Starch supplementation improves the reproductive performance of sows in different glucose tolerance status

Maternal or post-weaning dietary fructo-oligosaccharide supplementation reduces stillbirth rate of sows and diarrhea of weaned piglets

Fructo-oligosaccharides (FOS) are well-known prebiotics that have the potential to improve sow reproductive performance and increase piglet growth. However, previous studies were observed in sole FOS-supplemented diets of sows or weaned piglets and did not consider the sow-to-piglet transfer effect on the performance and diarrhea rate of weaned piglets. This study explores the effects of dietary FOS supplementation on the reproductive performance of sows, and the effects of FOS supplementation at different stages on the growth performance and diarrhea rate of weaned piglets. A split-plot experimental design was used with sow diet effect in the whole plot and differing piglet diet effect in the subplot. Fifty-two multiparous sows (223.24 ± 14.77 kg) were randomly divided into 2 groups (0 or 0.2% FOS). The experiment lasted from day 85 of gestation to day 21 of lactation. Reproductive performance, glucose tolerance, placental angiogenesis, and intestinal flora of sows were assessed. At weaning, 192 weaned piglets were grouped in 2 × 2 factorial designs, with the main effects of FOS supplemental level of sow diet (0 and 0.2%), and FOS supplemental level of weaned piglet diet (0 and 0.2%), respectively. The growth performance and diarrhea rate of the weaned piglets were analyzed during a 28-d experiment. Maternal dietary supplementation of FOS was shown to reduce the stillbirth and invalid piglet rates (P < 0.05), improve the insulin sensitivity (P < 0.05) and fecal scores (P < 0.05) of sows, increase the abundance of Akkermansia muciniphila (P = 0.016), decrease the abundance of Escherichia coli (P = 0.035), and increase the isovalerate content in feces (P = 0.086). Meanwhile, the placental angiogenesis marker CD31 expression was increased in sows fed FOS diet (P < 0.05). Moreover, maternal and post-weaning dietary FOS supplementation reduced the diarrhea rate of weaned piglets (P < 0.05) and increased the content of short-chain fatty acids in feces (P < 0.05). Furthermore, only post-weaning dietary FOS supplementation could improve nutrient digestibility of weaned piglets (P < 0.05). Collectively, FOS supplementation in sows can reduce stillbirth rate, perinatal constipation, and insulin resistance, as well as improve placental vascularization barrier. Additionally, maternal and post-weaning dietary FOS supplementation reduced the diarrhea rate of weaned piglets, but only FOS supplementation in piglets alone at weaning stage could improve their nutrient digestibility.

KLF4 down-regulation underlies placental angiogenesis impairment induced by maternal glucose intolerance in late pregnancy

Maternal glucose intolerance in late pregnancy can easily impair pregnancy outcomes and placental development. The impairment of placental angiogenesis is closely related to the occurrence of glucose intolerance during pregnancy, but the mechanism remains largely unknown. In this study, the pregnant mouse model of maternal high-fat diet and endothelial injury model of porcine vascular endothelial cells (PVECs) was used to investigate the effect of glucose intolerance on pregnancy outcomes and placental development. Feeding pregnant mice, a high-fat diet was shown to induce glucose intolerance in late pregnancy, and significantly increase the incidence of resorbed fetuses. Moreover, a decrease was observed in the proportion of blood sinusoids area and the expression level of CD31 in placenta, indicating that placental vascular development was impaired by high-fat diet. Considering that hyperglycemia is an important symptom of glucose intolerance, we exposed PVECs to high glucose (50 mM), which verified the negative effects of high glucose on endothelial function. Bioinformatics analysis further emphasized that high glucose exposure could significantly affect the angiogenesis-related functions of PVECs and predicted that Krüppel-like factor 4 (KLF4) may be a key mediator of these functional changes. The subsequent regulation of KLF4 expression confirmed that the inhibition of KLF4 expression was an important reason why high glucose impaired the endothelial function and angiogenesis of PVECs. These results indicate that high-fat diet can aggravate maternal glucose intolerance and damage pregnancy outcome and placental angiogenesis, and that regulating the expression of KLF4 may be a potential therapeutic strategy for maintaining normal placental angiogenesis.

Effects of dietary supplementation of different levels of gamma-aminobutyric acid on reproductive performance, glucose intolerance, and placental development of gilts

This study aimed to investigate the effects of dietary gamma-aminobutyric acid (GABA) supplementation on reproductive performance, glucose intolerance, and placental development of gilts during mid-late gestation. Based on the principle of backfat thickness consistency, 124 gilts at 65 d of gestation were assigned to three dietary groups: CON (basic diet, n = 41), LGABA (basic diet supplemented with 0.03% GABA, n = 42), and HGABA (basic diet supplemented with 0.06% GABA, n = 41). The litter performance, glucose tolerance, placental angiogenesis, and nutrients transporters were assessed. The LGABA group improved piglet vitality and placental efficiency and decreased area under the curve of glucose tolerance test compared to the CON group (P < 0.05). Meanwhile, the LGABA group enhanced placental vessel density, platelet endothelial cell adhesion molecule-1 levels and gene expression of fibroblast growth factor 18 (P < 0.05). Furthermore, LGABA showed an uptrend in glucose transporter type 1 mRNA level (P = 0.09). Taken together, this study revealed that the dietary supplementation of 0.03% GABA can improve piglet vitality, glucose intolerance, and placental development of gilts.

Dietary fiber supplementation during the last 50 days of gestation improves the farrowing performance of gilts by modulating insulin sensitivity, gut microbiota, and placental function

Our previous study found dietary konjac flour (KF) supplementation could improve insulin sensitivity and reproductive performance of sows, but its high price limits its application in actual production. This study aimed to investigate the effects of supplementation of a cheaper combined dietary fiber (CDF, using bamboo shoots fiber and alginate fiber to partially replace KF) from the last 50 days of gestation to parturition on farrowing performance, insulin sensitivity, gut microbiota, and placental function of gilts. Specifically, a total of 135 pregnant gilts with a similar farrowing time were blocked by backfat thickness and body weight on day 65 of gestation (G65d) and assigned to 1 of the 3 dietary treatment groups (n = 45 per group): basal diet (CON), basal diet supplemented with 2% KF or 2% CDF (CDF containing 15% KF, 60% bamboo shoots fiber, and 25% alginate fiber), respectively. The litter performance, insulin sensitivity and glucose tolerance parameters, placental vessel density, and short-chain fatty acids (SCFAs) levels in feces were assessed. The gut microbiota population in gilts during gestation was also assessed by 16S rDNA gene sequencing. Compared with CON, both KF and CDF treatments not only increased the piglet birth weight (P < 0.05) and piglet vitality (P < 0.01) but also decreased the proportion of piglets with birth weight ≤ 1.2 kg (P < 0.01) and increased the proportion of piglets with birth weight ≥ 1.5 kg (P < 0.01). In addition, KF or CDF supplementation reduced fasting blood insulin level (P < 0.05), homeostasis model assessment-insulin resistance (P < 0.05), serum hemoglobin A1c (P < 0.05), and the level of advanced glycation end products (P < 0.05) at G110d, and increased the placental vascular density (P < 0.05) at farrowing. Meanwhile, KF or CDF supplementation increased microbial diversity (P < 0.05) and SCFAs levels (P < 0.05) in feces at G110d. Notably, the production cost per live-born piglet was lower in CDF group (¥ 36.1) than KF group (¥ 41.3). Overall, KF or CDF supplementation from G65d to farrowing could improve the farrowing performance of gilts possibly by improving insulin sensitivity, regulating gut microbiota and metabolites, and increasing placental vascular density, with higher economic benefits and a similar effect for CDF vs. KF, suggesting the potential of CDF as a cheaper alternative to KF in actual production.

Effect of dietary resveratrol on placental function and reproductive performance of late pregnancy sows

Placental function is vital to the fetal growth of sows, and resveratrol (RES) can protect cells against oxidative stress, which is one of the major factors impairing placental function. This study aimed to investigate the effect of dietary resveratrol (RES) on placental function and reproductive performance during late pregnancy in a sow model from the aspects of oxidative stress, insulin resistance, and gut microbiota. A total of 26 hybrid pregnant sows (Landrace × Yorkshire) with similar parity were randomly allocated into two groups (n = 13) and fed with a basal diet or a diet containing 200 mg/kg of resveratrol from day 85 of gestation until parturition. The dietary supplementation of RES increased the litter weight at parturition by 12.53% (p = 0.145), with ameliorated insulin resistance (HOMA-IR), increased triglyceride (TG) levels, and decreased interleukin (IL)-1β and IL-6 levels in serum (p &lt; 0.05). Moreover, resveratrol increased the placental vascular density (p &lt; 0.05) with the enhanced expression of nutrient transporter genes (SLC2A1 and SLC2A3) and antioxidant genes, such as superoxide dismutase 2 (SOD2) and heme oxygenase-1 (HO-1) but declined the expression of inflammatory genes, such as IL-1β and IL-6 (p &lt; 0.05). The characterization of the fecal microbiota revealed that resveratrol decreased the relative abundance of the Christensensllaceae R-7 group and Ruminococcaceae UCG-008 (p &lt; 0.05), which had a positive linear correlation with the expression of IL-1β and IL-6 (p &lt; 0.05), but had a negative linear correlation with the expression of SOD2, HO-1, SLC2A1, and SCL2A3 genes (p &lt; 0.05). These data demonstrated that dietary supplementation with resveratrol can improve placental function with ameliorated insulin resistance, oxidative stress, and inflammation potentially by regulating Ruminococcaceae UCG-008 and the Christensensllaceae R-7 group in sows.

Targeting gut microbiota-derived butyrate improves hepatic gluconeogenesis through the cAMP-PKA-GCN5 pathway in late pregnant sows

Short chain fatty acids (SCFAs) produced by gut microbiota affected hepatic glucose metabolism via the gut-liver axis. The present study aimed to investigate the effects of butyrate produced by gut microbiota on hepatic gluconeogenesis in late-pregnancy sows. A total of 240 primiparous sows in late pregnancy were tested for blood glucose using a glucose meter before feeding and grouped according to their blood glucose level as follows: 0-3.0 mmol L^-1 (low blood glucose group, LG group) and 3.1-5.0 mmol L^-1 (normal blood glucose group, NG group). Colonic SCFAs and microbiota, SCFAs in the portal vein and liver, and acetylation and phosphorylation levels in the liver samples were analyzed. Hepatocytes from pregnant sows were examined for the effect of butyrate on hepatic glucose gluconeogenesis. In vivo experiments showed that the reproductive performance, serum glucose metabolism index, colonic butyrate and butyrate-producing bacteria decreased in the LG group compared with the NG group. Correlation analysis found a positive correlation among colonic butyrate, butyrate-producing bacteria and the serum glucose metabolism index. Moreover, the hepatic cAMP concentration, PKA activity, GCN5 phosphorylation, and the expression of G6P and PEPCK were decreased and PGC1-α acetylation was increased in the LG group compared with the NG group. In vitro, sodium butyrate significantly stimulated the cAMP concentration, PKA activity, GCN5 phosphorylation, and the expression of G6P and PEPCK and inhibited PGC-1α acetylation in the LG group of hepatocytes from late-pregnancy sows. Interestingly, another in vivo experiment showed that dietary 1-kestose, a natural regulator of gut bacteria, significantly increased butyrate and butyrate-producing bacteria, and improved the reproductive performance and serum glucose metabolism index in late-pregnancy sows. Taken together, we found that targeting gut microbiota-derived butyrate could improve hepatic gluconeogenesis through the cAMP-PKA-GCN5 pathway in late-pregnancy sows.

Effect of maternal dietary starch-to-fat ratio and daily energy intake during late pregnancy on the performance and lipid metabolism of primiparous sows and newborn piglets

The present study evaluated the effects of maternal dietary energy intake and starch-to-fat ratio during late gestation on the performance and lipid metabolism of sows and their offspring. On day 84 of gestation, 80 Landrace × Yorkshire primiparous sows were assigned to 2 × 2 factorial arrangements according to body weight following a randomized complete block design. The factors were daily energy intake (8,375 kcal ME/d [CE] vs. 9,600 kcal ME/d [HE]) and dietary starch-to-fat ratio (10:1 [CR] vs. 15:1 [HR]). All sows were fed one of four diets from day 85 of gestation until farrowing. Data were analyzed using the GLM procedure in SPSS. High energy intake increased the body weight of sows on day 110 of gestation (P = 0.031) as well as the weight of piglets at birth (P = 0.018). Increased energy intake elevated the plasma triglyceride concentrations in sows (P = 0.027) and piglets (P = 0.044). Maternal high energy intake altered the liver metabolome of newborn piglets in terms of metabolites related to carbohydrate and linoleic acid metabolism. Moreover, maternal high energy intake increased hepatic total cholesterol (P = 0.023) and triglyceride (P = 0.026) concentration in newborn piglets. Furthermore, maternal high energy intake significantly increased the transcript abundance of fatty acid synthase (FAS; P = 0.001) and protein abundance of phosphorylated protein kinase B (P =0.001) in the liver of newborn piglets. A high starch-to-fat ratio reduced low-density lipoprotein cholesterol (LDL-C) concentration in the plasma of sows (P = 0.044) and newborn piglets (P = 0.048) as well as in the liver of newborn piglets (P = 0.015). Furthermore, maternal high starch-to-fat ratio increased the transcript abundances of FAS (P = 0.004) in newborn piglets. In conclusion, high daily energy intake of sows increased the birth weight of newborn piglets. Moreover, maternal high daily energy intake and high dietary starch-to-fat ratio improved the lipid metabolism of newborn piglets.

UPLC-Orbitrap-MS/MS Combined With Biochemical Analysis to Determine the Growth and Development of Mothers and Fetuses in Different Gestation Periods on Tibetan Sow Model

Pregnancy is a complex and dynamic process, the physiological and metabolite changes of the mother are affected by different pregnancy stages, but little information is available about their changes and potential mechanisms during pregnancy, especially in blood and amniotic fluid. Here, the maternal metabolism rules at different pregnancy stages were investigated by using a Tibetan sow model to analyze the physiological hormones and nutrient metabolism characteristics of maternal serum and amniotic fluid as well as their correlations with each other. Our results showed that amniotic fluid had a decrease (P < 0.05) in the concentrations of glucose, insulin and hepatocyte growth factor as pregnancy progressed, while maternal serum exhibited the highest concentrations of glucose and insulin at 75 days of gestation (P < 0.05), and a significant positive correlation (P < 0.05) between insulin and citric acid. Additionally, T4 and cortisol had the highest levels during late gestation (P < 0.05). Furthermore, metabolomics analysis revealed significant enrichment in the citrate cycle pathway and the phenylalanine/tyrosine/tryptophan biosynthesis pathway (P < 0.05) with the progress of gestation. This study clarified the adaptive changes of glucose, insulin and citric acid in Tibetan sows during pregnancy as well as the influence of aromatic amino acids, hepatocyte growth factor, cortisol and other physiological indicators on fetal growth and development, providing new clues for the normal development of the mother and the fetus, which may become a promising target for improving the well-being of pregnancy.

A review of the amino acid metabolism in placental function response to fetal loss and low birth weight in pigs

The fertility of sows mainly depends on the embryo losses during gestation and the survival rate of the post-farrowing piglets. The selection of highly-prolific sows has been mainly focused on the selection of genotypes with high ovulatory quota. However, in the early- and post-implantation stages, the rate of embryo losses was increased with the increase of zygotes. Among the various factors, placental growth and development is the vital determinant for fetal survival, growth, and development. Despite the potential survival of fetuses with deficient placental development, their life-conditions and growth can be damaged by a process termed intrauterine growth retardation (IUGR). The newborn piglets affected by IUGR are prone to increased morbidity and mortality rates; meanwhile, the growth, health and welfare of the surviving piglets will remain hampered by these conditions, with a tendency to exacerbate with age. Functional amino acids such as glycine, proline, and arginine continue to increase with the development of placenta, which are not only essential to placental growth (including vascular growth) and development, but can also be used as substrates for the production of glutathione, polyamines and nitric oxide to benefit placental function in many ways. However, the exact regulation mechanism of these amino acids in placental function has not yet been clarified. In this review, we provide evidence from literature and our own work for the role and mechanism of dietary functional amino acids during pregnancy in regulating the placental functional response to fetal loss and birth weight of piglets. This review will provide novel insights into the response of nutritionally nonessential amino acids (glycine and proline) to placental development as well as feasible strategies to enhance the fertility of sows.