Effects of spirulina supplementation on lipid metabolism disorder, oxidative stress caused by high-energy dietary in Hu sheep

Emerging microalgal feed additives for ruminant production and sustainability

The global demand for animal-derived foods has led to a substantial expansion in ruminant production, which has raised concerns regarding methane emissions. To address these challenges, microalgal species that are nutritionally-rich and contain bioactive compounds in their biomass have been explored as attractive feed additives for ruminant livestock production. In this review, we discuss the different microalgal species used for this purpose in recent studies, and review the effects of microalgal feed supplements on ruminant growth, performance, health, and product quality, as well as their potential contributions in reducing methane emissions. We also examine the potential complexities of adopting microalgae as feed additives in the ruminant industry.

Genome wide transcriptome analysis provides bases on hepatic lipid metabolism disorder affected by increased dietary grain ratio in fattening lambs

BACKGROUND

The liver is a principal metabolic organ and has a major role in regulating lipid metabolism. With the development of rapidly fattening livestock in the modern breeding industry, the incidence of hepatic steatosis and accumulation in animals was significantly increased. However, the molecular mechanisms responsible for hepatic lipid metabolic disturbances in a high concentrate diet remain unclear. The objective of this study was to evaluate the effects of increasing concentrate level in a fattening lamb diet on biochemical indices, hepatic triglycerides (TG) concentration, and hepatic transcriptomic profiles. In the present study, 42 weaned lambs (about 3 ± 0.3 months old) were randomly assigned to the GN60 group (60% concentrate of dry matter, GN60, n = 21) or GN70 group (70% concentrate of dry matter, n = 21) for a 3-months feeding trial.

RESULTS

No difference was observed in the growth performance or plasma biochemical parameters between the GN60 group and the GN70 group. The hepatic TG concentration was higher in the GN70 group than GN60 group (P < 0.05). Hepatic transcriptomic analysis showed that there were 290 differentially expressed genes identified between GN60 and GN70 groups, with 125 genes up-regulated and 165 genes down-regulated in the GN70 group. The enriched Gene Ontology (GO) items and KEGG pathways and protein-protein interaction (PPI) network of differentially expressed genes (DEGs) revealed that the majority of enriched pathways were related to lipid metabolism. Further analysis revealed that the fatty acid synthesis was up-regulated, while fatty acid transport, oxidation, and TG degradation were down-regulated in the GN70 group when compared with the GN60 group.

CONCLUSIONS

These results indicated that GN70 induced excess lipid deposition in the liver of lambs during the fattening period, with high synthesis rates and low degradation rates of TG. The identified mechanisms may help understand hepatic metabolism in lambs with a high concentrate diet and provide insight into decreasing the risk of liver metabolism disorder in animals.

Dietary spirulina supplementation modifies rumen development, fermentation and bacteria composition in Hu sheep when consuming high-fat dietary

Introduction

This study aims to investigate the long-term effects of spirulina supplementation in a high-fat diet (HFD) on rumen morphology, rumen fermentation, and the composition of rumen microbiota in lambs. Spirulina is a blue-green microalgae that has been shown to have high nutritional value for livestock.

Methods

Fifty-four lambs were randomly divided into three groups: a normal chow diet (NCD) group, a high-fat diet (HFD) group, and a high-fat diet supplemented with 3% spirulina (HFD+S) group. Rumen morphology, rumen fermentation, and rumen microbiota were analyzed at the end of the study.

Results

Spirulina supplementation improved the concentration of volatile fatty acids and rumen papilla length. Additionally, there was a tendency for an increase in rumen weight and an upregulation of the genes Claudin-1, Claudin-4, and Occludin in the HFD+S group. Pyrosequencing of the 16S ribosomal RNA gene also showed that spirulina supplementation significantly changed the rumen microbiota composition in the HFD group, with a decrease in richness and diversity. Specifically, the relative abundance of Prevotella 9 and Megasphaera was significantly increased in the HFD group compared to the NCD group, while spirulina supplementation reversed these changes.

Discussion

This study suggests that 3% spirulina supplementation can improve rumen development and fermentation, and effectively relieve rumen microbe disorders in lambs caused by a high-fat diet. However, further research is needed to confirm the findings and to examine the long-term effects of spirulina supplementation in different types of livestock and under different dietary conditions.

Effects of different levels of spirulina (Arthrospira platensis) supplementation on productive performance, nutrient digestibility, blood metabolites, and meat quality of growing Najdi lambs

In a 90-day study, 32 growing lambs aged 3 months were utilized to evaluate the effects of various levels of spirulina dietary supplement on productive performance, nutritional digestibility, and meat quality in growing Najdi lambs. The lambs were put into 4 groups of 8 lambs each at random. The diet consisted of a total mixed ration (TMR) without spirulina (CONT), and the TMR diet supplemented with spirulina at the levels of 2 ppm (SPP2), 4 ppm (SPP4), and 8 ppm (SPP8). The treatment groups, especially SPP8, showed a significant (p < 0.05) increase in body weight and average daily gain (p < 0.05) compared to the CONT group. Dry matter intake and acid detergent fiber were also significantly (p ≤ 0.05) higher in SPP8 compared to other treated groups and CONT. The N absorption, N retention, and percentage of N digestibility coefficient were greater (P < 0.05) in lambs in the treatment groups than in the CONT. Blood biochemistry variables were not significantly (p ≤ 0.05) affected by the treatments, with the exception of the serum concentration of triglyceride and bilirubin. Carcass profile and meat quality, including back fat, body wall fat, and cooking loss, were increased significantly (p ≤ 0.05) with dietary spirulina. From the results of the present study, it was concluded that spirulina dietary supplementation at the level of 8 ppm increased weight gain, nutritional digestibility, nitrogen utilization, and meat composition in growing Najdi lambs.

Distribution characteristics and regulation of amino acids and fatty acids in muscle and adipose tissues of sheep grown in natural grazing environment

The composition of amino acid and fatty acid has a vital function on meat quality and animal health. However, the underlying mechanism of amino acid and fatty acid metabolism in sheep during different grazing periods is still unclear. In this study, a total of 12 sheep were employed in different grazing periods. Our results showed that the composition of amino acids and fatty acids in muscle and adipose tissues was significantly altered between dry grass (DG) period and green grass (GG) period. Changes in the activities of the metabolism-related enzymes including BCKD, BCAT2, ACC, SCD, HSL, GSK3β, p-GSK3β, and FABP4 were observed in muscle and adipose during different grazing periods. In addition, the mRNA expression levels of ACC, FAS, SCD, HSL, LPL, and DGAT1 in muscle and adipose tissue were changed markedly in different grazing periods. Furthermore, the expression levels of mTOR and β-catenin/PPARγ/C/EBPα pathway-related proteins were predominantly altered in muscle and adipose among DG and GG. Taken together, all investigations simplified the process of amino acid and fatty acid metabolism disorders caused by different grazing periods, and the mTOR and β-catenin/PPARγ/C/EBPα play the essential role in this process, which provided an underlying mechanism of metabolism and meat quality.

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 < 0.05) plasma concentrations of calcium and albumin but reduced (P < 0.005) weights of ceca and bursa compared with those fed NE diets. Dietary supplementation with 10 ppm FA significantly increased (P < 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 < 0.0001), and crypt depth (CD; P = 0.0332). Among the NE group, birds fed 5–15 ppm FA had reduced (P < .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 mulberry leaf silage on antioxidant and immunomodulatory activity and rumen bacterial community of lambs

Background

Rumen is a natural fermentation system and the microorganisms inside can effectively utilize plant bioresource and interact with host metabolism. Here, analysis of rumen microbiome, together with animal performance and serum metabolism in a lamb model were performed to identify the potential use of mulberry leaf silage (MS) to replace alfalfa silage (AS) as a new functional feed resource and to mining the novel specific mulberry leaf associated rumen bacteria interact with host metabolism.

Results

The lambs fed with MS diet showed improved antioxidant capacity and immune function compared to those fed AS diet. The MS diet significantly altered rumen microbiota α- and β-diversity and taxonomic composition. Microbial analysis revealed that Bifidobacterium, Lactobacillus and Schwartzia were enhanced, and Ruminococcaceae UCG-010 and Lachnospiraceae_XPB1014_group were down-regulated in the rumen of MS group. A strong association was also found between these rumen microbial taxa and host antioxidant and immunomodulatory capacity.

Conclusion

These findings indicated that mulberry leaf silage can be a high-quality feed source or bioactive pharmaceutical that is responsible for ruminant’s health benefits. The modified rumen microbial community by mulberry leaf silage were associated with the enhanced antioxidant capacity and immunomodulatory of lambs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02311-1.

γ-Linolenic Acid Prevents Lipid Metabolism Disorder in Palmitic Acid-Treated Alpha Mouse Liver-12 Cells by Balancing Autophagy and Apoptosis via the LKB1-AMPK-mTOR Pathway

Excessive fat deposition is the main character in nonalcoholic fatty liver disease (NAFLD), while γ-linolenic acid (GLA) is a polyunsaturated fatty acid that can reduce lipid deposition. This study investigated the effect and regulatory mechanism of GLA (100 μM) on lipid metabolism in alpha mouse liver 12 (AML-12) cells treated by 400 μM palmitic acid (PA). GLA reduced lipid content and increased fatty acid β oxidation, as indicated by decreasing triglyceride and cholesterol contents and increasing mRNA and protein expressions of CPT1α and PPARα. GLA relieved oxidative stress caused by PA, upregulated mRNA levels of superoxide dismutase and glutathione peroxidase, and decreased reactive oxygen species content. GLA reduced apoptosis, as indicated by decreases in the BAX/BCL2 expression level and apoptosis percentage. GLA activated autophagy, autophagosome-lysosome fusion, and LKB1-AMPK-mTOR signaling and upregulated mRNA and protein expressions of Beclin-1, autophagy-related 5, and liver kinase B1 (LKB1). These effects of GLA on lipid metabolism disorders of PA-treated hepatocytes were reversed by autophagy inhibitor 3MA and AMPK inhibitor compound C, confirming our conclusions. Overall, GLA can protect AML-12 cells from lipid metabolism disorder caused by PA via balancing autophagy and apoptosis mediated by the LKB1-AMPK-mTOR pathway. Consequently, GLA, as a dietary supplement, can help to prevent and treat NAFLD by regulating lipid metabolism and autophagy.

Effects of dietary betaine supplementation on biochemical parameters of blood and testicular oxidative stress in Hu sheep

Betaine, a highly valuable feed additive, has been observed to alter the distribution of protein and fat in the bodies of ruminants and to exhibit strong antioxidant properties. However, the effects of dietary betaine supplementation on the biochemical parameters of blood and on testicular oxidative stress remain unknown. This study aimed to investigate the effects of dietary betaine supplementation on lipid metabolism, immunity, and testicular oxidative status in Hu sheep. Experimental sheep (n=3, three sheep per group) were fed betaine-containing diets, a basal diet supplemented with 0 g/day (control group), 1 g/day (B1), and 3 g/day betaine (B2). There were no differences in the serum concentrations of triglycerides and cholesterol in Hu sheep receiving diets supplemented with betaine. The ratio of basophils significantly increased in the B1 and B2 groups. ELISA (enzyme-linked immunosorbent assay) results showed that testicular superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity were significantly higher, whereas malondialdehyde (MDA) content significantly decreased, after feeding betaine-supplemented diets. qPCR results showed that the mRNA expression levels of CAT, SOD2, and GSH-Px were significantly upregulated in both the B1 and B2 groups compared to those in the control group. Furthermore, the expression of proliferating cell nuclear antigen (PCNA) was significantly lower in the testes of betaine-treated Hu sheep than in the control group. Moreover, LKB1 (liver kinase B1) expression significantly increased, and mRNA expression of AMPK (AMP-activated serine/threonine protein kinase) significantly decreased in the B1 group. The relative gene expression of mTOR (mechanistic target of rapamycin) was significantly higher in the B2 group than in the control group. RAPTOR expression significantly increased in the B1 group. Western blot revealed that the ratio of P-mTOR and mTOR significantly increased after feeding betaine-supplemented diets. In conclusion, betaine supplementation improved serum lipid metabolism, immune response, and increased the testicular antioxidant capacity of Hu sheep, which might be regulated via mTOR signaling pathway.

Spirulina supplementation improves lipid metabolism and autophagic activities in the liver and muscle of Hu lambs fed a high-energy diet

The current study aimed to examine the effects of dietary spirulina supplementation in high-energy (HE) diets on fatty acid metabolism in sheep, and preliminarily explored the potential mechanisms underlying the associated autophagy-mediated regulation of lipid metabolism. In a 2 × 3 factorial design, including six treatment combinations of two metabolisable energy diets (10 and 11 MJ/kg DM), three spirulina supplementation levels (0, 1%, and 3%) were used. Serum alanineaminotransferase (ALT) (p = 0.003) and aspartatetransaminase (AST) (p = 0.002) activities increased, whereas total PUFA content (p < 0.001) decreased in the liver of lambs fed a HE diet. With the addition of spirulina, serum ALT (p = 0.037) and AST (p = 0.014) activities decreased, whereas EPA (p = 0.004), GLA (p = 0.019), n-6 PUFA (p = 0.005), and total PUFA contents (p = 0.019) increased. Moreover, the crude protein content in the Longissimus thoracis et lumborum (LTL) increased (p = 0.013), the expression of PPARα and PPARγ was up-regulated, while ELOVL2 was down-regulated in liver and LTL (p < 0.05). Spirulina supplementation increased mRNA expression levels of autophagy-associated genes, including that of Beclin-1, AMPK, and ULK1 (p < 0.05). In conclusion, spirulina supplementation in a HE diet exerted a protective effect on the liver, increased PUFA content, and modulated expression levels of autophagy-related genes in growing lambs.