B. Isabel

Effect of free-range feeding on n - 3 fatty acid and α-tocopherol content and oxidative stability of eggs

Abstract This study was carried out to compare the fatty acid and α-tocopherol composition and the susceptibility to oxidation of egg yolks from hens fed grass and a commercial mixed diet under free-range conditions or in cages with only the commercial diet. Grass had a relative high proportion of α-linolenic acid (534 g kg−1 total fatty acids) and α-tocopherol (162.3 mg kg−1 DM). Eggs from hens fed under free-range conditions had a higher concentration of total (n−3) fatty acids than eggs from hens fed the commercial diet (P

Dietary CLA alters intramuscular fat and fatty acid composition of pig skeletal muscle and subcutaneous adipose tissue.

The present study was conducted to determinate the responsiveness of different levels of dietary conjugated linoleic acid (CLA) on intramuscular fat (IMF) and fatty acid composition of skeletal muscle and fat in pigs fed from 59.5 to 133.5kg. Forty female Large Whitex(Large WhitexLandrace) pigs were used. Four levels (0%, 0.5%, 1% and 2%) of a commercial enriched CLA oil supplementation (60% of CLA isomers, 30% cis-9, trans-11 and 30% trans-10, cis-12) were fed to pigs. Carcass, ham, foreleg and loin weights were recorded. Dietary CLA enrichment increased the loin weight (P<0.01) and the combined weights of hams+forelegs+loins (P<0.02). IMF content in Longissimus dorsi was also increased by dietary CLA treatment (P<0.001) and a linear response was observed. Dietary CLA increased saturated fatty acids (SFA) and decreased monounsaturated fatty acids (MUFA) in muscle and adipose tissue (P<0.001). Feeding 1% CLA to finishing swine increases IMF in heavy pigs slaughtered at an average weight of 133.5kg.

Dietary acorns provide a source of gamma-tocopherol to pigs raised extensively

Pigs raised extensively and fed acorns and grass had a higher concentration of alpha and gamma-tocopherol in longissimus dorsi muscle and microsome extracts than pigs fed in confinement with mixed diets (P < 0.001). This is attributable to the high concentration of alpha-tocopherol in grass (over 200 mg kg−1 DM) and gamma-toco-pherol in acorns (60–70 mg kg−1 DM). Key words: Pig, acorn, gamma-tocopherol, diet

EFFECT OF VITAMIN E SUPPLEMENTATION AND PARTIAL SUBSTITUTION OF POLY- WITH MONO-UNSATURATED FATTY ACIDS IN PIG DIETS ON MUSCLE, AND MICROSOME EXTRACT a-TOCOPHEROL CONCENTRATION AND LIPID OXIDATION

The experiment was organized in a 3×2 factorial arrangement with three dietary fat blends and a basal (20 mg kg−1 diet) or supplemented (220 mg kg−1) level of α-tocopheryl acetate. Dietary vitamin E and monounsaturated to polyunsaturated fatty acid ratio (dietary MUFA/PUFA) affected muscle α-tocopherol concentration (α-tocopherol [log μg g−1]=0.18 (±0.105)+0.0034 (±0.0003)·dietary α-tocopherol [mg kg−1 diet] (P<0.0001)+0.39 (±0.122)·dietary MUFA/PUFA (P<0.0036)). An interaction between dietary α-tocopherol and dietary MUFA/PUFA exists for microsome α-tocopherol concentration (α-tocopherol [log μg g−1]=1.14 (±0.169) (P<0.0001)+0.0056 (±0.00099)·dietary α-tocopherol [mg kg−1 diet] (P<0.0001)+0.54 (±0.206)·dietary MUFA/PUFA (P<0.0131)−0.0033 (±0.0011)·dietary α-tocopherol [mg kg−1)]×dietary MUFA/PUFA (P<0.0067)), and hexanal concentration in meat (hexanal [ng·g−1]=14807.9 (±1489.8)−28.8 (±10.6) dietary α-tocopherol [mg·kg−1] (P<0.01)−8436.6 (±1701.6)·dietary MUFA/PUFA (P<0.001)+24.0 (±11.22)·dietary α-tocopherol·dietary MUFA/PUFA (P<0.0416)). It is concluded that partial substitution of dietary PUFA with MUFA lead to an increase in the concentration of α-tocopherol in muscle and microsome extracts. An interaction between dietary α-tocopherol and fatty acids exists, in which at low level of dietary vitamin E inclusion, a low MUFA/PUFA ratio leads to a reduction in the concentration of α-tocopherol in microsome extracts and a concentration of hexanal in meat above the expected values.

Influence of dietary α-tocopheryl acetate supplementation of pigs on oxidative deterioration and weight loss in sliced dry-cured ham.

The effect of feeding high levels of α-tocopherol to pigs on the susceptibility to oxidative deterioration and weight loss in dry cured hams was investigated. The α-tocopherol concentration in thigh muscle from pigs fed the basal and the supplemented diet (200 mg kg(-1) α-tocopheryl acetate) in unprocessed thighs was 8.69 and 16.87, μg g(-1) dry matter, not including ash, respectively (p-value=0.015), while the concentration was 6.65 and 14.28 μg g(-1), respectively, in the final products (p-value=0.011). Hams from pigs fed the basal diet oxidized more during storage (p-value=0.015) as measured by formation in thiobarbituric acid reactive substances and had a higher rate of weight loss (p-value=0.0001). The total loss in red color after 4 days of storage was similar in all treatments. However, the rate of discoloration was more pronounced during the first 2 days of storage in hams from pigs fed the basal diet (p-value=0.016). This result indicates that high dietary level of α-tocopheryl acetate to pigs increases the oxidative stability in dry cured hams manufactured on the basis of such pigs.

Dietary Fat Reduces Odd‐Numbered and Branched‐Chain Fatty Acids in Depot Lipids of Rabbits

Forty eight Californian x New Zealand White rabbits were randomly distributed in three groups of 16 animals each. A control (with no added fat) and two diets enriched at a rate of 30 g fat kg -1 were used. Olive oil and sunflower oil were used as sources of fat for the fat-supplemented diets. Branched chain (BCFA) and n-odd-numbered carbon fatty acids (ONFA) in the perirenal fat depots of control animals were respectively 5 and 22 mg g -1 of total fatty acids, while in fat-enriched diets they were around 3 and 16 mg g -1 , respectively. The ratio of unsaturated: saturated fatty acid in perirenal fat was 1.25:1 when the control diet was administered and around 1.80-1.95:1 in fat-enriched diet groups, which represents approximately a 50% increase (P < 0.01). However the melting points of the fats showed little difference (NS) between the control group and the group with olive oil addition whilst the sunflower oil-supplemented group showed only a 5.7% lower value (P < 0.01). In a second experiment in which diets with equal digestible energy and protein were used, reductions in total amounts of ONFA (P < 0.01) and BCFA (P < 0.05) were observed in the perirenal fat of animals receiving the fat-enriched diets. The addition of fat depressed the concentrations of ONFA and BCFA, which may act to maintain the consistency of fat in a narrow range, avoiding to some extent the production of undesirable soft and floppy carcasses.

Comparative Analysis of Muscle Transcriptome between Pig Genotypes Identifies Genes and Regulatory Mechanisms Associated to Growth, Fatness and Metabolism

Iberian ham production includes both purebred (IB) and Duroc-crossbred (IBxDU) Iberian pigs, which show important differences in meat quality and production traits, such as muscle growth and fatness. This experiment was conducted to investigate gene expression differences, transcriptional regulation and genetic polymorphisms that could be associated with the observed phenotypic differences between IB and IBxDU pigs. Nine IB and 10 IBxDU pigs were slaughtered at birth. Morphometric measures and blood samples were obtained and samples from Biceps femoris muscle were employed for compositional and transcriptome analysis by RNA-Seq technology. Phenotypic differences were evident at this early age, including greater body size and weight in IBxDU and greater Biceps femoris intramuscular fat and plasma cholesterol content in IB newborns. We detected 149 differentially expressed genes between IB and IBxDU neonates (p < 0.01 and Fold-Change > 1. 5). Several were related to adipose and muscle tissues development (DLK1, FGF21 or UBC). The functional interpretation of the transcriptomic differences revealed enrichment of functions and pathways related to lipid metabolism in IB and to cellular and muscle growth in IBxDU pigs. Protein catabolism, cholesterol biosynthesis and immune system were functions enriched in both genotypes. We identified transcription factors potentially affecting the observed gene expression differences. Some of them have known functions on adipogenesis (CEBPA, EGRs), lipid metabolism (PPARGC1B) and myogenesis (FOXOs, MEF2D, MYOD1), which suggest a key role in the meat quality differences existing between IB and IBxDU hams. We also identified several polymorphisms showing differential segregation between IB and IBxDU pigs. Among them, non-synonymous variants were detected in several transcription factors as PPARGC1B and TRIM63 genes, which could be associated to altered gene function. Taken together, these results provide information about candidate genes, metabolic pathways and genetic polymorphisms potentially involved in phenotypic differences between IB and IBxDU pigs associated to meat quality and production traits.

Effect of dietary lard on performance, fatty acid composition and susceptibility to lipid peroxidation in growing-finishing female and entire male pigs

The effect of increasing the energy concentration of growing-finishing pig diets through inclusion of lard on performance, carcass and meat composition and lipid susceptibility to peroxidation was studied. A total of 720 Landrace × Large White male and female pigs (equal number of entire males and females) were used. Experimental diets were formulated to have a low (3000 kcal ME kg−1) or high (3200 kcal ME kg−1) energy level, but in all cases to have a constant lysine:ME ratio. This was achieved using a low (6.8 g kg−1) and a high (49.3 g kg−1) level of dietary lard inclusion. Gilts had lower daily gain (P < 0.0001) and worse feed conversion efficiency (P < 0.0001) than entire males. Susceptibility to oxidation was not affected by sex. Fat concentration in pig diets equilibrated in metabolizable energy and protein did not modify average gain, but reduced feed intake (P < 0.02), improved the gain:feed ratio (P < 0.0001), increased dressing percentage (P < 0.02) and produced higher carcass weight (P < 0.01)...

Response of ApoA-IV in pigs to long-term increased dietary oil intake and to the degree of unsaturation of the fatty acids.

ApoA-IV is a protein constituent of HDL particles; the gene coding for it is a member of the ApoA-I-ApoC-III-ApoA-IV cluster. To investigate the effects of the quantity and the degree of saturation of dietary lipid on the long-term response of this Apo, and on the hypothetical coordinated regulation of the cluster in vivo, pigs were fed isoenergetic, cholesterol-free, low-lipid or lipid-enriched diets (containing either extra olive oil (rich in MUFA) or sunflower oil (rich in n-6 PUFA)) for 42 d. In animals fed on the control diet, ApoA-IV was mainly associated with plasma lipoproteins. An increase in plasma ApoA-IV concentration, mainly in the lipoprotein-free fraction, was induced by the lipid-enriched diets, independent of the degree of saturation of the fatty acids involved. The latter diets also led to increases in hepatic ApoA-I, ApoA-IV and ApoC-III mRNA levels, more so with the sunflower oil-rich diet. The present results show that porcine plasma ApoA-IV levels and their association with lipoproteins are very sensitive to increases in dietary lipids, independent of the degree of fatty acid saturation. Furthermore, hepatic expression of RNA appears to be coordinated along with that of the other members of the gene cluster.

Evolution of the fatty acid profile of subcutaneous back-fat adipose tissue in growing Iberian and Landrace × Large White pigs.

The lipid content and fatty acid (FA) profile in pig tissues are strongly influenced by genotype and nutrient supply, with implications in meat quality. The de novo lipid synthesis and pattern of FA unsaturation could be an important cause of variation in the overall efficiency of energy utilization among breeds. To test the effects of pig genotype and CP supply on the evolution of back-fat tissue FA profile throughout the growing and finishing stages, 32 Iberian (IB) and Landrace × Large White (LR × LW) barrows were offered one of two diets differing in CP content (13% or 17% as fed). A pair-fed procedure (0.8 × ad libitum intake of IB pigs) was used. Subcutaneous fat samples were taken at the dorso-lumbar region at ∼38, 50, 65, 90 and 115 kg BW. Higher proportions of total monounsaturated FA (MUFA; P < 0.01) and lower proportions of total saturated FA (SFA; P < 0.01 to 0.05) were found in the outer back-fat layer of pigs both at 50 and 115 kg BW. Pig genotype affected the FA composition of both subcutaneous back-fat layers. The proportions of C18:0 and SFA in fat tissue were higher in IB than in LR × LW pigs from 38 to 65 kg BW, especially in the outer layer. In addition, MUFA contents were higher in IB pigs at 115 kg BW in both layers (+5% on average; P < 0.01). Increased proportions of C18:2 n-6 and polyunsaturated FA (PUFA) were found in LR × LW pigs, irrespective of the stage of growth and back-fat layer (P⩽0.02). At 50 kg BW, pigs receiving the high-protein diet presented the highest C18:2 n-6, C18:3 n-3, C20:5 n-3 and PUFA contents. A significant genotype × CP content interaction was observed for C18:3 n-3 because of the increased concentration of this FA in LR × LW pigs when offered the 17% CP diet (P < 0.05). Higher C16:0 and SFA contents (+5%; P = 0.03) were found in pigs offered the 13% CP diet and slaughtered at 115 kg BW. There was a genotype × CP interaction for MUFA concentration because of the higher MUFA content observed in IB pigs offered the highest protein content diet (P = 0.03). Our results suggest that genetic variation in de novo lipid synthesis and pattern of FA unsaturation might contribute to explain differences in back-fat FA profile of IB and LR × LW pigs under identical nutritional management. They could be also relevant to explain the low efficiency of nutrient and energy utilization in the IB pig.