Effects Of Dietary Fiber In Gestation Diet On Sow Reproductive Performance And Gut Microbiota

Dietary fiber is an important nutrient to improve the intestinal health and reproductive performance of sows.Our previous studies have shown that increasing fiber intake during pregnancy for one and two reproductive cycles could improve sow reproductive performance.But there are also conflicting reports.There may be three reasons for the inconsistent results.Firstly,fiber level in gestation diet was different.Excessive high dietary fiber intake would reduce the nutrient digestibility of diet,but low dietary fiber intake had no significant effect.The effect of fiber supplementation in gestation diet need to be studied further.Secondly,fiber treatment time during gestation was different.Researches have confirmed that adding fiber during gestation for successive parites could significantly improve the reproductive performance of sows,such as increasing litter size and litter weight.However,the mechanism of fiber supplementation during successive parities to improve sow reproductive performance remains unclear.At last,fiber types used in gestation diet was different.The content of insoluble fiber(ISF)and soluble fiber(SF)in different fiber materials is different,resulting in huge differences in ISF/SF ratio of diets.Studies have shown that dietary ISF/SF ratio could influence nutrient digestibility,which may be one of the important factors affecting sow reproductive performance.However,the effect of ISF/SF ratio in gestation diet on sow reproductive performance has not been reported.Both the level and type of fiber can affect the composition and diversity of intestinal microbiota,and whether the fiber addition during pregnancy can improve sow reproductive performance is related to microorganisms needs to be investigated.Therefore,this research aims to investigate the effect of fiber addition and ISF/SF ratio during gestation on sow reproductive performance for successive parities,and to explore the possible ways that dietary fiber can improve sow reproductive performance from the perspective of gut microbiota.The main contents and results are presented as follows:Experiment 1 Effects of dietray fiber supplementation in gestation diet on sow reproductive performance and gut microbiota for three successive paritiesXA total of 36 Large White × Landrace crossbred gilts with similar body weight(BW,132.34 ± 1.22 kg),backfat thickness(BF,14.33 ± 0.48 mm)and age(232 ± 1 d)were used in a single-facter design.After insemination at the third estrus,gilts were assigned randomly to 2 treatments(low-fiber group and high-fiber group,n = 18).Sows in the high-fiber group(HF)consumed three times as much SF and ISF as those in the low-fiber group(LF)every day during gestation for three successive reproductive cycles to investigate sow reproductive perfromance.The daily dietary fiber intake per sow in LF group for three successive cycles averaged 224.96 g from 1 to 89 d,265.80 g from 90 to112 d;HF group averaged 674.89 g from 1 to 89 d,797.40 g from 90 to 112 d.Sows were fed the same diet during the lactation period to investigate the growth performance of piglets.The main results of the experiment were as follows:(1)Compared with LF group,HF group significantly increased the total litter weight,birth weight alive and placental weight in the second and third parities(P < 0.05),increased the mean total-and live-born litter weight for all four cycles(P < 0.05),and shortened parturition progress and birth interval of piglets in the first parity(P < 0.05),showed a trend of reducing the birth interval of piglets in the second parity and increasing the live-born litter size in the third parity(P < 0.1);(2)HF group markedly increased sow feed intake during day 0 to 14 of lactation,the piglet BW at weaning,body weight gain during day 0 to 28 of lactation in the first parity(P < 0.05);increased piglet BW at weaning and body weight gain during day 0 to 28 of lactation(P < 0.05);(3)HF group prominently enhanced the fecal observed＿species and chao 1 index of sow fecal microbiota in second parities(P < 0.05),had a significantly different β diversity during gestation in the first and second parity(P < 0.05),and a trend of different βdiversity was observed on lactation 28(P = 0.060)compared with LF;(4)HF group markedly decreased the relative abundance of Tenericutes,Actinobacteria,Clostridium＿sensu＿stricto＿1,Streptococcus and Ruminococcus＿1(P < 0.05),significantly increased the relative abundance of Fibrobacteres,Lactobacillus,Christensenellaceae＿R-7＿group,[Eubacterium]＿coprostanoligenes＿group and Lachnospiraceae＿AC2044＿group(P < 0.05).The abundance of Tenericutes and Ruminococcus＿1 were significantly negative correlation with litter weight(P < 0.05),while the relative abundance of Lactobacillus,Christensenellaceae＿R-7＿group and[Eubacterium]＿coprostanoligenes＿group were significantly positive correlation with litter weight in the second parity(P < 0.05).The results of this experiment showed that(1)The continuous high-fiber treatment during gestation in a three successive parity could increase litter weight and placenta weight in the second and third parity,shorten the delivery preogress and increase fecal score;(2)Significantly changes in the composition and diversity of sow fecal microbiota during gestation happened when treated to the second parity by high-fiber diet;(3)High fiber treatment for a three successive parity improving sow reproductive performance in the second and third parity might be related to the increased abundance of beneficial bacteria and fiber-degrading bacteria of feces on day 30 of gestation in the corresponding parity.Experiment 2 Effect of dietary fiber supplementation on fecal microbiome and plasma metabolites: based on the metagenomics and metabonomicsThe experiment design was the same as experiment 1.Eight sows were selected from each treatment group to collect blood and feces on the gestation day 30,60,90 and 110 in the third parity.Besides,placental samples were collected to investigate the m RNA expression of genes related to the development and function of placenta in the third parity.Blood and feces samples on day 30 of gestation were used for the determination of metabolomics and metagenomics,repectively.Results were as follows:(1)Compared with LF group,HF group significantly increased the sow fecal acetic acid,butyrate and total volatile fatty acids(VFAs)levels(P < 0.05),with a trend to increase the level of propionate(P = 0.076).The levels of acetate,propionate,butyrate and total VFAs were significantly increased at 60,90 and 110 days of gestation in the third parity(P <0.05);(2)HF group significantly increased serum and placental serotonin levels and placental progesterone concentrations of sows in the third parity(P < 0.05).The m RNA expression levels of SERT,5-HT2 BR,5-HT7 R,IGF-2,CYP11A1,Slc38a1 and GLUT2 in placenta were up-regulated(P < 0.05),and the m RNA expressions of TPH1 and H19 were down-regulated by high-fiber treatment(P < 0.05);(3)At the phylum level,Firmicutes and Bacteroidetes were the dominate species in HF and LF group.The Firmicutes/Bacteroidetes ratio in the HF group was significantly lower than that in the LF group(P < 0.05),the relative abundance of Bacteroidetes,Proteobacteria and Fibrobacteria was significantly higher than that in the LF group(P <0.05).At the genus level,the species with the highest relative abundance in LF group was Clostridium,and the species with the highest relative abundance in HF group was Prevotella.The relative abundance of Clostridium and Tuicibacter in HF group was significantly lower than that in LF group(P = 0.001),the relative abundance of Prevotella and Oscillibacter was significantly higher than that in LF group(P < 0.05),and the relative abundance of Prevotella,Oscillibacter,Eubacterium,Alistipes,Faecalibacterium and Fibrobacter were all higher than that in LF group(P < 0.05).At the species level,the relative abundance of Firmicutes bacterium CAG: 110,which was the highest in both groups,in HF group was significantly higher than that in LF group(P < 0.05);(4)The differentially expressed genes were compared with the KEGG database,and it was found that there were significant differences among the 23 clustering systems(P <0.05).The first 35 pathways with significant differences in relative abundance were enriched by KEGG pathways(P < 0.05),which were mainly related to the synthesis,metabolism and transport of nutrients.By comparing the sample genes with the CAZy database,it was found that the gene abundance associated with glucosidase hydrolyase and glucosidase transferase was the highest.The first 35 enzymes with significant difference in relative abundance were all enriched in HF group(P < 0.05);(5)Compared with KEGG database,it was found that there were significant differences in KEGG pathway Tryptophan metabolism,Benzoxazinoid biosynthesis,Phenylalanine,Tyrosine and Tryptophan biosynthesis(P < 0.05);(6)Correlation analysis of metagenomics and metagenomics shows that Firmicutes bacterium CAG: 110 shows a significant negative correlation with the synthesis of indoles(P < 0.05).The results of this experiment showed that(1)Dietary fiber supplemented in gestation diet for three successive parity can increase the abundance of fiber degrading bacteria and VFAs production,and reduce the abandunce of pathogens in sow feces on day 30 of gestation in the third parity.(2)Dietary fiber supplemented in gestation diet for three successive parity can increase the relative abundance of VFAs producing bacteria,Eubacteria and Firmicutes bacterium CAG: 110 in sow feces,increase the serotonin concentration in sow serum and placenta,improve placental development and function,and thus improve sow reproductive performance.Experiment 3 Effects of dietary fiber in gestation diet on sow colonic and placental serotonin concnentrationA total of 10 Large White × Landrace crossbred gilts with similar body weight and age were used in a single-facter design.After insemination at the third estrus,gilts were assigned randomly to 2 treatments(non-fiber(NF)group and fiber(F)group,n = 5).The NF group was fed a homozygous diet without fiber,and the diet of the F group was an additional 8.33 g inulin and 200 g cellulose per kg of NF diet.The experiment period was from mating to 106 d of gestation.The samples collected mainly included blood samples,colon tissue and chyme samples,and placental tissue samples from the sows at 106 days of gestation.The main results are as follows:(1)Compared with NF group,F group significantly inceased the litter weight(P < 0.05,but did not affect litter size on day 106 of gestation(P > 0.05);(2)F group significantly increased the serum and colonic serotonin concentrations in sows(P < 0.05),up-regulated the m RNA expression of TPH1 gene(P < 0.05),and increased the colonic TPH concentration(P < 0.05).Non-fiber treatment significantly up-regulated the m RNA expression of SERT(P < 0.05);XIV(3)F group significantly increased the expression of placental serotonin transport(P <0.05),and increased the concentration of placental serotonin(P < 0.05).NF group significantly increased the concentration of placental TPH1(P < 0.05).The above results showed that(1)Fiber treatment could stimulate the synthesis of colonic serotonin and improve the level of serum serotonin;non-fiber treatment promoted colonic serotonin transport;(2)Fiber treatment could promote the transport of maternal serotonin to the placenta,while non-fiber treatment could promote the synthesis of placental serotonin.Experiment 4 Effects of the ratios of insoluble to soluble fiber in the gestation diets on sow and litter performance for four successive paritiesSixty-four Large White × Landrace crossbred gilts with similar BW(153.23 ± 1.02kg),BF(15.76 ± 0.34 mm)and age(284 ± 1 d)were used in a single-facter design.After insemination at the fourth estrus,gilts were assigned randomly to 4 treatments with the ratios of ISF to SF of 3.89,5.59,9.12,12.81 in the gestation diets for four successive reproductive cycles,respectively,expressed as T1,T2,T3 and T4.Sows were feed the same diet during the lactation period.For all the cycels,sow BW and BF were measured on the day of breeding,day 110 of gestation,the day of delivery and weaning,and sow reproductive,lactation performance and feed intake during lactation were recorded,and 8sows were selected from each treatment group to collect blood and feces on the day 30,60,90 and 110 of gestation.Besides,placental samples were collected to investigate the m RNA expression of genes related to the development and function of placenta in the third parity.The main results of the experiment were as follows.(1)The fiber ratio did not affect the total born number and the litter weight of each parity(P > 0.05),but T1 and T2 groups had higher average total litter size,litter size alive and total litter weight on four cycles than that in T3 group(P < 0.05),and the litter size alive in T2 group was the highest;(2)The dietary fiber ratio had no significant difference in the lactation feed intake of different fetal sows,but the dietary treatment had a significant impact on the piglet growthperformance in the first parity.Weaning weight and litter weight of piglets in T1 and T2 groups were significantly higher than that in T4 group(P < 0.05);(3)The piglet birth interval of T1 and T2 was 5.25 min and 6.44 min shorter than that of T3,respectively(P < 0.05),On the second parity.The parturition progress of T1 and T2 was 98.76 min and 97.40 min shorter than that of T3,respectively(P < 0.05);(4)On the first parity,fecal acetate concentration of T1 was significantly higher than that of T3 and T4,and the total VFAs concentration of T1 was significantly higher than that of T4(P < 0.05).On the second parity,the concentration of acetate and total VFAs in the T2 was significantly higher than that in the T3 and T4 groups(P < 0.05).On the third parity,fecal acetate content in T2 was the highest and significantly higher than that in T4group(P < 0.05).Serum serotonin concentration in T2 was significantly higher than that in other groups(P < 0.05).However,there were no significant differences in placental serotonin content and progesterone concentration among the four treatments(P > 0.05);(5)When ISF/SF ratio was 3.89 in gestation diet of nulliparous sows,the abundance of fiber-degrading bacteria Prevotella increased in the feces(P<0.05).When ISF/SF ratio was5.59 in gestation diet of multiparous sows,the abundance of pathogenic bacteria Streptococcus was decreased,while the abundance of beneficial bacteria Bifidobacterium and fiber-degrading bacteria Prevotella was increased in the feces;(6)During the first and second parity,there was no significant difference in theα-diversity among treatments on day 30,60 and 90(P > 0.05),while on the day 110 of parity 1,the chao 1 indexes in T1,T2 and T3 were significantly higher than that in T4(P <0.05).On the day 110 of gesation in the second parity,observed species and shannon index of T4 group were all significantly higher than those of T1,and chao 1 index of T1 had a tendancy to be lower than those of T3 and T4 groups(P < 0.10);(7)The community structure of T1 and T2 on gestation d 110 in the first and second parity tended to be consistent,and the community structure of T3 and T4 groups tended to be consistent,while the community structure of T1 and T2 was significantly different from that of T3 and T4.Compared with the fecal microbiota composition in the first parity,XVI higher Ruminococcaceae,Spirochaetaceae,Bacteroidales＿S24＿7,Lachnospiraceae and Rikenellaceae and lower Prevotellaceae,Lactobacillaceae,Streptococcaceae and Clostridiaceae＿1 were observed(P < 0.05).The results showed that(1)When the ISF/SF ratio in gestation diet were 3.89 and 5.59,it could increase the piglet weaning weight on the first parity,shorten parturition progress on the second and third parity,increase the mean total litter number,live litter number and total litter weight during the four successive paritie;(2)The appropriate ISF/SF ratio in gestation diet was 3.89 for primary sow and 5.59 for multiparous sows,which could increase the abundance of fiber degrading bacteria and VFAs production,improve the sow reproductive performance;(3)When the ISF/SF ratio in gestation diet was 5.59,it was benefical to the growth of Bifidobacterium.Experiment 5 Effects of the ratios of insoluble to soluble fiber in the gestation diet on piglet intestinal development,antioxidative capacity and gut microbiotaSixty-four Large White × Landrace crossbred gilts with similar BW(153.23 ± 1.02 kg),BF(15.76 ± 0.34 mm)and age(284 ± 1 d)were used in a single-facter design.After insemination at the fourth estrus,gilts were assigned randomly to 4 treatments with the ratios of ISF to SF of 3.89,5.59,9.12,12.81 in the gestation diets,respectively,expressed as R1,R2,R3 and R4.A total of 24 piglets,6 each treatmen,were slaughted at birth and weaning,respectively.Blood sample was collected before slaughter.After evisceration,liver and intestinal samples were collected for measurement.The main results of the experiment were as follows.(1)Duodenal V/C of newborn piglets in group R3 was significantly higher than that in group R4(P < 0.05),and jejunal V/C in groups R1 and R2 were significantly higher than those in groups R3 and R4(P < 0.05).Lactase activity in R1 group was significantly higher than that in R3 and R4 group,and R2 group was significantly higher than that in R4group(P<0.05).Sucrase activity in group R4 was significantly lower than that in the other three groups(P = 0.021);(2)Plasma TNF-α level of newborn piglets in R1 group was significantly lower thanthat in R3 and R4 group,and that in R2 group was significantly lower than that in R3group(P < 0.05);Plasma T-AOC of newborn piglets in R1 and R2 groups were significantly higher than those in R4 groups(P < 0.05),and plasma GSH-Px activities of newborn piglets in R1 and R2 group were significantly higher than that in the R3 and R4groups(P < 0.05).The liver GSH-Px activity of newborn piglets in group R1 was significantly higher than those in groups R3 and R4(P < 0.05),and that in R2 group was significantly higher than that in group R3(P < 0.05);(3)The relative liver Nrf2 m RNA expression in piglets was significantly higher in R1 than in R3 and R4(P < 0.05),and in R2 than in R4(P < 0.05).Piglets in R1 and R2 had significantly higher relative HO-1 m RNA expression in the liver than piglets in R4(P <0.05).Moreover,the offspring of sows fed R1 and R2 diets showed significant down-regulation of the relative liver NF-κB m RNA expression(P < 0.05);(4)The acetate,butyrate and total SCFAs concentrations in the colon of newborn piglets in R1 and R2 groups were significantly higher than those in R3 and R4 groups(P<0.05),and the propionate concentration of piglets in R1 and R2 groups were higher than those in R3 and R4 groups(P < 0.10);(5)PCo A clustering showed that R1 and R2 had similar microbial composition,while R3 and R4 had similar microbial composition.The microbial flora related to fiber degradation in the colon of piglets in R1 and R2 groups was significantly increased.In addition,the relative abundance of unidentified＿Enterobacteriaceae in the colon of piglets in the R1 and R2 groups was significantly lower than that of the R4 group(P < 0.05).The above results showed that when the ISF/SF ratio in the diets of pregnant sows was3.89 and 5.59,the intestinal development and antioxidant capacity of the offspring of newborn piglets were improved and the inflammatory response was decreased,which may be related to the change of intestinal microbiota of piglets.As mentioned above,the following conclusions could be drawn in this article:(1)In the current study,when the daily dietary fiber intake per sow for three successive cycles averaged 674.89 g from 1 to 89 d,797.40 g from 90 to 112 d,litter weight was increased inthe second and third parity,which might due to feeding high-fiber diets to sows during successive parities increased the relative abundance of VFAs producing bacteria,Eubacteria and Firmicutes bacterium CAG: 110 in sow feces,promoted the serotonin synthesis in the colon,increased the serotonin concentration in sow serum and placenta and improved the development and function of placenta.(2)In the current study,higher piglet weaned weight in the first parity and averaged litter size and litter weight over four reproductive cycles were observed when the ISF/SF ratio were 3.89 and 5.59.The optimal ISF/SF ratio was 3.89 in gestation diet of nulliparous sows,while the optimal ISF/SF ratio was 5.59 in gestation diet of multiparous sows.(3)The ratio of insoluble to soluble dietary fiber in gestation diet could influence offspring gut microbiota composition,and the similarity of intestinal microbiota community of newborn piglets was similar to that of their mothers.