Effects Of Dietary Folic Acid Research Articles

High Dietary Folic Acid Supplementation Reduced the Composition of Fatty Acids and Amino Acids in Fortified Eggs.

The study aimed to evaluate the effects of dietary folic acid (FA) on the production performance of laying hens, egg quality, and the nutritional differences between eggs fortified with FA and ordinary eggs. A total of 288 26-week-old Hy-Line Brown laying hens (initial body weights 1.65 ± 0.10 kg) with a similar weight and genetic background were used. A completely randomized design divided the birds into a control group and three treatment groups. Each group consisted of six replicates, with twelve chickens per replicate. Initially, all birds were fed a basal diet for 1 week. Subsequently, they were fed a basal diet supplemented with 0, 5, 10, or 15 mg/kg FA in a premix for a duration of 6 weeks. Supplementation of FA could significantly (p < 0.05) enhance the FA content in egg yolks, particularly when 10 mg/kg was used, as it had the most effective enrichment effect. Compared to the control group, the Glu content in the 10 and 15 mg/kg FA groups showed a significant (p < 0.05) decrease. Additionally, the contents of Asp, Ile, Tyr, Phe, Cys, and Met in the 15 mg/kg FA group were significantly (p < 0.05) lower compared to the other groups. Adding FA did not have significant effects on the levels of vitamin A and vitamin E in egg yolk, but the vitamin D content in the 5 and 10 mg/kg FA groups showed a significant (p < 0.05) increase. Furthermore, the addition of FA did not have a significant effect on the levels of Cu, Fe, Mn, Se, and Zn in egg yolk. The dietary FA did not have a significant effect on the total saturated fatty acids (SFA) and polyunsaturated fatty acid (PUFA) content in egg yolk. However, the total monounsaturated fatty acid (MUFA) content in the 5 and 10 mg/kg groups significantly (p < 0.05) increased. These changes in nutritional content might be attributed to the increased very low-density lipoprotein (VLDL) protein content. The significant decrease in solute carrier family 1 Member 1 (SLC1A1), solute carrier family 1 Member 2 (SLC1A2), and solute carrier family 1 Member 3 (SLC1A3) gene expression compared to the control group appeared to be the reason for the decrease in amino acid content in egg yolk within the dietary FA group. The findings suggest that the appropriate addition of FA can enhance the levels of MUFA and vitamin D in egg yolks, thereby improving their nutritional value. Excessive intake of FA can decrease the effectiveness of enriching FA in egg yolk and impact the enrichment of certain amino acids. The yolk of eggs produced by adding 10 mg/kg of FA to the feed contains the optimal amount of nutrients. This study informs consumers purchasing FA-fortified eggs.

Folic acid for the primary prevention of stroke: a systematic review and meta-analysis.

Results from studies were inconsistent with regard to the effect of folic acid on the primary prevention of stroke. The aim of this study was to analyze the association between folic acid and the primary prevention of stroke using the data from observational studies and randomized controlled trials (RCTs). Eligible publications published until June 2024 were searched in the database of PubMed, Web of Science and Embase. This study included all observational studies and RCTs of folic acid with first stroke as the reporting endpoints. Relative risks (RRs) and 95% confidence intervals (CIs) were pooled in the random-effects model to assess the effect of folic acid on the primary prevention of stroke. Results from 12 observational publications with 16 research, including 312,320 participants, were combined to explore the association between dietary folic acid intake and the primary prevention of stroke. The results showed that high dietary folic acid intake was associated with a 17% reduction in stroke incidence (RR:0.83; 95% CI: 0.73-0.94), and the effect of dietary folic acid was greater in areas without grain fortification (RR:0.80; 95% CI: 0.67-0.95). The pooled results from 12 RCTs, totaling 75,042 participants, indicated that folic acid supplementation was not associated with the stroke primary prevention (RR:0.92; 95% CI: 0.80-1.05), but folic acid supplementation was effective in areas without grain fortification (RR:0.78; 95% CI: 0.68-0.89). Our meta-analysis demonstrated that dietary folic acid is effective in stroke primary prevention, and folic acid supplementation is effective in stroke primary prevention only in areas without grain fortification. https://www.crd.york.ac.uk/PROSPERO/#myprospero, identifier CRD42024516991.

Effects of Dietary Folic Acid Supplementation on Growth Performance and Immune Parameters in Weanling Piglets

In order to study the effects of dietary folic acid (FA) supplementation on growth performance and immune status in weanling piglets, a single factorial randomized block design trial was conducted with six diets supplemented with FA at 0, 0.30, 3.00, 6.00, 9.00 or 15.00 mg/kg. A total of 108 crossbred (Landrace × Yorkshire) castrated weanling piglets (at 21 d of age) were allocated by body weight into 36 feeding cages (3 piglets/cage), which were allotted randomly into six dietary groups (six cages/group). Piglets were fed ad libitum for 24 days. Blood samples were collected on the 24th day. The growth performance and immune parameters were measured. Results showed that FA supplementation increased the serum FA level of weaned piglets (p &lt; 0.01) and tended to increase the body weight (BW) at 45 d of age (p &lt; 0.1) and the average daily gain (ADG) from 29 d to 45 d of age (p &lt; 0.1). FA addition improved the feed efficiency (G/F) from 21 to 45 d of age (p &lt; 0.01) with supplementary FA levels of 0.3, 3.0, and 9.0 mg/kg compared with the control group with no FA supplementation. FA supplementation showed a trend (p &lt; 0.1) to increase the peripheral blood CD3+CD8+ lymphocyte subpopulation and a tendency (p &lt; 0.1) to decrease the CD3+CD4+/CD3+CD8+ ratio; in particular FA supplementation of 0.3 and 3.0 mg/kg showed significant differences in comparison to the non-supplemented control group. Moreover, FA addition increased the serum interferon-γ (IFN-γ) level (p &lt; 0.05) and tended to reduce the ratio of tumor necrosis factor-α to interleukin-4 (TNF-α/IL-4, p &lt; 0.1) and immunoglobulin G (IgG, p &lt; 0.1) in serum, but had no significant effect on serum IL-4, TNF-α, and nitric oxide. In conclusion, FA supplementation up to 3 mg/kg to the diet showed a tendency to improve immune function, while FA supplementation of up to 9 mg/kg improved feed efficiency, which resulted in a trend for higher growth in weaned piglets between 7 to 11 kg BW.

Dietary Folic Acid Supplementation Inhibits HighFat DietInduced Body Weight Gain through Gut Microbiota-Associated Branched-Chain Amino Acids and Mitochondria in Mice.

The effects of folic acid on body weight gain in obesity and gut microbiota-associated branched-chain amino acids (BCAAs) and mitochondrial function were investigated. Three- to four-wk-old male C57BL/6J conventional (CV) and germ-free (GF) mice were fed a high-fat diet (HD), folic acid-supplemented HD (FSHD) and a normal-fat diet (ND) for 25 wk. In CV mice, the HD-induced increases in body weight and plasma BCAA concentrations, downregulated expression of genes related to BCAA catabolism (Bcat2, Bckdha, or Ppm1k), mitochondrial biogenesis (Pgc-1α, Cox1, Nd1 or Nd6), fusion (Mfn1, Mfn2 or Opa1) and mitophagy (Pink1 or Park2), and upregulated expression of the fission-associated gene Drp1 in epididymal fat were reversely corrected with FSHD feeding. In contrast, the expression of these genes in the liver was the opposite under HD feeding or folic acid supplementation. In GF mice, plasma BCAA concentrations were much less affected by HD feeding and were reduced by FSHD feeding, with almost no alterations in the expression of genes associated with BCAA catabolism and mitochondrial function. Further analysis indicated a correlation between adipose and hepatic Mt C/N and plasma BCAA concentrations, and the latter had a close association with specific gut bacteria. Therefore, dietary folic acid supplementation differentially affected body weight gain, BCAA catabolism, and mitochondrial dynamics and metabolism under HD feeding between CV and GF mice, suggesting that gut bacteria-altered BCAAs and mitochondria might partially share the responsibility for the beneficial effects of dietary folic acid on obesity.

Effects of dietary folic acid on growth performance, body wall folate content, immune and antioxidant enzyme activity of juvenile sea cucumber, Apostichopus japonicus

A 60-day feeding trial was conducted to investigate the effects of dietary folic acid on the growth performance, growth gene expression, body wall folate content, and digestive, immune and antioxidant enzyme activity of juvenile sea cucumber (initial body weight: 0.60 ± 0.01 g). Five diets were prepared and supplemented with 0 mg/kg (V0), 3 mg/kg (V1), 5 mg/kg (V2), 10 mg/kg (V3) and 15 mg/kg (V4) folic acid. The final body weight, weight gain rate and specific growth rate in the V1, V2 and V3 groups were significantly higher than in the V0 group (p < 0.05), while the feed conversion rate in these groups was significantly lower than in the V0 group (p < 0.05), and optimal dietary folic acid supplemented amount was estimated to be 7 mg/kg. The c-myc, MAPK-7 and FGFR-1 gene expression levels in the V1, V2 and V3 groups were significantly higher than in the V0 group (p < 0.05). In addition, the body wall folate content in the folic acid supplemented group was significantly higher than in the V0 group (p < 0.05). Moreover, the activities of lipase, pepsin and α-amylase in the V2 and/or V3 groups were significantly higher than in other groups (p < 0.05). The activities of alkaline phosphatase and lysozyme in the V2 group were significantly higher than in the V0 group (p < 0.05), and the activity of acid phosphatase in the folic acid supplemented group was significantly higher than the V0 group (p < 0.05). With dietary folic acid increasing, the total superoxide dismutase, catalase and total superoxide dismutase activities in V2 and/or V3 groups were significantly higher than in the V0 group (p < 0.05). In conclusion, the current results demonstrated the significant progress of dietary supplementation with folic acid on the growth and physiological response of juvenile sea cucumbers.

Dietary folic acid supplementation improves semen quality and spermatogenesis through altering autophagy and histone methylation in the testis of aged broiler breeder roosters

The aging phenomenon often exerts a significant reduction in the reproduction performance of aged animals. The objective of this project was to investigate the effects of dietary Folic acid (FA) supplementation on the reproductive performance of aged broiler breeder roosters. A total of 16 aged ROSS 308 broiler breeder roosters (50-week-old) were randomly divided into two groups. The treatments were basal diet (CON), a basal diet supplemented with 10 mg/kg Folic acid (FAS) for four weeks. At the end of the experiment, semen quality, histopathological studies, serum concentrations of testosterone and relative mRNA and protein expressions of testes were evaluated. The results showed that dietary FA supplementation dramatically improved semen quality of aged roosters, manifested by increasing semen volume, sperm concentration, sperm motility, and sperm membrane functional integrity. Furthermore, seminiferous tubule epithelial height (SEH) and testis scores were increased by dietary supplementation with FA. Dietary FA also remarkably augmented the transcription level of spermatogenesis-related gene (CREM, PCK2, DDX4, and GDNF). No significant differences were observed in serum concentrations of testosterone between FAS and CON groups. We noted significant upregulation Beclin-1 and ATG5 protein expressions, and the ratio of LC3-Ⅱ/Ⅰ, as well as significant downregulation of p-mTOR protein expressions in testicular tissue of aged roosters with FA supplementation. In addition, dietary FA supplementation significantly increased the protein expression of H3K9me2 and reduced the protein expression of H3K27me2. In summary, dietary FA supplementation improved the testicular autophagy through the mTOR-signaling pathway, and altered histone methylation in the testis. Dietary supplementation with FA can ameliorate semen quality and spermatogenesis of aged roosters.

Effect of dietary folic acid and energy density on immune response, gut morphology, and oxidative status in blood and breast muscle of broiler chickens

Folic acid (FA) plays essential roles in many metabolic functions and has been reported to have antioxidant effects. Therefore, dietary supplementation with high levels of FA may improve gut health and prevent potential oxidative stress caused by feeding a high energy density diet to broiler chickens. Broiler chickens were assigned into eight treatments, consisting of either a normal energy (NE) or high energy (HE) density diet, and four FA levels (2.2, 5, 10, and 15 ppm). Data were analyzed by SAS 16 GLM procedure. Birds-fed HE diets had increased (P &lt; 0.05) plasma concentrations of calcium and albumin but reduced (P &lt; 0.005) weights of ceca and bursa compared with those fed NE diets. Dietary supplementation with 10 ppm FA significantly increased (P &lt; 0.05) birds’ heart weight and bile acid concentration. Folic acid and energy density interactions were significant for jejunal villus height (VH; P = 0.0226), villus width (VW; P &lt; 0.0001), and crypt depth (CD; P = 0.0332). Among the NE group, birds fed 5–15 ppm FA had reduced (P &lt; .0001) VW, while in the HE groups, 15 ppm FA supplementation resulted in an increased jejunal VH (P = 0.0317) compared with other treatments. In conclusion, dietary supplementation with increased levels of FA in HE diets could be beneficial for the intestinal health of broiler chickens.

Effects of varying dietary folic acid during weaning stress of piglets.

The present study was conducted to evaluate the effect of dietary folic acid on the growth performance, intestinal morphology, and intestinal epithelial cells renewal in post-weaning piglets. Twenty-eight piglets (weaned at day 21, initial body weight of 6.73 ± 0.62 kg) were randomly allotted to 4 treatments with 7 pens per diet and 1 piglet per pen. The piglets were fed the same antibiotic-free and zinc oxide-free basal diets supplemented with folic acid at 0, 3, 9, and 18 mg/kg for 14 days. The results showed that dietary supplementation with folic acid increased villus height (VH) (P = 0.003; linear, P = 0.001), VH-to-crypt depth (VH:CD) ratio (P = 0.002; linear, P = 0.001), villus surface area (VSA) (P = 0.026; linear, P = 0.010). The analyzed parameters ADG, serum urea nitrogen (BUN) content, VH, VSA, and serum folate (SF) concentration responded linearly to the dietary folic acid concentration when the dietary folic acid concentration was below 4.42, 5.26, 4.79, 3.47, and 3.53 mg/kg respectively (R2 = 0.995, 0.995, 0.999, 0.999, 0.872, P = 0.09, 0.07, 0.09, 0.09, 0.36, respectively), as assessed by a two-linear broken-line regression. Above these breakpoints, the response of ADG, VH, VSA, and SF plateaued in response to changes in dietary folic acid concentration. Moreover, dietary supplementation with folic acid significantly increased the lactase (P = 0.001; linear, P = 0.001) and sucrase activities (P = 0.021; linear, P = 0.010) in the jejunal mucosa of weaned piglets. The mRNA expression of solute carrier family 6 member 19 (SLC6a19), solute carrier family 1 member 1 (SLC7a1), tumor necrosis factor-α (TNF-α), the number of Ki67 positive cells, and cell shedding rate had a significant linear contrast (P = 0.023, 0.021, 0.038, 0.049, and 0.008, respectively) in dietary folic acid groups. In conclusion, our results indicate that folic acid supplementation can improve the growth performance and intestinal morphology of weaned piglets by maintaining the balance of epithelial cell renewal.

Dietary folic acid improved growth performance, immuno-physiological response and antioxidant status of fingerling Siberian sturgeon, Acipenser baerii (Brandt 1896)

To investigate the effect of dietary folic acid (FA) on growth performance, proximate composition, blood parameters, antioxidant status, and immune response of Siberian sturgeon, Acipenser baerii, six isonitrogenous and isolipidic experimental diets were formulated to contain graded levels of FA (0.60, 1.63, 2.71, 3.59, 4.82, and 5.68 mg kg−1). Each diet was fed to triplicate groups of fish (4.36 ± 0.18 g) in a flow through water system for 8 weeks. Weight gain ratio (WGR) and specific growth rate (SGR) were thrived with increasing FA level up to 2.71 mg kg−1 and decreased gradually thereafter (P < 0.05). The whole-body crude protein content was also highest in fish fed with 2.71 mg FA kg−1 diet followed by those fed 3.59 and 1.63 mg FA kg−1 diet. The muscle and liver FA concentrations were enhanced with increasing dietary FA supplementation with the values significantly higher in fish fed diets supplemented by equal to or more than 3.59 and 4.82 mg FA kg−1, respectively. Red blood cells (RBCs), white blood cells (WBCs), hemoglobin (Hb), hematocrit (Hct), and lymphocyte count showed significant positive correlation with dietary FA level, whereas the neutrophil count was significantly declined by enhancing dietary FA supplementation (P < 0.05). Serum superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities were also intensified by increasing dietary FA concentration. Fish fed diets supplemented with more than 1.63 and 2.71 mg FA kg−1 had significantly higher lysozyme activity and immunoglobulin M (IgM) compared to those fed the basal diet. The dietary FA requirement of fingerling Siberian sturgeon was estimated by subjecting the SGR, crude protein content, liver FA content, and WBC count against varying levels of dietary FA which revealed the FA requirement in the range of 1.82–4.41 mg kg−1.

The effect of dietary folic acid on flesh quality and muscle antioxidant status referring to Nrf2 signalling pathway in young grass carp (Ctenopharyngodon idella)

To investigate the effect of dietary folic acid on fish flesh quality, muscle antioxidant status and the potential mechanism, young grass carp (Ctenopharyngodon idella) were fed diets containing 0.10–3.12 mg/kg diet of folic acid for 8 weeks. The results showed that optimum folic acid increased muscle contents of protein, lipid, pH, shear force, amino acids, unsaturated fatty acids, hydroxyproline and glutathione, whereas contents of moisture, cooking loss, lactate and saturated fatty acids and cathepsin L activity showed an opposite trend (p < .05). Moreover, optimum folic acid elevated antioxidant enzyme activities and mRNA levels, as well as NF‐E2‐related factor 2 and casein kinase 2 mRNA levels (p < .05). However, optimum folic acid decreased reactive oxygen species (ROS) content and Kelch‐like ECH‐associated protein 1a (Keap1a) and Keap1b mRNA levels (p < .05). Interestingly, excess folic acid induced negative effects on above‐mentioned parameters (p < .05). Summarily, this study indicated that optimum folic acid improved fish flesh quality and muscle antioxidant system associated with Nrf2‐Keap1 pathway. Based on muscle cathepsin L activity and ROS content, the folic acid requirements for young grass carp were 1.87 and 1.80 mg/kg diet, respectively, regarding to the flesh quality and antioxidant status.

The effect of dietary folic acid on biochemical parameters and gene expression of three heat shock proteins (HSPs) of blunt snout bream (Megalobrama amblycephala) fingerling under acute high temperature stress

The effects of dietary folic acid on biochemical parameters and gene expression of three heat shock proteins (HSPs) of blunt snout bream (Megalobrama amblycephala) fingerling under acute high temperature stress. Six dietary folic acid groups (0.0, 0.5, 1.0, 2.0, 5.0, and 10.0) mg/kg diets were designed and assigned into 18 tanks in three replicates each (300l/tank) and were administered for 10weeks in a re-circulated water system. The fingerlings with an initial weight of 27.0±0.03g were fed with their respective diets four times daily. At the end of the experiment, samples were collected before challenge, 0, 24, 72h, and 7days. Serum total protein (TP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), cortisol, glucose, complement C3 (C3), complement C4 (C4, immunoglobulin M (IgM) hepatic superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and the expression of heat shock protein 60 (HSP60), 70 (HSP70), and 90 (HSP90) were studied. The results showed that fish fed with dietary folic acid between 1.0, 2.0, and 5.0mg/kg significantly (P<0.05) increased serum TP, C3, C4 hepatic SOD, CAT, and the expression of HSP60, HSP70, and HSP90 before and after temperature challenge of 32°C. Also, serum ALP, cortisol, glucose, and hepatic MDA were significantly (P<0.05) reduced by supplementation of dietary folic acid level 1.0, 2.0, and 5.0mg/kg before and after the same temperature challenge of 32°C. Before stress, 0, 24, 72h, and 7days significantly (P<0.05) affects serum biochemical parameters, immune and antioxidant capacities, and expression level of three HSPs. Furthermore, there was no statistical evidence to show that dietary folic acid inclusion level and temperature duration have significant interactive effect on serum biochemical parameters, antioxidant parameters, and gene expression level (P>0.05) of the three HSPs. However, there were statistical significant interactive effect between dietary folic acid inclusion level and temperature duration on serum C3 and C4 (P<0.05) except IgM (P>0.05). The present results indicate that supplementation of basal diet from 1.0mg/kg; 2.0 and 5.0mg/kg can enhance acute high temperature resistance ability in M. amblycephala fingerling to some degree and improve physiological response, immune and antioxidant capacities, and expression level of three HSPs.

Immunity decreases, antioxidant system damages and tight junction changes in the intestine of grass carp (Ctenopharyngodon idella) during folic acid deficiency: Regulation of NF-κB, Nrf2 and MLCK mRNA levels.

This investigation used the same growth trial as the previous study, which showed that folic acid deficiency retarded growth in young grass carp (the percent weight gain of Groups 1-6 were 102.32±3.41%, 137.25±10.48%, 179.78±3.95%, 164.33±3.21%, 143.35±8.12% and 115.28±2.66%) [1]. In the present study, we investigated the effects of dietary folic acid on the immune response, antioxidant status and tight junctions in the intestine of young grass carp (Ctenopharyngodon idella). A total of 540 young grass carp were fed diets containing graded levels of folic acid at 0.10, 0.47, 1.03, 1.48, 1.88 and 3.12mgkg(-1) diet for 8 weeks. The results indicated that acid phosphatase and lysozyme activities, and the complement component 3 content in the proximal intestine (PI), mid intestine (MI) and distal intestine (DI) were decreased with folic acid deficiency (0.1mgkg(-1))(P<0.05). Folic acid deficiency (0.1mgkg(-1)) up-regulated interleukin 1β, interleukin 8, tumor necrosis factor α, nuclear factor κB p65 (NF-κB p65), IκB kinase α (IKK-α), IKK-β and IKK-γ gene expression, meanwhile down-regulated interleukin 10, transforming growth factor β, IκB and target of rapamycin gene expression in the PI, MI and DI (P<0.05). These data suggested that folic acid deficiency decreased fish intestinal innate immune function may be partly contributed to the regulation of NF-κB p65 pathway. Moreover, the activities and corresponding gene expression of glutathione content, Cu/Zn superoxide dismutase, catalase, glutathione peroxidase, glutathione s-transferases and glutathione reductase in fish intestine were depressed by deficient folic acid diet (0.1mgkg(-1))(P<0.05). Furthermore, folic acid deficiency (0.1mgkg(-1)) down-regulated NF-E2-related factor 2 (Nrf2) gene expression, up-regulated Kelch-like-ECH-associated protein 1a (Keap1a) and Keap1b gene expression in fish intestine (P<0.05). These data indicated that deficient folic acid diet damaged fish intestinal antioxidant capacity partly by regulating Nrf2/Keap1 pathway. Additionally, folic acid deficiency (0.1mgkg(-1)) down-regulated claudin-b, claudin-c, claudin-3, occludin and zonula occludens 1 gene expression; whereas folic acid deficiency (0.1mgkg(-1)) up-regulated claudin-12, claudin-15, myosin light chain kinase (MLCK) and p38 mitogen activated protein kinase (p38 MAPK) gene expression in the PI, MI and DI (P<0.05), suggesting that folic acid deficiency may damage fish intestinal tight junctions associated with the mediation of MLCK and p38 MAPK gene expression. In conclusion, folic acid deficiency (0.1mgkg(-1)) impaired fish intestinal immunity, antioxidant capacity and tight junctions.

Effects of dietary folic acid on the growth, digestive enzyme activity, immune response and antioxidant enzyme activity of blunt snout bream (Megalobrama amblycephala) fingerling

This study carried out a 10-week feeding trial to investigate the effects of dietary folic acid on the growth, digestive enzyme activity, immune response and antioxidant enzyme activity of blunt snout bream (Megalobrama amblycephala) fingerlings. For this purpose, six semi-purified diets were formulated to contain graded levels of folic acid (0.0, 0.5, 1.0, 2.0, 5.0, and 10.0mg/kg diets), and three tanks (300l/tank) were randomly arranged and assigned to each experimental diet. Blunt snout bream fingerlings (initial weight 27.0±0.03g) were fed with the diets to near satiation four times daily. The results showed that final body weight, weight gain rate, specific growth rate and feed efficiency ratio significantly (P<0.05) increased with an increasing dietary folic acid level of up to 1.0mg/kg, plateaued at up to 2.0mg/kg and thereafter reduced. Fish fed with 1.0–5.0mg/kg dietary folic acid showed a significant rise (P<0.05) in Fulton condition factor compared to those fed with an un-supplemented diet, while reverse trends were observed in viscerosomatic and hepatosomatic indexes. Serum urea content of the groups fed with 1.0 and 2.0mg/kg dietary folic acid, and alkaline phosphate activity of the group fed with a 2.0mg/kg diet were significantly lower than those fed with the control diet. Muscle crude protein content, serum total protein, complement 3, complement 4 and immunoglobulin M contents, and intestinal amylase, lipase, trypsin and chymotrypsin activities were significantly (P<0.05) enhanced as the dietary folic acid level increased up to 1.0mg/kg and thereafter plateaued. Malondialdehyde activity in fish fed with 1.0–5.0mg/kg dietary folic acid was significantly lower than those fed with un-supplemented diet, while reverse patterns were found in superoxide dismutase and catalase activities (P<0.05). Based on the broken line-regression analysis of weight gain rate, specific growth rate and hepatosomatic index, the optimum dietary folic acid for blunt snout fingerlings was estimated to be 0.68, 0.68 and 0.82mg/kg, respectively. Statement of relevanceVitamins are considered as low molecular weight organic compounds that are required in small amounts for the maintenance of metabolism, normal growth and health of fish. Folic acid is a form of water-soluble vitamin B9, which is important in amino acid and nucleotide metabolism, growth and health of most aquatic animals. Blunt snout bream is a Chinese freshwater herbivorous species that has been recognized as a main aquaculture species, with high economic value which is mostly used in the fresh water polyculture system. Because of an increase in consumer demand and the relatively low production costs of this species, its production has rapidly expanded in China with 0.7Mt in 2012. Nowadays, several nutritional requirements have been reported about this fish including some vitamin requirements. However, no information is available regarding the folic acid requirement of blunt snout bream. Therefore, this study hypothesized that dietary folic acid may improve growth and digestion, immune and antioxidant capacities of blunt snout bream fingerlings.

Folic acid deficiency impairs the gill health status associated with the NF-κB, MLCK and Nrf2 signaling pathways in the gills of young grass carp (Ctenopharyngodon idella).

The aim of this study was to investigate the effect of dietary folic acid on fish growth, the immune and barrier functions of fish gills, and the potential mechanisms of these effects. Young grass carp (Ctenopharyngodon idella) were fed diets containing graded levels of folic acid at 0.10 (basal diet), 0.47, 1.03, 1.48, 1.88 and 3.12 mg kg(-1) diet for 8 weeks. The results showed that acid phosphatase and lysozyme activities and the complement component 3 content in fish gills decreased with folic acid deficiency (P < 0.05). Folic acid deficiency up-regulated liver-expressed antimicrobial peptide 1, interleukin 1β, interleukin 8, tumor necrosis factor α, nuclear factor κB p65, IκB kinase α (IKK-α), IKK-β and IKK-γ gene expression. Folic acid deficiency down-regulated interleukin 10, transforming growth factor β, IκB and target of rapamycin gene expression in fish gills (P < 0.05). These results showed that limited folic acid decreased fish gill immune status. Furthermore, folic acid deficiency down-regulated claudin-b, claudin-c, claudin-3, occludin and zonula occludens 1 gene expression, whereas folic acid deficiency up-regulated claudin-12, claudin-15, myosin light chain kinase and p38 mitogen activated protein kinase gene expression in fish gills (P < 0.05). These results suggested that folic acid deficiency disrupted tight junction-mediated fish gill barrier function. Additionally, folic acid deficiency increased the content of reactive oxygen species, protein carbonyl and malondialdehyde (MDA); Mn superoxide dismutase activity and gene expression; and Kelch-like-ECH-associated protein 1a (Keap1a) and Keap1b gene expression (P < 0.05). Conversely, folic acid deficiency decreased Cu/Zn superoxide dismutase, catalase, glutathione peroxidase, glutathione s-transferases and glutathione reductase activities and gene expression as well as NF-E2-related factor 2 gene expression in fish gills (P < 0.05). All of these results indicated that folic acid deficiency impaired fish gill health status via regulating gene expression of cytokines, tight junction proteins, antioxidant enzymes, NF-κB p65, MLCK and Nrf2. Based on percent weight gain, LZ activity and MDA content in the gills, the dietary folic acid requirements for young grass carp were 1.60, 2.07 and 2.08 mg kg(-1), respectively.

Effects of dietary folic acid on growth, antioxidant capacity, non-specific immune response and disease resistance of juvenile Chinese mitten crabEriocheir sinensis(Milne-Edwards, 1853)

An 8-week study was conducted to determine folic acid requirement and its effect on antioxidant capacity and immunity in juvenile Chinese mitten crab Eriocheir sinensis (Milne-Edwards, 1853), followed by a challenge assay with the pathogen Aeromonas hydrophila for 2 weeks. Folic acid was added to a basal diet at seven levels (0, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0 mg folic acid kg−1 diet), and a diet free of folic acid and vitamin B12 was also included as a control. Crabs were fed twice daily in 32 tanks with 7.76–8.17 mg oxygen L−1, 25.0–31.0 °C and 7.5–8.3 pH. Growth and feed efficiency were significantly greater in crabs fed ≥2.0 mg folic acid kg−1, but not significantly different between crabs fed diets >2.0 mg folic acid. The superoxide dismutase activity and glutathione S-transferase activity were highest in crabs fed ≥2.0 mg folic acid kg−1, followed by those fed 0.5 and 1.0 mg folic acid kg−1, and the control diet. The malondialdehyde content was highest in crabs fed the control diet, followed by those fed 0 mg folic acid kg−1, and the lowest value occurred in those fed ≥0.5 mg folic acid kg−1. Phenoloxidase activity and total haemocytes were significantly higher in crabs fed ≥2.0 mg folic acid kg−1 than other diets. Crabs fed 2.0 mg folic acid kg−1 had the highest lysozyme, acid phosphatase and alkaline phosphatase activities but the lowest cumulative mortality. The optimum dietary folic acid requirement by E. sinensis was estimated at 2.29–2.90 mg kg−1 diet.

Performance, serum biochemical responses, and gene expression of intestinal folate transporters of young and older laying hens in response to dietary folic acid supplementation and challenge with Escherichia coli lipopolysaccharide

The present study was conducted to investigate the effects of dietary folic acid (FA) supplementation on performance, serum biochemical indices, and mRNA abundance of intestinal folate transporters in young and older laying hens after acute lipopolysaccharide (LPS) challenge. Two experiments were conducted separately involving 48 Shaver White young laying hens (24 wk of age) in experiment 1 and 48 Shaver White older laying hens (58 wk of age) in experiment 2. Birds were fed 2 diets in a complete randomized design. The diets were wheat-soybean meal based, with or without supplemental 4 mg of FA/kg of diet. Birds were fed for 8 wk, during which time feed consumption and egg production were monitored. At the end of each feeding experiment, 6 hens from each dietary treatment were injected intravenously with 8 mg/kg of BW of either Escherichia coli LPS or sterile saline. Four hours after injection, blood and intestinal samples were collected for further analysis. Compared with the control, dietary FA supplementation increased egg weight and egg mass and decreased serum glucose levels in the young laying hens, and reduced serum uric acid in the older laying hens (P < 0.05). Relative to saline injection, plasma homocysteine, serum calcium, and phosphorus levels were found to be lower in both young and older laying hens after LPS challenge (P < 0.05). Other serum biochemical variables and the mRNA expression of 2 folate transport genes in the small and large intestine were differentially affected by LPS challenge, and some of those responses varied with the age of the birds. Additionally, interactions between diet and LPS challenge were specifically found in the older laying hens. In summary, in addition to improving production performance, there were effects of dietary FA supplementation and its interaction with LPS challenge on biochemical constituents, and age played a role in the development of responses to diet and bacterial LPS infections.

Response of older laying hens to an Escherichia coli lipopolysaccharide challenge when fed diets with or without supplemental folic acid

Folic acid plays a key role in nucleic acids and protein synthesis, and has been associated with anti-inflammatory effects in LPS-induced infections. To this end, a study was conducted to investigate the effects of dietary folic acid (FA) supplementation in older laying hens (58 to 66 wk of age) challenged with Escherichia coli lipopolysaccharide (LPS). A total of 24 Shaver White laying hens at 58 wk were fed 2 diets. The diets were wheat-soybean-based, with either 0 or 4 mg of supplemental FA per kg of diet. After 8 wk of feeding and at 66 wk, the hens were injected intravenously with 8 mg of LPS or saline per kg of BW. Four hours after injection, blood was collected and hens were euthanized to obtain spleen and cecal tonsils. The T cell subsets in the blood and the spleen (CD4+ and CD8+), total IgG, and biochemical constituents (total protein, albumin, globulin, and fibrinogen) were not influenced (P > 0.05) by dietary FA supplementation. However, LPS injection decreased (P < 0.05) biochemical constituents, CD4+, and CD8+ cells in the blood, whereas CD4+:CD8+ ratio and total IgG increased (P < 0.05), and fibrinogen was not influenced. Gene expression in the spleen and cecal tonsils was not influenced by dietary FA supplementation except a diet × challenge interaction for interleukin (IL)-8 in the spleen; IL-8 decreased in FA-fed hens that were treated with LPS. Also, FA supplementation decreased the expression of IL-8 in cecal tonsils. Relative to saline-injected hens, expression of IL-1β, interferon-γ, and IL-10 increased in the LPS-injected hens in the spleen and cecal tonsils, IL-8 increased in LPS-injected hens only in the cecal tonsils, whereas Toll-like receptor 4, IL-4, IL-17, and IL-18 increased in the LPS-injected hens only in the spleen; however, LPS decreased expression of IL-13 in the cecal tonsils. In conclusion, FA did not affect inflammatory responses in older laying hens; more studies are required to investigate possible protective effects of FA in laying hens.

Immunomodulation in young laying hens by dietary folic acid and acute immune responses after challenge with Escherichia coli lipopolysaccharide

We investigated the effects of dietary folic acid (FA) supplementation on immunological parameters in young laying hens under acute conditions of lipopolysaccharide (LPS) challenge. Twenty-four Shaver White laying hens at 24 wk were fed 2 diets in a completely randomized design. The diets were wheat-soybean based, with either 0 or 4 mg of supplemental FA per kilogram of diet. At 32 wk of age, 6 hens from each dietary treatment were injected intravenously with 8 mg/kg of BW of either LPS or saline. Four hours after injection, blood was collected and the hens were euthanized to obtain spleen and cecal tonsils. Heterophil:lymphocyte ratio, CD3+, CD4+, CD8+ T cells, and CD4+:CD8+ cells in the blood and spleen were not affected by dietary FA. Relative to saline-injected hens, LPS-injected hens had fewer (P < 0.05) CD3+, CD4+, CD8+, and CD4+:CD8+ cells in the blood, and no difference was found in the spleen. Total protein, albumin, and globulin were found to be higher (P < 0.05) in FA-supplemented hens compared with the control. However, total protein, albumin, and globulins decreased (P < 0.05) in the LPS-injected hens compared with the saline control. Expression of interleukin (IL)-1β in cecal tonsils decreased (P < 0.05) in FA-supplemented hens, but no dietary influence was found on the expression of other genes in both the spleen and cecal tonsils. Lipopolysaccharide upregulated (P < 0.05) expression of IL-10 and interferon (IFN)-γ in the spleen, and IL-1β, IL-10, and IFN-γ in the cecal tonsils, whereas the expression of Toll-like receptor (TLR)-4 and IL-8 was not influenced by LPS in the spleen and cecal tonsils. There was a diet × challenge interaction for total IgG, and cytokines IL-1β and IL-18 in the spleen as well as IL-18 in the cecal tonsils. In conclusion, there were few interactions of dietary FA and LPS; however, FA increased biochemical constituents, enhanced generation of total IgG, as well as exhibiting pleoitropic effects in inflammatory responses.

Investigating the effects of dietary folic acid on sperm count, DNA damage and mutation in Balb/c mice

To date, fewer than 50 mutagens have been studied for their ability to cause heritable mutations. The majority of those studied are classical mutagens like radiation and anti-cancer drugs. Very little is known about the dietary variables influencing germline mutation rates. Folate is essential for DNA synthesis and methylation and can impact chromatin structure. We therefore determined the effects of folic acid-deficient (0mg/kg), control (2mg/kg) and supplemented (6mg/kg) diets in early development and during lactation or post-weaning on mutation rates and chromatin quality in sperm of adult male Balb/c mice. The sperm chromatin structure assay and mutation frequencies at expanded simple tandem repeats (ESTRs) were used to evaluate germline DNA integrity. Treatment of a subset of mice fed the control diet with the mutagen ethylnitrosourea (ENU) at 8 weeks of age was included as a positive control. ENU treated mice exhibited decreased cauda sperm counts, increased DNA fragmentation and increased ESTR mutation frequencies relative to non-ENU treated mice fed the control diet. Male mice weaned to the folic acid deficient diet had decreased cauda sperm numbers, increased DNA fragmentation index, and increased ESTR mutation frequency. Folic acid deficiency in early development did not lead to changes in sperm counts or chromatin integrity in adult mice. Folic acid supplementation in early development or post-weaning did not affect germ cell measures. Therefore, adequate folic acid intake in adulthood is important for preventing chromatin damage and mutation in the male germline. Folic acid supplementation at the level achieved in this study does not improve nor is it detrimental to male germline chromatin integrity.

Effects of folic acid supplementation to rations differing in the concentrate to roughage ratio on ruminal fermentation, nutrient flow at the duodenum, and on serum and milk variables of dairy cows

The present study was undertaken to determine the effects of dietary folic acid (FOL) supplementation on ruminal fermentation, duodenal nutrient flow, serum and milk variables, and on B-vitamin concentration in serum. The study was divided into two experiments: in Exp. 1 the forage to concentrate (F:C) ratio of the diet (DM basis) was 34:66 (high concentrate, HC), while in Exp. 2 the F:C ratio was 66:34 (high forage, HF). In addition, the cows received 0 or 1 g FOL/d. In Exp. 1, two German Holstein cows equipped with cannulas in the dorsal sac of the rumen and in the proximal duodenum were dry and five were lactating (186 ± 144 days in milk); in Exp. 2 four cows were dry and four were lactating (165 ± 57 days in milk). In cows fed the HC diet, FOL supplementation decreased the ruminally-fermented organic matter. Thus, less energy was available for ruminal microorganisms, which resulted in a reduced microbial crude protein flow at the duodenum. Feeding the HF diet, FOL supplementation only increased the apparent ruminal digestibility of acid detergent fibre (ADF). With the HF diet, FOL had no influence on the serum levels of glucose, non-esterified fatty acids, beta-hydroxybutyrate, urea, thiamine, riboflavin, pyridoxal-5′-phosphate, pyridoxic acid, pyridoxal, pyridoxine, pyridoxamine, pantothenic acid, nicotinamide or nicotinic acid, whereas supplementing FOL to the HC diet lowered the serum glucose and riboflavin levels. In both experiments, the supplementation of FOL had no effects on milk composition. Folic acid supplementation to both diets increased the concentrations of serum 5-methyl-tetrahydrofolate. However, no beneficial effects to dairy cows were obvious. Therefore, to achieve certain results, studies with a higher number of non-fistulated cows would be necessary.