Intramuscular Fatty Acid Composition Research Articles

Meat quality of veal: Discriminatory ability of weaning status

The physicochemical and fatty acid compositions of meat from 81 calves were measured in order to prove whether the extension of suckling period could distinguish “Normal” from “Suprema” class calves. Three groups of animals were investigated depending on their weaning status: NW (animals were milk-fed until seven months), W1 and W2 (animals which were weaned at different ages and reared either in family farms or in feedlot, respectively). There was no difference among animals in relation to the main components (moisture, protein and ash). Significant differences (p<0.05) were found regarding intramuscular fat; the contents were higher in animals weaned at early ages. Color and texture parameters were significantly affected by weaning status. The intramuscular fatty acid composition in the three types of animals showed that saturated fatty acids were the predominant ones in the three groups with values ranging between 48.71% and 49.52% of total methyl esters. Significant differences (p<0.001) were found depending on weaning status in linolenic acid and in the n-6/n-3 ratio, obtaining the highest values in NW animals. Factor analysis method using principal component was applied to the data. The data matrix constructed was subjected to a canonical discriminant analysis in order to classify the NW, W1 and W2 groups. These results showed that 96.6% for the NW group, and 66.7% and 82.4% for W1 and W2 groups respectively, were correctly classified.

Transcriptional analysis of intramuscular fatty acid composition in the longissimus thoracis muscle of Iberian × Landrace back‐crossed pigs

This study aimed at identifying differential gene expression conditional on the fatty acid profile of the longissimus thoracis (Lt) muscle, a prime cut of economic relevance for fresh and cured pork production. A population of 110 Iberian (25%)×Landrace (75%) back-crossed pigs was used, because these two breeds exhibit extreme profiles of intramuscular saturated fatty acid, monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) contents. Total RNA from Lt muscle was individually hybridized to GeneChip Porcine Genome arrays (Affymetrix). A principal component analysis was performed with data from the 110 animals to select 40 extreme animals based on the total fatty acid profile and the MUFA composition (MAP). Comparison of global transcription levels between extreme fatty acid profile pigs (n=40) resulted in 219 differentially expressed probes (false discovery rate <0.10). Gene ontology, pathway and network analysis indicated that animals with higher percentages of PUFA exhibit a shift toward a more oxidative muscular metabolism state, with a raise in mitochondria function (PPARGC1A, ATF2), fatty acid uptake and oxidation (FABP5, MGLL). On the other hand, 87 probes were differentially expressed between MUFA composition groups (n=40; false discovery rate <0.10). In particular, muscles rich in n-7 MUFA expressed higher levels of genes involved in lipid metabolism (GLUL, CRAT, PLA2G15) and lower levels of fatty acid elongation genes (ELOVL5). Moreover, the chromosomal position of FABP5, PAQR3, MGLL, PPARGC1A, GLUL and ELOVL5 co-localized with very relevant QTL for fat deposition and composition described in the same resource population. This study represents a complementary approach to identifying genes underlying these QTL effects.

Analysis of porcine adipose tissue transcriptome reveals differences in de novo fatty acid synthesis in pigs with divergent muscle fatty acid composition

BackgroundIn pigs, adipose tissue is one of the principal organs involved in the regulation of lipid metabolism. It is particularly involved in the overall fatty acid synthesis with consequences in other lipid-target organs such as muscles and the liver. With this in mind, we have used massive, parallel high-throughput sequencing technologies to characterize the porcine adipose tissue transcriptome architecture in six Iberian x Landrace crossbred pigs showing extreme phenotypes for intramuscular fatty acid composition (three per group).ResultsHigh-throughput RNA sequencing was used to generate a whole characterization of adipose tissue (backfat) transcriptome. A total of 4,130 putative unannotated protein-coding sequences were identified in the 20% of reads which mapped in intergenic regions. Furthermore, 36% of the unmapped reads were represented by interspersed repeats, SINEs being the most abundant elements. Differential expression analyses identified 396 candidate genes among divergent animals for intramuscular fatty acid composition. Sixty-two percent of these genes (247/396) presented higher expression in the group of pigs with higher content of intramuscular SFA and MUFA, while the remaining 149 showed higher expression in the group with higher content of PUFA. Pathway analysis related these genes to biological functions and canonical pathways controlling lipid and fatty acid metabolisms. In concordance with the phenotypic classification of animals, the major metabolic pathway differentially modulated between groups was de novo lipogenesis, the group with more PUFA being the one that showed lower expression of lipogenic genes.ConclusionsThese results will help in the identification of genetic variants at loci that affect fatty acid composition traits. The implications of these results range from the improvement of porcine meat quality traits to the application of the pig as an animal model of human metabolic diseases.

Genome-wide association study for intramuscular fatty acid composition in an Iberian × Landrace cross1

The lipid content and fatty acid (FA) profile have an important impact in human health as well as in the technological transformation and nutritional and organoleptic quality of meat. A genome-wide association study (GWAS) on 144 backcross pigs (25% Iberian × 75% Landrace) was performed for 32 traits associated with intramuscular FA composition and indices of FA metabolism. The GWAS was carried out using Qxpak 5.0 and the genotyping information obtained from the Porcine SNP60K BeadChip (Illumina Inc., San Diego, CA). Signals of significant association considering a false- discovery rate (q-value < 0.05) were observed in 15 of the 32 analyzed traits, and a total of 813 trait-associated SNP (TAS), distributed in 43 chromosomal intervals on almost all autosomes, were annotated. According to the clustering analysis based on functional classification, several of the annotated genes are related to FA composition and lipid metabolism. Some interesting positional concordances among TAS and previously reported QTL for FA compositions and/or other lipid traits were also found. These common genomic regions for different traits suggest pleiotropic effects for FA composition and were found primarily on SSC4, SSC8, and SSC16. These results contribute to our understanding of the complex genetic basis of FA composition and FA metabolism.

Effects of growth hormone gene polymorphism on lipogenic gene expression levels in diaphragm tissues of Japanese black heifers.

Two SNPs, i.e. L127V and T172M, of bovine growth hormone (GH) causing the presence of GH gene haplotypes A, B, and C was previously shown to alter intramuscular fatty acid (FA) composition in Japanese Black (JB) heifers. To determine the SNP effect on somatotropic hormone concentration and lipogenesis, we measured plasma GH, insulin, and insulin-like growth factor-1 (IGF-1) concentrations. We also measured mRNA levels of fatty acid synthase (FASN), stearoyl-coA desaturase (SCD), and sterol regulatory element binding proteins-1 (SREBP-1) and FA composition in diaphragm tissues. Heifers with genotype CC had the lowest plasma insulin concentration and FASN and SCD mRNA levels among genotypes. FASN mRNA levels in haplotype A tended to positively correlate with saturated FA (SFA) content and negatively correlated with C18:2 and unsaturated FA (USFA) contents. SCD mRNA levels in haplotype A positively correlated with monounsaturated FA (MUFA) contents and negatively correlated with C18:0 content. They also tended to positively correlate with C16:1, C18:1, and USFA contents and USFA/SFA ratio and negatively correlate with SFA content. Taken together, GH gene polymorphism affects the lipogenic genes expression levels and their relationships with fatty acid compositions in diaphragm tissues of JB heifers at 31 months of age.

Liver transcriptome profile in pigs with extreme phenotypes of intramuscular fatty acid composition.

BackgroundNew advances in high-throughput technologies have allowed for the massive analysis of genomic data, providing new opportunities for the characterization of the transcriptome architectures. Recent studies in pigs have employed RNA-Seq to explore the transcriptome of different tissues in a reduced number of animals. The main goal of this study was the identification of differentially-expressed genes in the liver of Iberian x Landrace crossbred pigs showing extreme phenotypes for intramuscular fatty acid composition using RNA-Seq.ResultsThe liver transcriptomes of two female groups (H and L) with phenotypically extreme intramuscular fatty acid composition were sequenced using RNA-Seq. A total of 146 and 180 unannotated protein-coding genes were identified in intergenic regions for the L and H groups, respectively. In addition, a range of 5.8 to 7.3% of repetitive elements was found, with SINEs being the most abundant elements. The expression in liver of 186 (L) and 270 (H) lncRNAs was also detected. The higher reproducibility of the RNA-Seq data was validated by RT-qPCR and porcine expression microarrays, therefore showing a strong correlation between RT-qPCR and RNA-Seq data (ranking from 0.79 to 0.96), as well as between microarrays and RNA-Seq (r=0.72). A differential expression analysis between H and L animals identified 55 genes differentially-expressed between groups. Pathways analysis revealed that these genes belong to biological functions, canonical pathways and three gene networks related to lipid and fatty acid metabolism. In concordance with the phenotypic classification, the pathways analysis inferred that linolenic and arachidonic acids metabolism was altered between extreme individuals. In addition, a connection was observed among the top three networks, hence suggesting that these genes are interconnected and play an important role in lipid and fatty acid metabolism.ConclusionsIn the present study RNA-Seq was used as a tool to explore the liver transcriptome of pigs with extreme phenotypes for intramuscular fatty acid composition. The differential gene expression analysis showed potential gene networks which affect lipid and fatty acid metabolism. These results may help in the design of selection strategies to improve the sensorial and nutritional quality of pork meat.

The effect of sex and DGAT1 gene polymorphism on fat deposition traits in simmental beef cattle

This study investigated diacylglycerol O-acyltransferase 1 (DGAT1) gene K232A mutation in Simmental cattle and its effects on fat deposition traits. The sample (n=26) consisted of yearling bulls and beef heifers from an intensive rearing system in Croatia. Carcass fatness was assessed by total dissection method, whereas intramuscular fat (m. longissimus dorsi) content was determined using Soxhlet extraction with hydrolysis. Intramuscular fatty acid composition was determined by gas liquid chromatography using in situ transesterification. The muscle DNA was extracted and Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCRRFLP) analysis of the 411 bp fragment of DGAT1 gene was applied. The DGAT1 K allele was less frequent in heifers than in bulls, with the overall allelic frequency of 17% K allele. Only KA and AA genotypes were obtained, without deviation from the Hardy-Weinberg equilibrium. Heifers showed a higher degree of carcass and muscle fattening with more unsaturated intramuscular fat than bulls; however, there was no interaction between sex and DGAT1 gene. Generally, no significant difference between DGAT1 AA and KA animals was observed for any of the examined traits, except the slightly higher carcass share of the fattest beef category and higher intramuscular C14:0 desaturation index in KA heterozygous.

Effect of morning vs. afternoon grazing on intramuscular fatty acid composition in lamb

The aim of this study was to assess whether different grazing management affect animal performance and meat fatty acid composition. Thirty-five lambs were divided into three groups: 12 lambs grazed from 9am to 5pm (8h group); 11 lambs grazed from 9am to 1pm (4hAM group) and 12 lambs grazed from 1pm to 5pm (4hPM group). The trial was conducted over 72days. The 8h lambs had greater DMI (P<0.0005) and final body weight (P<0.05) than the 4hPM and 4hAM lambs while carcass weight was not different between the three groups. The meat of the 4hPM lambs contained greater (P<0.05) percentages of polyunsaturated fatty acids, C18:2 cis-9 trans-11 and lower saturated fatty acids and C18:0 than the meat of the 8h and 4hAM lambs. It is concluded that allowing lambs to graze during the afternoon rather than during 8h does not compromise the carcass yield and results in a healthier meat fatty acid profile.

Effect of an elevated monounsaturated fat diet on pork carcass and meat quality traits and tissue fatty acid composition from York-crossed barrows and gilts

Fifty-seven York-crossed barrows and gilts were fed either a grain and soy diet (CONTROL with 28% C18:1) or a similar diet enriched with oleic acid (HO with 43% C18:1, Greedy-Grass OLIVA®). There were no interactions between dietary treatment and gender and there were no differences in intramuscular and subcutaneous fatty acid composition between sexes (P>0.05). Similar primal cut yields, composition of major primal cuts, and carcass and meat quality characteristics were found for HO and CONTROL fed pigs. Apart from a few significant but small differences for some fatty acids, intramuscular fatty acid composition was similar for both dietary treatments. Subcutaneous fat from HO fed pigs had a 6.9% increase in total monounsaturated fatty acids and a 9.3% reduction in total polyunsaturated fatty acids (P<0.05) compared with CONTROL fed animals, without adversely affecting carcass quality and producing suitable hams for processing by the meat industry.

Influence of stall finishing duration of Italian Merino lambs raised on pasture on intramuscular fatty acid composition

Forty male Italian Merino lambs were used to study the effects of four feeding systems on muscle fatty acids composition: S group—ten lambs were kept indoors, and fed with concentrate for all experimental period (89 days); P group—ten lambs were allowed to graze a pasture for all experimental period; PS37 group—ten lambs were allowed to graze a pasture for 52 days and shifted indoor, fed with concentrate, 37 days before slaughtered; PS14 group, where 10 lambs were fed on pasture for 75 days and shifted indoor, fed with concentrate, 14 days before slaughtered. Grazing lowered the levels of C12:0, C14:0, C16:0 and n-6 PUFA and increased n-3 PUFA and CLA isomer compared to concentrate feeding. After a short period of indoor finishing with concentrate, the fatty acid characteristics of the meat retain a part of the benefits occurring from grazing, while a longer period seems to erase almost all the benefits from grazing.

Evaluation of the Chinese indigenous pig breed Dahe and crossbred Dawu for growth and carcass characteristics, organ weight, meat quality and intramuscular fatty acid and amino acid composition

The objectives of the experiment were to evaluate growth and carcass characteristics, organ weight, meat quality and intramuscular fatty acid (FA) and amino acid composition between the Chinese indigenous pig breed Dahe and the crossbred Dawu. The Dahe pigs had lower average daily gain (P < 0.001) and a higher feed conversion ratio (P < 0.001) compared with the Dawu pigs. The Dahe pigs contained less lean meat percentage (P < 0.001) and more carcass fat percentage (P < 0.001) compared with the Dawu pigs. For organ weight, the Dahe pigs had lower relative heart weight and small intestine weight, respectively, compared with that of the Dawu pigs (P < 0.001). In addition, the Dahe pigs showed higher pH values (at 45 min and 24 h, P < 0.001 and P < 0.001, respectively), higher Marbling score (P < 0.05), lower Minolta L values (at 45 min and 24 h, P < 0.001 and P < 0.05, respectively) and lower muscle fiber area (P < 0.05) than did the Dawu pigs. C18:1, C16:0, C18:0 and C18:2 were the main FAs and nine essential amino acids were found in the Longissimus dorsi of the two breeds.

Lamb meat quality and intramuscular fatty acid composition as affected by concentrates including different legume seeds

The aim of this experiment was to study the effect of concentrates including legume seeds (Vicia faba var. minor or Pisum sativum) on lamb performances and meat quality, emphasizing the intramuscular fatty acid composition. Thirty lambs (14.5±3.45 kg live weight) were randomly assigned to three dietary treatments: i) group fed on concentrate including 400 g/kg of peas (PEA); ii) group fed on concentrate including 380 g/kg of faba bean (FB); iii) group fed on concentrate including 180 g/kg of soybean meal (SBM). Growth and slaughter performances were not affected by treatments as well as physical and proximate chemical meat characteristics. FB and SBM meat showed higher (P<0.001) vaccenic acid levels compared to PEA meat. Oleic acid was higher (P<0.05) in PEA meat compared to SBM meat while its level in FB meat was similar to counterparts. Linoleic acid levels tended to increase (P<0.10) in SBM lambs compared with PEA animals. PEA group showed higher (P<0.001) α-linolenic acid proportions compared with FB and SBM groups and a tendentially higher (P<0.10) eicosapentaenoic acid content compared with SBM meat. As a result, total n-3 fatty acids were higher (P<0.05) in PEA meat compared to SBM one while the proportions in FB meat were at intermediate level. These findings accounted for a lower and more favourable (P<0.001) n-6/n-3 ratio in PEA group compared with counterparts. Peas based-concentrate seemed to be more effective than faba bean- or soybean meal-included concentrates to improve the acidic profile of meat leading to higher α-linolenic acid levels and a lower n-6/n-3 ratio.

Intramuscular fatty acid composition of lambs fed diets containing alternative protein sources

Thirty male Merinizzata italiana lambs were divided into three groups after weaning according to live weight. The diet of the three groups differed in the main protein source used in the concentrate, soybean meal for treatment SBM, faba bean for treatment FB and peas for treatment PEA. Lambs were fed ad libitum and slaughtered at about 160 days of age. Meat from the PEA group had higher proportions of the essential fatty acids C18:2 ω-6 and C18:3 ω-3 than from FB and SBM lambs and consequently its derivatives, C20:4 ω-6 and C20:5 ω-3 respectively, were higher in meat from PEA animals, compared to SBM and FB ones. The total n-3 fatty acids were highest in meat from PEA lambs and consequently PEA lambs showed a more favourable n-6/n-3 ratio. In conclusion the use of legume seeds such as peas in lamb diets positively affected intramuscular fatty acid composition.

Intramuscular fatty acid composition of “Galician Mountain” foals breed

The effects of sex, slaughtered age (9 vs. 12 months) and livestock production system (freedom extensive system vs. semi extensive system) of "Galician Mountain" foals breed on the fatty acid composition were studied. The sex and slaughtered age of the animals had no statistical significance in the intramuscular fatty acids. Furthermore, the livestock production system showed differences in the fatty acid profiles from the Longissimus dorsi. The feeding system showed significant differences in PUFA content (P<0.001) higher in freedom extensive production system that semi extensive system, whereas MUFA content was significantly (P<0.001) higher in semi extensive system. This major PUFA content in freedom extensive production showed a significant (r=0.70, P<0.01) correlation with C18:3n-3 content and can be attributed to their eaten only pasture until slaughtered. The higher MUFA contents (P<0.001) observed for semi extensive production system foals were very significant (r=0.98, p<0.01) correlated with C18:1cis-9 content and less significant (r=0.81, P<0.01) correlated with C16:1cis-9 content. In addition, the data reinforced the evidence that foals from extensive production system on wood pasture have a higher nutritional quality (mainly due to the higher levels of n-3 PUFA) when compared to concentrate-fed foals, as a result of the beneficial effects of grass on meat fatty acid profiles.

Performance, meat fatty acid profile and meat colour of dairy bulls finished on grazed pasture or grass silage-based diets with similar concentrate allowances

The objective of this study was to determine the impact of grazed grass (PAS bulls) and grass silage-based (UB bulls) diets on the performance, intramuscular fatty acid composition and muscle colour of finishing dairy bulls with similar concentrate allowances, ages and carcass weights. There were no differences in gain, carcass conformation, carcass fat score or meat colour between treatments. The dressing proportion of the PAS bulls was 3% higher than that of the UB bulls (p<0.01). The Longissimus muscle (LM) of the UB bulls contained a higher proportion of 14:0 and 16:0 fatty acids and saturated fatty acids than that of the PAS bulls (p<0.05). The LM of the PAS bulls contained a higher proportion of 18:1n-7, 18:2n-6, 20:4n-6 and 20:5n-3 fatty acids and polyunsaturated fatty acids than that of the UB bulls (p<0.05). There were no differences in the 18:2 cis-9, trans-11 conjugated linoleic acid or monounsaturated fatty acid profiles between treatments.

Effect of sodium bentonite and vegetable oil blend supplementation on growth, carcass quality and intramuscular fatty acid composition of lambs

Abstract The effect of dietary sodium bentonite and a blend of sunflower and linseed oils at 1:2 (v/v) on growth, carcass and meat quality and fatty acid (FA) composition of longissimus dorsi muscle of lambs was studied. Thirty-two Merino Branco lambs with initial live weights (LW) of 16.2 ± 2.93 kg were divided according to a completely randomized experimental design within a 2 × 2 factorial arrangement of treatments in order to evaluate effects of the vegetable oil blend supplementation (0 g/kg versus 60 g/kg DM) and sodium bentonite inclusion in diets (0 g/kg versus 20 g/kg DM). The basal diet consisted of pellets with 750 g dehydrated lucerne/kg DM and 250 g manioc/kg DM. The experimental period was 6 weeks. Bentonite affected neither daily LW gain, dry matter (DM) intake, nor carcass composition. However, bentonite decreased the a* meat colour parameter (redness; P =0.004). Oil supplementation affected neither daily LW gain, nor DM intake. However, it increased fat proportion in chump and shoulder cuts ( P P P P P =0.007), mostly by increasing proportions of n -3 PUFA and biohydrogenation derived PUFA. Oil supplementation decreased n -6 long chain PUFA ( P n -3 long chain PUFA was not affected by oil supplementation, so the increase in n -3 PUFA from 1.99 g/100 g of total FA to 4.23 g/100 g of total FA ( P P n -3 long chain PUFA concentration from 20 to 31 mg ( P cis -11 18:1 which decreased, and cis -13 18:1 and trans -8, cis -10 18:2 which were unchanged. Conjugated linoleic acid increased with oil supplementation from 0.50 to 1.72 g/100 g of total FA ( P trans -11 18:1, but prevented the increase of trans -10 18:1 in meat from oil supplemented lambs ( P Trans -11, cis -15 18:2, cis -9, cis -15 18:2 and cis -9, trans -11, cis -15 18:3 increased with dietary bentonite inclusion.

Meat colour, fatty acid profile and carcass characteristics of Hereford bulls finished on grazed pasture or grass silage-based diets with similar concentrate allowance

The objective of this study was to determine the impact of grazed grass (PAS bulls) and grass silage-based (UB bulls) diets on muscle colour, intramuscular fatty acid composition and carcass characteristics of Hereford bulls with similar concentrate allowances, ages, growth rates and carcass weights. The carcass fat score of the UB bulls was 14% higher than that of the PAS bulls ( P < 0.05). Muscle lightness was 5%, redness 5% and yellowness 8% higher in the UB bulls than in the PAS bulls ( P < 0.05). The Longissimus muscle (LM) of the UB bulls contained a higher proportion of 14:1 and 16:0 fatty acids compared to that of the PAS bulls ( P < 0.05). In contrast, the LM of the PAS bulls contained a higher proportion of 18:3 n-3 fatty acid and 18:2 cis-9 trans-11 CLA compared to that of the UB bulls ( P < 0.01). There were no differences in saturated fatty acid, monounsaturated fatty acid or polyunsaturated fatty acid proportions of the LM muscle between treatments.

Effect of high dietary digestible fibre content on the fatty acid composition of two muscles in fattening rabbits

The effect of a high (260 g DF/kg DM) vs. a low (180 g DF/kg DM) dietary digestible fibre level on the intramuscular fatty acid composition of Longissimus lumborum and Biceps femoris was investigated in 24 fattening rabbits, allotted in two groups: low digestible fibre (LDF) and high digestible fibre (HDF). The animals were slaughtered at 2.77 kg and muscles were excised from the carcasses after chilling at 4 °C for 24 h. Muscle fatness and saturated fatty acids were not affected by the dietary digestible fibre, whereas monounsaturated fatty acids were lower ( p < 0.01) in HDF rabbits. An increase in the polyunsaturated fatty acids ( p < 0.05) observed for the HDF rabbits was attributed to its higher linoleic acid percentage (+ 1.2%). Microbial origin, namely odd-numbered (ONFA) and branched-chain (BCFA) fatty acids were higher ( p < 0.001) in both muscles by the high dietary digestible fibre content. Muscles in the HDF rabbits differed significantly in fatty acid composition and enzyme indices due to fatness mostly, but no significant interactions with the dietary digestible fibre were observed. Microbial origin fatty acids were different ( p < 0.001) between muscles independently of fatness. However, branched relative to odd-numbered fatty acids appeared to be distributed in the fatter Biceps muscle at a higher degree, as suggested by the lower ( p < 0.001) ONFA:BCFA ratio. Data adjustment for fatness showed that differences in fatty acid profile between muscles might be related to factors other than fatness. Considering the biological significance of branched-chain fatty acids the extent to which the influence of dietary digestible fibre occurs in different muscles of rabbit carcass, should be further investigated.

Genetic parameters for intramuscular fatty acid composition and metabolism in pigs1

The aim of this study was to estimate genetic parameters for pork intramuscular fatty acid (FA) composition and indices for desaturase and elongase activities involved in n-3 and n-6 PUFA metabolism. The LM of 437 slaughter pigs was analyzed for FA composition (expressed as g/100 g of FA). Indices for enzyme activities were calculated from product to precursor FA ratios. Genetic parameters were estimated with single- and multi-trait animal models. The total FA content, reflecting the intramuscular fat content, was either included or not in the model. Results from the models without total FA content showed relatively high heritability estimates, generally above 0.50, for the proportion of the most important MUFA and PUFA, compared with much smaller values for the SFA. When total FA content was included in the models, heritability values decreased (P < 0.001) for most individual FA and for all sums of FA groups, except for C18:0, C18:3n-6, and C18:3n-3. Heritability estimates for the ratios C20:4n-6/C18:2n-6 and C22:6n-3/C18:3n-3, reflecting the overall conversion in the n-6 and n-3 PUFA pathway, respectively, were 0.29 and 0.35, respectively, with total FA content in the model and increased to 0.38 and 0.49, respectively, if total FA content was not in the model. Heritabilities for other more specific indices were of the same order. Genetic correlations between PUFA proportions and indices for enzyme activities with ADG were mostly negative, whereas the correlations with carcass lean meat percentage were mostly positive. It was concluded that there is meaningful genetic variation for long-chain PUFA metabolism that is only partly dependent on the carcass and muscle fat content. This may allow selection for improved FA composition of pork.

Supplementation with barley or spineless cactus ( Opuntia ficus indica f. inermis) cladodes on digestion, growth and intramuscular fatty acid composition in sheep and goats receiving oaten hay

An 84-day experiment, comprising growth and digestibility trials, was conducted to evaluate the effect of replacing barley with spineless cactus ( Opuntia ficus indica f. inermis) cladodes (cactus) on feed intake, digestion, blood metabolites, growth and meat quality of male lambs and kids consuming oaten hay. The replacement of barley by cactus decreased drinking water intake ( P = 0.002) but had no effect on feed intake, diet digestibility and N balance ( P > 0.05). Irrespective of animal species, the barley diet exhibited higher concentrations of allantoin in urine ( P = 0.005) and therefore a higher microbial N supply ( P = 0.063) than the cactus diet. Average daily gain was greater for the barley than for the cactus diet ( P < 0.05), with a tendency for a greater difference for goats (46 g/day vs. 24 g/day) than for sheep (46 g/day vs. 39 g/day). The replacement of barley with cactus did not produce major differences in meat intramuscular fatty acid composition. Vaccenic acid concentration was significantly affected by treatment, being higher in meat of animals offered the cactus diet compared with the barley diet, while the accumulation of conjugated linoleic acid was not affected by the inclusion of cactus in the diet. Total saturated fatty acids, monounsaturated fatty acids (FA) and polyunsaturated FA were not influenced by supplementation with cactus. Despite the higher level of total n-6 FA in kids’ meat, the n-6/n-3 ratio had a very low value, which is favourable for human health. It is concluded that, in terms of equivalent energy, cactus cladodes could replace barley in the diet of lambs and kids without substantial detrimental effects on digestion, growth and meat quality. Therefore, cactus could be used as a cost-effective feed supplement for sheep and goats on low quality roughages raised in dry areas.