Effect of age at the beginning of the free-range fattening period on growth and carcass and fat quality in Iberian pigs

Abstract

This experiment was carried out to study the influence of age at the beginning of the free-range fattening period (traditional pigs, TP, age 12 months vs. young pigs, YP, age 8 months) on the performance of Iberian pigs. During 152 days prior to the fattening period, TP and YP pigs received 1.7 and 2.6 kg feed per day, respectively. During fattening, TP pigs had a higher average daily gain (p < 0.05) than YP pigs. The proportions of PUFA and n-3 fatty acids of the outer and inner layers of subcutaneous backfat were higher in TP than in YP pigs (p < 0.05), while the proportions of C16:0 and SFA in the inner layer of subcutaneous backfat were greater in YP than in TP pigs (p < 0.05). The ratio of n-6/n-3 in subcutaneous backfat was lower in TP than in YP pigs (p < 0.05). The percentage of intramuscular fat in longissimus dorsi muscle was higher in TP than in YP pigs (p < 0.05). The relationship between the percentage of intramuscular fat in longissimus dorsi muscle and average daily gain during the free-range fattening period adjusted to a quadratic function (p < 0.05). The concentration of α- and γ-tocopherol in subcutaneous backfat at slaughter was significantly higher in TP than in YP pigs (p < 0.05). It is concluded that Iberian pigs that have 8 months of age at the beginning of free-range feeding have adequate commercial quality.     

Feeding level in the period previous to the late fattening phase influences fat composition at slaughter in free-ranged Iberian pigs

A group of 11 pigs was fed with 70 g feed per kg of metabolic weight (H pigs) and another group of 11 pigs was fed with 50g feed per kg of metabolic weight (L pigs). In both experimental groups (H and L pigs), it was observed that the higher initial proportion of C16:0, C18:0 and C18:2 (n-6) in backfat at the beginning of the free-range feeding period, the greater decrease rate of these fatty acid proportions regarding weight gain during the free-range fattening period took place. On the other hand, the greater initial proportion of C18:1 (n-9), the smaller increase rate in the concentration of this fatty acid was observed. The intramuscular neutral lipids from L pigs had higher C18:3 (n-3) and lower proportions of monounsaturated fatty acids (MUFA) than those from H pigs, while intramuscular polar lipids from L pigs had significantly higher proportions of C18:0, PUFA, C18:3 (n-3) and (n-3) and significantly lower MUFA and C18:1 (n-9) proportions than those from H pigs. The alpha-tocopherol concentration found in Longissimus dorsi from L pigs was significantly higher (p < 0.012) than those from H pigs.     

Feeding level in the period previous to the late fattening phase influences fat composition at slaughter in free-ranged Iberian pigs

Abstract

A group of 11 pigs was fed with 70 g feed per kg of metabolic weight (H pigs) and another group of 11 pigs was fed with 50 g feed per kg of metabolic weight (L pigs). In both experimental groups (H and L pigs), it was observed that the higher initial proportion of C16:0, C18:0 and C18:2 (n-6) in backfat at the beginning of the free-range feeding period, the greater decrease rate of these fatty acid proportions regarding weight gain during the free-range fattening period took place. On the other hand, the greater initial proportion of C18:1 (n-9), the smaller increase rate in the concentration of this fatty acid was observed. The intramuscular neutral lipids from L pigs had higher C18:3 (n-3) and lower proportions of monounsaturated fatty acids (MUFA) than those from H pigs, while intramuscular polar lipids from L pigs had significantly higher proportions of C18:0, PUFA, C18:3 (n-3) and (n-3) and significantly lower MUFA and C18:1 (n-9) proportions than those from H pigs. The α-tocopherol concentration found in Longissimus dorsi from L pigs was significantly higher (p < 0.012) than those from H pigs.     

Effect of level of feed restriction during growth and/or fattening on fatty acid composition and lipogenic enzyme activity in heavy pigs

The influence of feeding system on growth performance, carcass characteristics, and fatty acids profile of subcutaneous backfat and lipogenic enzymes activity was studied. The following feeding systems were applied: HH: group of 12 pigs fed with a high feeding level during growth and fattening periods; HL: group of 12 pigs fed with a high feeding level during growth period and a low feeding level during fattening period; LH: group of 12 pigs fed with a low feeding level during growth period and a high feeding level during fattening period; LL: group of 12 pigs fed with a low feeding system during growth and fattening periods. The high and low feeding levels applied during growth and fattening periods were 70 and 35 g feed/kg live weight^0.75 (LW^0.75) day and 121 and 87 g feed/kg LW^0.75 day, respectively. The duration of the growth period was 163 days in all groups. The ages at slaughter of HH, HL, LH and LL pigs were approximately 383, 406, 439 and 503 days, respectively. The HH and LL pigs had the higher and lower average daily gain respectively, while the LH pigs presented the best feed conversion ratio during fattening period. At slaughter, the LL pigs had the higher value of loin width and the lower values of backfat thicknesses and Longissimus dorsi muscle intramuscular fat percentage (P<0.05). The subcutaneous backfat outer and inner layers from LH and LL pigs had a significantly (P<0.05) higher proportion of C18:1 n-9 and ΣMUFA (monounsaturated) acids than those from HH and HL pigs. The subcutaneous backfat inner layer from LL pigs had a lower C16:0 and ΣSFA (saturated) acids proportions than those from remaining groups of pigs. The activity of the fatty acid synthase (FAS) and glucose-6-phosphate dehydrogenase (G6PD) enzymes, measured in subcutaneous backfat, at the end of growing period was significantly (P<0.05) higher in pigs fed high feeding level during growing phase. An increase of feeding level during the fattening phase led to an increase in the activity of G6PD enzyme. In conclusion, a marked effect of feeding system was observed on pig productivity and fatty acid composition.     

The influence of age at the beginning of Montanera period on meat characteristics and fat quality of outdoor Iberian pigs

A total of 120 Iberian pigs of the Lampiña line that grew under outdoor conditions were used to study the effect of the age at the beginning of Montanera period (AM) on meat characteristics and fatty acid (FA) profile of subcutaneous fat. AM period is a free-range fattening phase from November to February in which pigs ate mainly acorns and grass. There were two treatments with two AM (20 pigs per treatment); 18 (P18) and 12 months (P12). Barrows and gilts were in the same proportion within each treatment. All the animals were slaughtered at the same time (at the end of Montanera period) reaching an average 160 kg of body weight. Meat from P18 had less protein and was more red (a*) (P < 0.05), but tended to show higher intramuscular fat content (P < 0.10) than meat from P12. Loin from P18 had lower thawing (P < 0.001) and cooking losses (P < 0.10) than loin from P12. The fat from P18 had higher monounsaturated FA content than fat from P12 pigs (P < 0.01) due to the higher level of C18:1 (P < 0.01) and C20:1 (P < 0.001). However, fat from P12 had higher polyunsaturated FA content than fat from P18 pigs (P < 0.01) because of the higher level of C18:2 (P < 0.001). It is concluded that both 12 and 18 months are adequate AM for purebred Iberian pigs from the commercial point of view. However, if the aim is to produce high-quality dry-cured Iberian products, the P18 pigs would be more advisable because had better meat and fat characteristics than the P12 pigs.     

Effect of sex,dietary glycerol or dietary fat during late fattening,on fatty acid composition and positional distribution of fatty acids within the triglyceride in pigs

The effect of sex, source of saturated fat (lard v. palm oil) and glycerol inclusion in the fattening diet on composition and fatty acid positional distribution in the triglyceride molecule was studied in pigs from 78 to 110 kg BW. Average daily gain and carcass characteristics, including ham and loin weight, were not affected by dietary treatment but sex affected backfat depth (P<0.01). A significant interaction between sex and glycerol inclusion was observed; dietary glycerol increased lean content in gilts but not in barrows (P<0.05 for the interaction). Individual and total saturated fatty acid (SFA) concentrations were greater in barrows than in gilts. In contrast, the concentration of total polyunsaturated fatty acids (PUFA) and of C18:2n-6, C18:3n-3, C20:3n-9 and C20:4n-6 in the intramuscular fat (IMF) was higher (P<0.05) in gilts than in barrows. Sex did not affect total monounsaturated fatty acids (MUFA) concentration in the IMF. The proportion of SFA in the subcutaneous fat (SF) was higher in barrows than in gilts (P<0.001). Within the individual SFA, sex affected only the concentrations of C14:0 and C16:0 (P<0.001). Dietary fat did not affect total SFA or PUFA concentrations of the IMF but the subcutaneous total MUFA concentration tended to be higher (P=0.079) in pigs fed lard than in pigs fed palm oil. Dietary glycerol increased total MUFA and C18:1n-9 concentration in the IMF and increased total MUFA and decreased C18:2n-6, C18:3n-3 and total PUFA concentrations in the SF. The data indicate that altering the fatty acid composition of the triglyceride molecule at the 2-position, by dietary intervention during the fattening phase, is very limited.     

Effects of dietary incorporation of different antioxidant extracts and free-range rearing on fatty acid composition and lipid oxidation of Iberian pig meat

This investigation was designed to evaluate the effects of feeding either free range or in confinement using concentrated diets with the same ingredients and oil source (5.5% of olive oleins) but with different antioxidant supplementation [control diet with a basal level of α-tocopheryl acetate (control); 200 mg/kg synthetic all-rac-α-tocopheryl acetate (Eall-rac); 200 mg/kg natural RRR-α-tocopheryl-acetate (ERRR-); flavonoid extract-enriched diet (AFlav); and phenolic compound-enriched extract (APhen)] on the fatty acid composition and lipid oxidation of Iberian pig muscle longissimus dorsi. The α-tocopherol concentration was significantly higher in muscles from free-range and ERRR- pigs than in muscles from Eall-rac pigs, and γ-tocopherol was only detected in muscles from free-range pigs. Longissimus dorsi muscles from free-range pigs had a significantly lower content of saturated fatty acids and higher content of polyunsaturated fatty acids than muscles from the other five groups of pigs fed in confinement; however, no significant effect on monounsaturated fatty acids was observed. No effect of dietary antioxidant supplementation (synthetic or natural α-tocopherol, flavonoid extract, or phenol extract) on the fatty acid composition of muscles was observed. A significant influence of dietary treatment on lipid oxidation was observed after 3 (P < 0.01), and 7 and 10 (P < 0.001) days of refrigerated storage, respectively. The lowest thiobarbituric acid-reactive substances (TBARS) values were found in pork chops from the free-range and ERRR- groups, intermediate values from the Eall-rac group, followed by AFlav and APhen, while the highest TBARS values corresponded to muscles from pigs fed the control concentrate. The source of α-tocopherol had a significant effect on lipid oxidation (P < 0.05), whereas the AFlav and APhen groups had similar TBARS values.     

Expression and genome polymorphism of ACSL1 gene in different pig breeds

Acyl coenzyme A long-chain 1 synthetase (ACSL1) plays a key role in animal fat synthesis and fatty acid β-oxidation. In order to research the function of the ACSL1 gene in pig, we analyzed the mRNA expression in liver, backfat and longissimus dorsi muscle by quantitative real-time PCR in Tibet pig (TP, n = 10), Diannan small ear pig (DSP, n = 10) and large white pig (LW, n = 10). The results showed that the mRNA expressions of the ACSL1 gene in liver and longissimus dorsi muscle of DSP and TP were significant higher than that of LW (P < 0.01). However, the expression in backfat of LW was significant higher than that of TP (P < 0.01) and DSP (P < 0.05). In addition, four SNPs located in 5' flanking region (T-1191C), exon 6(G173A), exon 14(C36T) and exon 17(T46C) were identified, and the allele frequencies of the four SNPs were significant different in indigenous and introduced pig breeds. The results indicated that the ACSL1 gene might be relative to the capacity of fat deposition and meat quality in pig breeds.     

PPARγ与c/EBPα基因在苏太猪不同组织中的表达水平探究

为探究PPARγ与c/EBPα基因在苏太猪不同组织中的表达与脂肪沉积的关系,本实验以10月龄苏太猪为研究对象,运用实时荧光定量PCR (q RT-PCR)技术检测PPARγ与c/EBPα基因mRNA在苏太猪心、肝、脾、肺、肾、胃、背最长肌和皮下脂肪8个组织中的表达水平。结果表明,PPARγ与c/EBPα基因在苏太猪的8个组织中均有不同程度的表达,其中,PPARγ基因在苏太猪脾脏组织中的表达量最高,皮下脂肪中的表达水平仅次于脾;以背最长肌中PPARγ基因的相对表达量作对比,背最长肌与脾、肺和皮下脂肪的相对表达差异极显著(p<0.01),其余为差异不显著(p>0.05),表达量高低顺序为脾>皮下脂肪>肺>心>胃>肾>肝>背最长肌;c/EBPα基因在苏太猪的皮下脂肪的表达量最高,以背最长肌中c/EBPα基因的相对表达量作对比,在肝、脾、皮下脂肪组织中表达差异极显著(p<0.01),肺的相对表达差异显著(p<0.05),其余组织中差异不显著(p>0.05),表达量的高低顺序为皮下脂肪>肝>脾>肺>肾>心>胃>背最长肌。两基因在各组织中表达趋势趋于一致。试验结果表明PPARγ和c/EBPα基因可能对猪脂肪沉积有重要影响。     

The effect of immunocastration on adipose tissue deposition and composition in pigs

Immunocastrated pigs (IC) exhibit intensive fat deposition after immunisation, but the underlying mechanisms of intensified fat metabolism and deposition are not yet fully understood. Moreover, there is also a lack of comparative studies performed on IC, entire males (EM) and surgical castrates (SC). The main objective of our research was, therefore, to characterise the adipose tissue from the quantitative, histo-morphological and biochemical perspectives in IC 5 weeks after their immunisation in comparison to EM and SC. Immunocastrated pigs had an intermediate position in carcass fatness traits between EM (the leanest) and SC (the fattest). The histo-morphological traits of the subcutaneous adipose tissue of IC were similar to those of SC and differed from those of EM; i.e., they exhibited larger adipocytes in the outer backfat and a larger lobulus surface area in both backfat layers than EM. Intensive fat tissue development in IC was corroborated with higher activities of lipogenic enzymes (i.e., fatty acid synthase, malic enzyme, glucose 6-phosphate dehydrogenase, citrate cleavage enzyme), which was especially pronounced in the subcutaneous adipose tissue of IC (1.5- to 2.7-fold higher activity than in EM or SC). The fatty acid composition of the backfat in IC was similar to that in EM pigs. Both IC and EM exhibited less saturated and more polyunsaturated fatty acids than SC. In contrast, the fatty acid composition of the intramuscular fat of longissimus dorsi muscle in IC pigs was more similar to SC than to EM (higher monounsaturated and lower polyunsaturated fatty acid content in IC and SC than EM). In this study, it was demonstrated that immunocastration notably influenced lipid metabolism. This was shown by increased quantity of lipid depots and with changes in adipose tissue cellularity compared to EM, with changes in the fatty acid composition of the intramuscular fat and enhanced lipogenic activity compared to both EM and SC. These results provide new insights into the specificity of adipose tissue development and deposition in IC compared to EM and SC.     

Productive performance, carcass and meat quality of intact and castrated gilts slaughtered at 106 or 122 kg BW

A total of 200 (Landrace × Large White dam × Pietrain × Large White sire) gilts of 50 ± 3 days of age (23.3 ± 1.47 kg BW) were used to investigate the effects of castration (intact gilt, IG v. castrated gilt, CG) and slaughter weight (SW; 106 v. 122 kg BW) on productive performance, carcass and meat quality. Four treatments were arranged factorially and five replicates of 10 pigs each per treatment. Half of the gilts were ovariectomized at 58 days of age (8 days after the beginning of the trial at 29.8 ± 1.64 kg BW), whereas the other half remained intact. The pigs were slaughtered at 106 or 122 kg BW. Meat samples were taken at Musculus longissimus thoracis at the level of the last rib and subcutaneous fat samples were taken at the tail insertion. For the entire experimental period, CG had higher (P < 0.05) BW gain and higher (P < 0.001) backfat and Musculus gluteus medius fat thickness than IG. However, IG had higher (P < 0.05) loin and trimmed primal cut yields than CG. Meat quality was similar for IG and CG but the proportion of linoleic acid in subcutaneous fat was higher (P < 0.001) for IG. Pigs slaughtered at 122 kg BW had higher (P < 0.001) feed intake and poorer feed efficiency than pigs slaughtered at 106 kg BW. An increase in SW improved (P < 0.001) carcass yield but decreased (P < 0.05) trimmed primal cut yield. Meat from pigs slaughtered at the heavier BW was redder (a*; P < 0.001) and had more (P < 0.01) intramuscular fat and less thawing (P < 0.05) and cooking (P < 0.10) loss than meat from pigs slaughtered at the lighter BW. In addition, pigs slaughtered at 122 kg BW had less (P < 0.01) linoleic acid content in subcutaneous fat than pigs slaughtered at 106 kg BW. Castration of gilts and slaughtering at heavier BW are useful practices for the production of heavy pigs destined to the dry-cured industry in which a certain amount of fat in the carcass is required. In contrast, when the carcasses are destined to fresh meat production, IG slaughtered at 106 kg BW is a more efficient alternative.     

Feeding vegetable oils to lactating ewes modifies the fatty acid profile of suckling lambs

The objective of this study was to evaluate the effects of vegetable oil supplementation of ewe diets on the performance and fatty acid (FA) composition of their suckling lambs. Forty-eight pregnant Churra ewes (mean BW 64.3±0.92 kg) with their 72 newborn lambs (prolificacy=1.5) were assigned to one of four experimental diets, supplemented with 3% of hydrogenated palm (PALM), olive (OLI), soya (SOY) or linseed (LIN) oil. Lambs were nourished exclusively by suckling from their respective mothers. Ewes were milked once daily, and milk samples were taken once a week. When lambs reached 11 kg, they were slaughtered and samples were taken from musculus longissimus dorsi (intramuscular fat) and subcutaneous fat tissue. No changes were observed in milk yield, proximal composition or lamb performance (P>0.10). Milk and lamb subcutaneous and intramuscular fat samples from the PALM diet had the highest saturated fatty acid concentration, whereas those of the OLI, SOY and LIN diets had the lowest (P<0.05). The greatest monounsaturated fatty acid concentration was observed in milk from ewes fed OLI, and the least in milk and in lamb subcutaneous and intramuscular fat samples from LIN and PALM diets. Milk and lamb fat from ewes fed PALM displayed the highest 16:0 proportion and the lowest 18:0 (P<0.05). There were higher concentrations of cis-9 18:1 in OLI samples (P<0.05), more 18:2n-6 in SOY lambs and milk fat (P<0.001) and the highest levels of 18:3n-3 and 20:5n-3 in LIN samples (P<0.01). Milk and lamb subcutaneous and intramuscular samples from SOY and LIN diets contained the most cis-9, trans-11 conjugated linoleic acid, whereas PALM samples had the least (P<0.01). Sheep diet supplementation with different oils, constituting up to 3% of their diets, resulted in changes in the FA composition of milk and the subcutaneous and intramuscular fat of suckling lambs, but did not affect either milk production or lamb performance.     

Chemical composition and oxidative status of tissues from Iberian pigs as affected by diets: extensive feeding v. oleic acid- and tocopherol-enriched mixed diets

The present work was intended to analyse the chemical composition and oxidative stability of the muscle biceps femoris and adipose tissues from Iberian pigs fed different finishing diets: free-range feeding on grass and acorns in a 'Montanera' traditional system (MON), fed in confinement with a mixed diet containing high-oleic sunflower oil (115 g/kg of diet) and supplemented with 250 mg/kg α-tocopherol (HOVE), and fed in confinement with a tocopherol-non-supplemented control mixed diet (CON). Muscles from MON pigs contained significantly (P < 0.05) higher amounts of intramuscular fat than those from HOVE and CON pigs. Muscles from MON and HOVE pigs had significantly higher levels of α-tocopherol than muscles from CON pigs whereas free-range feeding provided significantly higher levels of γ-tocopherol to muscles from MON pigs than the experimental diets did to CON and HOVE pigs. Adipose tissues from MON and HOVE pigs contained significantly lower proportions of saturated fatty acids and significantly higher levels of oleic acid and monounsaturated fatty acids than those from CON pigs. Tissues from MON pigs contained significantly smaller levels of polyunsaturated fatty acids than those from CON and HOVE pigs. To a higher extent, feeding background affected the fatty acid composition of polar lipids from the muscle biceps femoris than that of neutral lipids. Tissues from MON pigs contained significantly smaller ω-6/ω-3 values than those from pigs fed mixed diets. Compared to tissues from CON pigs, those from MON and HOVE pigs exhibited a higher oxidative stability as a likely result of a most favourable fatty acid composition and the presence of higher tocopherol levels.     

Breed difference and regulation of the porcine adipose triglyceride lipase and hormone sensitive lipase by TNFα

Adipose triglyceride lipase (ATGL) and hormone sensitive lipase (HSL) are major novel triglyceride lipases in animals. The aim of this study was to determine if there are differences in the porcine ATGL ( pATGL ) and HSL genes between Jinhua pigs (a fatty breed) and Landrace pigs (a leaner breed). In addition, the effect of TNFα and pATGL-specific siRNA ( pATGL-siRNA ) on the expression of pATGL and HSL in porcine adipocytes was also examined. Compared with Landrace pigs, the body weight ( BW ) of Jinhua pigs was lower ( P <  0.01), while intramuscular fat content (in the longissimus dorsi muscle), as well as the back fat thickness and body fat content were higher ( P <  0.01). The expression of pATGL and HSL mRNA in Jinhua pigs was lower ( P <  0.01) in subcutaneous adipose tissue, and greater ( P <  0.01) in longissimus dorsi muscle compared with Landrace pigs. In vitro treatment of porcine adipocytes with TNFα decreased ( P <  0.01) the glycerol release and the gene expression of pATGL , HSL and PPARγ in porcine adipocytes. Furthermore, transfection with pATGL-siRNA significantly decreased ( P <  0.01) the expression of pATGL , while it had no effect on the expression of HSL . Treatment with 25 ng/ml TNFα in conjunction with pATGL-siRNA significantly decreased ( P <  0.01) the expression of pATGL and HSL in cultured porcine adipocytes. These results provide useful information to further the understanding of the function of pATGL and HSL in porcine lipid metabolism, which should be applicable to the regulation of fat deposition and improvement of meat quality.     

The mRNA of lipin1 and its isoforms are differently expressed in the <Emphasis Type="Italic">longissimus dorsi</Emphasis> muscle of obese and lean pigs

Lipin1 has been documented to play an important role in adipogenesis. In the present study, the mRNA expression level of lipin1 and its isoforms in longissimus dorsi muscle were determined by semi-quantification RT-PCR in lean PIC and obese Rongchang pigs. Further, we determined mRNA expression for lipin1 and its two isoforms in Rongchang obese pigs which had either a high or low intramuscular fat content. We demonstrate for the first time that porcine lipin1 has two alternative forms, lipin-α and lipin-β. Unlike mice and humans where the lipin-β has 99 more nucleotides than lipin-α, we found that in swine, lipin-β has 108 more nucleotides than lipin-α. Our results indicate that the longissimus dorsi muscle of Rongchang obese pigs have a higher level of mRNA expression for lipin1 and its isoforms than PIC lean pigs. Furthermore, Rongchang pigs with higher intramuscular fat content had a higher lipin1 and lipin-β mRNA expression in longissimus dorsisi muscle than Rongchang pigs with lower intramuscular fat content (P < 0.05), whereas no difference was seen in lipin-α mRNA expression between Rongchang pigs with high or low intramuscular fat. The ratio of lipin-β mRNA to lipin-α mRNA was also significantly different between Rongchang pigs distinguished by a high intramuscular fat content compared with those with low intramuscular fat (P < 0.05). These data suggested that the lipin1 gene may have a crucial effect on body lipid accumulation in pigs, whereas the lipin-β isoform may play an important role in intramuscular fat deposition in obese pigs.     

Phenotypic and genetic parameters compared during repeated measures of longissimus muscle area and subcutaneous fat thickness in Nelore cattle

Real-time ultrasound is currently used for in vivo carcass evaluation of beef cattle. We estimated heritability and repeatability coefficients for ultrasound-measured carcass traits in Nelore cattle. We measured longissimus muscle area, backfat thickness, and rump fat thickness in male and female animals ranging in age from 10 to 26 months. The variance components were estimated by single-trait analysis using the derivative-free restricted maximum likelihood method, under an animal model. The complete data file included 3077 records of 1172 animals born between 2003 and 2008. Two analyses were performed using a repeatability model: a) all records of longissimus muscle area, backfat thickness, and rump fat thickness of animals aged 10 to 26 months, and b) considering two age periods (11 to 17 and 18 to 24 months). The heritability estimates ranged from 0.33 to 0.46 for longissimus muscle area, from 0.20 to 0.26 for backfat, and from 0.26 to 0.29 for rump fat, demonstrating that direct selection for these traits can provide genetic gain. The repeatability estimates were moderate, ranging from 0.42 to 0.73. The highest repeatability estimates were obtained for longissimus muscle area in both the first (0.70) and second (0.73) analyses. The repeatability estimates suggest that ultrasound measures are precise; higher precision was obtained for longissimus muscle area than for subcutaneous fat thickness. The latter could be obtained during periods of greater feed availability to increase precision.     

Rearing system and oleic acid supplementation effect on carcass and lipid characteristics of two muscles from an obese pig breed

Quality of pork depends on genotype, rearing and pre- and post-slaughter conditions. However, no information is available on rearing system changes and oleic acid supplementation on carcass characteristics and fatty acid (FA) profile of pork from the Alentejano (AL) pig, an obese breed. This study evaluates the effects of feeding low (LO) or high oleic acid diets (HO) to AL pigs reared in individual pens (IND) or outdoor (OUT) with access to pasture. Carcass composition was obtained and longissimus dorsi and semimembranosus samples were collected to analyse chemical composition and neutral and polar intramuscular lipids FA profile by gas chromatography. Statistical analysis was performed by a two-way ANOVA for rearing system and diet effects. OUT-reared pigs presented leaner carcasses than IND-reared ones. Both muscles presented lower intramuscular lipid content in OUT-reared pigs. Treatments affected the FA profile of muscles. Overall, OUT-reared pigs presented lower n-6/n-3 FA ratios, whereas pigs fed the HO diet exhibited lower saturated fatty acids (SFA), higher monounsaturated fatty acids (MUFA) levels and lower thrombogenic indexes on neutral intramuscular lipids than LO-fed pigs. On the polar fraction, OUT-reared pigs presented lower SAT and n-6/n-3 FA ratio, and higher polyunsaturated fatty acids (PUFA) levels on both muscles. Pigs fed the HO diet exhibited higher MUFA and lower PUFA levels on both muscles, and lower SAT levels on semimembranosus. This study shows rearing system and oleic acid supplementation have complementary effects and influence carcass composition and the nutritional quality of meat.     

Influence of dietary vitamin E and C supplementation on vitamin E and C content and thiobarbituric acid reactive substances (TBARS) in different tissues of growing pigs

To investigate the influence and possible interactions of dietary vitamin E and C supplementation on vitamin content of both vitamins and oxidative stability of different pork tissues 40 Large White barrows from 25 kg to 106 kg were allocated to four different cereal based diets: Basal diet (B), dl-alpha-tocopherylacetate + 200 mg/kg (E), crystalline ascorbic acid + 300 mg/kg (C) or both vitamins (EC). At slaughtering samples of liver, spleen, heart, kidney, backfat outer layer, ham and M. tongissimus dorsi were obtained. Growth performance of the pigs and carcass characteristics were not influenced by feeding treatments. Dietary vitamin E supplementation had a significant effect on the vitamin E and alpha-tocopherol concentration in all investigated tissues. Backfat outer layer, liver, spleen, kidney and heart had higher vitamin E concentrations than ham and M. longissimus dorsi. Dietary vitamin C supplementation tended towards enhanced vitamin E levels except for ham samples. Therefore, some synergistic actions without dietary vitamin E supplementation between the two vitamins could be shown. The vitamin C concentration and TBARS were increased or at least equal in all tissues due to vitamin C supplementation. Dietary alpha-tocopherol supplementation resulted in lower TBARS in backfat outer layer (malondialdehyde 0.35 mg/kg in B vs. 0.28 mg/kg in E), but increased in heart and ham. When both vitamins were supplemented (EC) TBARS were lower in M. longissimus dorsi and backfat outer layer, equal in heart and higher in liver and ham compared to a single vitamin C supplementation. Rancimat induction time of backfat outer layer was 0.3 h higher in C compared to B and 0.17 h higher in EC than in E. Correlations between levels of both vitamins were positive for kidney (r = 0.169), M. longissimus dorsi (r = 0.499) and ham (r = 0.361) and negative for heart (r = -0.350). In liver and spleen no interaction could be found. In backfat outer layer vitamin E was positively correlated with rancimat induction time (r = 0.550) and negatively with TBARS (r = -0.202), but provided no evidence that dietary vitamin E supply led to better oxidative stability.     

Contrasting cellularity on fat deposition in the subcutaneous adipose tissue and longissimus lumborum muscle from lean and fat pigs under dietary protein reduction

The production of pork with high amounts of intramuscular fat (IMF) without an increase in subcutaneous fat is highly desirable for the pig industry and consumers. Herein, we question the impact of dietary protein reduction (18% v. 13%) on fat deposition in the subcutaneous adipose tissue (SAT) and longissimus lumborum (LL) muscle using genetically diverse pigs for body fatness (lean v. fat). A clear effect of genotype was observed on plasma insulin (P=0.004) and leptin (P<0.001), as well as on backfat thickness (P<0.001), with the fat pigs having higher values. Accordingly, IMF was higher in the fat pigs, when compared with their lean counterparts (P=0.003), which was supported by enlarged adipocytes (P<0.001). The area of lipid droplets within the LL fibres (P=0.039) and extramyocellular lipids number (P=0.017) were increased in pigs fed reduced protein diets, regardless of genotype, which is consistent with higher levels of plasma triacylglycerols (P=0.002). The gene-expression pattern of lipogenic factors in the SAT was distinct from the LL muscle. In the SAT, PPARG expression was similar among genotypes (P>0.05), whereas in the LL muscle it was higher in the lean pigs (P=0.023), especially when fed on low protein diet (P=0.057). The CEBPA and FABP4 mRNA levels were increased in the SAT of fat pigs (P<0.001), without changes in the LL muscle (P>0.05). The influence of diet on FABP4 expression in the SAT was dependent on pig’s genetic background (P=0.005). In conclusion, fat deposition was clearly influenced by genotype and, to a lesser extent, by dietary protein level, the SAT being more sensitive than the LL muscle. One can speculate that the pathways involved in lipid metabolism are downregulated in intramuscular adipocytes when compared with SAT fat cells. This result might be a direct consequence of the relatively low proportion of adipocytes found in the LL muscle.