Iberian Pig Production Research Articles

Use of Lupinus albus as a Local Protein Source in the Production of High-Quality Iberian Pig Products.

The replacement of soybean meal with sweet white lupin (Lupinus albus L.) seeds was investigated in the diets of Iberian pigs during the growing and fattening phases, evaluating its effects on growth performance, carcass traits, and meat quality. Iberian pigs (n = 50) were divided into two dietary groups (n = 25 per group), receiving either a lupin-based concentrate or a soybean meal-based concentrate. The data were analysed using one-way analysis of variance (ANOVA), with a significance level of p < 0.05. The results showed that lupin substitution had no adverse effect on body weight, average daily gain, or carcass characteristics. No significant differences were observed in meat quality parameters such as pH, colour, and texture. However, significantly (p = 0.007) lower levels of saturated fatty acids (SFA) content were found in the intramuscular fat of pre-finishing (primor) pigs fed lupin-based diets. In addition, these pigs had lower plasma triglyceride levels at the end of the growing phase. Overall, the results suggest that sweet white lupin is a viable alternative protein source in Iberian pig production, offering potential health benefits in line with consumer preferences for sustainably produced, healthier meat products, without compromising production efficiency or product quality.

Heat Production of Iberian Pig Exposed to High Temperature and Effect of Dietary Supplementation with Betaine or Zinc.

The effect of heat, and dietary betaine or zinc on the heat production (HP) of Iberian pigs was studied. Thirty barrows (44 kg) were individually housed for 28 days and assigned to one of five treatments: (1) thermoneutrality (20 °C) and fed a control diet (TN-CON) ad libitum; (2) hot (30 °C) and fed a control diet (HT-CON) ad libitum; (3) thermoneutrality and pair fed a control diet (TN-CON-PF) to HT-CON; (4) hot and fed a betaine-supplemented (0.5%) diet (HT-BET) ad libitum; and (5) hot and fed a zinc-supplemented (0.012%) diet (HT-ZN) ad libitum. On the 18th day, pigs were moved to a respirometry chamber (two chambers) under their respective treatment. The metabolizable energy (ME) intake, HP and respiratory quotient (RQ) were measured over 24 h. No differences (p > 0.05) were found in HP and RE between treatments. For RQ, TN-CON was greater (p < 0.01) than HT treatments, except for HT-BET. All RQs indicated an overall lipogenesis where betaine supplementation showed an intermediate value, indicating that it may have a positive effect on lipogenesis and overall growth. At 30 °C, betaine or zinc had no effect on HP and RE; ME intake was not reduced, indicating a genetic adaptation of Iberian pigs to heat.

Prediction of the Fatty Acid Profiles of Iberian Pig Products by Near Infrared Spectroscopy: A Comparison Between Multiple Regression Tools and Artificial Neural Networks

AbstractIn this study, the feasibility of predicting the lipid profiles of Iberian ham and shoulder samples by using near infrared (NIR) spectroscopy was evaluated. Gas chromatography analysis was the reference method used. The muscles analyzed and recorded by NIR spectroscopy were 76 Biceps femoris for Iberian hams and 72 Brachiocephalicus for Iberian shoulders. NIR calibrations were carried out by using two methods: modified partial least squares regression (MPLS) and artificial neural networks (ANN). With the MPLS method, it was possible to obtain equations with regression’s coefficients (RSQ) of &gt; 0.5 for 5 individual fatty acids and 3 summations: polyunsaturated fatty acids, n3 and n6. The use of neural networks made it possible to find equations with RSQ of &gt; 0.5 for 10 individual fatty acids, all of which are present in over 90% of the samples, and 5 summations of saturated, monounsaturated, and polyunsaturated fatty acids (SFA, MUFA, PUFA), n3 and n6, finding that the calibration curves of the fatty acids C18:1, C18:2n6, and C18:3n3 presented RSQ’s of &gt; 0.7. The results obtained indicate that NIR spectroscopy could be a very useful technology for the quality control of cured products as it allows estimating the main fatty constituents quickly and without using reagents.

Free-range acorn feeding results in negative carbon footprint of Iberian pig production in the dehesa agro-forestry system

Iberian pig production has its own quality regulation, which defines different handling and feeding systems for this breed. These differences influence production costs, market price and environmental impact. The most extensive system of fattening Iberian pigs is based on foraging acorns in a silvopastoral system named dehesa, and consumers usually associate the Iberian pork with this system, although nowadays more intensive systems are dominant due to their productivity and management simplicity. The aim of this study is to assess the Carbon Footprint (CF) of the different Iberian pig production systems using the Life Cycle Assessment (LCA) methodology.This study is based on data collected from 19 Iberian pig farms producing nursery growers (≤25 kg, 2 farms), pre-finished pigs (100–110 kg, 3 farms) and 3 types of finished pigs (150–175 kg), including free-range fattened pigs (17 farms), outdoor intensively fattened pigs (2 farms) and indoor intensively fattened pigs (2 farms). The CF was calculated with a “cradle to farm gate” approach using the kg of live weight (kgLW) as functional unit, and including C sequestration in soils and biomass, which was calculated by field monitoring in a selection of measuring points. The average CFs of the final products were 9.2 ± 2.5 kg CO2eq kgLW−1 for nursery growers, 5.6 ± 2.42 kg CO2eq kgLW−1 for pre-finished pigs, −5.6 ± 6.5 kg CO2eq kgLW−1 for free-range fattened pigs, 3.1 ± 1.5 kg CO2eq kgLW−1 for outdoor intensively fattened pigs and 7.7 ± 0.3 kg CO2eq kgLW−1 for intensively fattened pigs. The main C sinks of the dehesa system (trees and soil) sequestered an average of 3.18 t CO2eq ha−1 year−1. This C sequestration, averaging −10.2 ± 6.7 kg CO2eq kgLW−1 in free-range pig production, offsets 223% of the GHG emissions in those systems, which resulted in a negative CF (net CO2 sequestration). There was a direct relationship between CF and pig stocking rate, leading to strongly negative CF values on those farms with the lowest pig stocking rates.

Inclusion of olive by-products in growing diets causes minor effects on meat quality of Iberian pigs fattened in a traditional system

Aim of study: To evaluate two experimental diets based on olive cake supplied during the growth period as an alternative to the restricted feeding applied in the production of Iberian pigs fattened with acorn (Montanera system). Area of study: Southwest of Badajoz, Spain Material and methods: 44 Iberian pigs were divided in three diet groups: 1) control (C) group (n=15), 2) dry olive pulp (DOP) group, fed a compound feed elaborated with olive pulp (n=14), and 3) wet crude olive cake (WCOC) group, fed a compound feed and olive cake silage supplied ad libitum (n=15). Subcutaneous fat biopsies were taken and backfat thickness and longissimus thoracis et lumborum (LTL) area were measured. In addition, quality traits (intramuscular fat percentage, color, pigment content, water holding capacity and shear force) were measured in LTL. Backfat fatty acid profile and intramuscular fat were also analysed. Main results: Significant differences were observed between groups for most of the fatty acids in backfat at 95 kg but differences were of lower magnitude at 160 kg and affected only to C16:1, C18:0, C18:1, C20:0, C20:1 and ΣSFA. Otherwise, lower values for red color and myoglobin content and higher for thawing water losses were observed for DOP pigs. The WCOC did not affect the analysed quality traits. Research highlights: Experimental diets did not have an important impact on growth, carcass composition or meat quality. Therefore, WCOC dietary treatment could be an interesting alternative that could reduce the undesirable effects of feed restriction.

Exploring Sustainable Food Choices Factors and Purchasing Behavior in the Sustainable Development Goals Era in Spain

The aim of the present study was (1) to investigate what consumers include within the concept of food sustainability and its link with sustainable consumption, by identifying meaningful consumer typologies from the concept of food sustainability and food choice factors framed by SDG 12, and (2) to know how different farm systems attributes affecting purchase behavior are associated with such typologies. Consumers from two Spanish regions (n = 403) answered a paper questionnaire to know their degree of knowledge of sustainability, and beliefs, behavior, attitudes and preferences towards food sustainability, and the importance given to product characteristics and shopping practices. A principal component analysis was conducted to identify groups with similar answers, to average some of the questions before the final analysis of variance, which includes demographic classes as fixed effects. A cluster analysis using the most representative questions identified two clusters. cluster 1 (68.4%) responded to more sustainability-related attributes, and cluster 2 (31.5%) presented a less-expanded concept of sustainability. The origin of the product and quality certification (local, organic) was important for food purchase practices. The place of residence and gender differences of the consumers were the most influential factors. In the conjoint study, regarding the purchase of Iberian pork, cluster 1 remained unwilling to sacrifice outdoor systems and local breed at the expense of the price, in the case of the Iberian pig production. The most important demographic differentiator was the region of residence of the consumer. In conclusion, consumers are not aware of the wider aspects included in the sustainability concept. Moreover, the concept of sustainability elicits different meanings to the segments of the consumers identified.

Analysis of the Sustainability of Fattening Systems for Iberian Traditional Pig Production through a Technical and Environmental Approach.

Simple SummaryIberian traditional pig production has been linked to the use of the natural resources of the dehesa ecosystem. In the last decades, the Spanish livestock sector has experienced a significant transformation towards the intensification of livestock systems. The intensification of the system combined with the increased demand for high-quality Iberian products resulted in a greater demand for feedstuffs as inputs into the Iberian pig production system. For these reasons, the Iberian pig exploitation in the dehesa ecosystem should be studied considering economic and environmental criteria to identify strategies for more sustainable livestock production. From the analyses carried out, the relationship between livestock management and environmental values obtained has been determined. Iberian traditional pig production has room for improvement in terms of economic and environmental values. In order to achieve this, appropriate fattening strategies should be implemented to optimize the use of available resources and improve economic-environmental performance for sustainable development. The importance of exploring sustainable management on this animal system derives because a sustainable Iberian traditional pig production has an important role in maintaining the population in rural areas through livestock activity as an economic engine.At present, two types of fattening are carried out in Iberian traditional pig production. The montanera is the fattening system where fatteners are fed on acorns and pasture in the dehesa, and cebo de campo is the fattening where the pigs are fed on compound feed and natural resources, mainly pasture. The aim of this paper is to analyze Iberian fattening production from an economic and environmental approach in order to identify fattening strategies to increase the sustainability of this traditional livestock activity. Based on technical-economic and environmental variables, the differences between Iberian farms according to the types of fattening were determined using discriminant analysis techniques. The model based on environmental variables showed a greater predictive ability than that found in the model based on technical-economic variables. Consequently, environmental variables can be used as reference points to classify the Iberian farms according to the type of fattening. Furthermore, canonical correlation analysis allowed to study the relationships between both sets of variables, showing that environmental values had a strong correlation with technical-economic variables. The results of this study show that it is possible to improve the sustainability of Iberian traditional pig production through fattening strategies in both types of fattening.

Isolation, Genotyping, and Mouse Virulence Characterization of Toxoplasma gondii From Free Ranging Iberian Pigs.

The present study aimed to isolate and perform molecular and phenotypic characterization of Toxoplasma gondii strains infecting Iberian pigs bred under semi-free conditions and destined for human consumption. Blood and heart tissue samples from 361 fattening pigs from 10 various herds selected in the main areas of Iberian pig production were collected at a slaughterhouse; the sera were tested for anti-T. gondii antibodies using a commercial indirect ELISA kit, and a mouse bioassay was carried out using heart muscle of seropositive individual representatives from each geographical location. Seventy-nine (21.9%) of the 361 animals tested positive for anti-T. gondii antibodies according to the serology test. Fifteen samples of myocardial tissue were subjected to bioassay and 5 isolates (TgPigSp1 to TgPigSp5) were obtained. The isolates were characterized by using 11 PCR-RFLP genetic markers; three isolates had a ToxoDB #3 genotype (3/5) and two isolates had a ToxoDB #2 genotype (2/5). The TgPigSp1 and TgPigSp4 isolates were selected for virulence in mice characterization as instances of each different RFLP-genotype found. The TgPigSp1 isolate (#2 genotype) was virulent in mice with notable cumulative mortality (87.5%) and morbidity rates (100%); the TgPigSp4 (#3) was nonvirulent and triggered mild clinical signs in 42.1% of seropositive mice. Infection dynamics and organ distribution of both isolates were analyzed; the data revealed significant differences, including substantially higher parasite load in the lung during the acute phase of infection, in mice infected with TgPigSp1 than in the case of TgPigSp4 (median parasite load 7.6 vs. 0 zoites/mg, respectively; p < 0.05). Furthermore, degrees of severity of detected histopathological lesions appeared to be related to higher parasite burdens. Taking into account the unexpectedly high mortality rate and parasite load associated with the clonal genotype III, which is traditionally considered nonvirulent in mice, the need for further investigation and characterization of the T. gondii strains circulating in any host in Europe is emphasized.

Understanding consumers' perceptions towards Iberian pig production and animal welfare

The Spanish market offers a greater variety of Iberian pork products. The aim of this paper is to determine the perception of consumers of several aspects of Iberian pig production and animal welfare depending on the consumers' characteristics. Consumers from two Spanish regions (n = 403) answered a questionnaire about their beliefs and the importance of pig production, their purchase intentions and their willingness to pay. Consumers were segmented according to their level of knowledge about Iberian pig production. The results of this work indicate that consumers have poor knowledge about Iberian pig production. Even so, consumers show a remarkable preference for Iberian products, especially when the animals are reared freely and in natural conditions, giving great importance to animal welfare. Consumer preferences indicate the importance of emphasizing Iberian traditional pig product characteristics on the label to promote their purchase choices.

Probabilistic classification models for the in situ authentication of iberian pig carcasses using near infrared spectroscopy

Iberian pig ham is one of several high value European food products that are the subject of significant attempts at fraud because of the high price differences between commercial categories. Iberian pig products are classified by the Spanish regulations into different categories, mainly depending on the feeding regime during the fattening phase and the race involved, being of Premium quality those products obtained from the animals fed with acorns and other natural resources. Most of the previous NIRS studies related to the Iberian pig have involved the use of at-line instruments to predict quantitative quality parameters. This paper explores the use of the NIR spectra (369 for training and 199 for validation) to classify samples according to the categories Premium (animals fed with acorn) and Non Premium (animals fed with compound feeds), using a MicroNIR™ Pro1700 microspectrometer to analyse individual carcasses in situ at the slaughterhouse line. Four discriminant methods were explored: linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), Kernel Bayes and Logistic Regression. These are all discriminant methods that naturally produce classification probabilities to quantify the uncertainty of the results. Rules were tuned and methods compared using both classification error rates and a probability scoring rule. LDA gave the best results, attaining an overall accuracy of 93% and providing well-calibrated classification probabilities.

Nuevas alternativas en la alimentación del cerdo Ibérico: uso de la avellana Gevuína

espanolLa produccion de cerdos Ibericos en montanera esta muy limitada por la produccion de bellota disponible. Con el objeto de ofrecer una alternativa se ha planteado el uso de la avellana Gevuina (Gevuina avellana), procedente de Chile, en la alimentacion de cerdos Ibericos. Para el estudio los animales se dividieron en dos grupos (n = 6 por grupo), a uno de ellos se le administro un pienso compuesto (a voluntad) y a un segundo grupo ademas del pienso, se le administro 2 kg de avellanas/animal y dia, hasta el momento del sacrificio. El analisis de las avellanas mostro que estas contienen una elevada cantidad de grasa (44 %) con una alta proporcion de acidos grasos monoinsaturados (MUFA) (93,94 %), cuyos acidos grasos mayoritarios fueron el palmitoleico (29,99 %) y el oleico (50,60 %). Los resultados mostraron que el incremento de C18:1n-9 con el tiempo en los cerdos suplementados con avellana fue superior (P = 0,0001) lo que se tradujo en un descenso en C16:0 mayor (P = 0,001) en comparacion con los que solo recibieron pienso, aunque el valor final de acido oleico en los animales suplementados con avellanas no supero a los animales no suplementados. Se observaron cambios en la relacion C16:1/C16:0 o C18:1/C18:0 de diferente magnitud que hace pensar en posibles efectos a nivel metabolico debidos a la diferencia en la ingestion de alimentos. Nuevos estudios son necesarios para indagar mas profundamente en los efectos que este fruto puede tener en la alimentacion de cerdos Ibericos y en la calidad de sus producto EnglishIberian pig production in the free-range system is limited by acorn production. In order to provide an alternative, the use of the Gevuina hazelnut has been proposed. Pigs were split up in two groups (n = 6 per group), one of those was provided with commercial feed (according to appetite) and the other was given a commercial feed and 2 kg of hazelnut/ animal and day until slaughter. The hazelnut analysis revealed they have a great proportion of fat (44 %), with a high amount of monounsaturated fatty acids (MUFA) (93.94 %), of which the main fatty acids where palmitoleic acid (29.99 %) and oleic acid (50.60 %). The C18:1n-9 concentration increased in the hazelnut group, as time increased (P = 0.0001), this led to a greater decrease of C16:0 concentration (P = 0.001) in the hazelnut group than in the other group. Although, the final level of C18:1n-9 in the hazelnut group did not exceed that reached by the mixed diet. Changes in C16:1/C16:0 and C18:1/C18:0 relations were observed, but of different magnitude, possibly due to metabolic effects because of the different feeding level of the two dietary groups. New studies are required to deeply examine the effects of this product may have in Iberian pig feeding and quality of their products

Automatic identification of the area covered by acorn trees in the dehesa (pastureland) Extremadura of Spain

The acorn is the fruit of oak trees and is an important crop in the Spanish dehesa extremeña because of the value it provides to feeding Iberian pigs to obtain the “acorn-fed” certification. For this reason, it is desirable to maximise production of Iberian pigs with the appropriate weight. Knowing the area covered by the acorn treetops to determine the Tree-Covered Area (TCA), a value required to estimate the number of Iberian pigs that can be released per hectare, as regulated by the Royal Decree 4/2014, issued by Spain in January of 2014. In this work, we propose a method to automatically estimate the TCA through digital aerial images (orthophotos) of the pastureland of Extremadura and, with this, to facilitate determining the number of Iberian pigs that can be released in a specific parcel of land. Requirements for automatic detection include the correct identification of acorn trees, correctly discerning their shadows, and discerning arbuscles (young acorn trees that are still unproductive, or shrubs that are not oaks). These requirements represent challenges that apply to both automatic and manual segmentations. The automated segmentation in this study is based on the modified version of the Gustafson-Kessel clustering algorithm presented by Babuska. The results of this work are promising when compared with the actual images and when compared with the results of manual segmentation. The entire set of 38 aerial images used in this work correspond to an approximate area of 15.56 hectares, and the results are of great interest to producers of Iberian pork with the “acorn-fed” certification.

Life Cycle Assessment of Iberian Traditional Pig Production System in Spain

Traditional Iberian pig production is characterized by outdoor systems that produce animals fed with natural resources. The aim of this study was to assess the environmental impacts of such systems through Life Cycle Assessment. Environmental impacts were analysed per kilogram of live weight at farm gate. Iberian pig production in montanera had the lowest impacts for climate change (CC), acidification (AC), eutrophication (EU) and cumulative energy demand (CED), being 3.4 kg CO2 eq, 0.091 molc H+ eq, 0.046 kg PO43− eq, and 20.7 MJ, respectively, due to the strict use of natural resources (acorns and grass) during the fattening period. As Iberian farms had a greater dependence on compound feed in cebo campo, environmental impacts on CC, AC, EU and CED were 22, 17, 95 and 28% higher, respectively, than with montanera. For land occupation (LO), however, cebo campo had a lower impact (31.6 m2·year) than montanera (43.0 m2·year) system. Traditional Iberian pig production systems have environmental impacts higher than conventional systems studied in literature but are similar to other traditional systems. Based on the present assessment, it is necessary to account for the contribution of emissions resulting from the consumption of natural resources to avoid the underestimation of environmental impacts.

Programa de selección genética enfocada en la calidad de cerdos Ibéricos puros de montanera

Selection programs are not frequent in the extensive Iberian porcine sector. The traditional company of Iberian pig products located in Jabugo (Sierra de Huelva), Sanchez Romero Carvajal (SRC), with the collaboration and assessment of the Animal Breeding Department of INIA, is making since the year 2012 an unusual effort to develop and implement a breeding selection scheme focused on the Iberian purebred products labelled as Bellota. The animals involved in this program belong to one herd which is placed in two different farms, Montecastilla and Tejarejo (La Granada de Riotinto). 1,205 animals of known pedigree were controlled for selection of growth, body composition, meat and fat quality traits. The main registered traits were average daily gain in montanera, slaughter and carcass weight and weight of premium cuts (ham, shoulders and loins). Besides, backfat fatty acid profile and quality traits as intramuscular fat percentage, color, thawing and cooking water loss and shear force were measured in loin as quality traits. Breeding values for these traits were estimated using an Animal model. Genetic predictions for maternal traits (number of piglets born alive and litter weight at weaning) were performed also using Animal models. Data from 5,134 litters born in 88 batches of 1456 dams and 22 sires were used. This information allowed estimating heritability and genetic correlation as well as to build a combined index for each trait weighting the breeding values by their corresponding economic values. In addition to this, molecular genetic studies on some of the traits cited above are also being implemented. These studies will allow increasing the efficiency of the conventional selection program in the future.

Performance and carcass characteristics of immunocastrated and surgically castrated Iberian pigs fed diets of different protein concentration. Preliminary results

espanolLa inmunocastracion ha resultado una estrategia util en el cerdo para prevenir el olor sexual en la carne. En trabajos previos se indica que los cerdos inmunocastrados (IC) pueden presentar mejores indices productivos que los castrados quirurgicamente (SC). Ademas de las ventajas en bienestar animal que conlleva esta practica, la mejora en produccion puede tener interes en razas como la Iberica, con capacidad de crecimiento limitada. El objetivo de este estudio ha sido examinar los efectos de la inmunocastracion sobre los indices productivos del cerdo Iberico, el uso de la proteina en la dieta y las caracteristicas de la canal, en animales alimentados con dietas de diferente concentracion proteica. Se utilizaron 27 animales de tres sexos (machos IC, machos SC, y hembras IC) alimentados con 3 dietas isoenergeticas (160, 140 y 120 g PB/kg materia seca), con tres animales por cada combinacion de tratamientos. Los animales se vacunaron contra la hormona liberadora de gonadotropina a los 4,3 (40 kg) y 6 meses de edad (70-80 kg). Los tratamientos se ofrecieron a los animales, que permanecieron alojados individualmente, desde los 40 a los 100 kg de peso. Se realizaron ensayos de digestibilidad y balance de N a los 50 y 90 kg de peso. A los 100 kg se sacrificaron los animales. Los resultados preliminares indican que los machos IC tuvieron un ritmo de crecimiento superior (803 vs 706 and 696 g/d, para machos IC, machos SC y hembras IC, respectivamente; P EnglishImmunocastration has proved to be an effective strategy to prevent sexual development and boar taint in pigs. Previous results indicate that immunocastrated (IC) pigs exhibit better performance than surgically castrated (SC) pigs. In addition to animal welfare benefits, this fact could be of interest for Iberian pigs, as their growth capacity rapidly diminishes as animal ages. The purpose of this study was to examine the effects of immunocastration on Iberian pig performance, protein utilization, and carcass traits under different dietary protein concentrations. Pure Iberian pigs (n=27) were used as follows: 3 sexes (IC males, IC females, SC males); 3 isoenergetic diets (160, 140 and 120 g CP/kg DM); 3 pigs/ group. Pigs were vaccinated against Gonadotropin Releasing Hormone at 4.3 months (40 kg) and 6 months (70-80 kg) of age. Experimental diets were offered to individually-housed pigs from 40 to 100 kg BW. Digestibility and N-balance assays were performed at 50 and 90 kg BW, respectively. Pigs were slaughtered at 100 kg BW. Preliminary results indicate greater growth rate for IC males (803 vs 706 and 696 g/d, for IC males, SC males and IC females, respectively; P

Developmental Stage, Muscle and Genetic Type Modify Muscle Transcriptome in Pigs: Effects on Gene Expression and Regulatory Factors Involved in Growth and Metabolism.

Iberian pig production includes purebred (IB) and Duroc-crossbred (IBxDU) pigs, which show important differences in growth, fattening and tissue composition. This experiment was conducted to investigate the effects of genetic type and muscle (Longissimus dorsi (LD) vs Biceps femoris (BF)) on gene expression and transcriptional regulation at two developmental stages. Nine IB and 10 IBxDU piglets were slaughtered at birth, and seven IB and 10 IBxDU at four months of age (growing period). Carcass traits and LD intramuscular fat (IMF) content were measured. Muscle transcriptome was analyzed on LD samples with RNA-Seq technology. Carcasses were smaller in IB than in IBxDU neonates (p < 0.001), while growing IB pigs showed greater IMF content (p < 0.05). Gene expression was affected (p < 0.01 and Fold change > 1.5) by the developmental stage (5,812 genes), muscle type (135 genes), and genetic type (261 genes at birth and 113 at growth). Newborns transcriptome reflected a highly proliferative developmental stage, while older pigs showed upregulation of catabolic and muscle functioning processes. Regarding the genetic type effect, IBxDU newborns showed enrichment of gene pathways involved in muscle growth, in agreement with the higher prenatal growth observed in these pigs. However, IB growing pigs showed enrichment of pathways involved in protein deposition and cellular growth, supporting the compensatory gain experienced by IB pigs during this period. Moreover, newborn and growing IB pigs showed more active glucose and lipid metabolism than IBxDU pigs. Moreover, LD muscle seems to have more active muscular and cell growth, while BF points towards lipid metabolism and fat deposition. Several regulators controlling transcriptome changes in both genotypes were identified across muscles and ages (SIM1, PVALB, MEFs, TCF7L2 or FOXO1), being strong candidate genes to drive expression and thus, phenotypic differences between IB and IBxDU pigs. Many of the identified regulators were known to be involved in muscle and adipose tissues development, but others not previously associated with pig muscle growth were also identified, as PVALB, KLF1 or IRF2. The present study discloses potential molecular mechanisms underlying phenotypic differences observed between IB and IBxDU pigs and highlights candidate genes implicated in these molecular mechanisms.

Copy number variants in a highly inbred Iberian porcine strain

We carried out a comprehensive genomic analysis of porcine copy number variants (CNVs) based on whole-genome SNP genotyping data and provided new measures of genomic diversity (number, length and distribution of CNV events) for a highly inbred strain (the Guadyerbas strain). This strain represents one of the most ancient surviving populations of the Iberian breed, and it is currently in serious danger of extinction. CNV detection was conducted on the complete Guadyerbas population, adjusted for genomic waves, and used strict quality criteria, pedigree information and the latest porcine genome annotation. The analysis led to the detection of 65 CNV regions (CNVRs). These regions cover 0.33% of the autosomal genome of this particular strain. Twenty-nine of these CNVRs were identified here for the first time. The relatively low number of detected CNVRs is in line with the low variability and high inbreeding estimated previously for this Iberian strain using pedigree, microsatellite or SNP data. A comparison across different porcine studies has revealed that more than half of these regions overlap with previously identified CNVRs or multicopy regions. Also, a preliminary analysis of CNV detection using whole-genome sequence data for four Guadyerbas pigs showed overlapping for 16 of the CNVRs, supporting their reliability. Some of the identified CNVRs contain relevant functional genes (e.g., the SCD and USP15 genes), which are worth being further investigated because of their importance in determining the quality of Iberian pig products. The CNVR data generated could be useful for improving the porcine genome annotation.

Longissimus dorsi transcriptome analysis of purebred and crossbred Iberian pigs differing in muscle characteristics.

BackgroundThe two main genetic types in Iberian pig production show important phenotypic differences in growth, fattening and tissue composition since early developmental stages. The objective of this work was the evaluation of muscle transcriptome profile in piglets of both genetic types, in order to identify genes, pathways and regulatory factors responsible for their phenotypic differences. Contemporary families coming from pure Iberian pigs (IB) or from crossing with Duroc boars (DU×IB) were generated. Piglets (14 from each genetic type) were slaughtered at weaning (28 days) and longissimus dorsi was sampled for composition and gene expression studies. RNA was obtained and hybridized to Affymetrix Porcine Genechip expression arrays.ResultsLoin muscle chemical composition showed significant differences between genetic types in intramuscular fat content (6.1% vs. 4.3% in IB and DUxIB animals, respectively, P = 0.009) and in saturated (P = 0.019) and monounsaturated fatty acid proportions (P = 0.044). The statistical analysis of gene expression data allowed the identification of 256 differentially expressed (DE) genes between genetic types (FDR < 0.10), 102 upregulated in IB and 154 upregulated in DU×IB. Transcript differences were validated for a subset of DE genes by qPCR. We observed alteration in biological functions related to extracellular matrix function and organization, cellular adhesion, muscle growth, lipid metabolism and proteolysis. Candidate genes with known effects on muscle growth were found among the DE genes upregulated in DU×IB. Genes related to lipid metabolism and proteolysis were found among those upregulated in IB. Regulatory factors (RF) potentially involved in the expression differences were identified by calculating the regulatory impact factors. Twenty-nine RF were found, some of them with known relationship with tissue development (MSTN, SIX4, IRX3), adipogenesis (CEBPD, PPARGC1B), or extracellular matrix processes (MAX, MXI1). Correlation among the expression of these RF and DE genes show relevant differences between genetic types.ConclusionThese results provide valuable information about genetic mechanisms determining the phenotypic differences on growth and meat quality between the genetic types studied, mainly related to the development and function of the extracellular matrix and also to some metabolic processes as proteolysis and lipid metabolism. Transcription factors and regulatory mechanisms are proposed for these altered biological functions.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-413) contains supplementary material, which is available to authorized users.

Carcass and meat quality traits of Iberian pig as affected by sex and crossbreeding with different Duroc genetic lines

A total of 144 pigs were used to study the effects of sex (barrows or gilts) and terminal sire line (Iberian or three genetic lines of Duroc: Duroc 1, Duroc 2 and Duroc 3) on performance and carcass and meat quality traits. Gilts showed slightly lower average daily gain, shoulder weight and trimming losses, but slightly better primal cuts yields and higher loin weight, while there was no significant effect of sex on meat quality traits or on the fatty acid composition of lard and muscle. There were important differences in performance and in carcass and primal cuts quality traits between pure Iberian pigs and all Iberian × Duroc crossbreeds evaluated, partly due to the lower slaughter weights reached by the formers. The different sire lines showed differences in several traits; Duroc 1 group showed lower backfat thickness and ham and shoulder trimming losses, and higher primal cut yields than Duroc 2 and Duroc 3 groups. Intramuscular fat (IMF) content remained unaffected by crossbreeding, but meat color resulted more intense and redder in crosses from the Duroc 1 sire line. The accumulation of fatty acids in lard was not affected by Duroc sire line, while animals of the group Duroc 2 showed higher levels of monounsaturated fatty acid and lower of polyunsaturated ones in IMF. These results highlight the importance of considering not only performance, but also carcass and meat quality traits when deciding the Duroc sire line for crossbreeding in Iberian pig production.

Predictive ability of the feeding system in Iberian pig by means of several analytical methods

The reliability of several analytical methods proposed to predict the feeding system received by Iberian pigs during the fattening period has been contrasted. Samples of subcutaneous adipose tissue were analyzed from 38 batches of pigs fattened in three seasons of montanera (acorn and pastures feeding). They corresponded to the four categories described in the Quality Standard for Iberian pig products: 251 samples of bellota , 164 of recebo , 197 of cebo de campo and 137 of cebo. To perform the study, the following analytical methods were used: fatty acid quantification, NIR, alpha and gamma tocopherol, chemical sensor, triacilglycerides, stable isotopes and neophytadiene. The laboratories received the samples without any information about the fattening system to which they belonged and remitted their predictions with respect to the above categories. The results showed a high percentage of accurate predictions of the methods when the fattening type corresponds to the extreme categories (bellota and cebo ), however, the methods had difficulty in discerning between samples from a mixed feeding regime with acorn and feed (recebo) and problems when pigs are fattened with compound feeds including vegetable fats with high levels of oleic acid. Although a simplification into only two categories ( cebo/campo and recebo/bellota ) results in a success rate higher than 90% for some methods, the combination of two or three techniques with problematic samples allows for differentiating among the four categories with the same accuracy.