title: Dietary supplementation of high levels of saturated and monounsaturated fatty acids to ewes during late gestation reduces thermogenesis in newborn lambs by depressing fatty acid oxidation in perirenal brown adipose tissue.
abstract: We hypothesized that dietary supplementation of (n-6) plus (n-3) PUFA during late gestation would increase uncoupling protein-1 (UCP1) gene expression and thereby increase thermogenic capacity of newborn lambs. Thirty twin-bearing ewes were fed rumen-protected fat (2, 4, or 8%) high in saturated and monounsaturated fatty acids (SMFA) or high in (n-6) and (n-3) PUFA. Lambs (n = 7-10 per ewe treatment group) were placed in a cold chamber at 0 degrees C for 2 h. Rectal temperature was higher at birth and increased more with cold exposure in lambs from ewes fed 2 or 4% supplemental fat than in lambs from ewes fed 8% SMFA (fat type x fat level interaction, P = 0.001). Cytochrome c oxidase activity was greatest in brown adipose tissue (BAT) lambs from ewes fed 2% SMFA or 4% PUFA (fat type x fat level interaction, P = 0.01). BAT of lambs from ewes fed 2 or 4% PUFA had nearly 7-fold more (P = 0.05) UCP1 mRNA than BAT of lambs from ewes fed 8% PUFA. UCP1 expression decreased by over 80% by 24 h of age. Supplementation of 8% fat tended to depress palmitate esterification into lipids (P = 0.07) and decreased palmitate oxidation (P = 0.003) in lamb BAT in vitro, especially in those lambs from ewes fed 8% SMFA. Thus, supplementing the diets of ewes with 8% SMFA depressed cold tolerance in newborn lambs, which was reflected in their decreased ability to oxidize fatty acids in vitro.
authors.affiliation: Department of Animal Science, Texas A&M University, College Station, 2471 TAMU, TX 77843, USA.
authors.forename: Ching Yi
authors.initials: CY
authors.lastname: Chen
authors.forename: Gordon E
authors.initials: GE
authors.lastname: Carstens
authors.forename: Corey D
authors.initials: CD
authors.lastname: Gilbert
authors.forename: Casey M
authors.initials: CM
authors.lastname: Theis
authors.forename: Shawn L
authors.initials: SL
authors.lastname: Archibeque
authors.forename: Michael W
authors.initials: MW
authors.lastname: Kurz
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Slay
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Smith
mesh_terms: D002001:Adipose Tissue, Brown / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D001833:Body Temperature Regulation / Q000187:drug effects*; D019587:Dietary Supplements; D005227:Fatty Acids / Q000008:administration & dosage / Q000494:pharmacology*; D005229:Fatty Acids, Monounsaturated / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006153:Guanosine Diphosphate / Q000378:metabolism; D007473:Ion Channels / Q000187:drug effects / Q000235:genetics; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000187:drug effects / Q000235:genetics; D011247:Pregnancy; D012756:Sheep; D000071256:Uncoupling Protein 1
chemical_list: D005227:Fatty Acids; D005229:Fatty Acids, Monounsaturated; D007473:Ion Channels; D024101:Mitochondrial Proteins; D000071256:Uncoupling Protein 1; D006153:Guanosine Diphosphate