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J Anim Sci. 2014 Dec;92(12):5426-36. doi: 10.2527/jas.2014-7855. Epub 2014 Nov 17.

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

Author information

1
Department of Animal Science, Universidade Federal de Lavras, Lavras, Minas Gerais, Brazil, 37.200-000.
2
Department of Biology, Universidade Federal de Lavras, Lavras, Minas Gerais, Brazil, 37.200-000.
3
Department of Animal Science, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil, 36.570-000.
4
Department of Agricultural Sciences, Universidade Federal de Tocantins, Gurupi, Tocantins, Brazil, 77.402-970.
5
Department of Chemistry, Universidade Federal de Lavras, Lavras, Minas Gerais, Brazil, 37.200-000.
6
Department of Animal Science, Purdue University, West Lafayette, IN 47906.
7
Department of Animal Science, Universidade Federal de Lavras, Lavras, Minas Gerais, Brazil, 37.200-000 mladeira@dzo.ufla.br.

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.

KEYWORDS:

PPAR-α; SREBP-1c; ionophores; mRNA; oilseeds

PMID:
25403202
DOI:
10.2527/jas.2014-7855
[Indexed for MEDLINE]

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