus,and CON mainly included g＿＿Treponema＿2,f＿＿Clostridiaceae＿1,g＿＿norank＿f＿＿Muribaculaceae,and g＿＿norank＿f＿＿p＿251＿o5.Stevia residue supplementation significantly increased the abundance of beneficial bacteria,such as g＿＿Lachnospiraceae＿XPB1014＿group,g＿＿Christensenellaceae＿R-7＿group,and g＿＿Ruminococcaceae＿UCG-005(P(27)0.05),and significantly reduced the abundance of harmful bacteria,such as Treponema＿2(P(27)0.05).(8)20% and 30% Stevia residue could significantly reduce the content of estradiol in feces and urine of pregnant sows(P<0.05).Compared with the control group,the levels of progesterone in feces and urine of the 20%,30% and 40% level groups were significantly increased(P<0.05),and the 30% level group increased the most,by 38.40% and 39.17% respectively.(9)Stevia residue could improve the expression of genes related to nutrient transport in sow placenta.Compared with the control group,the expression of neutral amino acid tran sporter 2(SNAT2)gene was significantly increased in the 20% level group(P<0.05).In the 30% level group,the expression of neutral amino acid transporter 1(SNAT1),neutral amino acid transporter2(SNAT2),glutamate transporter 3(EAAT3),glucose transporter 2(GLUT2),insulin-like growth factor(IGF2)gene were significantly increased(P<0.01),and peptide transporter 1(Pep T1)gene expression was significantly increased(P<0.05).In 40% level group,glutamate transporter 3(EAAT3),peptide transporter 1(Pep T1),glucose transporter 2(GLUT2),insulin-like growth factor-2(IGF-2)gene expression was significantly increased(P<0.01)and the expression of SNAT1 gene was significantly increased(P<0.05).In conclusion,Stevia residue can improve the reproductive performance and growth performance of pregnant sows,improve the growth performance of piglets,promote the embryonic development of pregnant sows,improve the intestinal balance and evenness index of the intestinal flora in pregnant sows,promote the relative abundance of beneficial bacteria,inhibit the relative abundance of harmful bacteria,reduce feed cost.The optimal supplementation level of the stevia residue was found to be 30 %. |
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