Intramuscular Lipid Research Articles

Fatty acid transport proteins and insulin resistance

Disturbed fatty acid metabolism and homeostasis is associated with insulin resistance. The aim of this review, therefore, is to summarize recent developments relating to the relevance and importance of the fatty acid transport proteins (FATPs) in the aetiology of insulin resistance. In particular, the potential differences between the six members of the FATP family will be considered. FATP1 knockout mice failed to develop insulin resistance associated with lipid infusion or a high-fat diet, as wild-type mice did. FATP1-mediated fatty acid uptake may cause intramuscular lipid accumulation leading to insulin resistance in muscle if the fatty acids are not oxidized. While mouse models demonstrated an absolute requirement for FATP4 for survival, they provided no direct evidence for a role of FATP4 in insulin resistance. However, expression of FATP4 in human adipose tissue was increased in obesity (independent of genetic factors). While other members of the FATP family have important roles in fatty acid metabolism, they have not been clearly linked to insulin resistance. FATP-mediated fatty acid uptake may be driven by intrinsic acyl-CoA synthase activity. Any role in the development of insulin resistance is likely to be different for each member of the FATP family. So far, both FATP1 and FATP4 have been associated with parameters related to insulin resistance. Whether increased FATP-mediated fatty acid uptake is beneficial or detrimental may be dependent on the tissue in question and on the subsequent fate of the fatty acids. These issues remain to be resolved.

Effect of dietary conjugated linoleic acid (CLA) supplementation on CLA isomers content and fatty acid composition of dry-cured Parma ham

To evaluate the effects of dietary conjugated linoleic acid (CLA) supplementation on cis-9, trans-11 and trans-10, cis-12 isomer content and on the fatty acid composition of subcutaneous adipose tissue and intramuscular lipids of biceps femoris, the lipids of 24 dry cured Parma hams, obtained from Large White pigs fed isoenergetic diets supplemented with either 0 (CON) or 0.25% (T1) CLA from 97 to 172 kg live weight, were analysed by Ag +-HPLC and capillary GLC. The dietary treatment had no influence on lipid content of BF and subcutaneous adipose tissue but increased ( P < 0.01) the content of both isomers, more markedly in the latter tissue. CLA supplementation increased ( P < 0.01) myristic, palmitic, palmitoleic and total saturated fatty acids, and decreased oleic and eicosenoic acids in both tissues. In adipose tissue, an increase ( P < 0.05) in stearic acid content was observed. Supplementing the finishing diet of heavy pigs with CLA has thus shown to be an effective tool for increasing the CLA content in cured ham and, also, the saturated:unsaturated ratio of the lipids, a positive effect from a technological point of view. From a human nutritional standpoint, the changes occurring in fatty acid composition negatively affect the atherogenic and thrombogenic indexes, but probably these changes are of no particular concern, as they would only partly offset the progressive increase in the degree of unsaturation of heavy pig lipids that has occurred in recent years, as a consequence of reduced adipose depots in carcasses.

Effect of dietary vitamin E and partial replacement of poly‐ with monounsaturated fat on fatty acid patterns of backfat and intramuscular fat in heavy pigs (Iberian × Duroc)

The effects of partial replacement of dietary polyunsaturated fatty acid (PUFA) with monounsaturated fatty acid (MUFA) on fatty acid profiles of subcutaneous and intramuscular fat and rheological properties of fat were studied in heavy pigs. No effect of dietary fat was observed on total saturated fatty acids proportion in outer and inner backfat layers or intramuscular neutral and polar lipids. The partial substitution of dietary PUFA by MUFA produced a rise in MUFA of intramuscular polar lipids (p < 0.01) but neutral lipids were not affected. Moreover, it also decreased (p < 0.01) the n-6 proportion of outer and inner backfat layers and intramuscular polar lipids, but no effect was observed for the n-6 in the intramuscular neutral lipids. No significant effect of dietary fat treatment was observed on n-3 fatty acids in outer and inner backfat layers, but the partial substitution of PUFA by MUFA increased (p < 0.01) the n-3 proportion of intramuscular lipid fractions and the consequent decreased in the n-6/n-3 ratio in all lipid location. Significant effects of dietary vitamin E were observed on springiness, cohesiveness and adhesiveness of backfat inner layer. However, consistency was not affected by dietary fat. Further research is needed to establish the effects of different ranges of dietary oil combination in the feeding of heavy pigs.

Influence of conjugated linoleic acid (CLA) on intramuscular fatty acid composition in rabbit

RiassuntoEffetto dei coniugati dell’acido linoleico (CLA) sulla composizione acidica del grasso intramuscolare del coniglio. Sono stati utilizzati 42 conigli, del peso vivo (p.v.) medio di circa 1,8 kg, suddivisi in 3 gruppi ed alimentati fino alla macellazione (circa 3,1 kg p.v.) con mangimi che differivano per i livelli d’integrazione di CLA (0; 0,25 o 0,50%). Sul grasso intramuscolare del Longissimus dorsi sono stati determinati il contenuto degli isomeri CLA cis-9,trans-11 e trans-10, cis-12 ed il profilo acidico. Il trattamento alimentare ha determinato un incremento (P<0,01) del tenore di entrambi gli isomeri CLA nel grasso intramuscolare e ne ha modificato il profilo acidico causando un aumento (P<0,01) degli acidi grassi saturi, una riduzione (P<0,01) degli acidi grassi monoinsaturi e variazioni modeste nel tenore in polinsaturi. L’aggiunta di CLA alla dieta del coniglio risulta un mezzo efficace per aumentarne il contenuto nelle carni, anche se aumenta il rapporto saturi/insaturi e gli indici di aterogenicità e di trombogenicità.

Effect of exercise training on muscle glucose transporter 4 protein and intramuscular lipid content in elderly men with impaired glucose tolerance.

This study determined the effects of exercise training on adaptations of skeletal muscle including fibre composition, capillarity, intra-muscular triglyceride concentration (IMTG), as well as glucose transporter 4 protein (GLUT4) and metabolic enzyme activities. Percutaneous muscle biopsies from the vastus lateralis muscle were obtained from non-obese elderly Korean men (n = 10; age range 58-67 years) with impaired glucose tolerance. Subjects performed 12 weeks of endurance exercise training (60-70% of the heart rate reserve). The training program improved the total GLUT4 protein expression (P < 0.01), decreased the IMTG, increased the fatty acid oxidation capacity, and the number of capillaries around type 1 fibres (P < 0.05), whereas no significant alteration was observed around type II fibres. All data are presented as the means together with the standard deviation. The results suggest that endurance training evokes morphological and biochemical changes in the skeletal muscle of elderly men with impaired glucose tolerance that may be considered to limit the development of type 2 diabetes.

Blockade of the renin-angiotensin system decreases adipocyte size with improvement in insulin sensitivity.

Based on results of in vitro studies, it has been hypothesized that blockade of the renin-angiotensin system (RAS) promotes the recruitment and differentiation of pre-adipocytes and that increased formation of small insulin-sensitive adipocytes counteracts ectopic deposition of lipids, thereby improving insulin sensitivity. We investigated the effect of RAS blockade on insulin sensitivity, adipocyte size, and intramuscular lipid content in fructose-fed rats (FFR) as a model of insulin-resistant hypertension. Six-week-old male Sprague-Dawley rats were divided into two groups: those fed a standard chow (control) and those fed a fructose-rich chow for 6 weeks. FFR were treated with a vehicle or with 1 mg/kg per day of temocapril, an angiotensin-converting enzyme inhibitor, or 0.1 mg/kg per day of olmesartan, an angiotensin II type 1 receptor blocker, for the last 2 weeks. Insulin sensitivity (M value: mg/kg per min) was estimated by the euglycemic hyperinsulinemic glucose clamp method. Sizes of adipocytes derived from epididymal fat and triglyceride content in the soleus muscle were determined. FFR had lower M value, higher blood pressure, larger adipocyte size, higher ratio of epididymal fat pads over body weight (%fat pads), and higher intramuscular triglyceride than did the control rats. Both temocapril and olmesartan significantly improved the M value and decreased blood pressure and adipocyte size without change in %fat pads in FFR. Adipocyte size was negatively correlated with the M value. Treatment for 2 weeks decreased, but not significantly, intramuscular triglyceride. RAS blockade decreases adipocyte size without change in epididymal %fat pads accompanied by improvement in insulin sensitivity.

Efeitos do sexo e do tempo de maturação sobre a qualidade da carne ovina

A study to verify the effects of sex and aging time of selected carcass cuts on meat quality was conducted. Longissimus dorsi and Semimembranous muscles from five intact males, five castrated males and five female lambs with average slaughter weight of about 35kg were used. Meat pH, myofibrillar fragmentation index, cooking losses, shear force, intramuscular lipids, color and sensorial tenderness were measured after 1, 3, 7 and 14 days of aging at 2oC. Meat from castrated males and from female lambs showed lower shear force values than those from intact male lambs. Higher levels of fat and lower cooking losses were observed in meat from castrated animals related to those from intact lambs. Aging time did not significantly (p>0.05) affect shear force or sensory tenderness of meats. This observation suggests that lamb meat, mainly from castrated males, can enter the fresh meat market soon after holding carcasses for 24 hours at 2oC.

Restriction of Dietary Energy and Protein Induces Molecular Changes in Young Porcine Skeletal Muscles

Little is known about the molecular changes in response to dietary restriction (energy and/or protein) in young growing skeletal muscles. To profile such changes and to gain insights into the signaling molecules that could mediate the diet effects, a dedicated porcine skeletal muscle cDNA-microarray approach was used to characterize differential muscle gene expression between conventionally fed and diet-restricted (20% less protein and 7% less energy) growing pigs, reared from 9 to 21 wk of age. In both red and white muscles, diet restriction resulted in the accumulation of significantly more intramuscular fat, and in the increased expression of genes involved in substrate (protein, glycogen, and lipid) turnover, in translation and mitochondrial function, and in raising glycolytic and oxidative phosphorylation potentials. The unexpected increase in intramuscular lipids in diet-restricted growing pigs could have important health implications for restricted diets in childhood. Despite reduced circulating insulin, more genes, including several novel growth modulatory genes, had higher expression levels, indicating that the cellular response to dietary restriction is an active process. One such responsive gene, P311, was most highly expressed in striated muscles and had a differentiation-dependent increase of expression in murine C2C12 cells, suggesting a role in differentiation/postdifferentiation phenotype determination.

Study of the branched hydrocarbon fraction of intramuscular lipids from Iberian dry-cured ham

Branched hydrocarbons from the unsaponifiable lipid fraction of intramuscular fat from Iberian dry-cured hams were analyzed. Thirty-four hams were distributed into four groups according to the feed system of the pigs (extensive system “ Montanera” and intensive system “ Pienso”) and genotype (Iberian and Iberian × Duroc). A total of 35 different hydrocarbons were identified in this study. Some differences were found in the levels of branched, cyclical and unsaturated hydrocarbons as a function of the diet of the pigs (3-hexyl-1,1-dimethyl cyclopentane, p < 0.05; 3-octadecene, p < 0.01; neophytadiene, p < 0.001; 1-ethylundecyl benzene, p < 0.01; cyclohexadecane, p < 0.001; cyclotriacontane, p < 0.05). However, the genotype had a limited effect in the level of branched hydrocarbons found. The study of branched hydrocarbons in intramuscular fat from dry-cured Iberian ham allows differentiation between the pigs management systems.

Effect of particle size and soybean oil supplementation on growth performance, carcass and meat quality and fatty acid composition of intramuscular lipids of lambs

Thirty-two Merino Branco (MB) ram lambs were used to evaluate the effects of lucerne particle size and soybean oil supplementation in growth, carcass and meat quality and fatty acid composition of longissimus thoracis muscle. The lambs were divided into four groups and submitted to four diets: conditioned hay of lucerne; conditioned hay of lucerne plus soybean oil; ground and pelleted lucerne; and ground and pelleted lucerne plus soybean oil. Lambs were weighed weekly and slaughtered after 6 weeks of trial. Hay fed lambs showed lower intake, lower average daily weight gain and lower slaughter and carcass weights. Dietary oil decreased intake, especially for pellets, reducing lambs growth rate and slaughter and carcass weights. Physical form of the diet and lipid supplementation had minor effects in carcass and meat quality traits. The results of oil inclusion were not conclusive for meat sensory attributes. Fatty acid composition was strongly affected by treatments and the high number of significant interactions showed that the effect of oil inclusion on fatty acid composition was highly dependent on forage particle size. With oil supplementation, C18:1 trans-11 and C18:2 cis-9 trans-11 increased, but this effect was more pronounced with hay. Linoleic acid also increased but this effect was larger in pellets. The ratio n-6/n-3 fatty acids was lower for hay. It increased with oil supplementation and, with pellets, the value was above the suggested threshold of 4.

Weight loss and exercise: implications for muscle lipid metabolism and insulin action.

Implications for Muscle Lipid Metabolism and An accumulation of intramuscular lipid has been reported with obesity and linked with insulin resistance. The purpose of this paper is to discuss: 1) mechanisms that may be responsible for intramuscular lipid accumulation with obesity, and 2) the effects of common interventions (weight loss or exercise) for obesity on skeletal muscle lipid metabolism and intramuscular lipid content. Data suggest that the skeletal muscle of morbidly obese humans is characterized by the preferential partitioning of lipid toward storage rather than oxidation. This phenotype may, in part, contribute to increased lipid deposition in both muscle and adipose tissue, and promote the development of morbid obesity and insulin resistance. Weight loss intervention decreases intramuscular lipid content, which may contribute to improved insulin action. On the other hand, exercise training improves insulin action and increases fatty acid oxidation in the skeletal muscle of obese/morbidly obese individuals. In summary, the accumulation of intramuscular lipid appears to be detrimental in terms of inducing insulin resistance; however, the accumulation of lipid can be reversed with weight loss. The mechanism(s) by which exercise enhances insulin action remains to be determined.

Palmitic acid metabolism in the soleus muscle in vitro in hypo- and hyperthyroid rats.

The aim of this study was to establish whether the rate of fatty acid (FA) incorporation and its utilization by the isolated soleus muscle is modified under conditions of thyroid hormone deficit or excess. The rate of palmitic acid (PA) uptake, oxidation and incorporation into intramuscular lipids with increasing PA concentration (0.5-1.5 mM) in the incubation medium were determined. In hypothyroid rats intramuscular triacylglycerol (TG) synthesis was increased, while the rate of PA oxidation to CO2 and incorporation into mono- and diacylglycerols (MG/DG) and phospholipids (PL) remained unchanged. In rats with triiodothyronine (T3) excess the rate of all processes studied was enhanced, although the percentage incorporation of PA into different classes of intramuscular lipids was fairly constant and, independently of thyroid state and FA concentration in the medium, was 56-66% for TG, 9-14% for MG/DG and 24-32% for PL. Our results thus indicate that even short-term T3 excess accelerates the rate of FA uptake and metabolism in the oxidative soleus muscle, whereas in hypothyroid rats only intramuscular TG synthesis is affected.

Effects of supplemental rumen-protected conjugated linoleic acid or corn oil on fatty acid composition of adipose tissues in beef cattle.

Thirty-six Angus x Hereford heifers (365 +/- 60 kg) were used to determine the effects of supplemental dietary lipid sources on fatty acid composition of i.m., perianal (p.a.), and s.c. lipid depots. Lipid was supplied to diets as either corn oil or a rumen-protected conjugated linoleic acid (CLA) salt for two specific treatment periods of either the final 32 or 60 d on feed. Following an initial 56-d feeding period, heifers were fed one of three dietary treatments (DM basis): 1) basal diet containing 88% concentrate and 12% grass hay (CON), 2) basal diet plus 4% corn oil (OIL), or 3) basal diet plus 2% rumen-protected CLA salt (RPCLA) containing 31% CLA. The trans-10, cis-12 CLA concentration was greatest (P < 0.05) for heifers fed RPCLA and OIL diets and least (P < 0.05) for CON, regardless of time on dietary treatment. Heifers fed supplemental RPCLA had greater (P < 0.05) total CLA content than either CON- or OIL-fed heifers. Adipose tissue concentration of trans-11 vaccenic acid (TVA) was less (P < 0.05) for CON than OIL or RPCLA, which did not differ (P > 0.05). Percentages of C18:1 trans-10 were least (P < 0.05) in i.m. lipid compared with p.a. and s.c., which did not differ (P > 0.05). Following 60 d of lipid supplementation, heifers fed OIL and RPCLA had lower (P < 0.05) concentrations of oleic acid and total monounsaturated fatty acids (MUFA) compared with CON. The ratio of cis-9, trans-11 CLA:TVA was higher (P < 0.05) for heifers fed 60 vs. 32 d, but did not differ (P > 0.05) between adipose depots. Feeding OIL increased (P < 0.05) adipose concentration of C18:2 fatty acid, whereas feeding RPCLA increased (P < 0.05) total CLA isomers by 22%. Intramuscular lipid contained the lowest (P < 0.05) percentage of cis-9, trans-11 CLA, total CLA, C18:1 cis-9, C18:1 trans-10, and TVA. Total CLA and cis-9, trans-11 CLA isomers were increased (P < 0.05) in p.a. and s.c. adipose depots, whereas i.m. adipose tissue contained increased (P < 0.05) amounts of total PUFA. Results from this study indicate that short-term lipid supplementation to feedlot cattle can increase adipose tissue CLA concentrations, but only marginally (8.3 to 17.5%). Moreover, observed decreases in oleic acid and total MUFA concentrations of adipose tissues from heifers fed rumen-protected CLA or corn oil suggest that lipid supplementation may decrease delta9 desaturase activity in adipose tissues, which in turn would lower the conversion of TVA to cis-9, trans-11 CLA isomer.

Free-range rearing of pigs during the winter: Adaptations in muscle fiber characteristics and effects on adipose tissue composition and meat quality traits1

This research aimed to determine whether outdoor free-range rearing during the winter (average ambient temperature of 5°C) vs. indoor housing (22°C) affects meat quality, muscle metabolic traits, and muscle fiber characteristics. Forty Large White gilts and barrows were blocked by weight within each gender (20 per gender) and allotted randomly into two groups of pigs, with one reared indoors (IN) in individual pens (2.6 m2) and the other reared outdoors (OUT) from December to March in a 0.92-ha pasture. Both groups had free access to the same grower-finisher diet from 23 to 105 kg. At slaughter, adipose (backfat [BF] and omental fat [OF]) and muscle tissues (longissimus muscle [LM], rectus femoris [RF], and semitendinosus [ST]) were obtained from the right side of each carcass. Muscle fibers were stained and classified on the basis of stain reaction as slow-oxidative (SO), fast oxidative-glycolytic (FOG), and fast glycolytic (FG); fiber area and distribution were determined. Also assessed were carcass characteristics, initial and ultimate pH, L*a*b* values, drip loss percent, glycolytic potential (GP), and intramuscular lipid content, as well as the fatty acid profile of each muscle and adipose tissue. The OUT pigs had lower (P < 0.05) ADG and leaner (P < 0.05) carcasses than IN pigs. Rearing environment did not (P > 0.63) affect the intramuscular lipid content of the ST, but intramuscular lipid content was lower (P < 0.01) in the LM and tended to be higher (P = 0.06) in the RF of OUT than in those of IN pigs. In the BF outer layer of the OUT pigs, the higher PUFA content was compensated by both a lower (P < 0.01) saturated and monounsaturated fatty acid (MUFA) content, whereas in the OF, LM, and dark portion of the ST, only the percentage of MUFA was decreased (P < 0.01). In all tissues of the OUT pigs, the linolenic acid content was higher (P < 0.01) and the n–6:n–3 ratio was lower (P < 0.01). The GP of all muscles was higher (P < 0.01), and the ultimate pH of the RF and ST was lower (P < 0.01), in OUT compared with IN pigs. Lightness (L*) values were lower (P < 0.01) in the LM. Percentages of drip loss were higher (P < 0.05) in the LM and light portion of the ST of OUT than in those of IN pigs. The LM and RF of OUT pigs had more (P < 0.01) FOG and fewer (P < 0.01) FG fibers than muscles of IN pigs. Results suggest that rearing pigs outdoors increases aerobic capacity of glycolytic muscles but has little concomitant influence on meat quality traits.

Free-range rearing of pigs during the winter: Adaptations in muscle fiber characteristics and effects on adipose tissue composition and meat quality traits1

This research aimed to determine whether outdoor free-range rearing during the winter (average ambient temperature of 5 degrees C) vs. indoor housing (22 degrees C) affects meat quality, muscle metabolic traits, and muscle fiber characteristics. Forty Large White gilts and barrows were blocked by weight within each gender (20 per gender) and allotted randomly into two groups of pigs, with one reared indoors (IN) in individual pens (2.6 m2) and the other reared outdoors (OUT) from December to March in a 0.92-ha pasture. Both groups had free access to the same grower-finisher diet from 23 to 105 kg. At slaughter, adipose (backfat [BF] and omental fat [OF]) and muscle tissues (longissimus muscle [LM], rectus femoris [RF], and semitendinosus [ST]) were obtained from the right side of each carcass. Muscle fibers were stained and classified on the basis of stain reaction as slow-oxidative (SO), fast oxidative-glycolytic (FOG), and fast glycolytic (FG); fiber area and distribution were determined. Also assessed were carcass characteristics, initial and ultimate pH, L*a*b* values, drip loss percent, glycolytic potential (GP), and intramuscular lipid content, as well as the fatty acid profile of each muscle and adipose tissue. The OUT pigs had lower (P < 0.05) ADG and leaner (P < 0.05) carcasses than IN pigs. Rearing environment did not (P > 0.63) affect the intramuscular lipid content of the ST, but intramuscular lipid content was lower (P < 0.01) in the LM and tended to be higher (P = 0.06) in the RF of OUT than in those of IN pigs. In the BF outer layer of the OUT pigs, the higher PUFA content was compensated by both a lower (P < 0.01) saturated and monounsaturated fatty acid (MUFA) content, whereas in the OF, LM, and dark portion of the ST, only the percentage of MUFA was decreased (P < 0.01). In all tissues of the OUT pigs, the linolenic acid content was higher (P < 0.01) and the n-6:n-3 ratio was lower (P < 0.01). The GP of all muscles was higher (P < 0.01), and the ultimate pH of the RF and ST was lower (P < 0.01), in OUT compared with IN pigs. Lightness (L*) values were lower (P < 0.01) in the LM. Percentages of drip loss were higher (P < 0.05) in the LM and light portion of the ST of OUT than in those of IN pigs. The LM and RF of OUT pigs had more (P < 0.01) FOG and fewer (P < 0.01) FG fibers than muscles of IN pigs. Results suggest that rearing pigs outdoors increases aerobic capacity of glycolytic muscles but has little concomitant influence on meat quality traits.

Glucose induces de novo lipogenesis in rat muscle satellite cells through a sterol-regulatory-element-binding-protein-1c-dependent pathway.

We previously reported that sterol-regulatory-element-binding-protein-1c (SREBP-1c) mediates insulin upregulation of genes encoding glycolytic and lipogenic enzymes in rat skeletal muscle. Here, we assessed whether glucose could regulate gene expression in contracting myotubes deriving from cultured muscle satellite cells. Glucose uptake increased twofold after a 30 minute treatment with a high glucose concentration, suggesting an acute glucose-stimulated glucose uptake. Time-course experiments showed that, within 3 hours, glucose stimulated the expression of hexokinase II, fatty acid synthase and acetyl-CoA-carboxylase-2 proteins, leading to an increased lipogenic flux and intracellular lipid accumulation in contracting myotubes. Furthermore, kinetic experiments indicated that glucose upregulated SREBP-1c precursor and nuclear proteins within 30 minutes, SREBP-1c nuclear translocation being confirmed using immunocytochemistry. In addition, the knockdown of SREBP-1 mRNA using a RNA-interference technique totally abrogated the glucose-induced upregulation of lipogenic enzymes, indicating that SREBP-1c mediates the action of glucose on these genes in rat skeletal muscle. Finally, we found that glucose rapidly stimulated SREBP-1c maturation through a Jak/STAT dependent pathway. We propose that increased intramuscular lipid accumulation associated with muscle insulin resistance in obesity or type-2 diabetes could arise partly from de novo fatty acid synthesis in skeletal muscle.

Fatty acids and triacylglycerols profiles from different types of Iberian dry-cured hams

Thirty hams were allotted into four groups according to fattening diet (“Montanera” – acorns and pasture; and “Pienso” – concentrated diet) and genotype of pigs (Iberian and Iberian × Duroc pigs). Total lipids, triacylglycerol composition and fatty acids from neutral lipids fraction were measured in biceps femoris muscle. Fattening diet largely affected lipid composition of hams. Total intramuscular lipids and triacylglycerols content were higher in Montanera hams than in Pienso hams. In Montanera hams, triacylglycerols contained more oleic acid (C18:1) and less stearic (C18:0) and palmitic (C16:0) acids ( p<0.001) and accordingly less PSO, PPL, PPO, PPS, SSO ( p<0.001) and more OLL, OOL, OOO triacylglycerols compared to Pienso hams ( p<0.001). Genotype of pigs has an important effect in triacylglycerols composition but only a limited effect on their fatty acids composition. So, Iberian hams contained more of PLLn, PLL, POLn and POL + SLL compared to Iberian × Duroc hams ( p<0.001) and POO and SOO were present in a higher quantity in Iberian × Duroc hams ( p<0.01).

Effects of breed, diet and muscle on fat deposition and eating quality in pigs

A study in 192 entire male pigs examined the effects of breed, diet and muscle on growth, fatness, sensory traits and fatty acid composition. There were four breeds: two modern breeds, Duroc and Large White and two traditional breeds, Berkshire and Tamworth. The diets differed in energy:protein ratio, being conventional (C) and low protein (LP) diets, respectively. Muscles investigated were the `white' longissimus dorsi (LD) and the `red' psoas major (PS). Breed influenced growth rate and fatness, the modern breeds being faster-growing with leaner carcasses. However, the concentrations of neutral lipid fatty acids and marbling fat (neutral lipid + phosopholipid fatty acids) were higher in Berkshire and Duroc, in both LD and PS. Relationships between marbling fat and P2 fat thickness showed clear breed effects, with Duroc having high marbling fat at low P2 and Tamworth low marbling fat at high P2. Breed effects on sensory scores given by the trained taste panel to griddled LD and PS steaks were relatively small. Breed affected the fatty acid composition of intramuscular neutral lipid, with high % values for the saturated fatty acids, 14:0 and 16:0 in Berkshire and Tamworth (fat carcasses) and high values for polyunsaturated fatty acids in Duroc and Large White (lean carcasses). Duroc had particularly high concentrations of the long-chain polyunsaturated fatty acids, 20:5 n−3 and 22:6 n−3 in phospholipid of both muscles. Diet influenced growth rate and fatness, the LP diet slowing growth and producing fatter meat, more so in the two modern breeds, and particularly in intramuscular rather than subcutaneous fat. This diet produced more tender and juicy meat, although pork flavour and flavour liking were reduced. The PS muscle had higher tenderness, juiciness, pork flavour, flavour liking and overall liking scores than LD. The concentration of phospholipid fatty acids was higher in PS than LD but neutral lipid fatty acid content and marbling fat were higher in LD.

Composition and proteolytic and lipolytic enzyme activities in muscle Longissimus dorsi from Iberian pigs and industrial genotype pigs

In this study, composition and fatty acid profiles of intramuscular lipid fractions, proteolytic and lipolytic muscle enzyme activities in muscle Longissimus dorsi have been determined in three lines of Iberian pigs (“ Lampi ñ o”, “ Retinto” and “ Torbiscal”) reared under the free-range system and slaughtered at 90kg live weight and industrial genotype pigs (IGP) (Large White-Landrace × Large White) reared intensively. Intramuscular fat content was significantly higher ( p<0.05) in Iberian pig lines (IPL) than in IGP. Neutral lipids of IPL showed higher ( p<0.05) percentages of palmitic, oleic, total saturated fatty acids and monounsaturated fatty acids and lower ( p<0.05) percentages of polyunsaturated acids and linoleic acid in neutral and polar lipids than IGP. No statistical differences were found in cathepsin B or B + L or phospholipase residual activities between IPL and IGP, while cathepsin H residual activity was significantly ( p>0.05) higher in IGP than in IPL. The ratio cathepsin B + L/B was significantly lower ( p<0.05) in IGP and “ Lampi ñ o” line than in “ Retinto” and “ Torbiscal” lines. Acid lipase residual activity showed a significantly ( p<0.05) higher activity in IPL than in IGP. The activity of neutral lipase was significantly higher ( p<0.05) in “ Torbiscal” line and lower in the “ Lampi ñ o” line while the “ Retinto” line and IGP showed intermediate activities. Acid esterase activity was higher ( p<0.05) in “ Retinto” and“ Torbiscal” lines than in IGP and the “ Lampi ñ o” line. The different enzyme patterns in fresh meat may explain the wide proteolysis and lipolysis variations usually observed in the processing of dry-cured ham.

Fatty Acid Composition in Diploid and Triploid Populations of Tench (Tinca tinca L.)

Buchtova, H., M. Smutna, L. Vorlova, Z. Svobodova, M. Flaj‰hans: Fatty Acid Composition in Diploid and Triploid Populations of Tench (Tinca tinca L.). Acta Vet. Brno 2004, 73: 235-245. The aim of the study was to determine the differences in the composition of fatty acids of intramuscular lipids between diploid (2n) and triploid (3n) tench of identical genetic specifications and raised under the same conditions, in relation to sex (F-female vs. M-male) and age (T 3 -36 months vs. T 3+ - 42 months). A total of 137 tench (Tinca tinca L.) siblings were analyzed. The control group consisted of 72 diploid tench (39 F and 33 M) and the experimental group of 65 triploid tench (38 F and 27 M). Elevated levels of fatty acids C16:0, C16:1n-9c and C18:1n-9c were found in lipids of tench of both age groups (T3 and T3+). Among T3 tench, significant ploidy-level related differences were ascertained in the content of specific SFA (C12:0, C13:0, C14:0, C15:0; p < 0.01) and C22:1n-9 (p < 0.05) in favour of 2n males. A significant effect of sex was found only in the diploid tench population: C14:0, p < 0.01 and C14:1n-9c, p < 0.05 in favour of 2n male tench and C18:1n-9c, p < 0.01 in favour of 2n female tench. In the T3+ age group, the ploidy-level effect was apparent in both sexes (C15:0, P < 0.05 and C18:2n-9c, t11, p < 0.05 in favour of 2n female tench, C16:1n-9c, p < 0.01 in favour of 3n male tench, C18:2n-6c, p < 0.01 and C18:3n-3, p < 0.05 in favour of 2n male tench). In the T 3+ age group, the effect of sex was apparent for both ploidy levels (C16:1n-9c, p < 0.01 in favour of 2n female tench, and C14:0, p < 0.05 in favour of 3n male tench). The qualitative as well as quantitative composition of lipids of specific fatty acids was significantly affected (p < 0.05, p < 0.01, p < 0.05) by age. The study demonstrated that the factors monitored (ploidy, sex and age) may, under specific experimental conditions, influence the composition of lipid fatty acids of the tench. Fatty acids, diploid and triploid tench, genome polyploidy