Mechanisms Of Soluble Fiber Inclusion In Gestation Diet Manipulating Satiety During Gestation And Feed Intake During Lactation Of Sows

Maximizing feed intake during lactation is critical to improve overall sow performance and determine profitability in swine enterprises. Sow’s reproductive cycle is a entirety. Appropriate feed intake level during gestation would improve litter weight and lactation feed intake, while inadequate feed intake during lactation results in lower milk yield of sows leading to lower 21-day litter weaning weights. Inadequate feed intake and excessive weight loss during lactation were indicators of tissue catabolism in exchange for meeting metabolic damands of mammary gland and had adverse effects on subsequent reproduction of sow. Therefore, pregnant sows are recommended to be fed restrictively. However, sows managed under this regimen have greater feeding motivation after feeding, which resulted in development of abnormal behavior and had a negative influence on the reproductive performance of sows. Additionally, the mechanism by which dietary fiber exert their beneficial effects on lactation feed intake is poor understood.There is some evidence that sows provided with high-fiber diet during gestation to promote satiety, and were also shown to increase sow voluntary feed intake during lactation, but results remain equivocal. Many factors including fiber type, duration of feeding and dosage may contribute to the inconsistent results, but the physicochemical properties and fermentability of dietary fiber could influence satiety and food intake. It is important to development of novel dietary fibers which have functional properties similar to konjac flour(KF), and also have a similar effect on satiety and lactation feed intake among the sows fed those dietary fibers.In this study, we firstly investigated the effects of soluble fiber inclusion in gestation diet with varying fermentability characteristics on insulin sensitivity and lactation feed intake of sows over two parities. Subsequently, we clarified the potential mechanisms of dietary soluble fiber for pregnant sow manipulation in feed intake during lactation using 16 S r DNA gene pyrosequencing was analyzed. Lastly, we developed of novel dietary fibers which have functional properties similar to KF, and also have a similar effect on satiety and lactation feed intake among the rats fed those dietary fibers. The main contents and results are as follows:In the first part, the aim of this study was to investigate the effects of soluble fiber inclusion in gestation diet with varying fermentability characteristics on insulin sensitivity, lactation feed intake of sows and their piglet growth over two parities. After breeding, ninety multiparous Landrace sows were assigned random Ly to 1 of 3 experimental diets: the control diet, 2.2 % konjac flour(KF) diet or 18.5% sugar beet pulp(SBP) diet. All diets had the similar levels of NE, CP, insoluble fiber and NDF, but KF and SBP diets had higher SF levels than the control diet. The sows were restrict-fed with the three different diets during gestation, yet during lactation they were fed with the same diet ad libitum. In vitro fermentation of enzymolysis residues of three gestation diets, gas and short chain fatty acid(SCFAs) production were monitored during fermentation. The main results are as follows:1. Fermentation of enzymolysis residues of KF or SBP diets resulted in higher final asymptotic gas volume than that of the control diet. Fermentation of enzymolysis residues of KF diet mainly comes from rapidly fermented fractions, whereas that of SBP diet mainly comes from slowly fermented fractions. Fermentation of enzymolysis residues of KF diet produced lower(FRD0)1 than the control and SBP diets(P<0.01). Compared with the KF diet,(T1/2)1 from rapidly fraction was lower in SBP diet(P<0.01), while there were no differences between the control diet and SBP diet. Acetic acid, butyrate acid and total SCFAs concentrations after in vitro fermentation of enzymolysis residues of KF diet were higher(P<0.01) than control and SBP diets.2. On day 90 of gestation, sows fed the KF diet had higher plasma concentration of SCFAs at 4 h after feeding than sows fed the control diet. In addition, the inclusion of KF in gestation diet of sows reduced plasma free fatty acid(FFA) concentration(P<0.01) at 4 h after feeding, and reduced the value of homeostasis model assessment-insulin resistance(HOMA-IR)(P<0.05), but increased the value of HOMA-IS(P<0.01).3. Sows fed the KF diet increased feed intake during lactation(P<0.01) and weaned significantly heavier pigs(P<0.01) than those fed the control diet. However, these effects were not found in sows fed the SPB diet.In the second part, the study investigated the effects of supplementation of KF to sow gestation diets over two successive reproductive cycles on constipation in peripartal period, quality of colostrum and milk, lactation feed intake of sows and piglet performance in the second reproductive cycle. Multiparous large white sows(n=72) were assigned random Ly to one of two experimental treatments: the control diet; 2.2% KF diet. The sows remained on the dietary treatments for two reproductive cycles. The main results are as follows:1. Dietary treatments had no effect on body weight, backfat thickness, weaning-to-estrus interval, faecal moisture content or the composition of colostrum or milk.2. Sows fed the KF diets had higher faecal scores on day 113 of gestation(P<0.05), days 4(P<0.01) and 5(P<0.05) of lactation than their control counterparts. Supplementation of the diet with KF increased faecal Lactobacillus counts and reduced Clostridium counts(P<0.01).3. Sows fed the KF diets also ate more feed during lactation(P<0.05) and weaned significantly heavier pigs(P<0.01) than those fed the control diet.In the third part, we clarified the potential mechanisms of dietary KF for pregnant sow manipulation in feed intake during lactation using 16 S r DNA gene pyrosequencing was analyzed. At 2h postprandial on day 10, 60, 90 and 109 of gestation, and on day 1, 3, 7, and 21 of lactation, before feeding on day 10 and 109 of gestation and on day 3 and 7 of lactation, blood samples were collected from sows and analyzed of oxidative stress parameters, TNF-α, IL-6, HOMA value, SCFAs and FFA. The main results are as follows:1. Our results showed that serum levels of reactive oxygen species(ROS)(P<0.05), 8-hydroxy-deoxyguanosine(8-OHd G)(P<0.05) and thiobarbituric acid reactive substances(TBARS)(P<0.05) were higher during gestation and lactation than in early gestation. The KF diet significantly reduced sows’ serum concentrations of 8-OHd G(P<0.05) and ROS(P<0.05) on day 1 of lactation.2. On day 109 of gestation, sows fed the KF diet had higher plasma concentration of SCFAs at 4 h after feeding than sows fed the control diet. In addition, the inclusion of KF in gestation diet of sows reduced plasma FFA concentration(P<0.01) at 4 h after feeding, and reduced the value of HOMA-IR(P<0.05), but increased the value of HOMA-IS(P<0.01). Additionally, sows fed the KF diet decreased the plasma concentration of TNF-α than the control group(P<0.05).3. A total of 9 phyla were detected in the sow gut community. Regardless of the diet, Firmicutes(38.69%), Proteobacteria(17.12%) and Bacteroidets(16.95%) were found to be the dominant bacterial phyla in the sows. However, inhibition of Bacteroidets and increased the Firmicutes were clearly evident in the KF group. in addition, the KF group elevated the levels of Roseburia,Ruminococcus,Lactobacillus,Akkermansia genera(P<0.0001) while decreased the levels of Prevotella, Bacteroides and Chloroflexi compared with the control group.4. The PCo A revealed that the composition of sow microbiotas. During gestation, the control and KF groups were scattered. However, during lactation, the two groups were clustered together, because they received the same feed during lactation. This indicates that the KF inclusion in gestation diet can change the diversity of the faecal microbiota of sows.5. We performed a Spearman correlation analysis in order to evaluate the potential link between significant changes in gut microbiota composition and sow’s metabolism. We found that the Akkermansia were negatively associated with the HOMA-IR(r=-0.61, P<0.05), while were positively associated with the HOMA-IS(r=0.63, P<0.05) and acetate acid(r=0.62, P<0.05). Clostridium- Ⅺ were negatively associated with the 8-OHd G(r=-0.74, P<0.05). Bacteroides were positively associated with the butyrate acid(r=0.64, P<0.05) and SCFA(r=0.73, P<0.05), while were negatively associated with the FFA(-r=0.64, P<0.05). Ig G in the colostrum were positively associated with the Roseburia(r=0.80, P<0.05) and Blautia(r=0.84, P<0.05).In the fourth part, we developed of novel dietary fibers which have functional properties similar to KF, and also have a similar effect on lactation feed intake among the rats fed those dietary fibers. Sprague-Dawley rats were randomized into four treatment groups: the control, 2% konjac flour(KF), 2% fiber combination 1(FC1), and 2% fiber combination 2(FC2). Diets with order of water binding capacity(WBC), and swelling capacity(SC) were FC1> KF>FC2>control. The main results are as follows:1. FC1 and KF groups reduced the average daily food intake and cumulative food intake compared with the control group(P<0.05), mainly due to the decreased feeding behavior and increased satiety, as indicated by decreased meal numbers and increased inter-meal intervals.2. FC1 and KF groups had higher concentrations of acetate acid and propionate acid in the cecal contents than the control group(P<0.05). Supplementation of FC1 and KF with high WBC and SC increased the WBC and SC of the stomach digesta. Notably, the correlation coefficients for the daily food intake were negatively correlated with the WBC(r=-0.44, P<0.05) or SC(r=-0.37, P<0.05) of stomach digesta.3. Compared with the control group, the FC1 and KF groups increased the cecal digesta weight, due to increase in the cecal moisture content(P<0.05).In the fifth part, we evaluated maternal consumption of fermentable fiber with high hydrating properties during pregnancy: impact on maternal glucose tolerance and insulin sensitivity, lactation food intake, and their offspring growth in rats. Sprague-Dawley rats were randomized to four groups and fed the control diet or diet containing 2% KF, FC1, and FC2 during gestation. Dams from all four groups were fed the same level with their respective diets during gestation and offered food ad libitum during lactation. Glucose tolerance test(GTT) and insulin tolerance test(ITT) were examined on day 18 or 19 of gestation. The main results are as follows:1. Dams in KF and FC1 groups decreased the area under the curve during the GTT and decreased the HOMA-IR values compared with the control group(P<0.05).2. FC1 group significantly increased the food intake of lactation and weaned heavier litter weights than the control group(P<0.05).In conclusion, our research demonstrated KF inclusion in gestation diet increased the lactation feed intake and improved the litter weights. It was suggested that the beneficial effect of KF on lactation feed intake might be achieved by the fiber’s fermentability to improve insulin sensitivity as shown by the sow’s higher plasma concentrations of SCFAs. On the other hand, KF induced changes of the gut microbiota composition, for example, Akkermansia, and reduced oxidative stress and inflammation, then, improved insulin sensitivity of sows during late gestation. Lastly, we developed of a novel dietary fiber which have functional properties similar to KF, and also have a similar effect on satiety, and lactation feed intake among the rats fed this fiber.