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Intramuscular fat depot is of major interest for consumers, producers, and the industry. To predict intramuscular (i.m.) lipid deposition in cattle of continental breeds, different models were constructed for different muscles in bulls, steers, and cows. Two independent databases (DB1 and DB2) were developed with homogeneous individual data collected in the same slaughterhouse and total lipids, phospholipids, and triglycerides were analyzed in the same lab with the same procedures. Database DB1 was used with the meta-analysis methodology to fit the predictive models of i.m. lipids, phospholipids, and triglycerides with carcass fatness. Database DB2 was used to evaluate the accuracy of the models predicted. Total lipid and triglyceride contents varied linearly with carcass fatness in bulls, steers, and cows, but phospholipids were more independent of carcass fatness, regardless of the type of cattle studied. In bulls, LM had a lower minimal value (intercept in the model) and greater slope than semitendinosus (ST) and triceps brachii (TB) muscles. In cows, LM showed a greater intercept than ST and TB muscles but a similar slope. In steers, lipid content increased similarly in LM, rectus abdominis (RA) muscle, and ST muscle with carcass fatness. Bulls had a lower intercept than steers but showed a similar trend with carcass fatness. According to the external evaluation using DB2, the models obtained to predict total lipids in LM were more accurate than those obtained in the ST muscle in bulls and cows and in the RA muscle in steers. The models proposed for cows should be used only in the range of carcass fatness used to fit the equations, and further data are needed to fully validate them. [ABSTRACT FROM AUTHOR]

To evaluate the effect of feeding thermally oxidized vegetable oils and animal fats on growth performance, liver gene expression, and liver and serum fatty acid and cholesterol concentration in young pigs, 102 barrows (6.67 ± 0.03 kg BW) were divided into 3 groups and randomly assigned to dietary treatments in a 4 x 3 factorial arrangement. The main factors were lipid source (n = 4; corn oil [CN], canola oil [CA], poultry fat [PF], and tallow [TL]) and lipid peroxidation level (n = 3; original lipids [OL], slow oxidation [SO] through heating at 95°C for 72 h, or rapid oxidation [RO] through heating at 185°C for 7 h). Pigs were provided ad libitum access to diets in group pens for 28 d followed by controlled feed intake in metabolism crates for 10 d. On d 39, all pigs were euthanized for liver samples to determine liver weight, lipid profile, and gene expression patterns. Lipid oxidation analysis indicated that compared with the OL, SO and RO of lipids had a markedly increased concentrations of primary and secondary peroxidation products, and the increased lipid peroxidation products in CN and CA were greater than those in PF and TL. After a 28-d ad libitum feeding period, pigs fed RO lipids tended to have reduced ADFI (P = 0.09) and ADG (P < 0.05) compared with pigs fed OL, and pigs fed CA had reduced G:F (P < 0.05) compared with pigs fed all other lipids. Pigs fed RO lipids tended to have increased relative liver weight (P = 0.09) compared with pigs fed OL. Liver triglyceride concentration (LTG) in pigs fed OL was greater (P < 0.05) than in pigs fed SO lipids and tended to be greater (P < 0.07) than in pigs fed SO. The reduced LTG were consistent with increased (P < 0.05) mRNA expression of PPARa factor target genes (acyl-CoA oxidase, carnitine palmitoyltransferase 1, and mitochondrial 3-hydroxy-3-methylglutary-CoA synthase) in pigs fed SO and RO lipids compared with pigs fed OL. Pigs fed CN or CA tended to have increased LTG {P = 0.09) compared with pigs fed TL. Liver cholesterol concentration in pigs fed CN was less (P < 0.05) than in pigs fed PF and tended to be less (P = 0.06) than in pigs fed TL, whereas pigs fed CA had a reduced (P < 0.05) liver cholesterol compared with pigs fed PF or TL. In conclusion, feeding thermally oxidized lipids negatively affected growth performance and LTG of young pigs, which was associated with an upregulation of fatty acid catabolism pathways. [ABSTRACT FROM AUTHOR]

The performance of a genome scan for serum lipid traits at 45 and 190 d in 5 half-sib families of Duroc pigs allowed us to detect several pig chromosomal regions with significant effects on these phenotypes. In the current work, we aimed to refine the position of 1 chromosome 4 (SSC4) genome-wide significant QTL for serum triglyceride concentration at 190 d. Genotyping of 4 additional microsatellites allowed reduction of the 90% confidence interval of this QTL to the genomic interval between markers SW2409 and SW839. Sequencing experiments were performed to characterize the variability of 2 lipid-related genes, the lipoprotein receptor-related protein 12 (LRP12) and tribbles homolog 1 (TRIB1) loci, that map to this region. In this way, 2 (c.771A > G and C.1101A > G) and 1 (C.* 156 157del) polymorphisms were identified at the LRP12 coding region and TRIB13' untranslated region, respectively. Association analyses between LRP12 and TRIB1 genotypes did not reveal any significant effect on serum lipid concentrations, suggesting that variation of these two loci does not explain the segregation of the SSC4 QTL. However, highly significant associations were observed for gluteus medius saturated fatty acid content (LRP12 C.1101A > G, P = 0.0006; TRIBl c.*156 157del, P = 0.0003). In the light of these and other findings, the potential involvement of LRP12 and TRIBl in muscle lipid metabolism deserves to be further explored. [ABSTRACT FROM AUTHOR]

The storage and mobilization of lipid energy are central functions of adipocytes. Lipid energy is stored as triglyceride in lipid droplet structures that are now recognized as hona fide organelles and whose functions are greatly influenced by members of the perilipin family of lipid droplet scaffolds. Recent work indicates that the signaling events underlying fatty acid mobilization involve protein trafficking to a specialized subset of lipid droplets. Furthermore, the core lipolytic machinery is composed of evolutionarily conserved proteins whose functions are conserved in avian and mammalian production species. Lipolysis affects many aspects of animal nutrition and physiology, which can have an important influence on growth efficiency, lactation, and meat quality. This review focuses on recent research that addresses the organization and trafficking of key players in hormone-stimulated lipolysis, and the central role of perilipin 1A in adipocyte lipolysis. The review emphasizes recent work frpm the laboratories of the authors that utilizes imaging techniques to explore the organization and interactions among lipolytic effectors in live cells during lipolytic activation. A mechanistic understanding of lipolysis may lead to new strategies for promoting human and animal health. [ABSTRACT FROM AUTHOR]

Previous research has implicated linseed oil in altering lipid metabolism of dairy cattle when infused intravenously as lipid emulsion. The objective was to determine the effects of abomasal linseed oil (LO) infusion on liver triglyceride (TG) accumulation and subcutaneous adipose tissue lipolysis during fatty liver induction. Eight nonpregnant, nonlactating Holstein cows were randomly assigned to treatments in a replicated 4 x 4 Latin square design. Treatments included abomasal infusion of water (W), tallow (T), LO, or half tallow plus half LO (LOT) at a rate of 0.56 g/kg BW per day for 4 d. Daily treatments were administered directly into the abomasum, divided into 6 doses and administered every 4 h. Infusion of treatments was concurrent with a 4 d fast. Cows were fed ad libitum for 24 d between periods of fasting and lipid infusion. T contained 43% C18:1, 24% C16:0 and 14% C18:0. LO contained 51% C18:3, and 17% C18:2. For most parameters, contrasts were: W vs. LO + LOT + T (effect of lipid), LO vs. T (linear effect of LO), and LOT vs. LO + T (nonlinear dose effect of LO). For measurement of blood fatty acid composition, differences among treatment means were determined using the PDIFF procedure of PROC MIXED. Infusion of linseed oil (LO or LOT) increased α-linolenic acid (g/100 g fatty acid) in serum (P < 0.05) but not in the nonesterified fatty acid (NEFA) fraction of plasma. Treatments had no effect on plasma NEFA concentrations. Infusion of LO increased total serum fatty acid concentration (nonlinear dose effect; P = 0.06). Abomasal infusion of lipid significantly increased isoproterenol stimulated lipolysis by subcutaneous adipose tissue explants in vitro. Liver TG content increased 4.8, 4.9, 2.3 and 2.3 μg TG/ μg of DNA during the fast for W, LO, LOT and T, respectively; infusion of lipid decreased liver TG accumulation (P = 0.06) when compared to W, but this was due to T (LO vs. T; P = 0.03). Abomasal LO infusion failed to reduce liver TG accumulation, plasma NEFA concentration or alter subcutaneous adipose tissue lipolysis. [ABSTRACT FROM AUTHOR]