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Several genetic markers, previously associated with meat quality traits, have been proposed to be included in Iberian pig breeding programs. However, before being implemented, effects of these candidate SNPs on premium cuts' yield should be evaluated to avoid potential undesirable antagonistic effects. Therefore, the main goals of this study were to evaluate the effects of a set of 26 polymorphisms on premium cuts weights and to corroborate their effects on meat quality in a larger population. Phenotypic data of approximately 1550 Iberian pigs were recorded. The PRKAG3_rs319678464C and PRKAG3_rs1108399077G alleles were associated with an increase of shear force, water losses and color values and a reduction of average daily gain (ADG). The CAST_rs196949783G > A and ADIPOQ_rs3476515794T > G SNPs mainly affected IMF content, with this last SNP being the only one with significant effects on any of the carcass measures, specifically Longissimus thoracis et lumborum (LTL) weight. The ELOVL6_rs3473714672A, FASN_rs331694510A, MTTP_rs335896411C and ACACA_rs340781986C alleles were linked to a higher percentage of oleic acid and monounsaturated FA and a decrease in palmitic, palmitoleic and saturated FA. Besides, suggestive effects were observed between ELOVL6_rs3473714672A > G and ham and shoulder weights, and between MTTP_rs335896411T > C and LTL muscle weight. Finally, the NR6A1_rs326780270T allele was associated with a significant increase in ADG and tended to reduce the ham weight. The SNPs mapped to PRKAG3 (rs319678464G > C), ACACA, FASN and CAST genes could be implemented in breeding programs to improve meat quality traits without undesirable effects on carcass composition. The SNPs mapped to PRKAG3 (rs1108399077G > A) ELOVL6, MTTP and NR6A1 should continue to be tested in a larger number of animals.

This study investigated the effects of feeding protein-restricted diets during the growing period on performance and carcass quality traits of Duroc (boars) x Iberian (sows) crossbred pigs slaughtered at commercial weight for local pig production. Two trials were conducted in different management conditions, with 28 and 33 barrows, respectively. In each trial, pigs were divided into two dietary groups, one group received a control diet (CD, 16.5 % crude protein, CP) and the other one was fed a protein restricted diet (PRD_1 for Trial 1: 12.4 % CP; and PRD_2 for Trial 2: 10.0 % CP). At 100 kg of body weight (BW), five pigs per group and trial were slaughtered, while the remaining pigs were fattened on a standard finishing diet until reaching 160 kg BW before slaughter. No significant changes in growth, carcass and ham composition or backfat thickness due to decreased protein supply during the growing period were observed. However, the intramuscular fat content increased in Longissimus thoracis et lumborum (LTL) and ham muscles of PDR_2 pigs. Furthermore, the backfat fatty acid (FA) profile presented higher proportion of oleic and monounsaturated FAs in pigs fed PRD diets, while polyunsaturated FA decreased in PDR_2 pigs. The PRD_1 group exhibited higher redness and thawing water loss in LTL, while PDR_2 group showed greater redness, yellowness and thawing water loss values compared to the CD group. Overall, the results indicate that feeding protein-restricted diets during growing period did not have a substantial impact on growth or meat quality. The success of implementing such diets may be influenced by factors such as the protein restriction level and the animal management conditions.

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 finding

Near infrared spectroscopy (NIRS) can be useful in order to determine meat quality traits as a rapid and non-destructive technique. The aim of the present study is to assess the accuracy of NIRS technique to determine meat quality traits on Longissimus thoracis et lumborum muscle of open-air free-range Iberian pig (n = 287) both in intact and minced samples. Traits were measured by instrumental-chemical techniques: colour (L*, a* and b*), myoglobin content, centrifuge force water loss and texture: shear force and texture profile analysis (TPA: hardness, cohesiveness, springiness, chewiness). Calibration models between instrumental-chemical measures and NIRS spectral data were developed employing partial least square regressions (PLS). The samples were split in two random datasets (80 % in training set, 20 % in external validation set). An internal full cross-validation method was applied. Results were evaluated in terms of coefficient of determination (R2), root-mean-square error (RMSE), residual prediction deviation (RPD) and range error ratio (RER). Full spectral range was used to develop mathematical equations. As regard external validation procedure, the highest coefficients of determination (R2p) in intact loin samples were achieved for hardness, redness (a*) and yellowness (b*) (0.70.7. The models developed suggest the ability of NIRS for quantitative prediction of shear force and for a rough classification of colour parameters L*, a*, b* in minced samples as well as hardness in intact samples.

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.

Immunocastration (IC, vaccination against gonadotropin releasing hormone (GnRH)) is one alternative to surgical castration (SC) for preventing sexual development and boar taint in male pigs. A temporal increase in performance has been described for IC pigs before the second vaccination against GnRH. The objective of this work was to assess the effects of IC on Iberian male and female pigs (fed diets of increasing CP content) on performance, nitrogen retention (NR) and digestibility, and carcass traits. Fifty-four pure Iberian pigs individually housed were allocated to a 3 × 3 factorial arrangement with three sex groups (IC males, IC females and SC males), three diets (153, 137 and 119 g CP/kg DM; 14 MJ metabolisable energy/kg DM) and six pigs per treatment combination. Pigs were vaccinated at 18 weeks of age (40 kg BW) and seven weeks later (70–80 kg BW) and fed at 0.9 × ad libitum on BW basis. Two digestibility and nitrogen balance assays were performed before and after the second vaccination, respectively. Pigs were slaughtered at 105 kg BW. Before the second vaccination, Iberian IC males showed higher growth rate (g/day), feed efficiency, NR (g/day) and efficiency of NR than the other groups (P < 0.001). The NR and efficiency of NR was 40% greater in IC v. SC males (P < 0.001). After the second vaccination, no differences in performance between sex groups were detected (P > 0.05). Growth rate and feed efficiency were higher in IC males than in the other groups for the whole experimental period (from the first vaccination to slaughter; P < 0.001). After the second vaccination, differences among sex groups in NR and the efficiency of NR disappeared (P > 0.05). NR efficiency was 0.177 on average. No significant effects of dietary CP were detected on performance. The NR was greater in pigs fed the 153 CP diet (17 to 37%; P > 0.05). Lean components of carcass (sirloin, loin and butt lean) were greater in IC males than in the other groups (0.001 < P < 0.05). There were

Optimal foraging theory has typically paid little attention to species feeding on mobile prey and has emphasised energy intake rather than the nutritional contribution of food. The difficulty of capturing food has rarely been included in foraging models, even when it is a potentially important modulator of time devoted to foraging. From the central place foraging and provisioning perspectives, it is posited that at high levels of prey selectivity, the time spent to capture prey is longer than at low levels of prey selectivity. Furthermore, in the case of carnivorous predators, it is thought that nutritional composition does not influence foraging strategies. To explore these issues, we investigated the influence of abundance, size, difficulty of capture, gross energy and nutritional composition (fat, protein, protein-fat ratio and amino acid contents) of prey species on the foraging behaviour of a predator species, the common kestrel Falco tinnunculus, in a region of high diversity of prey species. Our results show that capturability index and load-size explain the foraging behaviour of kestrels. Preferred prey take longer to be provisioned, both selectivity and capturability might explain this result. It is also shown that specific nutritional components, such as protein and amino acid contents, are likely to explain food preference in this carnivorous-insectivorous species.

The main characteristics of the Iberian breed, an autochthonous pig breed of the Iberian Peninsula, are presented in this chapter along with the results of a literature review on productive traits. Reproductive performance was estimated by sow age at first parturition, litters per sow and year, piglets alive per litter, piglet weight at birth and at weaning, percentage of stillborn per litter, mortality at weaning, lactation length and farrowing interval. For growth performance, average daily gain and daily feed intake during lactation and in different growing phases are provided. Carcass traits were evaluated by age and weight at slaughter, hot carcass weight, carcass yield, backfat thickness measurements, muscle thickness and loin eye area. Meat quality traits of longissimus muscle (pH, objective colour measurements and intramuscular fat) were also assessed. The main part of the studies considered simulated practical production conditions in Iberian pig rearing although others evaluated a defined growing period, sometimes quite far from the usual commercial slaughter weight of this breed. Therefore, some figures should be interpreted with caution. Although a considerable number of studies on Iberian pig were included in the current review, scientific papers on reproductive performance and some meat quality parameters are still rather scarce.

The main characteristics of the Iberian breed, an autochthonous pig breed of the Iberian Peninsula, are presented in this chapter along with the results of a literatura review on productive traits. Reproductive performance was estimated by sow age at first parturition, litters per sow and year, piglets alive per litter, piglet weight at birth and at weaning, percentage of stillborn per litter, mortality at weaning, lactation length and farrowing interval. For growth performance, average daily gain and daily feed intake during lactation and in different growing phases are provided. Carcass traits were evaluated by age and weight at slaughter, hot carcass weight, carcass yield, backfat thickness measurements, muscle thickness and loin eye area. Meat quality traits of longissimus muscle (pH, objective colour measurements and intramuscular fat) were also assessed. The main part of the studies considered simulated practical production conditions in Iberian pig rearing although others evaluated a defined growing period, sometimes quite far from the usual comercial slaughter weight of this breed. Therefore, some figures should be interpreted with caution. Although a considerable number of studies on Iberian pig were included in the current review, scientific papers on reproductive performance and some meat quality parameters are still rather scarce.

Amino acid (AA) composition of body protein is considered constant although there are evidences that AA pattern in pigs may be altered by different factors. Pigs with different body composition and protein deposition rates—like fatty and lean pigs—may differ in AA composition, with possible consequences on their AA requirements. This work investigates effects of genotype and dietary lysine deficiency on AA composition of carcass and muscles of Iberian and Landrace × Large White pigs. Twenty-eight barrows (10 kg body weight [BW]), 14 from each breed, were used. They were randomly assigned to two experimental diets according to a factorial arrangement (two breeds × two diets). Diets were isonitrogenous and isoenergetic (200 ± 1 g CP/kg dry matter (DM); 14.7 ± 0.1 MJ ME/kg DM) and with identical chemical composition except for lysine concentration (10.9 and 5.20 g lysine/kg DM, for lysine-adequate (AL) diet and lysine-deficient (DL) diet respectively). Pigs were individually housed, and daily feed allowance was adjusted on a weekly basis according to BW. Pigs were slaughtered at 25 kg BW. Isoleucine, valine and phenylalanine concentration were higher in carcass protein of Iberian pigs (p <.01). In longissimus muscle, higher concentration of arginine, isoleucine, phenylalanine, lysine and valine (p <.001–p <.05), and lower of methionine (p <.001) were detected in Iberian pigs, whereas phenylalanine, leucine, lysine, threonine and methionine concentration decreased and arginine increased (p <.001–p <.05) when pigs were fed DL diet. Genotype and lysine deficiency effects were moderate in the AA composition of protein of biceps femoris muscle. The results show that AA proportions in protein of carcass and longissimus muscle can be influenced by pig genotype and conditions of lysine shortage. The biceps femoris muscle, with different functional and metabolic properties, shows more constant AA composition than longissimus, which seem to prevail independent from genotype or n

The purpose of this study was to investigate potential mechanisms involved in fat deposition promoted by dietary lysine deficiency, particularly intramuscular fat (IMF), and differential responses between fatty and lean pigs. Carcass traits and lipogenic enzyme activities and gene expression levels in muscles and adipose tissue were investigated in Iberian (fatty) and Landrace × Large White (LDW) pigs under identical feeding level (based on body weight (BW)) and management conditions. Twenty-eight barrows of 10 kg initial BW, 14 per breed, were fed two isoproteic (200 g CP /kg DM) and isocaloric (14.7 MJ metabolizable energy/kg DM) diets with identical composition except for the lysine content (1.09% for diet adequate in lysine and 0.52% for diet deficient in lysine). At a BW of 25 kg, pigs were slaughtered. Compared with pigs fed the lysine-adequate diet, in both genotypes lysine-deficient diet led to lower carcass protein concentration, lower relative proportions of leaner components (loin, ham and shoulder; P < 0.01), and higher carcass fatty components and carcass lipid concentration (P < 0.001). Irrespective of diet, the activity and gene expression of lipogenic enzymes (fatty acid synthase (FAS), malic enzyme (ME) and glucose-6-phosphate dehydrogenase (G6PDH)) were greater in Iberian than in LDW pigs, particularly in adipose tissue where transcriptional regulators involved in the control of adipogenesis and lipogenesis were also upregulated in Iberian animals. In backfat tissue, there was a small decrease induced by or no effects of lysine-deficient diet on the activity and gene expression of lipogenic enzymes, nor in gene expression levels of upstream regulators of lipogenesis and adipogenesis. In longissimus muscle, the activity of FAS, G6PDH and ME increased with lysine deficiency in both genotypes (P < 0.01) and an upregulation of gene expression of lipogenic enzymes was specifically observed in Iberian pigs (P < 0.05 to P < 0.001). In biceps femoris muscl

This study analyzes quality traits of longissimus lumborum and gluteus medius in surgically castrated (SC) males, inmunocastrated (IC) males and IC female Iberian pigs reared in intensive conditions (n = 18/sex). Vaccination with Improvac® was applied at 18 and 26 weeks of age and slaughtering at 31 weeks. At such conditions, notable sex differences were found. Both muscles of IC males were less red (P <.01), longissimus had lower intramuscular fat (P <.01) and gluteus less Fe content (P <.01) than SC males and IC females. Loins from IC males also exhibited higher drip losses (2.7% at 24 h) than SC males (1.9%) and IC females (1.6%) (P <.001). Fatty acid composition of muscles differed among sexes, especially polyunsaturated fatty acids, which varied as follows: IC males > IC females > SC males in both muscles. It was concluded that meat quality traits differed between inmunocastrated and surgically castrated male Iberian pigs.

In pig production, factors such as nutritional system and genotype affect quality characteristics of meat. This study was aimed to evaluate differences in nutritional composition and colour of meat between Iberian (IB) and Landrace × Large White (LLW) pigs reared under identical nutrition and management conditions. Nutrient composition, mineral content, fatty acid profile and instrumental colour of two muscles (longissimus thoracis and biceps femoris) were examined at two growing stages (50- and 115-kg weight). Significant differences were found in relation to genotype. IB muscles contained higher amounts of intramuscular fat, dry matter, monounsaturated fatty acids, iron and zinc, and were redder (higher a∗ value) and with less colour saturation (lower hue angle), than those from LLW pigs. Significant relationships between colour coordinates with the mineral content and the lipid profile of muscles were found: redness was mainly linked to iron, zinc and monounsaturated fatty acids levels, whereas yellowness was positively related with copper, polyunsaturated fatty acids and linoleic acid level. The results of the present study support that muscles from the IB pig genotype have special characteristics, which may enhance the overall quality of meat compared with conventional or high-lean porcine breeds, even under identical management system, due to its particular fat composition and colour attributes.

Immunocastration 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 < 0.001). Feed efficiency (G:F) was greater for IC males (0.289 vs 0.260 and 0.263; P < 0.01). Moreover, IC males exhibited increased carcass length and greater relative weights for most lean cuts, but they also had smaller carcass yield and belly proportions than the rest of groups. No relevant differences related to dietary treatments were detected. Further research would help to elucidate possible effects of immunocastration on Iberian pig lean growth.

Along this review we describe the results from a series of experiments performed to assess the utilization of dietary protein by the Iberian pig throughout different stages of its productive cycle. Nutritional dose-response studies involving several isoenergetic treatments differing in protein concentration -all with similar amino acid profile following the ideal protein concept- along with comparative growth and metabolic studies with conventional breeds have been performed. Our observations reveal that the capacity of this breed for protein accretion is rather limited compared to that of conventional breeds at similar stages of growth, and suggest the need for reducing the concentration of protein in the diet of the Iberian pig to comply with its metabolic profile. Basic comparative studies have brought to light information to help us explaining some of the metabolic peculiarities of this autochthonous breed of pigs, like the low capacity to accrete protein and lean tissue. We summarise all the information gathered in several experiments and provide recommendations on the concentration and composition of dietary protein in the diet for purebred animals during different phases of growth. Adequate nutritional management, particularly dietary protein provision, improves the efficiency of utilization of dietary protein and results in relevant economic, environmental and animal welfare benefits.

Trace elements (i.e. Fe, Cu and Zn) are essential for maintaining importantphysiological processes, and dietary requirements in pigs should be carefully established. Asa valid approximation to study trace mineral needs, an experiment was conducted to analysethe content of Fe, Cu and Zn in muscles from two porcine genotypes. Sixteen pigs (8 Iberian, IB, and 8 Landrace × Large White, LDW) were used. They were fed isoenergetic diets (14 MJ/Kg DM) containing either 130 or 170 g CP/kg DM, to match protein requirements of each breed (4 pigs/genotype and CP level).The pigs were sacrificed at 115 kg LW, and samples of longissimus dorsiandbiceps femorismuscles were obtained.Fe and Zn concentration in muscles was significantly influenced by genotype, being higher amongIB pigs. Asignificant effect of dietary protein was observed in the IB group, as pigs fed with higher protein levels had lower values of Fe in both muscles. Cu content was not affected by genotype or diet. These results indicate that deposition of trace minerals, such as Fe and Zn, is under genetic control, and support the importance of meat from IB pigs as a good source of Fe and Zn

The main objective of this work was to investigate the effects of feeding Lys-deficient diets on muscle biochemical characteristics, particularly intramuscular fat concentration and fatty acid profile, in a fatty (Iberian) and a conventional pig genotype (Landrace × Large White [LDW]) maintained in identical experimental conditions. Performance and plasma metabolite changes were also monitored. Twenty-eight barrows of 10 kg initial BW, 14 of Iberian and 14 of LDW breed, were randomly assigned to each of 2 experimental diets in a 2 × 2 factorial arrangement (2 breeds × 2 diets). Seven pigs were allocated to each treatment combination. Diets (isonitrogenous and isoenergetic; 200 g CP/kg DM and 14.7 MJ ME) based on barley, corn, corn gluten meal, and soybean meal, with identical composition, except for their Lys content (10.9 g/kg for the diet adequate in Lys and 5.2 g/kg for the diet deficient in Lys), were assayed. Pigs were housed in individual 2 m pens and fed at 85% of ad libitum intake of the Iberian genotype, of greater intake capacity. Daily feed allowance was based on BW individually measured each week. At 25 kg BW, pigs were slaughtered by exsanguination after electrical stun- ning. Blood samples were taken and longissimus dorsi and biceps femoris muscles were rapidly dissected and stored frozen prior to analysis. Performance was reduced in both pig breeds when fed Lys-deficient diets, particularly in LDW pigs (breed × diet interaction, P < 0.05). Intramuscular fat content increased in longissimus dorsi of Iberian (P < 0.05) and in biceps femoris of both pig genotypes (P < 0.01) when fed Lys-deficient diets. Oleic acid increased (P < 0.05) and PUFA acid decreased (P < 0.01) in longissiumus dorsi and biceps femoris of pigs of both genotypes fed Lys-deficient diets. The proportion of oxidative fibers (P < 0.001) and free l-carnitine content (P < 0.05) increased in longissimus dorsi of both pigs types fed Lys-deficient diets. Plasma creatinine was greater in LDW

The objective of the present work wasto investigate the effect of dietary Lys deficiency upon intramuscular fat (IMF) concentrationand its fatty acid profile in an obese (Iberian, IB) and aconventional pig genotype (LDW). We used 28 castrated male pigsof 10 kg of initial BW, 14 from each type. Pigs were fed two diets, based on barley, maize, gluten meal and soybean meal, with identical composition,except for their Lys content (0.98% Lys, diet AL, adequate in Lys; and0.47% Lys, diet DL, deficient in Lys). The rest of nutrients met or exceeded recommendations. Seven pigs from each type were fed one of the dietsat 85% of ad libitumof the Iberian pigs. At 25 kg BW pigs were slaughtered and L. dorsiand B. femorismusclessampled.Performance was reduced in both pig types fed LD diets, particularly LDW pigs (P<0.05).Pigs fed LD diets showed higher IMF contentand oleic acid proportion,and lowerrelative percentage of poliinsaturated fatty acids. Feeding Lys deficient diets canbe a suitable strategy for increasing meat quality,both in obese and lean pig types,although further research is needed to deep our knowledge on the mechanism involved in thesechanges