Production Traits In Pigs Research Articles

Detection of pig genome regions determining production traits using an information theory approach

Abstract The objectives of the study were to detect the SNPs associated with pig production traits and estimate interactions between the most informative pairs of SNPs using entropy analysis. 1296 pigs were genotyped and phenotyped. The following traits were recorded: backfat, days to 110 kg, feed conversion ratio, percent lean meat and terminal line index for Maxgro™. After validation of the genotypic data, 50 951 SNPs were considered for further analysis. Entropy and conditional entropy for each SNP were estimated. Mutual information for most informative SNPs was performed to estimate an interaction between pairs of SNPs. Generally, the majority of loci showed relatively small contributions to the traits. The largest number of SNPs with high conditional entropy coefficients was identified on chromosome 1. The most important SNPs and pairs of them for all traits were mainly located on chromosomes: 1, 4, 6, 7, 9, 14, 16 and 17. High mutual information was estimated for SNPs located nearby. Many of the most prominent SNPs are localised within candidate genes affecting pig production traits.

Joint analysis of longitudinal feed intake and single recorded production traits in pigs using a novel Horizontal model1

A novel Horizontal model is presented for multitrait analysis of longitudinal traits through random regression analysis combined with single recorded traits. Weekly ADFI on test for Danish Duroc, Landrace, and Yorkshire boars were available from the national test station and were collected from 30 to 100 kg BW. Single recorded production traits of ADG from birth to 30 kg BW (ADG30), ADG from 30 to 100 kg BW (ADG100), and lean meat percentage (LMP) were available from breeding herds or the national test station. The Horizontal model combined random regression analysis of feed intake (FI) with single recorded traits of ADG100, LMP, and ADG30. In the Horizontal model, the FI data were horizontally structured with FI on each week as a "trait." The additive genetic and litter effects were modeled to be common across different FI records by reducing the rank of the covariance matrices using second- and first-order Legendre polynomials of age on test, respectively. The fixed effect and random residual variance were estimated for each weekly FI trait. Residual feed intake (RFI) was derived from the conditional distribution of FI given the breeding values of ADG100 and LMP. The heritability of FI varied by week on test in Duroc (0.12 to 0.19), Landrace (0.13 to 0.22), and Yorkshire (0.21 to 0.23). The heritability of RFI was lowest and highest in wk 6 (0.03) and 10 (0.10), respectively, in Duroc and wk 7 (0.04 and 0.02) and 1 (0.09 and 0.20), respectively, in Landrace and Yorkshire. The proportion of FI genetic variance explained by RFI ranged from 20 to 75% in Duroc, from 19 to 75% in Landrace, and from 11 to 91% in Yorkshire. Average daily gain from 30 to 100 kg BW and ADG30 heritabilities were moderate in Duroc (0.24 and 0.22, respectively), Landrace (0.34 and 0.25, respectively), and Yorkshire (0.34 and 0.22, respectively). Lean meat percentage heritability was moderate in Duroc (0.37) and large in Landrace (0.62) and Yorkshire (0.60). The genetic correlation of FI with ADG100 increased by week on test followed by a 32% decrease from wk 7 in Duroc and a 7% decrease in dam line breeds. Defining RFI as genetically independent of production traits leads to consistent and easy interpretable breeding values. The genetic parameters of traits in the feed efficiency complex and their dynamics over the test period showed breed differences that could be related to the fatness and growth potential of the breeds. The Horizontal model can be used to simultaneously analyze repeated and single recorded traits through proper modeling of the environmental variances and covariances.

Association of missense MTTP gene polymorphism with carcass characteristics and meat quality traits in pigs

Microsomal triglyceride transfer protein, coded by MTTP gene, has multiple functions including participation in formation of chylomicrons, low-density lipoproteins, and very low-density lipoproteins. Therefore MTTP protein plays a key role in the transport of fats and cholesterol between membrane vesicles, which can be associated with lipid metabolism. In the present study, ENSSSCT00000010052.2:c.2518C>T (rs335896411) missense polymorphism (Leu>Phe) located in exon 18 of MTTP gene was investigated in order to estimate its potential association with production traits of pigs. The analysis was performed with five breeds (Duroc, Landrace, Large White, Pietrain, Pulawska pigs) and totally 678 pigs, for which the genotypes of c.2518C>T polymorphism were identified by the polymerase chain reaction–restriction fragment length polymorphism method. The present study showed a significant association of c.2518C>T polymorphism with carcass yield. When analyzing the whole population, CC homozygotes showed significantly higher carcass yield than heterozygotes (P ≤ 0.05). Moreover, c.2518C>T single nucleotide polymorphism (SNP) affected pH measured in loin (m. longissimus dorsi) and ham (m. semimembranosus) 45 min after slaughter. For both parameters, the highest pH values were obtained for CC pigs, while the lowest for heterozygotes (P ≤ 0.05). The SNP analyzed was also related with meat colour (yellowness intensity (b*)). Previous research confirmed that ENSSSCP00000009789.2:p.Leu840Phe polymorphism, via affecting MTTP protein activity, influences metabolism of fatty acids. Additionally, results obtained in the present study suggest that the analyzed missense mutation in porcine MTTP gene can be one of the potential genetic factors associated with meat quality (pork pH and colour) and carcass yield.

Joint analysis of longitudinal feed intake and single recorded production traits in pigs using a novel Horizontal model

Joint analysis of longitudinal feed intake and single recorded production traits in pigs using a novel Horizontal model

Using RNA‐Seq SNP data to reveal potential causal mutations related to pig production traits and RNA editing

RNA-Seq technology is widely used in quantitative gene expression studies and identification of non-annotated transcripts. However this technology also can be used for polymorphism detection and RNA editing in transcribed regions in an efficient and cost-effective way. This study used SNP data from an RNA-Seq assay to identify genes and mutations underlying production trait variations in an experimental pig population. The hypothalamic and hepatic transcriptomes of nine extreme animals for growth and fatness from an (Iberian×Landrace)×Landrace backcross were analyzed by RNA-Seq methodology, and SNP calling was conducted. More than 125000 single nucleotide variants (SNVs) were identified in each tissue, and 78% were considered to be potential SNPs, those SNVs segregating in the context of this study. Potential informative SNPs were detected by considering those showing a homozygous or heterozygous genotype in one extreme group and the alternative genotype in the other group. In this way, 4396 and 1862 informative SNPs were detected in hypothalamus and liver respectively. Out of the 32 SNPs selected for validation, 25 (80%) were confirmed as actual SNPs. Association analyses for growth, fatness and premium cut yields with 19 selected SNPs were carried out, and four potential causal genes (RETSAT, COPA, RNMT and PALMD) were identified. Interestingly, new RNA editing modifications were detected and validated for the NR3C1:g.102797 (ss1985401074) and ACSM2B:g.13374 (ss1985401075) positions and for the COG3:g3.4525 (ss1985401087) modification previously identified across vertebrates, which could lead to phenotypic variation and should be further investigated.

Genome-wide association analyses using a Bayesian approach for litter size and piglet mortality in Danish Landrace and Yorkshire pigs.

BackgroundLitter size and piglet mortality are important traits in pig production. The study aimed to identify quantitative trait loci (QTL) for litter size and mortality traits, including total number of piglets born (TNB), litter size at day 5 (LS5) and mortality rate before day 5 (MORT) in Danish Landrace and Yorkshire pigs by genome-wide association studies (GWAS).MethodsThe phenotypic records and genotypes were available in 5,977 Landrace pigs and 6,000 Yorkshire pigs born from 1998 to 2014. A linear mixed model (LM) with a single SNP regression and a Bayesian mixture model (BM) including effects of all SNPs simultaneously were used for GWAS to detect significant QTL association. The response variable used in the GWAS was corrected phenotypic value which was obtained by adjusting original observations for non-genetic effects. For BM, the QTL region was determined by using a novel post-Gibbs analysis based on the posterior mixture probability.ResultsThe detected association patterns from LM and BM models were generally similar. However, BM gave more distinct detection signals than LM. The clearer peaks from BM indicated that the BM model has an advantage in respect of identifying and distinguishing regions of putative QTL. Using BM and QTL region analysis, for the three traits and two breeds a total of 15 QTL regions were identified on SSC1, 2, 3, 6, 7, 9, 13 and 14. Among these QTL regions, 6 regions located on SSC2, 3, 6, 7 and 13 were associated with more than one trait.ConclusionThis study detected QTL regions associated with litter size and piglet mortality traits in Danish pigs using a novel approach of post-Gibbs analysis based on posterior mixture probability. All of the detected QTL regions overlapped with regions previously reported for reproduction traits. The regions commonly detected in different traits and breeds could be resources for multi-trait and across-bred selection. The proposed novel QTL region analysis method would be a good alternative to detect and define QTL regions.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2806-z) contains supplementary material, which is available to authorized users.

Polymorphism of the porcine miR-30d is associated with adipose tissue accumulation, its fatty acid profile and the ME1 gene expression

The miR-30 gene family includes potential regulators of adipogenesis. We searched for polymorphism in this gene family in 4 pig breeds: Duroc, Pietrain, Polish Landrace (PL), Polish Large White (PLW) and a synthetic line (L990). Altogether 5 single nucleotide polymorphisms (SNPs) in 3 genes were found, including one already known SNP rs340704946 within the pre-miR-30d genomic sequence. An association of the rs340704946 with intramuscular fat (IMF) content, abdominal fat accumulation and daily body mass gain in L990 was found. Moreover, the AG genotype was associated with an increased content of monounsaturated fatty acids (MUFA) in subcutaneous (P=0.027) and visceral fat (P=0.007) tissues when compared to the GG genotype. Analysis of PLW pigs revealed an association of the rs340704946 with transcript level of the ME1 gene in longissimus dorsi (LD) muscle (P=0.002), as well as the ME1 protein product in the LD muscle (P<0.001) and subcutaneous fat (P<0.001). We conclude that the rs340704946 can be considered as a functional polymorphism for pig production traits and fatty acid profile in adipose tissue.

Genome Wide Association Analysis Reveals New Production Trait Genes in a Male Duroc Population.

In this study, 796 male Duroc pigs were used to identify genomic regions controlling growth traits. Three production traits were studied: food conversion ratio, days to 100 KG, and average daily gain, using a panel of 39,436 single nucleotide polymorphisms. In total, we detected 11 genome-wide and 162 chromosome-wide single nucleotide polymorphism trait associations. The Gene ontology analysis identified 14 candidate genes close to significant single nucleotide polymorphisms, with growth-related functions: six for days to 100 KG (WT1, FBXO3, DOCK7, PPP3CA, AGPAT9, and NKX6-1), seven for food conversion ratio (MAP2, TBX15, IVL, ARL15, CPS1, VWC2L, and VAV3), and one for average daily gain (COL27A1). Gene ontology analysis indicated that most of the candidate genes are involved in muscle, fat, bone or nervous system development, nutrient absorption, and metabolism, which are all either directly or indirectly related to growth traits in pigs. Additionally, we found four haplotype blocks composed of suggestive single nucleotide polymorphisms located in the growth trait-related quantitative trait loci and further narrowed down the ranges, the largest of which decreased by ~60 Mb. Hence, our results could be used to improve pig production traits by increasing the frequency of favorable alleles via artificial selection.

Polymorphism of fat metabolism genes as candidate markers for meat quality and production traits in heavy pigs

High meat quality is required for dry-cured ham production, which quality depends on meat fat quantity and composition. The aim was to study the polymorphisms of six genes involved in fat metabolism, namely, Stearoyl-CoA desaturase (SCD), Diacylglycerol acyltransferase 1 and 2 (DGAT1 &DGAT2), Microsomal triglyceride transfer protein (MTTP), Fatty acid synthase (FASN) and Heart fatty acid binding protein (H-FABP) in two traditional (Large White or Duroc×(Landrace×Large White)) and two industrial hybrids (Goland and Danbred), which are used for dry-cured ham production.Significant associations of SCD and MTTP were found with carcass weight. DGAT2 was associated with back fat thickness and L* fat colour (objective white colour score). Several genes (DGAT2, MTTP &FASN) were associated with weight loss during salting, first step in dry-cured ham production, affecting final yield. Finally, MTTP was associated with shear force. Our findings suggest that the SCD, DGAT2, MTTP and FASN polymorphisms are associated with quality of heavy pig meat products.

Polymorphisms of the membrane-associated ring finger 4, ubiquitin protein ligase gene (MARCH4) and its relationship with porcine production traits

Membrane-Associated Ring Finger (C3HC4) 4, E3 Ubiquitin Protein, encoded by MARCH4 gene, plays an important role in protein ubiquitination. MARCH4 gene may be one of the candidate genes related with some phenotypic traits due to its function and chromosome localization in QTLs associated with pork quality (meat color, pH, water holding capacity and texture parameters). In the present study, all exons and their flanking regions were screened for the presence of SNPs with the use of High Resolution Melt (HRM) method. The frequencies of two of eight identified polymorphisms were estimated on a large number of pigs represented by five breeds. The association study showed that SNPs ENSSSCG00000016176:g.576T>G (localized in the promoter region) and ENSSSCT00000017613.2:c.675+5C>A (in the second intron) affected growth traits and characteristics of carcasses as well as meat quality in pigs. Both SNPs were related with lean meat percentage, the weights of the most valuable cuts for example as ham and loin, loin eye area and backfat thickness (p≤0.01). Furthermore, analyzed polymorphisms affected the length of fattening period, feed:gain ratio and test daily gain. The presented influence of MARCH4 polymorphisms on meat quality parameters was not conclusive. The ENSSSCG00000016176:g.576T>G polymorphism was associated with meat pH, while ENSSSCT00000017613.2:c.675+5C>A SNP was related with meat color. The present research showed that porcine MARCH4 gene is an interesting candidate gene associated with important pig production traits.

Estimation of Genetic Associations between Production and Meat Quality Traits in Duroc Pigs.

Data collected from 690 purebred Duroc pigs from 2009 to 2012 were used to estimate the heritability, and genetic and phenotypic correlations between production and meat quality traits. Variance components were obtained through the restricted maximum likelihood procedure using Wombat and SAS version 9.0. Animals were raised under the same management in five different breeding farms. The average daily gain, loin muscle area (LMA), backfat thickness (BF), and lean percent (LP) were measured as production traits. Meat quality traits included pH, cooking loss, lightness (L*), redness (a*), yellowness (b*), marbling score (MS), moisture content (MC), water holding capacity (WHC), and shear force. The results showed that the heritability estimates for meat quality traits varied largely from 0.19 to 0.79. Production traits were moderate to highly heritable from 0.41 to 0.73. Genotypically, the BF was positively correlated (p<0.05) with MC (0.786), WHC (0.904), and pH (0.328) but negatively correlated with shear force (−0.533). The results of genetic correlations indicated that selection for less BF could decrease pH, moisture content, and WHC and increase the shear force of meat. Additionally, a significant positive correlation was recorded between average daily gain and WHC, which indicates pork from faster-growing animals has higher WHC. Furthermore, selection for larger LMA and LP could increase MS and lightness color of meat. The meat quality and production traits could be improved simultaneously if desired. Hence, to avoid further deterioration of pork characteristics, appropriate selection of traits should be considered.

Effect of increasing the dietary tryptophan to lysine ratio on plasma levels of tryptophan, kynurenine and urea and on production traits in weaner pigs experimentally infected with an enterotoxigenic strain of Escherichia coli‡

This experiment examined if immune system stimulation of weaner pigs, initiated by inoculation an enterotoxigenic strain of Escherichia coli (ETEC), increased the requirement for dietary tryptophan (Trp), modulated the inflammatory response, altered plasma levels of Trp and its metabolite kynurenine (Kyn) and effected post-weaning diarrhoea. Individually housed pigs (n = 72) weaned at 21 d of age were allocated to one of six treatments (n = 12) according to a two by three factorial arrangement of (1) with or without ETEC infection and (2) three dietary ratios of standardised ileal digestible (SID) Trp to lysine (Lys) (SID Trp:Lys) of 0.16, 0.20 or 0.24, in a completely randomised block design. Pigs had ad libitum access to diets (per kg 14.13 MJ ME, 12.4 g SID Lys, 195 g crude protein) for 3 weeks after weaning. Pigs were infected with ETEC (O149:K98:K88) at 72, 96 and 120 h after weaning and then bled on day 3, 11 and 19. An increased dietary Trp:Lys ratio increased plasma Trp and Kyn (p < 0.001) without effect of infection. On day 3, pigs fed 0.24 SID Trp:Lys had lower levels of plasma urea than at 0.20 Trp:Lys (p = 0.047) and on day 11, plasma urea was lower at 0.20 than at 0.16 SID Trp:Lys (p = 0.007). Infection increased (p = 0.039) the diarrhoea index and deteriorated faecal consistency from day 4–10 (p < 0.05). Treatments did not affect haptoglobin and acid soluble glycoprotein levels or daily gain and feed intake. However, 0.24 SID Trp:Lys improved (p = 0.021) feed efficiency without an effect of infection. In conclusion, in the absence of dietary antibiotic growth promotants, increasing the dietary SID Trp:Lys ratio to 0.24 improved feed conversion ratio after weaning and increased plasma levels of Trp and Kyn regardless of infection with E. coli.

Novel Polymorphisms in Porcine 3′UTR of the Leptin Gene, Including a Rare Variant within Target Sequence for MIR-9 Gene in Duroc Breed, not Associated with Production Traits

The leptin gene (LEP) is considered as a functional candidate for production traits in livestock due to its crucial role in energy homeostasis. Because polymorphisms in regulatory sequences may affect gene expression, we searched for them in the 3′UTR of LEP and analyzed their association with production traits. Four breeds and a composite line were studied. In the Polish Landrace and Polish Large White breeds, 8 SNPs and 1 indel were observed; whereas, in the Duroc breed, 9 specific SNPs were found. Pietrain and Line 990 were monomorphic. One SNP (g.+168C>T), observed in the Duroc breed only, was located within a target site for microRNA (miR-9). Association studies showed a weak association between one SNP (c.+846C>T) and abdominal fat weight in the Polish Landrace only. Thus, we concluded that contribution of polymorphisms in the 3′UTR to phenotypic variability of pig production traits is marginal. Moreover, we presented an overview of known polymorphisms (128) in the pig leptin gene.

Effect of VRTN gene polymorphisms on Duroc pig production and carcass traits, and their genetic relationships.

The thoracic vertebral number is associated with body length and carcass traits, and represents one of the most important traits in the pig industry. Recent studies have shown that vertnin (VRTN) gene is associated with variations in the vertebral number in commercial European pigs. However, the genetic relationships and effect of this VRTN gene in pig production and carcass traits remain uncertain. Therefore, we investigated the genetic relationships among traits such as vertebral numbers, carcass weight and length-related traits, and meat production traits, and the effect of VRTN gene polymorphisms on these traits in a Duroc purebred population selected for its meat production traits. Highly positive genetic correlations were obtained between the thoracic vertebral numbers and length-related traits (0.56 to 0.84), whereas low correlations were obtained with production traits and carcass weight (-0.16 to 0.05). VRTN gene polymorphisms indicated that the number of thoracic vertebrae and length-related traits were significantly associated with the VRTN genotype, but had no significant effect on production traits and carcass weight. The results indicate that VRTN gene may be used as an effective selection marker to obtain pigs with high thoracic vertebral numbers and length-related traits, without adversely affecting meat production traits.

Association of a new mobile element in predicted promoter region of ATP-binding cassette transporter 12 gene (ABCA12) with pig production traits

ABCA12 gene encodes the protein of ATP-binding cassette transporter 12, which is probably associated with transport of lipids through cell membrane. In human, the research reveals that a single nucleotide polymorphism of ABCA12 gene is associated with obesity. In turn in pigs, ABCA12 gene is located in the chromosome region that is rich in the quantity traits loci (QTLs) associated with meat quality. Therefore, in this study the regulatory part of ABCA12 gene in pigs was analyzed. In promoter region of the investigated gene a long insertion was discovered that recalled the retrotransposone mobile element terminated by long tandem repeats at 3׳ ends. The analysis of the effect of new polymorphism on the porcine traits was performed in four different breeds used in Polish breeding. It was observed, that a new mobile element in promoter region of ABCA12 gene had some impact on few growth and meat quality traits such as daily gain, feed:gain ratio or meat brightness. This would confirm the fact that in this region on chromosome 15 the QTLs associated with economically important pig traits were identified.

Imprinted loci in domestic livestock species as epigenomic targets for artificial selection of complex traits.

The phenomenon of genomic imprinting, whereby a subset of mammalian genes display parent-of-origin-specific monoallelic expression, is one of the most active areas of epigenetics research. Over the past two decades, more than 100 imprinted mammalian genes have been identified, while considerable advances have been made in elucidating the molecular mechanisms governing imprinting. These studies have helped to unravel the epigenome--a separate layer of regulatory information contained in eukaryotic chromosomes that influences gene expression and phenotypes without involving changes to the underlying DNA sequence. Although most studies of genomic imprinting in mammals have focussed on mouse models or human biomedical disorders, there is burgeoning interest in the phenotypic effects of imprinted genes in domestic livestock species. In particular, research has focused on imprinted genes influencing foetal growth and development, which are associated with economically important production traits in cattle, sheep and pigs. These findings, when coupled with the data emerging from the various different livestock genome projects, have major implications for the future of animal breeding, health and management. Here, we review current scientific knowledge regarding genomic imprinting in livestock species and evaluate how this information can be used in modern livestock improvement programmes.

Dynamic Expression of MicroRNA-127 During Porcine Prenatal and Postnatal Skeletal Muscle Development

MicroRNAs (miRNAs), evolutionarily conserved non-coding RNAs in length 21-24 bp, play a critical role in skeletal muscle development. In this study, to explore the function of mircoRNA-127 in porcine skeletal muscle development, eight tissue samples from adult pigs and longissimus muscle samples at 26 developmental stages were collected from Tongcheng and Landrace pigs. The spatial-temporal expression profiles of miRNA-127 were carried out using step-loop quantitative real-time PCR (stem-loop RT-PCR). To explore the molecular functions of miRNA-127, we predicted its target genes and performed functional annotation using bioinformatics methods. Results suggested that miRNA-127 was abundantly expressed in heart, ovary, uterus and spleen tissues and was weakly expressed in liver, lung, kidney and small intestine in both Tongcheng and Landrace pigs. And miRNA-127 showed significant expression differences in heart, ovary, spleen and uterus tissues between these two breeds. miRNA-127 basically kept at a relatively stable high level in middle and later embryonic stages and a low expression level in early embryonic stages and postnatal stages, but the expression levels of miRNA-127 were higher in Tongcheng pigs than in Landrace at most developmental stages. miRNA-127 potentially regulated 240 candidate genes. Results of Gene Ontology and KEGG pathway analysis indicated that these genes could be involved in many molecular functions and mechanisms, such as regulation of the force of heart contraction, regulation of transcription, regulation of T cell differentiation, MAPK signaling pathway and GnRH signaling pathway. Many significantly enriched GO terms and KEGG pathways were related to skeletal muscle development. This study will be helpful to understand the biological function for miRNA-127 and identify candidate gene associated with meat production traits in pigs.

Analysis of sequence variability in the pig CART gene and association of polymorphism with fatness traits in a F2 population.

CART (cocaine- and amphetamine-regulated transcript) peptides are neuromodulators that are involved in appetite control and energy homeostasis. It can inhibit food intake and reduce body weight that have received much attention, but a direct and comprehensive relationship with pigs differing in fatness which could be applied to breeding well has not been established. This study aims to search for polymorphism within the porcine CART gene and evaluate the effect of specific genotypes with regards to an association with fatness traits in a F2 population consisting of 230 individuals. Screening of 2264 bp DNA fragment covering the entire CART gene revealed 29 mutations and four indels (insertion or a deletion), in which four unlinked SNPs (single-nucleotide polymorphisms) could be digested by enzymes and subsequently genotyped in two purebreds and a F2 population. Landrace (lean-type), one of purebreds, presented significantly higher CART expression level than Lantang (obese-type) in most tissues studied. Association analysis revealed that three SNPs (T415C, C640T and C847T) displayed significantly association (p < 0.05) with fatness traits. Additionally, they are in almost complete linkage disequilibrium. Western blotting experiments on these three SNPs loci revealed difference in CART expression among individuals with different genotypes, and the individuals with lower average live backfat thickness (BFAW) expressed CART protein at a bit higher level than others. Our study screened and mapped the genetic variations in the porcine CART gene, and confirmed three functional SNPs which are promising molecular markers for pig production traits.

Investigating maternal effects on production traits in Duroc pigs using animal and sire models

Variance components for production traits were estimated using different models to evaluate maternal effects. Data analysed were records from the South African pig performance testing scheme on 22224 pigs from 18 herds, tested between 1990 and 2008. The traits analysed were backfat thickness (BFAT), test period weight gain (TPG), lifetime weight gain (LTG), test period feed conversion ratio (FCR) and age at slaughter (AGES). Data analyses were performed by REML procedures in ASREML, where random effects were successively fitted into animal and sire models to produce different models. The first animal model had one random effect, the direct genetic effects, while the additional random effects were maternal genetic and maternal permanent environmental effects. In the sire model, the random effects fitted were sire and maternal grand sire effects. The best model considered the covariance between direct and maternal genetic effects or between sire and maternal grand sire effects. Fitting maternal genetic effects into the animal model reduced total additive variance, while the total additive variance increased when maternal grand sire effects were fitted into the sire model. The correlations between direct and maternal genetic effects were all negative, indicating antagonism between these effects, hence the need to consider both effects in selection programmes. Direct genetic correlations were higher than other correlations, except for maternal genetic correlations of FCR with TPG, LTG and AGES. There has been direct genetic improvement and almost constant maternal ability in production traits as shown by trends for estimated (EBVs) and maternal breeding values (MBVs), while phenotypic trends were similar to those for EBVs. These results suggest that maternal genetic effects should be included in selection programmes for these production traits. Therefore, the animal-maternal model may be the most appropriate model to use when estimating genetic parameters for production traits in this population.

The influence of CAST/MspI, HinfI, RsaI polymorphism on production traits in pigs

The aim of this study was to perform the CAST gene polymorphism genotyping and to verify its possible influence on the quantitative and qualitative indicators characterizing carcass value in pigs. The study found a significant effect of the CAST gene on carcass value. In the case of alelle A present in the CAST/HinfI gene there was a higher lean meat share (i.e. lower fat content) and therefore the detected quality of pork meat was lower. The significant differences were found between the homozygotes AA and heterozygotes AB, mainly in the amount of fat content (P?0.05). Concerning the CAST/MspI gene, it was found that genotype CD caused higher lean meat share due to the higher shares of muscles in the main meat parts. However higher lean meat share does lead to lower quality of the meat. Another discovered influence was that of the allele D, which was associated with the intramuscular fat content (IMF) in the neck (P?0.05). Our results also show signifiant influence (P?0.05) of the allele C on the qualitative indicators of pork meat (MS EC50). Concerning the CAST/RsaI polymorphism, the study proved that this polymorphism doesn?t influence any of the monitored qualitative parameters.