Ruminant nutrition has significantly revolutionized a new and prodigious molecular approach in livestock sciences over the last decade. Wide-spectrum advances in DNA and RNA technologies and analysis have produced a wealth of data that have shifted the research threshold scheme to a more affluent level. Recently, the published literature has pointed out the nutrient roles in different cellular genomic alterations among different ruminant species, besides the interactions with other factors, such as age, type, and breed. Additionally, it has addressed rumen microbes within the gut health and productivity context, which has made interpreting homogenous evidence more complicated. As a more systematic approach, nutrigenomics can identify how genomics interacts with nutrition and other variables linked to animal performance. Such findings should contribute to crystallizing powerful interpretations correlating feeding management with ruminant production and health through genomics. This review will present a road-mapping discussion of promising trends in ruminant nutrigenomics as a reference for phenotype expression through multi-level omics changes.

Polyunsaturated fatty acids (PUFAs) constitute a significant lipid class with essential nutritional and health benefits for both animal and human health; however, their effect and interaction with the gut microbiota ecosystem are still unclear. Therefore, the present study aims to investigate the effect of fish oil (FO) on ruminal fermentation and bacterial abundance under high- and low-forage diets. Thirty-six ruminal fluid samples were allocated into two experiments. The first was on high-forage diet and included three groups: the control (basal diet with 70% forage and 30% concentrate), group 2 (basal diet + 5 mL/L FO), and group 3 (basal diet + 10 mL/L). The second experiment was on low-forage diet: the control (basal diet with 30% forage and 70% concentrate), group 2 (basal diet + 5 mL/L FO), and group 3 (basal diet + 10 mL/L). The results showed that although FO supplementation did not affect the pH level among different diets, it significantly decreased methane under a high-forage diet. In addition, regarding the fatty acids profile, FO supplementation in high-forage diet significantly decreased fatty acids in both; however, under a low-forage diet, FO groups showed significantly higher fatty acid content than the control. However, FO supplementation increased the abundance of Anaerovibirio, Selenomonas, pseudobutyrivibrio, and butyrivibrio through a high-forage diet. In contrast, the abundance of Prevotella, Rikenellaceae RC9 gut group, and Saccharofermentans was depressed with FO supplementation. Whereas under low-forage diet, FO supplementation increased Ruminobacter, Anaerovibirio, Megasphaera, Pseudobutyrivibrio, Streptococcus, Butyrivibrio, unclassified_lachnospiraceae; it also decreased Prevotella and Rikenellaceae RC9 abundance similar to the high-forage diet. Based on the KEGG pathway results, FO supplementation significantly downregulated genes mainly related to folding, sorting and degradation, environmental adaptation, cell motility, transcription, membrane transport, and signal transduction. The results revealed that FO has a depressing effect on ruminal fermentation and some bacterial population; however, this negative effect can be minimized in high-concentrate diets.

Over the past three decades, studies have shown that consuming polyunsaturated fatty acids (PUFAs) can enhance animal and human health and welfare through biological, biochemical, pathological, and pharmacological impacts. Furthermore, omega-6 plays key roles in the cardiopulmonary system, including promoting airway relaxation and inhibiting atherosclerosis and hypertension. However, findings from investigations of the effects of omega-6 fatty acids on molecular and cellular activity and discussions on their influence on biomarkers are still unclear. Therefore, the present study aimed to evaluate omega-6 fatty acids, the arachidonic acid (AA), and linoleic acid (LA) effects on C2C12 proliferation, myogenesis morphology, and relative myogenic biomarker expression through the Wnt pathway. C2C12 cells were cultured with and without 25, 50, 100, and 150 µM of LA and AA and then subjected to CCK8, Giemsa staining, RT qPCR, Western blotting, and RNA Sequencing. The CCK8 Assay results showed that 25, 50, 100, and 150 µM LA significantly decreased the viability after 72 h for 25, 50, 100, and 150 µM concentrations. Also, AA supplementation decreased cell viability after 24 h for 150 µM, 48 h for 150 µM, and 72 h for 50, 100, and 150 µM concentrations. Moreover, the LA and AA inhibitory effects noticed through Gimesa staining were morphological changes during myoblast differentiation. Both LA and AA showed inhibiting IGF1, Cola1, Col6a2, Col6a1, Itga10, Itga11, SFRP2, DAAM2, and NKD2 effects; however, the depressing effect was higher for AA compared to LA. The previous results were confirmed through Western blotting, which showed that 50 µM LA and AA significantly reduced DAAM2 and SFRP2 protein levels compared to the control. Regarding RNA sequencing results, LA and AA increased the number of differentially expressed (DE) Mt-rRNA and snoRNA; however, the numbers of lncRNA detected decreased compared to the control. Our findings demonstrate that high and moderate LA and AA concentrations reduce primary myoblast proliferation and differentiation. Also, they highlight novel biomarkers and regulatory factors to improve our understanding of how the nutrition of fatty acids can control and modulate the myogenesis and differentiation process through different biomarker families.