The designation omega-9 means that the ninth carbon from the methyl end of the fatty acid is a part of a double bond. Elongation and desaturation of two essential fatty acids, linoleate and linolenate, result in a variety of other polyunsaturated fatty acids PUFA. An important function of these PUFA is to serve as a precursor of eicosanoids.
In addition, PUFA are necessary constituents of a variety of structural lipids. Triacylglycerols TG are transported between tissues in lipoproteins and are stored as an energy reserve in adipose tissue. Most triacylglicerols synthesis occurs in adipocytes, liver, intestinal mucosa, and lactating mammary glands.
Adipose tissue can use circulating FA from chylomicrons and lipoproteins for TG synthesis. Thus, the absorbed FA and hepatic fats can influence the fatty acid composition of depot fats. Extracellular lipoprotein lipase, formed by fat cells, induces the release of FA from lipoproteins. Adipose tissue cannot, however, effectively utilize free glycerol released, and it must be returned to the liver for gluconeogenesis or must be utilized in other tissue.
As fat cells have low glycerokinase activity, they are dependent on the glycolytic pathways. This compound is a reduction product of dihydroxyacetone product in glycolysis. Emergency situations that activate the sympathoadrenal system also lead to lipolysis.
- Lipid metabolism in non-ruminant animals!
- Lipid Metabolism in Ruminant Animals;
- Lipid metabolism in the rumen.;
The key to the switch to lipolysis, or to the release of free fatty acids FFA from adipose tissue is hormone-sensitive lipase, a rate-limiting enzyme initiates the hydrolysis of TG upon activation by cyclic AMP cAMP. The catecholamines epinephrine, and norepinephrine increase the formation of cAMP and activate lipolysis and mobilisation of FFA from adipose tissue. In contrast, insulin counteracts cAMP formation and inhibits lipolysis. In the absence of insulin, marked mobilization of FFA occurs. After hydrolysis of TG, fatty acids released from adipose tissue form a complex with plasma albumin and carried via the blood to the liver and other organs.
Events, such as those leading to energy deficiency, anxietry or discomfort, can result in rapid mobilization of FFA into the bloodstream. Long-chain fatty acyl elongases ELOVL are endoplasmatic reticulum membrane-bound proteins responsible for the first regulatory step in the fatty acid elongation pathway condensation of activated fatty acids with malonyl-CoA , elongating fatty acid that are biosynthesized de novo or supplied by the diet [ 43 ]. Cherfaoui et al. Moreover, these authors also suggested that the low levels of DHA in the muscle tissues could be a consequence of its preferential peroxidation or of its preferential uptake by other tissues.
In summary, the present study suggests that liver has, among the bovine lipogenic tissues, a specific role in lipid metabolism. The small differences observed in gene expression levels could have additive effects, which may explain the differences found in the hepatic fatty acid profile, particularly in the LC-PUFA.
In summary, the results herein discussed are in line with the previous reports from this experiment, thus stressing the importance of devising custom-made feeding strategies which take into account the genetic background.
One Alentejana bull from the high silage fed group was later removed from the trial due to a limp. The detailed proximate and fatty acid composition of the experimental diets has been published in a previous paper [ 47 ]. Briefly, crude fat and starch were higher in the low silage The low silage diet had lower palmitic Animals were housed in eight adjacent pens, two pens per breed and diet.
Slaughters were performed at the INIAV experimental abattoir by exsanguination, after stunning with a cartridge-fired captive bolt stunner. VLDL-cholesterol and total lipids were calculated as described by Friedewald et al. Total lipids were extracted by the method of Folch et al. Fatty acids were then converted to methyl esters as described by Raes et al.
The quantification of FAME used nonadecanoic acid as the internal standard, added to lipids prior to saponification and methylation. Fatty acid composition was calculated assuming a direct relationship between peak area and fatty acid methyl ester weight. When possible, primer sets were designed to fall across exon—exon junctions.
Only those primers that did not present primer-dimer and a single band at the expected size in the gel were used for RT-qPCR. The accuracy of a primer pairs was also evaluated by the presence of a unique peak during the dissociation step at the end of RT-qPCR. A set of six candidate housekeeping genes was evaluated using geNorm and NormFinder, as described by Vandesompele et al. The target gene expression levels were calculated using the geometric mean of ribosomal protein S9 RSP9 and succinate dehydrogenase complex subunit A SDHA as a normaliser. The efficiency of RT-qPCR amplification for each gene was calculated using the standard curve method with five dilutions at each data point along the curve.
Dissociation curves were generated at the end of amplification to verify the presence of a single product. Reaction mixes of 6.
PCR analysis of cDNA samples was performed in duplicate, using no-transcription and no-template samples as controls. The specificity of the PCR amplification was confirmed by melt curve analysis and agarose gel electrophoresis of PCR products. The efficiency curves were used to assess accuracy, linearity and efficiency of the PCR reaction.
Statistical analyses were carried out with the Statistical Analysis Systems software package, version 9.
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The variances were tested for heteroscedasticity and, for most variables, variance was found to be heterogeneous. Therefore, subsequent data analysis was performed in order to account for heterogeneous variance. The final dataset was analysed using the MIXED procedure of SAS with a model that included breed, diet and their respective interaction as independent variables.
A principal component analysis PCA was performed using the fatty acid composition of liver, intramuscular fat, mesenteric and subcutaneous adipose tissue. The PRINCOMP procedure was applied to a data set of samples and 30 variables to reduce the dimensionality of the data set and to describe the variability of data in two dimensions. P Nutr Soc. Bell AW: Lipid metabolism in the liver and selected tissues and in the whole body of ruminant animals. Prog Lipid Res. J Nutr. Handbook of Muscle Foods Analysis. J Anim Sci.follow link
J Agric Food Chem. Indicators of Milk and Beef Quality. Eur J Lipid Sci Technol. Annu Rev Nutr. Int J Biol Sci.
J Hered. Livest Prod Sci. Meat Sci. Reprod Nutr Dev. Hocquette JF, Bauchart D: Intestinal absorption, blood transport and hepatic and muscle metabolism of fatty acids in preruminant and ruminant animals. Katoh N: Relevance of apolipoproteins in the development of fatty liver and fatty liver-related peripartum diseases in dairy cows.
J Vet Med Sci. J Dairy Sci. Biochem J. Cell Physiol Biochem. Citations PDF KB. Note: In lieu of an abstract, this is the article's first page. Cited By. This article is cited by 27 publications. The Journal of Nutrition , 1 , DOI: Michael L.
Carbohydrate and Lipid Metabolism in Farm Animals | The Journal of Nutrition | Oxford Academic
Lipids and Ketones. Kristensen, G. Huntington, D.
Chapter 17 Splanchnic carbohydrate and energy metabolism in growing ruminants. Patton, C.
Sorenson, A. Journal of Dairy Science , 87 7 , S 04 Kurt A. Black, Joyce L. Beskitt, Lavorgie Finch, Marilyn J.