The effect of dietary fatty acid composition on adipose tissue quality and expression of genes related to lipid metabolism in porcine livers

Eat like a Pig to Combat Obesity

Obesity and related metabolic health issues are a growing human threat, with many theories regarding its causes. In swine, physiologically alike to humans, considerable knowledge on obesity mechanisms has been accumulated. Calorie counting is the basis for managing swine diets and applied with great accuracy. Epigenetic programing predisposes pigs to insulin insensitivity, but pigs seem to sense this insensitivity and consequently eat less, preventing obesity. Pigs naturally prefer to eat small breakfasts and large dinners. Deviating from this eating pattern or providing diets with a high glycemic burden can trigger obesity; however, pigs will restrict food intake to prevent serious obesity. Interestingly, in practice, problems with obesity are rarely seen, even when pigs are fed poorly timed diets similar to junk food, likely because swine diets are balanced for every nutrient. Indeed, feeding pigs diets deficient in micronutrients does trigger obesity. For humans, several micronutrient requirements have not been set officially, and diets optimized for all micronutrients are rarely provided. In conclusion, various obesity triggers are being debated for humans, which have been proven in swine. Obesity problems in pigs are nevertheless less excessive, likely because pigs recognize unhealthy eating practices and consequently reduce food intake to avoid serious complications. Finally, swine diets are normally balanced for all nutrients, which may be an important practice to prevent obesity, from which human health could greatly benefit.

Malnourishment affects gene expression along the length of the small intestine

Malnourishment is a risk factor for childhood mortality, jeopardizing the health of children by aggravating pneumonia/acute respiratory infections and diarrheal diseases. Malnourishment causes morphophysiological changes resulting in stunting and wasting that have long-lasting consequences such as cognitive deficit and metabolic dysfunction. Using a pig model of malnutrition, the interplay between the phenotypic data displayed by the malnourished animals, the gene expression pattern along the intestinal tract, microbiota composition of the intestinal contents, and hepatic metabolite concentrations from the same animals were correlated using a multi-omics approach. Samples from the duodenum, jejunum, and ileum of malnourished (protein and calorie-restricted diet) and full-fed (no dietary restrictions) piglets were subjected to RNA-seq. Gene co-expression analysis and phenotypic correlations were made with WGCNA, while the integration of transcriptome with microbiota composition and the hepatic metabolite profile was done using mixOmics. Malnourishment caused changes in tissue gene expression that influenced energetic balance, cell proliferation, nutrient absorption, and response to stress. Repression of antioxidant genes, including glutathione peroxidase, in coordination with induction of metal ion transporters corresponded to the hepatic metabolite changes. These data indicate oxidative stress in the intestine of malnourished animals. Furthermore, several of the phenotypes displayed by these animals could be explained by changes in gene expression.

Transcriptome Profiles of the Liver in Two Cold-Exposed Sheep Breeds Revealed Different Mechanisms and Candidate Genes for Thermogenesis

Cold-induced thermogenesis plays an important role in the survival of lambs exposed to low air temperatures. The liver produces and mediates heat production in mammals; however, to date, little is known about the role of liver genes in cold-induced thermogenesis in lambs. In this study, the difference in the liver transcriptome between Altay and Hu ewe lambs was compared. Because of different backgrounds of the two breeds, we hypothesized that the transcriptome profiles of the liver would differ between breeds when exposed to cold. Cold-exposed Altay lambs activated 8 candidate genes (ACTA1, MYH1, MYH2, MYL1, MYL2, TNNC1, TNNC2, and TNNT3) involved in muscle shivering thermogenesis; 3 candidate genes (ATP2A1, SLN, and CKM) involved in muscle nonshivering thermogenesis related to the Ca²⁺ signal and creatine cycle; and 6 candidate genes (PFKM, ALDOC, PGAM2, ENO2, ENO3, and ENO4) involved in enhancing liver metabolism. In contrast, the liver may not act as the main tissue for thermogenesis in cold-exposed Hu lambs. We concluded that Altay lambs rely on liver-mediated shivering and nonshivering thermogenesis by muscle tissue to a greater extent than Hu lambs. Results from this study could provide a theoretical foundation for the breeding and production of cold-resistant lambs.

The Effect of Replacement of Soybean Meal with Corn Dried Distillers Grains with Solubles (cDDGS) and Differentiation of Dietary Fat Sources on Pig Meat Quality and Fatty Acid Profile

Simple Summary

The growing demand for protein and the reluctance of consumers to use genetically modified feeds necessitate the use of other protein feeds. Corn dried distillers grains with solubles (cDDGS) is a well-digested protein feed; however, it is rich in unsaturated fatty acids and can negatively affect the meat quality and oxidative stability. The negative influence of dietary unsaturated fatty acids on meat quality can be balanced by feed additives, e.g., a dietary saturated fat source increasing the iodine value of fat. To reduce the detrimental effect of corn DDGS in the present experiment, the beef tallow and coconut oil in a feed mixture were studied, as both of them are more saturated than corn DDGS and rapeseed oil. The aim of the study was to investigate mixtures comprising corn DDGS as a partial replacer for soybean meal as well as different dietary saturated fat sources to determine their effect on the meat quality and fatty acid profile. The relationships between dietary fatty acid profile and meat fatty acid profile and between various meat quality parameters were analyzed.

Abstract

The aim of the study was to investigate mixtures comprising corn distillers dried grain with solubles as a partial replacer for soybean meal (SBM) and different dietary fat sources, in order to determine their effect on the meat quality and fatty acid profile. Thirty-two crossbred fatteners were divided into four groups: I–SBM + rapeseed oil, II–cDDGS + rapeseed oil, III–cDDGS + beef tallow, IV–cDDGS + coconut oil. The experiment took place from 60 to 118 kg. At the end of fattening, all pigs were slaughtered and samples of meat (musculuslongissimus lumborum) were taken. The fatty acid profile, texture, and quality traits were analyzed. Corn DDGS affected drip loss. Beef tallow and coconut oil improved water holding capacity and drip loss and increased fat content, compared to the control group. The dietary fat type affected the fatty acid composition, iodine value, and consequently some quality traits of meat. However, these relationships varied. Fat content in the meat was inversely correlated with shear force and texture parameters, but positively with tenderness and juiciness. The fatty acid profile significantly influenced cohesiveness, chewiness, resilience and sensory traits, which were the most beneficial in meat with higher fat content and higher fat saturation index.

Application of Fat-Tailed Sheep Tail and Backfat to Develop Novel Warthog Cabanossi with Distinct Sensory Attributes

This study compared the use of pork backfat (PF) and fat-tailed sheep tail and backfat (SF) on the physicochemical, fatty acids and sensory attributes of warthog cabanossi. There were no differences between weight loss during drying, moisture content, pH, water activity, salt content and lipid oxidation between the cabanossi types. However, protein and ash contents were higher in PF cabanossi whilst fat content was higher in SF cabanossi. The PF cabanossi had higher polyunsaturated fatty acids (especially n-6), lower monounsaturated fatty acids whilst the saturated fatty acid content was similar between the two cabanossi products. The n-3:n-6 ratio was more beneficial in the SF cabanossi. The descriptive sensory analysis showed two distinct products where PF cabanossi scored higher for most attributes. Although SF cabanossi scored less for these attributes, this cabanossi had unique and acceptable sensory attributes. This study concluded that fat-tailed sheep tail and backfat could be used to produce a unique cabanossi product of acceptable quality.

3'quant mRNA-Seq of Porcine Liver Reveals Alterations in UPR, Acute Phase Response, and Cholesterol and Bile Acid Metabolism in Response to Different Dietary Fats

Animal fats are considered to be unhealthy, in contrast to vegetable fats, which are rich in unsaturated fatty acids. However, the use of some fats, such as coconut oil, is still controversial. In our experiment, we divided experimental animals (domestic pigs) into three groups differing only in the type of fat used in the diet: group R: rapeseed oil (n = 5); group B: beef tallow (n = 5); group C: coconut oil (n = 6). After transcriptomic analysis of liver samples, we identified 188, 93, and 53 DEGs (differentially expressed genes) in R vs. B, R vs. C, and B vs. C comparisons, respectively. Next, we performed a functional analysis of identified DEGs with String and IPA software. We observed the enrichment of genes engaged in the unfolded protein response (UPR) and the acute phase response among genes upregulated in B compared to R. In contrast, cholesterol biosynthesis and cholesterol efflux enrichments were observed among genes downregulated in B when compared to R. Moreover, activation of the UPR and inhibition of the sirtuin signaling pathway were noted in C when compared to R. The most striking difference in liver transcriptomic response between C and B was the activation of the acute phase response and inhibition of bile acid synthesis in the latest group. Our results suggest that excessive consumption of animal fats leads to the activation of a cascade of mutually propelling processes harmful to the liver: inflammation, UPR, and imbalances in the biosynthesis of cholesterol and bile acids via altered organelle membrane composition. Nevertheless, these studies should be extended with analysis at the level of proteins and their function.

Source of Dietary Fat in Pig Diet Affects Adipose Expression of Genes Related to Cancer, Cardiovascular, and Neurodegenerative Diseases

It has been known for many years that excessive consumption of saturated fats has proatherogenic properties, contrary to unsaturated fats. However, the molecular mechanism covering these effects is not fully understood. In this paper, we aimed to identify differentially expressed genes (DEGs) using RNA-sequencing, following feeding pigs with different sources of fat. After comparison of adipose samples from three dietary groups (rapeseed oil (n = 6), beef tallow (n = 5), coconut oil (n = 5)), we identified 29 DEGs (adjusted p-value < 0.05, fold change > 1.3) between beef tallow and rapeseed oil and 2 genes between coconut oil and rapeseed oil groups. No differentially expressed genes were observed between coconut oil and beef tallow groups. Almost all 29 DEGs between rapeseed oil and beef tallow groups are connected to neurodegenerative, cardiovascular diseases, or cancer (e.g., PLAU, CYBB, NCF2, ZNF217, CHAC1, CTCFL). Functional analysis of these genes revealed that they are associated with fluid shear stress response, complement and coagulation cascade, ROS signaling, neurogenesis, and regulation of protein binding and protein catabolic processes. Furthermore, gene set enrichment analysis (GSEA) of the whole datasets from all three comparisons suggests that both beef tallow and coconut oil may trigger changes in the expression level of genes crucial in the pathogenesis of civilization diseases.

Corn dried distillers grains with solubles (cDDGS) in the diet of pigs change the expression of adipose genes that are potential therapeutic targets in metabolic and cardiovascular diseases

Background

Corn dried distillers grains with solubles (cDDGS) are a byproduct of biofuel and alcohol production. cDDGS have been used in pig feed for many years, because they are readily available and rich in protein, fiber, unsaturated fatty acids and phytosterols. However, feed mixtures too high in cDDGS result in the worsening of backfat quality. We performed RNA-sequencing analysis of backfat from crossbred pigs fed different diets. The diets were isoenergetic but contained different amounts of cDDGS and various sources of fats. The animals were divided into four dietary groups during the two months of experimentation: group I (control (-cDDGS+rapeseed oil)), group II (+cDDGS+rapeseed oil), group III (+cDDGS+beef tallow), and group IV (+cDDGS+coconut oil). The aim of the present experiment was to evaluate changes in the backfat transcriptome of pigs fed isoenergetic diets that differed in cDDGS presence.

Results

Via DESeq2 software, we identified 93 differentially expressed genes (DEGs) between groups I and II, 13 between groups I and III, and 125 between groups I and IV. DEGs identified between group I (-cDDGS+rapeseed oil) and group II (+cDDGS+rapeseed oil) were highly overrepresented in several KEGG pathways: metabolic pathways (FDR < 1.21e-06), oxidative phosphorylation (FDR < 0.00189), fatty acid biosynthesis (FDR < 0.00577), Huntington’s disease (FDR < 0.00577), fatty acid metabolism (FDR < 0.0112), Parkinson’s disease (FDR < 0.0151), non-alcoholic fatty liver disease (NAFLD) (FDR < 0.016), Alzheimer’s disease (FDR < 0.0211) and complement and coagulation cascades (FDR < 0.02).

Conclusions

We observed that the addition of cDDGS positively affects the expression of several genes that have been recently proposed as potential targets for the treatment of obesity, diabetes, cardiovascular disease, and Alzheimer’s disease (e.g., FASN, AACS, ALAS1, HMGCS1, and VSIG4). Thus, our results support the idea of including cDDGS into the diets of companion animals and humans and encourage research into the bioactive ingredients of cDDGS.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5265-x) contains supplementary material, which is available to authorized users.

Gene expression profile changes in the jejunum of weaned piglets after oral administration of Lactobacillus or an antibiotic

The small intestine plays an essential role in the health and well-being of animals. Previous studies have shown that Lactobacillus has a protective effect on intestinal morphology, intestinal epithelium integrity and appropriate maturation of gut-associated tissues. Here, gene expression in jejunum tissue of weaned piglets was investigated by RNA-seq analysis after administration of sterile saline, Lactobacillus reuteri, or an antibiotic (chlortetracycline). In total, 401 and 293 genes were significantly regulated by chlortetracycline and L. reuteri, respectively, compared with control treatment. Notably, the HP, NOX1 and GPX2 genes were significantly up-regulated in the L. reuteri group compared with control, which is related to the antioxidant ability of this strain. In addition, the expression of genes related to arachidonic acid metabolism and linoleic acid metabolism enriched after treatment with L. reuteri. The fatty acid composition in the jejunum and colon was examined by GC-MS analysis and suggested that the MUFA C18:1n9c, and PUFAs C18:2n6c and C20:4n6 were increased in the L. reuteri group, verifying the GO enrichment and KEGG pathway analyses of the RNA-seq results. The results contribute to our understanding of the probiotic activity of this strain and its application in pig production.