title: Dietary energy sources affect the partition of body lipids and the hierarchy of energy metabolic pathways in growing pigs differing in feed efficiency.
abstract: The use and partition of feed energy are key elements in productive efficiency of pigs. This study aimed to determine whether dietary energy sources affect the partition of body lipids and tissue biochemical pathways of energy use between pigs differing in feed efficiency. Forty-eight barrows (pure Large White) from two divergent lines selected for residual feed intake (RFI), a measure of feed efficiency, were compared. From 74 d to 132 ± 0.5 d of age, pigs (n = 12 by line and by diet) were offered diets with equal protein and ME contents. A low fat, low fiber diet (LF) based on cereals and a high fat, high fiber diet (HF) where vegetal oils and wheat straw were used to partially substitute cereals, were compared. Irrespective of diet, gain to feed was 10% better (P < 0.001), and carcass yield was greater (+2.3%; P < 0.001) in the low RFI compared with the high RFI line; the most-efficient line was also leaner (+3.2% for loin proportion in the carcass, P < 0.001). In both lines, ADFI and ADG were lower when pigs were fed the HF diet (-12.3% and -15%, respectively, relatively to LF diet; P < 0.001). Feeding the HF diet reduced the perirenal fat weight and backfat proportion in the carcass to the same extent in both lines (-27% on average; P < 0.05). Lipid contents in backfat and LM also declined (-5% and -19%, respectively; P < 0.05) in pigs offered the HF diet. The proportion of saturated fatty acids (FA) was lower, but the percentage of PUFA, especially the EFA C18:2 and C18:3, was greater (P < 0.001) in backfat of HF-fed pigs. In both lines, these changes were associated with a marked decrease (P < 0.001) in the activities of two lipogenic enzymes, the fatty acid synthase (FASN) and the malic enzyme, in backfat. For the high RFI line, the hepatic lipid content was greater (P < 0.05) in pigs fed the HF diet than in pigs fed the LF diet, despite a reduced FASN activity (-32%; P < 0.001). In both lines, the HF diet also led to lower glycogen content (-70%) and lower glucokinase activity (-15%; P < 0.05) in the liver. These results show that dietary energy sources modified the partition of energy between liver, adipose tissue, and muscle in a way that was partly dependent of the genetics for feed efficiency, and changed the activity levels of biochemical pathways involved in lipid and glucose storage in tissues.
authors.affiliation: INRA, UMR1348 Pegase, F-35590 Saint-Gilles, France Agrocampus-Ouest, UMR1348 Pegase, F-35000 Rennes, France florence.gondret@rennes.inra.fr.
authors.forename: F
authors.initials: F
authors.lastname: Gondret
authors.affiliation: INRA, UMR1348 Pegase, F-35590 Saint-Gilles, France Agrocampus-Ouest, UMR1348 Pegase, F-35000 Rennes, France.
authors.forename: I
authors.initials: I
authors.lastname: Louveau
authors.affiliation: INRA, UMR1348 Pegase, F-35590 Saint-Gilles, France Agrocampus-Ouest, UMR1348 Pegase, F-35000 Rennes, France.
authors.forename: J
authors.initials: J
authors.lastname: Mourot
authors.affiliation: INRA, UR83 Recherches Avicoles, F-37380 Nouzilly, France.
authors.forename: M J
authors.initials: MJ
authors.lastname: Duclos
authors.affiliation: INRA, UMR1348 Pegase, F-35590 Saint-Gilles, France Agrocampus-Ouest, UMR1348 Pegase, F-35000 Rennes, France.
authors.forename: S
authors.initials: S
authors.lastname: Lagarrigue
authors.affiliation: INRA, UMR1388 GenPhySE, F-31326 Castanet-Tolosan cedex, France.
authors.forename: H
authors.initials: H
authors.lastname: Gilbert
authors.affiliation: INRA, UMR1348 Pegase, F-35590 Saint-Gilles, France Agrocampus-Ouest, UMR1348 Pegase, F-35000 Rennes, France.
authors.forename: J
authors.initials: J
authors.lastname: van Milgen
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D001823:Body Composition / Q000187:drug effects / Q000502:physiology*; D001835:Body Weight / Q000502:physiology; D004032:Diet / Q000662:veterinary*; D004041:Dietary Fats / Q000494:pharmacology; D004043:Dietary Fiber / Q000494:pharmacology; D002149:Energy Intake / Q000502:physiology*; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology*; D064429:Fatty Acid Synthases / Q000502:physiology; D050356:Lipid Metabolism / Q000187:drug effects / Q000502:physiology*; D008099:Liver / Q000378:metabolism; D008297:Male; D053858:Metabolic Networks and Pathways / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism; D013552:Swine / Q000235:genetics / Q000254:growth & development* / Q000502:physiology
chemical_list: D004041:Dietary Fats; D004043:Dietary Fiber; D064429:Fatty Acid Synthases
keywords: feed efficiency; fiber; glucokinase; lipid partition; lipogenesis