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Lipid metabolic flexibility

Body fatness and fat distribution in the body are important concerns in animal production because these traits contribute to the efficiency of meat production and robustness of animals. Metabolic flexibility, which is involved in the balance between storage and use of lipids within the body, can be considered to improve animal adaptation to different regimen. The competition between food and feed challenges the use of alternative resources such as fibrous feedstuffs in diets formulated for non-ruminants; adding fat to a high-fiber diet appears as a relevant strategy to improve its dietary energy value. However, this formulation changes nutrients and energy source in diets as compared to the standard cereal-based high-starch diet. A better understanding of the metabolic ways and upstream regulators by which growing animals may adapt to high-fat high-fiber diets is essential to refine nutritional recommendations and next selection schemes and to suggest biomarkers of animal phenotypes that can be used in precision farming.

Integration of various data in two non-ruminants species

Dozens of physiological and phenotypic data and several thousands of molecular data in different tissues were acquired in growing animals fed iso-caloric and iso-proteic diets but which were different in nutrient composition and energy source (fibers and lipids vs. starch).

In growing pigs

Growth performance and body adiposity were reduced in pigs fed a diet rich in fat and fiber (mainly insoluble) when compared with pigs fed a standard high-starch diet. The main biological pathways involved in these changes were related to glucose and lipid metabolisms, protein catabolism process, apoptosis, modulation of oxidative stress and immune or inflammatory defense mechanisms. Key upstream regulators in these pathways were proposed, such as MLXIPL, SREBF1, PPARD and RXRA genes; these transcription factors must be considered in next programs aiming to manage body composition.

In chickens

Unlike pigs, feeding chicken a high-fat high-fiber diet did not affect growth performance and body composition. Especially,  irrespective of dietary differences in fat content and energy source, chickens can synthesize and deposit a same amount of fat in different tissues. The hepatic metabolism played a key role in this adaptation, with a decrease in lipogenesis and glycogen synthesis but an increase in oxidative pathways with the high-fat high-fiber diet. We also observed that a massive duplication of free fatty acids receptors (FFAR2), that are activated by short-chain free fatty acids produced by the intestinal digestion of fibers, have occurred in the chicken genome along evolution, which may contribute to specificities in avian adaptation to diets.

In both species

In blood, various genes, including CPT1A, a key actor in lipid oxidation, were differentially-expressed between diets. This opens new perspectives in identifying circulating biomarkers of animal phenotypes that can be used in precision farming.

Nutritional recommendations in poultry and pigs

This study emphasizes the benefits of nutrigenomics to identify key actors in cellular flexibility and tissue adaptation. The variety in the metabolic responses to diets shows that it is important to consider different traits related to productive functions but also to non-productive functions (immunity, inflammation or oxidative stress) for further nutritional recommendations in pigs and poultry. The comparison between species generates new questions about adaptive strategies and animal robustness.

This work was carried out by Inra Units Pegase, URA and PRC and in collaboration with Irisa and Agrocampus-Ouest; it was granted by ANR (FatInteger project SVSE7-04-11). This was also part of the PhD of Maëva Jégou, funded by Inra (Phase division) and Région Bretagne.

References

• Gondret F, Vincent A, Houée-Bigot M, Siegel A, Lagarrigue S, Louveau I, Causeur D. Molecular alterations induced by a high-fat high-fiber diet in porcine adipose tissues: variations according to the anatomical fat location. BMC Genomics. 2016; 17:120. [DOI]
• Gondret F, Louveau I, Mourot J, Duclos MJ, Lagarrigue S, Gilbert H, van Milgen J. Dietary energy sources affect the partition of body lipids and the hierarchy of energy metabolic pathways in growing pigs differing in feed efficiency. J. Anim. Sci. 2014; 92: 4865-77. [DOI]
• Baéza E, Gondret F, Chartrin P, Le Bihan-Duval E, Berri C, Gabriel I, Narcy A, Lessire M, Métayer-Coustard S, Collin A, Jégou M, Lagarrigue S, Duclos MJ. The ability of genetically lean or fat slow-growing chickens to synthesize and store lipids is not altered by the dietary energy source. Animal. 2015; 9: 1643-52. [DOI]
• Jégou M, Gondret F, Lalande-Martin J, Tea I, Baéza E, Louveau I. NMR-based metabolomics highlights differences in plasma metabolites in pigs exhibiting diet-induced differences in adiposity. Eur. J. Nutr. 2015 May 22. [DOI]
• Meslin C, Desert C, Callebaut I, Djari A, Klopp C, Pitel F, Leroux S, Martin P, Froment P, Guilbert E, Gondret F, Lagarrigue S, Monget P. Expanding duplication of free fatty acid receptor-2 (GPR43) genes in the chicken genome. Genome Biol. Evol. 2015; 7: 1332-48. [DOI]
• Baéza E, Jégou M, Gondret F, Lalande-Martin J, Tea I, Le Bihan-Duval E, Berri C, Collin A, Métayer-Coustard S, Louveau I, Lagarrigue S, Duclos MJ. Pertinent plasma indicators of the ability of chickens to synthesize and store lipids. J. Anim. Sci. 2015; 93: 107-116. [DOI]