Expression of genes involved in lipid metabolism in the muscle of beef cattle fed soybean or rumen-protected fat, with or without monensin supplementation1

Abstract

Degree of unsaturation of fatty acids, which is influenced by lipid source and level of metabolism in the rumen, is a major determinant in how dietary lipids affect genes that regulate beef marbling. A total of 28 Red Norte bulls with an initial live weight of 361±32 kg (P>0.05) were used in a completely randomized experimental design to analyze the expression of genes that are involved in lipid metabolism in the longissimus dorsi (LD) when diets contained soybean grain or rumen-protected fat, with or without monensin. Treatments were arranged as a 2×2 factorial, with 4 treatments and 7 replicates per treatment. Half of the animals that received soybean or rumen-protected fat were supplemented with 230 mg head(-1) d(-1) of monensin. Gene expression was analyzed by reverse-transcription quantitative PCR (RT-qPCR). Expression of sterol regulatory element-binding protein-1c (SREBP-1c) in the LD muscle was not affected by lipid source or monensin (P>0.05). There was an interaction effect (P<0.05) between lipid source and monensin for peroxisome proliferator-activated receptor α (PPAR-α) and stearoyl-CoA desaturase (SCD) expression, where greater gene expression was found in animals fed soybean plus monensin and the lower gene expression was found in animals fed rumen-protected fat plus monensin. Expression of lipoprotein lipase (LPL) and fatty acid-binding protein 4 (FABP4) were greater (P<0.05) in the LD muscle of animals fed soybean. Monensin had no effect on LPL and FABP4 expression when soybean without monensin was fed, but when rumen-protected fat was fed, monensin increased LPL expression and decreased FABP4 expression (P<0.05). Linoleic and arachidonic acids had negative correlations (P<0.05) with the expression of PPAR-α, SCD, FABP4, and LPL genes. PPAR-α gene expression was not correlated with SREBP-1c but was positively correlated with SCD, FABP4, LPL, and glutathione peroxidase (GPX1) gene expression (P<0.001). Lipid sources and monensin interact and alter the expression of PPAR-α, SCD, acetyl CoA carboxylase α (ACACA), LPL, FABP4, and GPX1. These changes in gene expression were most associated with arachidonic and α-linolenic acids and the ability of lipid sources and monensin to increase these fatty acids in tissues.

Review: Nutrigenomics of marbling and fatty acid profile in ruminant meat

“…Furthermore, Herdmann et al (2010) reported that animals fed greater n-3 PUFA content on the diet have less SCD1 expression and thus, less CLA c9,t11-C18:2 and oleic acid on muscle. Ladeira et al (2014) also demonstrated an increase of CLA concentration in the muscle of animals fed soybean compared with those fed rumen-protected fat, and this result may be due to the greater gene expression of SCD1 in the muscle (Oliveira et al, 2014).…”

“…Chorner et al (2016) also reported that α-linolenic acid supplementation may result in increased intramuscular lipid content and whole body fat due to the greater rate of lipid transport (FATP and FAT/CD36). In a study of Oliveira et al (2014), the greater C18 fatty acid content in a soybean diet was responsible for greater expression of LPL and FABP4. Therefore, fatty acid profile of the diet may change the expression of membrane transporters, increasing fatty acid uptake.…”

“…However, Teixeira et al (2017) reported that bulls fed a diet with whole shelled corn and no forage did not increase intramuscular fat because this diet reduced rumen pH and increased t10,c12-C18:2, which reduced SREBF1 expression ( Figure 6). In this sense, SREBP-1c is an important transcription factor regulating lipogenesis, having positive correlation with expression of ACACA (Oliveira et al, 2014) and SCD1 (Waters et al, 2009).…”

Fat Deposition, Fatty Acid Composition, and Its Relationship with Meat Quality and Human Health

“…Thus, there is a wide interest in manipulating the chemical composition of meat, through the regulation of its biosynthesis. For better understanding of the effects of nutrition on lipid metabolism and consequently on the quality of meat, recent research has made association between gene expression and nutrition area known as nutrigenomics [20][21][22][23].…”

Nutrigenomics in livestock—recent advances

“…The authors speculated that the lack of effect of the whole shelled corn diet on marbling was caused by the lower level of SREBF1, since this diet reduced the pH in the rumen and increased the contents of linoleic acid (c9, c12-C18:2). The study of Oliveira et al (2014), where cattle received soybean supplementation, found that the expression of the genes involved in lipid metabolism-such as PPARA, SCD, ACACA, FABP4, lipoprotein lipase (LPL), and glutathione peroxidase (GPX1)-was altered in muscle tissue. On the other hand, alpha-amylase enzyme is often added to beef cattle diets to improve animal performance through improving starch fermentation.…”