Influence of dietary vitamin E and selenium on muscle fatty acid composition in pigs

Vitamin A regulates mitochondrial biogenesis and function through p38 MAPK-PGC-1α signaling pathway and alters the muscle fiber composition of sheep

BACKGROUND

Vitamin A (VA) and its metabolite, retinoic acid (RA), are of great interest for their wide range of physiological functions. However, the regulatory contribution of VA to mitochondrial and muscle fiber composition in sheep has not been reported.

METHOD

Lambs were injected with 0 (control) or 7,500 IU VA palmitate into the biceps femoris muscle on d 2 after birth. At the age of 3 and 32 weeks, longissimus dorsi (LD) muscle samples were obtained to explore the effect of VA on myofiber type composition. In vitro, we investigated the effects of RA on myofiber type composition and intrinsic mechanisms.

RESULTS

The proportion of type I myofiber was greatly increased in VA-treated sheep in LD muscle at harvest. VA greatly promoted mitochondrial biogenesis and function in LD muscle of sheep. Further exploration revealed that VA elevated PGC-1α mRNA and protein contents, and enhanced the level of p38 MAPK phosphorylation in LD muscle of sheep. In addition, the number of type I myofibers with RA treatment was significantly increased, and type IIx myofibers was significantly decreased in primary myoblasts. Consistent with in vivo experiment, RA significantly improved mitochondrial biogenesis and function in primary myoblasts of sheep. We then used si-PGC-1α to inhibit PGC-1α expression and found that si-PGC-1α significantly abrogated RA-induced the formation of type I myofibers, mitochondrial biogenesis, MitoTracker staining intensity, UQCRC1 and ATP5A1 expression, SDH activity, and enhanced the level of type IIx muscle fibers. These data suggested that RA improved mitochondrial biogenesis and function by promoting PGC-1α expression, and increased type I myofibers. In order to prove that the effect of RA on the level of PGC-1α is caused by p38 MAPK signaling, we inhibited the p38 MAPK signaling using a p38 MAPK inhibitor, which significantly reduced RA-induced PGC-1α and MyHC I levels.

CONCLUSION

VA promoted PGC-1α expression through the p38 MAPK signaling pathway, improved mitochondrial biogenesis, and altered the composition of muscle fiber type.

Evaluation of Commercial Meat Products of Red Chicken Reared under LED Lights

Simple Summary

The aim of the study was to investigate the role of three different light-color temperatures of Light-Emitting Diodes (LEDs) (Neutral, Cool and Warm) on some attributes of breast meat. Various changes were observed in the physical and chemical characteristics of breast meat samples and the results obtained in fatty and volatile profiles indicate that the LEDs change the characteristics of meat.

Abstract

The objective of our study was to investigate the role of three different light-color temperatures of Light-Emitting Diodes (LEDs) [Neutral (K=3300−3700); Warm (K=3000−2500) and Cool (K=5500−6000)] on the qualitative attributes of breast meat obtained from male AZ Extra Heavy Red chickens. The comparison was made with meat deriving from chickens reared in the presence of classic neon lighting (Control). The meat was analyzed for the determination of both physical and chemical properties (cooking loss, moisture, total lipids and fatty acid composition). Furthermore, meat samples subjected to cooking were also analyzed for the identification of volatile compounds produced during the process; such evaluation was performed both immediately after cooking (T0) and after 7 days (T7) of cooked-meat storage at 4 °C. Cooking-loss values were higher for samples from chickens raised with Neutral LED (p < 0.05) compared to the other groups. For the fatty acid profiles of the meat, higher values were found for monounsaturated fatty acids (MUFAs) such as C18:1, C9 and C16:1 in Cool LED compared to the Control. Regarding the volatile profile of cooked meat, compounds belonging to the families of aldehydes, alcohols, ketones, and aromatic compounds were identified. Compounds belonging to the aldehyde family, such as hexanal, increased in Cool LED samples at T0 in comparison to the Control. On the other hand, the amounts of 1-Pentanol, 1-Octanol and 2-Octen-1-ol, which belong to the alcohol family, increased at T7 in Cool LED samples compared to the Warm LED. In conclusion, LED lighting showed to be effective in inducing significant variations on chicken breast meat ready to be introduced to the market, in particular regarding fatty acid profiles and the accumulation of volatile compounds. However more in-depth evaluation is needed for the identification of modifications regarding the sensorial sphere, which could have an impact on the consumer acceptability of the product.

Effects of dietary grape seed proanthocyanidin extract supplementation on meat quality, muscle fiber characteristics and antioxidant capacity of finishing pigs

The aim of this study was to investigate effects of dietary grape seed proanthocyanidin extract (GSPE) supplementation on meat quality, muscle fiber characteristics and antioxidant capacity of finishing pigs. The data showed GSPE increased pH24 h, redness, crude protein content and decreased shear force, drip loss48 h, lactate content and glycolytic potential in longissimus dorsi (LD) muscle, accompanied by increased contents of total polyunsaturated fatty acid (PUFA), n-3 PUFA, and the ratio of PUFA to saturated fatty acid. GSPE promoted MyHC I mRNA and slow MyHC protein expression, and increased slow-twitch fiber percentage. The activities of total antioxidant capacity, total superoxide dismutase, catalase and glutathione peroxidase in LD muscle were increased by GSPE while malondialdehyde content was decreased. Together, this study demonstrated that dietary GSPE supplementation can effectively improve the color, water-holding capacity, tenderness and nutritional value of pork, and increase slow-twitch fiber percentage and antioxidant capacity of finishing pigs.

Meat quality, free fatty acid concentration, and oxidative stability of pork from animals fed diets containing different sources of selenium

This study evaluates the effect of the source of dietary selenium supplementation (organic versus mineral) and the combined effect of organic selenium and vitamin E on the fatty acid composition and lipolysis in pork intramuscular fat and other meat quality characteristics such as drip loss and lipid stability. Higher vitamin E deposition, lower drip loss, and higher stability against oxidation were detected in muscle from pigs fed organic selenium. Also higher proportion of free fatty acids was observed in intramuscular fat from pigs fed organic selenium than those fed inorganic selenium, being these mainly coming from neutral lipid fraction. In addition, the inclusion of vitamin E in the diet enhanced such effect. Dietary organic selenium also increased Δ9-desaturase and elongase indexes and C18:1n−9 concentration. A related decrease of C18:0 concentration was also observed. Described differences in the lipid fraction composition could affect sensory characteristics of meat and meat products.

A role for Sel-Plex™, a source of organic selenium in selenised yeast cell wall protein, as a factor that influences meat stability

Selenium is an important mineral required in the antioxidant system in animals, which is involved with oxidative stability in tissues, particularly membranes, and is involved in various aspects of meat quality and stability on the shelf, due to its protective properties on lipids, preventing rancidity. Se can be supplied in an inorganic or chemically organic form, and it is well known that the latter has beneficial properties and improved functionality in physiological systems compared to the former. Research has shown that organic Se is associated with increased tenderness and the prevention of certain problems in pale exudative meat, discolouration and off-flavours and odours in meat, although this depends on other components of the antioxidant system, such as vitamin E, being present as well. The change in prominence of glutathione peroxidase forms in their interaction with vitamin E in cell membranes is also noted. The following review (the third in a series) details the research that has been conducted into the role of Se in meat stability and related factors, with specific focus on organic forms of Se, namely the commercial product Sel-Plex™ (Alltech Inc, Nicholasville, KY, USA), which is derived from yeast and in which selenium replaces sulphur in methionine forming selenomethionine in yeast protein.

Effects of Astragalus membranaceus, Codonopsis pilosula and allicin mixture on growth performance, nutrient digestibility, faecal microbial shedding, immune response and meat quality in finishing pigs

A 12-week trial with 120 [(Landrace×Yorkshire)×Duroc] pigs (45.65 ± 1.93 kg) was conducted to evaluate the effects of Astragalus membranaceus, Codonopsis pilosula and allicin mixture (HM) supplementation on growth performance, nutrient digestibility, faecal microbial shedding, immune response and meat quality in finishing pigs. Pigs were allocated to one of three treatments with 0, 0.025% (HM1) and 0.05% (HM2) HM supplementation in a randomized complete block design according to sex and BW. Each treatment contained 10 replications with four pigs (two barrows and two gilts) per pen. Dietary HM resulted in a higher G:F (p < 0.05) than CON group during weeks 7 to 12 and the overall periods. Pigs fed HM2 diet had higher ADG than pigs fed CON diet. Pigs fed HM2 supplementation diet led to a higher (p < 0.05) apparent total tract digestibility (ATTD) of dry matter (DM) and gross energy (GE) than pigs fed CON diet at week 6, while the supplementation of HM led to a higher (p < 0.05) ATTD of DM and GE than pigs fed CON diet at week 12. The faecal E. coli counts were reduced, and Lactobacillus counts were increased by increasing HM supplementation (p < 0.05). Pigs fed HM1 diet had higher (p < 0.05) WBC concentration than those fed CON and HM2 diets at week 6. Pigs fed HM-supplemented diet had higher (p < 0.05) IgG and IgA concentrations than those fed CON diet at week 12. Pigs fed HM diet noted better (p < 0.05) meat colour and redness value than pigs fed CON diet. Pig fed HM2 reduced (p < 0.05) the lightness value compared with CON group. In conclusion, dietary HM supplementation exerted beneficial effects on growth performance, nutrient digestibility, intestinal microbial balance (increased Lactobacillus counts and decreased E. coli counts), immune response and meat quality.

Comparison Between Two Different Levels of Replacement of Free-range Rearing by an Oleic Acid and-tocopherol Enriched Diet on the Quality of Fresh Meat from Iberian Duroc (50%) Pigs

The aim of this work was to study the effect of two types of pig feeding systems (known as recebo) on fatty acid composition, tocopherols contents and susceptibility to lipid oxidation in muscle. A total of 26 Iberian Duroc (50%) barrows were divided into two groups (named as short replacement (SR) and long replacement (LR) groups) according to length of replacement of free-range rearing (based on acorn and pasture) by an oleic acid and B-tocopherol (200 mg/kg) enriched concentrate feed (SR group: 67 days in free-range rearing and finished during 20 days with concentrate diet; LR: 55 days in free-range rearing, finished 50 days with concentrate). No differences were found in chemical composition and colour of Gluteo biceps muscle between the two management systems, except for B-tocopherol content, which showed higher content (p 0.001) in LR pigs than in SR pigs. The fatty acid composition of subcutaneous fat was slightly affected by feeding system. Total intramuscular and neutral lipids from Gluteo biceps muscle presented a higher proportion of C18: 1 n 9 (p 0.05) in SR than in LR pigs; however, no differences were found in total saturated (SFA), monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA). Composition of polar lipids revealed a higher proportion of MUFA and lower of total n 3 fatty acids in LR than in SR pigs. Feeding regime significantly affected susceptibility of muscle to iron-ascorbate-induced peroxidation. Muscles from pigs reared on SR system showing higher levels (p 0.05) of MDA after 50 and 100 min of incubation. These results indicate that the content of oleic acid and tocopherol in muscle depends on the levels of both provided by dietary means, more than the practised handling.

Effect of oat by-product antioxidants and vitamin E on the oxidative stability of pork from pigs fed diets supplemented with linseed oil

The aim of the experiment was to compare the antioxidative potential of an oat by-product with the effect of vitamin E on the oxidative stability of pork from pigs fed a diet enriched with linseed oil. Thirty-four crossbreed barrows were fed individually from 39 to 109 kg body weight (BW) on one of four diets: a control diet based on barley-triticale-soybean (Diet C), a diet containing an oat byproduct (Diet O), and the same diets supplemented with vitamin E (100 mg/kg diet) (Diets CE and OE, respectively). The oat by-product, comprising oat hulls and bran, was included at 10 and 20% in the grower and finisher diets, respectively. To Diets O and OE, refined rapeseed oil was added to equalise their energy content to Diets C and CE. Compared to Diets C and CE, the inclusion of the oat by-product in Diets O and OE increased the antioxidative capacity of water-soluble and lipid soluble compounds in these diets. Dietary treatment did not influence growth performance, slaughter value, longissimus dorsi (LD) muscle quality measured by nutrient contents, pH, drip loss or colour. Vitamin E supplementation increased the alpha-tocopherol concentration in serum and meat (p < 0.01), and decreased the formation of thiobarbituric acid reactive substances (TBARS) in the fresh and stored LD (p < 0.01). In addition, diets with the oat by-product increased serum alpha-tocopherol concentration (p < 0.01) and decreased the TBARS levels in the fresh and stored LD (p < 0.05), without increasing muscle alpha-tocopherol concentration. The obtained results indicate that the phenolic compounds present in oat by-products have a considerable antioxidant potential and a beneficial effect on the pig organism and oxidative stability of meat. However, dietary inclusion with the oat by-product was not as efficient as supplementation with vitamin E.

Oxidative stability in grinds from omega-3 enhanced pork

Juárez, M., Dugan, M. E. R., Larsen, I. L., Thacker, R., Rolland, D. C. and Aalhus, J. L. 2011. Oxidative stability in grinds from omega-3 enhanced pork. Can. J. Anim. Sci. 91: 623–634. In order to investigate the effect of enhancing n-3 fatty acid levels in carcasses on the retail and sensory characteristics of pork grinds, as well as the ability of increasing dietary levels of vitamin E to stabilize the increase in PUFA levels from flaxseed supplementation, 81 pigs were used in a 3×3 factorial experiment. Dietary treatments included three lengths of time (0, 3 and 6 wk) of flaxseed supplementation and three levels of vitamin E (40, 200 and 400 mg kg feed−1). α-Tocopherol tissue levels increased with dietary vitamin E supplementation (P<0.001), and fat softness (P=0.018) and total PUFA and n-3 fatty acids (P<0.001) increased with flaxseed supplementation. Most other animal performance, carcass and lean pork quality traits were not affected (P>0.05) by dietary treatments. In ground pork, the increase in TBARS after 6 d in retail was lower (P<0.001) with increasing dietary vitamin E levels. However, vitamin E had no effect (P>0.05) on the higher (P<0.001) TBARS levels observed in grinds from flaxseed fed pigs. The dietary addition of flaxseed negatively modified (P<0.05) all the sensory attributes of both cooked and reheated products. Increasing the fat content of the grinds up to 30% seemed to counteract (P>0.05) the negative effects of feeding flaxseed for 3 wk. Feeding vitamin E was not able to prevent negative effects (P<0.05) observed during retail display in grinds with either increasing fat content or higher n-3 fatty acids from dietary flaxseed. However, increasing dietary vitamin E only showed a protective effect (P<0.05) on retail appearance after long periods of ageing.

Supranutritional selenium level affects fatty acid composition and oxidative stability of chicken breast muscle tissue

A total of 128 broilers were used to investigate the effect of selenium (Se) on fatty acid (FA) composition and oxidative stability of lipids in the breast muscle tissue. There were 4 replicates of 4 dietary treatments: T1 (basal diet with no added Se), T2 (T1 with 0.15 mg Se added per kg diet), T3 (T1 with 0.3 mg Se added per kg diet) and T4 (T1 with 3.0 mg Se added per kg diet). A yeast source was used for added Se. Breast muscle tissue was collected from two chickens per replicate pen for the determination of Se concentration by ICP-MS, FA profile by GC and lipid oxidation using thiobarbituric acid reactive substances method. Addition of supranutritional Se levels to chicken diets leads to the production of Se-enriched meat. Consumption of 100 g of breast meat from chickens fed diets supplemented with 0.15, 0.3 and 3 mg Se per kg of diet can provide 26, 41 and 220 μg of Se, respectively. Long-chain polyunsaturated fatty acids namely C20:3n-6, C20:4n-6, C20:5n-3, C22:5n-3 and C22:6n-3 increased linearly (p = 0.047, p < 0.001, p = 0.023, p = 0.003 and p = 0.002, respectively) as the Se inclusion levels in the diets increased. At slaughter, a linear decrease in lipid oxidation (p = 0.019) was observed with Se addition, possibly attributed to the antioxidant properties of Se. Addition of supranutritional Se to chicken diets, at levels well below those causing toxicity, leads to production of Se-enriched meat, protection of health-promoting long-chain FA like C20:5n-3 and C22:6n-3 and protection of meat quality from oxidation at day 1 after slaughter.

Meta-analysis of the effects of dietary vitamin E supplementation on α-tocopherol concentration and lipid oxidation in pork

Meta-analyses have been carried out to quantify the effect of dietary vitamin E on α-tocopherol accumulation and on lipid oxidation in porcine M. longissimus. Published results of 13 (vitamin E accumulation) and 10 (lipid oxidation) experiments respectively were used for the analyses. After a number of standardization procedures, a nonlinear relationship was found between the supplementary vitamin E and the accumulation of α-tocopherol in pork which approached a maximum value of 6.4 μg/g tissue. Pork lipid oxidation levels were described in terms of Thiobarbituric Acid Reacting Substances (TBARS) values. The statistical analysis revealed significant effect of vitamin E dose, muscle α-tocopherol concentration and supplementation time on TBARS, resulting in two prediction models for lipid oxidation. Meta-analysis has proven to be a valuable tool for combining results from previous studies to quantify the effects of dietary vitamin E. Further studies, carried out with standardized experimental protocols would be beneficial for model validation and to increase the predictive power of the derived models.

Effects of dietary vitamin E and fat supplementation on pork quality1

The effects of dietary vitamin E (VE, alpha-tocopherol acetate) and fat supplementation on growth and carcass quality characteristics, oxidative stability of fresh and cooked pork patty in storage, fatty acid profiles of muscle and adipose tissue, and VE concentrations of plasma, muscle, and adipose tissue were studied. Six hundred pigs were allocated to 1 of 6 diets and fed for 63 d in a 3 x 2 factorial design. The dietary treatments included 3 fat levels (normal corn, high oil corn, high oil corn plus added beef tallow) and 2 levels of VE supplementation (40 IU/kg, normal VE supplementation; and 200 IU/kg, high VE supplementation). At 113 kg of BW, 54 pigs were slaughtered as a subsample to evaluate dietary effects on pork quality. Growth performance and meat quality characteristics did not differ (P > 0.05) among treatment groups. The high level of VE supplementation had a beneficial effect on the oxidative stability of pork as indicated by thiobarbituric acid reactive substance (TBARS) values. Lean tissue had lower (P < 0.05) TBARS in the group fed the high VE than in those fed the normal VE level. The TBARS values differed among storage periods (0 to 6 d) and also between fresh and cooked ground ham. Fat type did not significantly affect total saturated and unsaturated fatty acids proportions in the neutral and polar fraction of muscle. Adding VE acetate led to greater (P < 0.05) monounsaturated and total unsaturated fatty acid proportions in neutral lipids of muscle and adipose tissues. Increasing dietary levels of VE acetate increased the concentration of VE in plasma and muscle. These results indicate that dietary VE acetate supplementation increased (P < 0.05) lipid stability and the VE concentration of muscle.