Effect of gestation dietary methionine/lysine ratio on placental angiogenesis and reproductive performance of sows1

Allicin in pregnancy diets modulates steroid metabolism in pregnant sows and placental sulphate metabolism promoting placental angiogenesis and foetal development

The low-birth-weight of piglets is an important factor affecting pig enterprises. The placenta, as a key organ for material exchange between mother and foetus, directly influences the growth and development of the foetus. Allicin exhibits various biological activities, including anti-inflammatory and antioxidant properties. It may also play a crucial role in enhancing sow reproductive performance and placental angiogenesis. In this study, we used 70 lactating Landrace × Yorkshire binary heterozygous sows to explore the effect of allicin on the reproductive performance of sows and placental development. The sows were randomly assigned into the Allicin group (Allicin), which was fed with a diet containing 0.25% allicin, and the negative control group, which was fed with basal feed. The experimental period lasted for 114 d from the date of mating to the end of farrowing. The results showed that the addition of allicin to the gestation diets increased the number of total born piglets, born alive piglets, and high-birth-weight piglets, reduced peripartum oxidative stress, alleviated dysregulation of glucose-lipid metabolism in sows, and increased the levels of antioxidant markers in the placenta. Differential analysis of metabolites in maternal plasma and placenta samples by non-targeted metabolomics revealed that allicin improved cholesterol metabolism, steroid biosynthesis, and increased plasma progesterone levels in sows. Allicin promoted sulphur metabolism, cysteine and methionine metabolism in placental samples and increased the hydrogen sulphide (H2S) content in the placenta. In addition, Quantitative Real-time PCR, Western blot and immunofluorescence results showed that allicin upregulated the expression of angiogenesis-related genes, VEGF-A, FLK 1 and Ang 1, in the placenta, implying that it promoted placental angiogenesis. These results indicate that supplementing the diet of pregnant sows with allicin reduces oxidative stress, alleviates dysregulation of glucose-lipid metabolism during the periparturient period, and promotes placental angiogenesis and foetal development by increasing plasma progesterone level and placental H2S content.

Impacts of Maternal Nutrition on Sow Performance and Potential Positive Effects on Piglet Performance

The objectives of this review are to identify the nutritional challenges faced by modern sows and present potential solutions to mitigate excessive maternal tissue loss and reproductive failure as it relates to recent genetic improvements. Current feeding programs have limitations to support the rapid genetic improvements in reproductive performance for modern sows. Since 2012, both litter size at birth and fetal weight have increased by 2.26 pigs per litter and 0.22 kg per piglet, respectively, thereby increasing the nutrient needs for sows during gestation and lactation. Prediction models generated in this review predict that modern sows would need 31% more lysine during gestation when compared with current feeding programs. Physiological challenges facing modern sows are also addressed in this review. High oxidative stress, pelvic organ prolapse, and lameness can directly affect the sow, whereas these physiological challenges can have negative impacts on colostrum and milk quality. In response, there is growing interest in investigating the functional roles of select bioactive compounds as feed additives to mitigate the severity of these challenges. Selenium sources, catechins, and select plant extracts have been utilized to reduce oxidative stress, calcium chloride and phytase have been used to mitigate pelvic organ prolapse and lameness, algae and yeast derivatives have been used to improve colostrum and milk quality, and fiber sources and probiotics have been commonly utilized to improve sow intestinal health. Collectively, this review demonstrates the unique challenges associated with managing the feeding programs for modern sows and the opportunities for revision of the amino acid requirements as well as the use of select bioactive compounds to improve reproductive performance.

Maternal folic acid and vitamin B12 supplementation during medium to late gestation promotes fetal development via improving placental antioxidant capacity, angiogenesis and amino acid transport

BACKGROUND

Folic acid and vitamin B12 (FV), being B vitamins, not only facilitate the remethylation of homocysteine (Hcy) but also contribute to embryonic development. This study aimed to assess the impact of FV supplementation during late pregnancy on sows' reproductive performance, amino acid metabolism, placental angiogenesis, and related parameters. Twenty primiparous sows at day 60 of gestation were randomly allocated to two groups: a basal diet (CON) group and a group receiving a basal diet supplemented with folic acid at 20 ppm and vitamin B12 at 125 ppb.

RESULTS

The findings revealed that dietary FV supplementation significantly reduced the incidence of intrauterine growth retardation compared to the CON group (P < 0.05). Furthermore, it led to a decrease in the Hcy levels in umbilical cord serum (P < 0.05) and activation of the placental mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway (P < 0.05). Additionally, FV supplementation lowered placental malondialdehyde levels (P < 0.05) and increased the expression of placental thioredoxin (P = 0.05). Moreover, maternal FV supplementation notably elevated placental vascular density (P < 0.05) and the expression of sodium-coupled neutral amino acid transporter 2 (SNAT2) (P < 0.05), as well as amino acid concentrations in umbilical cord blood (P < 0.05).

CONCLUSION

Maternal FV supplementation during medium to late gestation reduced Hcy levels in umbilical cord blood and positively impacted fetal development. This improvement was closely associated with increased placental antioxidant capacity and vascular density, as well as activation of the placental mTORC1-SNAT2 signaling pathway. © 2023 Society of Chemical Industry.

[Metformin ameliorates PM2.5-induced functional impairment of placental trophoblasts by inhibiting ferroptosis]

OBJECTIVE

To investigate the protective effect of metformin against PM2.5-induced functional impairment of placental trophoblasts and explore the underlying mechanism.

METHODS

Sixteen pregnant Kunming mice were randomly assigned into two groups (n=8) for intratracheal instillation of PBS or PM2.5 suspension at 1.5, 7.5, and 12.5 days of gestation. The pregnancy outcome of the mice was observed, and placental zonal structure and vascular density of the labyrinth area were examined with HE staining, followed by detection of ferroptosis-related indexes in the placenta. In cultured human trophoblasts (HTR8/SVneo cells), the effects of PM2.5 exposure and treatment with metformin on cell viability, proliferation, migration, invasion, and tube formation ability were evaluated using CCK8 assay, EDU staining, wound healing assay, Transwell experiment, and tube formation experiment; the cellular expressions of ferroptosis-related proteins were analyzed using ELISA and Western blotting.

RESULTS

M2.5 exposure of the mice during pregnancy resulted in significantly decreased weight and number of the fetuses and increased fetal mortality with a reduced placental weight (all P<0.001). PM2.5 exposure also caused obvious impairment of the placental structure and trophoblast ferroptosis. In cultured HTR8/SVneo cells, PM2.5 significantly inhibited proliferation, migration, invasion, and angiogenesis of the cells by causing ferroptosis. Metformin treatment obviously attenuated PM2.5-induced inhibition of proliferation, migration, invasion, and angiogenesis of the cells, and effectively reversed PM2.5-induced ferroptosis in the trophoblasts as shown by significantly increased intracellular GSH level and SOD activity, reduced MDA and Fe2+ levels, and upregulated GPX4 and SLC7A11 protein expression (P<0.05 or 0.01).

CONCLUSION

PM2.5 exposure during pregnancy causes adverse pregnancy outcomes and ferroptosis and functional impairment of placental trophoblasts in mice, and metformin can effectively alleviate PM2.5-induced trophoblast impairment.

Optimal protein concentration in diets for sows during the transition period

The aim of the present study was to determine the optimal concentration of dietary protein required in transition diets for multiparous sows that enhance the farrowing process, colostrum production, and subsequent lactation performance. Forty-eight multiparous sows were allotted to one of six dietary treatments according to body weight (290 ± 3 kg) and parity (3.8 ± 0.2) from day 108 of gestation until 24 h after the onset of farrowing. The diets were isoenergetic and contained increasing concentrations of dietary protein (expressed as standardized ileal digestible [SID] Lys) and were supplied at a daily feed supply of 3.8 kg. On day 108 of gestation and days 2, 7, 14, 21, and 28 of lactation, body weight, and back fat thickness were recorded, and blood was sampled on day 108 of gestation, at the onset of farrowing, and days 3, 10, 17, and 24 of lactation from the sows for analysis of plasma metabolites. On day 115 of gestation, urine, and feces were collected for nitrogen (N) balance. The number of liveborn and stillborn piglets and time of birth were recorded and blood from every fourth piglet was sampled at birth for blood gas analysis. Piglets were weighed individually from birth until weaning, to estimate the colostrum and milk yield of the sows. Colostrum and milk samples were collected, and their compositions were determined. On days 3 and 28 of lactation, sows were injected with deuterium oxide to estimate body composition. The N utilization was maximized when the concentration of SID Lys in the transition diet was 6.06 g/kg (P < 0.01). When urinary concentrations of urea were expressed relative to creatinine, the relative concentration of urea remained low until a dietary concentration of 6.08 g SID Lys/kg, above which the relative concentration of urea increased (P < 0.01). Stillbirth rate increased linearly with increasing SID Lys concentration in the transition diet (P < 0.001), thus the concentration of SID Lys should be kept as low as possible without impairing sow performance excessively. A carry-over effect on milk yield was observed, showing that a dietary SID Lys concentration of 5.79 g/kg during transition optimized milk production at an average yield of 13.5 kg/d (P = 0.04). Increasing loss of body fat in lactation was observed with increasing SID Lys concentration in the transition diet (P = 0.03). In conclusion, the transition diet of multiparous sows should contain 5.79 g SID Lys/kg when fed 3.8 kg/d (13.0 MJ ME/kg), for a total SID Lys intake of 22 g/d.

The Linear-Logistic Model: A Novel Paradigm for Estimating Dietary Amino Acid Requirements

This study aimed to determine whether current methods for estimating AA requirements for animal health and welfare are sufficient. An exploratory data analysis (EDA) was conducted, which involved a review of assumptions underlying AA requirements research, a data mining approach to identify animal responses to dietary AA levels exceeding those for maximum protein retention, and a literature review to assess the physiological relevance of the linear-logistic model developed through the data mining approach. The results showed that AA dietary levels above those for maximum growth resulted in improvements in key physiological responses, and the linear-logistic model depicted the AA level at which growth and protein retention rates were maximized, along with key metabolic functions related to milk yield, litter size, immune response, intestinal permeability, and plasma AA concentrations. The results suggest that current methods based solely on growth and protein retention measurements are insufficient for optimizing key physiological responses associated with health, survival, and reproduction. The linear-logistic model could be used to estimate AA doses that optimize these responses and, potentially, survival rates.

Effect of increasing dietary methionine-to-lysine ratio during early gestation on fetal development and piglet birth weight

It was hypothesized that increasing dietary methionine (Met) for sows in early gestation would have a positive effect on fetal and placental growth and development, thereby also increasing the birth weight of piglets. The objective of the study was to investigate the effect of increasing the total dietary methionine-to-lysine ratio (Met:Lys) from 0.29 (Control diet) to 0.41 (Met diet) from mating to day 50 of gestation. A total of 349 multiparous sows were allocated to either the Control or Met diet group. The sows' backfat thickness was measured pre-farrowing, post-farrowing, and at weaning in the previous cycle and on days 14, 50 and 112 of gestation in the current cycle. On day 50, three Control and six Met sows were slaughtered. In 116 litters, piglets were weighed and measured individually at farrowing. The dietary treatment did not affect the sows' backfat thickness before or during gestation (P > 0.05). The number of liveborn and stillborn piglets at farrowing were similar in both groups (P > 0.05) and no differences in average piglet birth weight, total litter weight at birth or within-litter variation in birth weight (P > 0.05) were observed. In conclusion, increasing the dietary Met:Lys ratio for sows in early gestation had no effect on piglet birth weight.

Effect of gestation dietary methionine-to-lysine ratio on methionine metabolism and antioxidant ability of high-prolific sows

The uptake and metabolism of methionine (Met) are critical for epigenetic regulation, redox homeostasis, and embryo development. Our previous study showed that appropriate supplementation of dietary Met promoted the birth weight and placental angiogenesis of high-prolific sows. To further explore the metabolic effect of Met on pregnant sows, we have evaluated the influence of dietary Met level on Met metabolism, and the relationship between metabolites of Met and reproductive performance, antioxidant ability, and placental angiogenesis throughout the gestation of high-prolific sows. Sixty sows (the 3rd parity, Large White) were randomly divided into 5 groups that were fed diets with standardized ileal digestible (SID) methionine-to-lysine (Met:Lys) ratios of 0.27 (control), 0.32, 0.37, 0.42, and 0.47 from the mating day (gestational d 0, G0d) until the farrowing day. HPLC-MS/MS analysis was used to simultaneously evaluate the metabolites related to Met, e.g. S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), homocysteine (Hcy), cysteine (Cys), and glutathione (GSH). The concentration of SAM and SAH in plasma had significant fluctuations, especially in late pregnancy. Increasing dietary Met supplementation significantly improved the plasma SAM and methylation potential (SAM-to-SAH ratio) at d 114 of pregnancy (G114d). Moreover, a positive association of the plasma SAM concentration at G114d was observed with the litter weight of born alive (P < 0.05; R 2 = 0.58). Furthermore, Hcy concentration in plasma was at the lowest level for 0.37 ratio group at G114d. However, it significantly increased during late pregnancy. Moreover, there were negative correlations between plasma Hcy concentration at G114d (P < 0.05) and the placental vascular density in the fold and stroma (P < 0.05). Compared with the control group, the expression of vascular endothelial growth factor-A (VEGF-A) in the placenta tissue of 0.37 ratio group increased significantly (P < 0.05). Collectively, these findings indicate that dietary Met:Lys ratio (0.37 to 0.57) in the pregnant diet dose not influence the antioxidant ability of the high-prolific sows; however, the improvement of fetal development and placental angiogenesis of high-prolific sows by supplementation of Met are closely associated to the key Met-related metabolite of SAM and Hcy, respectively.

Effect of Sows Gestational Methionine/Lysine Ratio on Maternal and Placental Hydrogen Sulfide Production

Simple Summary

Hydrogen sulfide (H₂S) is an important second messenger, which has been implicated in regulating placental angiogenesis. Our findings revealed that gestational dietary methionine could affect maternal and placental H₂S concentrations. With the increase of dietary methionine, maternal plasma and placental H₂S concentrations changed quadratically, which was consistent with placental vascular density and reproductive performance. The decrease in H₂S production caused by an increase in dietary methionine was likely to be the cause for the increase in the rate of low birth weight piglets and needs further study.

Abstract

The placenta is a unique bond between the mother and the fetus during pregnancy, and a proper placental angiogenesis is vital for fetal development. H₂S is an endogenous stimulator of angiogenesis that is mainly produced by the methionine transsulfurationpathway. The goal of this study was to evaluate the effect of gestational dietary methionine on maternal and placental H₂S production in sows. Multiparous sows (Large×White; third parity; n = 65) were randomly allocated into five groups, with feed diets comprisingstandardized ileal digestible methionine/lysine (Met/Lys) ratios of 0.27 (nutrient requirements of swine (NRC); 2012 level), 0.32, 0.37, 0.42, and 0.47, respectively. The litter size and weight at birth were measured and recorded. Maternal blood samples were obtained at embryonic day (E) E40 d, E90 d, and E114 d of gestation. The placental samples were collected at parturition. The results showed that maternal plasma H₂S concentration was not affected at E40 d. However, the maternal plasma H₂S concentration changed quadratically with the dietary Met/Lys ratio at E90 d (p < 0.01) and E114 d (p = 0.03). The maximum maternal plasma H₂S concentration was at the dietary Met/Lys ratio of 0.37. Meanwhile, maternal plasma H₂S concentration was positively correlated with piglets born alive (p < 0.01) and litter weight (p < 0.01). Consistent with the maternal plasma, the placental H₂S concentration also changed quadratically with the dietary Met/Lys ratio (p = 0.03); the Met/Lys ratio of 0.37 showed the maximum H₂S concentration. In conclusion, our findings revealed that the gestational dietary Met/Lys ratio could affect maternal and placental H₂S concentrations, which may be an important molecular mechanism affecting placental angiogenesis and piglet development.