Estimation of in vivo body composition of Iberian pigs using bioelectric impedance and ultrasonography techniques.

Iberian pigs are renowned for their high-quality products and distinctive characteristics, including high fat accumulation, low protein deposition rate, and a long productive cycle. The study aimed to assess in vivo body composition of purebred Iberian pigs using bioimpedance analysis (BIA) and ultrasonography. Accurate estimation of body composition in live animals is crucial for adopting decisions at the farm level. The experiment involved three groups of pure male Iberian pigs differing in body weight (BW; 60, 80 and 100 kg) with the same nutritional management. Body measurements, BIA and back fat and loin thickness (measured by ultrasonography) were obtained before slaughter. After slaughter pig carcasses were chemically analysed. A strong correlation between BIA measurements, specifically resistance (Rs) values, and body chemical parameters (total protein, lipids, ash, and water contents; p < 0.001 for all) was found. Reactance values (Xc), however, did not exhibit significant correlations. Regression analyses were conducted to predict carcass composition based on BIA measurements, BW, ultrasonography and linear corporal measurements. The prediction models achieved high R2 values for lipids, protein, total ash, water, and lean tissue (0.957, 0.968, 0.936, 0.961 and 0.976, respectively, p < 0.001 for all), indicating strong predictive power. These findings demonstrate the potential of non-invasive techniques such as BIA for estimating body chemical composition and quality of pig carcasses. However, it is important to acknowledge that the prediction models developed may not be applicable to other pig populations, as they were based on a specific sample of pigs.

Design of a low-density SNP panel for intramuscular fat content and fatty acid composition of backfat in free-range Iberian pigs.

Intramuscular fat (IMF) content and fatty acids (FA) profile determine important sensory and technological characteristics of the meat, being interesting traits to be included in breeding programs for Iberian pig. In a previous study, we analyzed the longissimus dorsi transcriptome of Iberian pigs with divergent breeding values for IMF identifying 63 and 12 functional candidate genes and long non-coding RNA being differentially expressed. The first objective of this work was to use the RNA-seq data generated in that study in order to design a low-density panel with 50 single-nucleotide polymorphisms (SNP). The second aim was to evaluate the effects of this SNP panel on IMF content and backfat FA profile in a closed commercial population of Iberian pigs. The IMF content and backfat FA composition were determined in 940 Iberian pigs. A total of 837 SNPs were identified in the selection of genes and lncRNA. Out of the 50 selected SNP, 11 were monomorphic in the population and 2 failed in their genotyping. Association analyses were carried out for the 37 SNP segregating in the population (minor allele frequency, MAF > 0.05). Regarding IMF content, a significant additive effect (q-value < 0.05) was observed for ADIPOQ:g.124646194T > G SNP, in which the G allele was linked to an increase of 7.59% (additive effect expressed as a percentage of the mean of the trait). For the backfat FA composition, we observed 24 SNP with significant associations. The strongest effects were detected for the ELOVL6:g.112186423A > G and FASN_rs331694510G > A SNP. The A allele of both SNPs were associated to a lower percentage of palmitic (C16:0) and palmitoleic (C16:1) acids and an increase in oleic acid (C18:1). In addition, the AMPD3:g.49043886C > G SNP had significant effects on C16:0, stearic (C18:0), C18:1 and on the sum of saturated and monounsaturated fatty acids. Finally, significant effects of the EGR2:66286345G > T SNP on C18:0 and C18:1 and other minor FA were observed. Our findings reveal ADIPOQ:g.124646194T > G, ELOVL6:g.112186423A > G, and FASN_rs331694510G > A may be useful in breeding programs for Iberian pigs including FA profile and IMF content as selection goals, provided that their potential effects on other traits of interest are controlled.

Fat infiltration of muscle and fatty acid profile of cover fat are essential traits in Iberian pig industry. However, their inclusion in genetic selection schemes can be tangled, since their determination is laborious and expensive. Molecular markers can be a useful alternative to improve these traits. In a previous study, we analyzed the longissimus dorsi transcriptome of Iberian pigs with divergent breeding values for intramuscular fat (IMF) identifying 63 and 12 functional candidate genes and long non-coding RNA being differentially expressed. From this information, we designed a low-density panel with 50 single-nucleotide polymorphisms, which we subsequently evaluated for IMF content and fatty acids (FA) backfat profile of 940 pigs. The present research identified five polymorphisms mapped to ADIPOQ, ELOVL6, FASN, AMPD3, and EGR2 genes that are associated to IMF content and backfat FA profile.

Genetic parameter estimation and gene association analyses for meat quality traits in open-air free-range Iberian pigs.

Meat quality of Iberian pigs is defined by the combination of their genetic characteristics and the particular production system. To carry out a genetic analysis of the main meat quality traits, we estimated their heritabilities, genetic correlations and the association effects of 32 selected SNPs of 12 candidate genes. A total of ten traits were measured in longissimus dorsi samples from 1,199 Iberian pigs fattened in the traditional free-range system: water holding capacity (thawing, cooking and centrifuge force water losses), instrumental colour (lightness L*, redness a* and yellowness b*), myoglobin content, shear force on cooked meat, and shear force and maximum compression force on dry-cured loin. Estimated heritability values were low to moderate (0.01 to 0.43) being the lowest for L* and the highest for cooking loss. Strong genetic correlations between water holding capacity traits (0.93 to 0.96) and between myoglobin content and a* (0.94) were observed. The association analyses revealed 19 SNPs significantly associated with different traits. Consistent and strong effects were observed between PRKAG3 SNPs (rs319678464G > C and rs330427832C > T), MYH3_rs81437544T > C, CASP3_rs319658214G > T and CTSL_rs332171512A > G and water losses. Also for CAPN1_rs81358667G > A and CASP3_rs319658214G > T and shear force. The SNPs mapping on PRKAG3 showed the highest effects on Minolta colour traits. Genotyping of these SNPs could be useful for the selection of Iberian young boars with similar estimated breeding values for productive traits.