Abstract This study used qRT-PCR to examine variation in the expression of 13 myogenes during muscle development in four prenatal periods (21, 40, 70 and 90 days post-insemination) in commercial (the three-way Duroc, Landrace and Large-White cross) and local Piau pig breeds that differ in muscle mass. There was no variation in the expression of the CHD8, EID2B, HIF1AN, IKBKB, RSPO3, SOX7 and SUFU genes at the various prenatal ages or between breeds. The MAP2K1 and RBM24 genes showed similar expression between commercial and Piau pigs but greater expression (p < 0.05) in at least one prenatal period. Pair-wise comparisons of prenatal periods in each breed showed that only the CSRP3, LEF1, MRAS and MYOG genes had higher expression (p < 0.05) in at least one prenatal period in commercial and Piau pigs. Overall, these results identified the LEF1 gene as a primary candidate to account for differences in muscle mass between the pig breeds since activation of this gene may lead to greater myoblast fusion in the commercial breed compared to Piau pigs. Such fusion could explain the different muscularity between breeds in the postnatal periods.

Para avaliar a influência do gene halotano sobre a curva de crescimento de suínos, bem como sua interação com o sexo do animal, foi proposta uma modelagem hierárquica Bayesiana. Nesta abordagem, os parâmetros dos modelos não-lineares de crescimento (Logístico, Gompertz e von Bertalanffy) foram estimados conjuntamente com os efeitos de sexo e genótipos do gene halotano. Foram utilizados 344 animais F2(Comercial x Piau) pesados ao nascer, aos 21, 42, 63, 77, 105 e 150 dias. O modelo Logístico foi aquele que apresentou melhor qualidade de ajuste por apresentar menor DIC (Deviance Information Criterion) que os demais. As amostras das distribuições marginais a posteriori para as diferenças entre as estimativas dos parâmetros do modelo Logístico indicaram que o peso dos machos à idade adulta com genótipo heterozigoto (HalNn) foi superior ao dos homozigotos (HalNN). A título de comparação, também foi considerada a abordagem frequentista tradicional, baseada em dois passos distintos, a qual, por apresentar um menor poder de discernimento estatístico, não mostrou diferenças significativas

A hierarchical Bayesian modeling was used to evaluate the influence of halothane gene and its interaction with sex on pig´s growth curves. Under this approach, the parameters from growth models (Logistic, Gompertz and von Bertalanffy) were estimated jointly with the effects of halothane gene and sex. A total of 344 F2 (Commercial x Piau) animals were weighted at birth, 21, 42, 63, 77, 105 and 150 days in life. The Logistic model has presented the best fit based on DIC (Deviance Information Criterion). Thus, the samples from marginal posterior distributions for the differences between the parameters estimates of Logistic model have indicated that the maturity weight of males with heterozygous genotypes (HalNn) was superior to males with homozygous genotypes (HalNN). In order to realize a comparison with the traditional methodology, the frequentist approach based on two distinct steps also was used, but there was not identified significant differences between growth curve parameter estimates from each group (combinations of halothane genotypes and sex)

Objetivou-se com este trabalho realizar o mapeamento de Locos de características quantitativas (QTL) nos cromossomo 16, 17 e 18 de suínos e associar seus efeitos com características de desempenho. Utilizou-se uma população F2 proveniente do cruzamento de dois varrões da raça naturalizada brasileira Piau com 18 fêmeas de linhagem comercial (Landrace x Large White x Pietrain). A população foi genotipada para 11 marcadores microssatélites e o mapa de ligação específico dos marcadores para a população foi construído. Os marcadores de microssatélites foram considerados adequados para estudos de características quantitativas quando analisado o conteúdo de informação polimórfica (PIC). Para identificação do QTL, utilizou-se o método de regressão por intervalo de mapeamento e realizaram-se as análises por meio do programa QTLExpress. Foram detectados QTL não descritos na literatura para: número de tetas no cromossomo 16; peso aos 63 e aos 77 dias de idade no cromossomo 17; e peso aos 21 dias e idade de abate no cromossomo 18. Foram também identificados QTL já descritos em outras populações, como para peso aos 21 dias de idade no SSC16. As informações dos QTL significativos encontrados servem para futuros estudos de mapeamento fino com identificação de genes e para maior entendimento dos fenótipos produtivos de suínos.

The objectives of this study were to map Quantitative Trait Loci (QTL) in chromosomes 16, 17 and 18 and to associate their effects with performance traits in a F2 pig population developed by mating two Brazilian Piau sires with 18 crossbred dams (Landrace x Large White x Pietrain). The linkage map for this population was constructed after genotyping the animals for 11 microsatellite markers and scoring the genotype. Estimates of polymorphic information content (PIC) indicated that the microsatellite markers were appropriate for QTL analyses. Data were analyzed by interval mapping using the QTLEXPRESS program. New QTL were identified for teat number on SSC16, weight at 63 and 77 days of age on SSC17, weight at 21 days of age and slaughter age on SSC18. QTL already known in other populations were also identified for weight at 21 days of age on SSC16. The information of the significant QTL detected in this study is useful for future fine-mapping studies for identification of genes and to improve the knowledge about production traits in pig populations.

The objective was to map QTL on porcine chromosome 4 and to associate them with carcass and internal organ traits in an F2 population. The F1 population was produced by outbreed crossing, using two native Brazilian breed Piau boars and 18 commercial sows. A total of 617 F2 animals issued from 11 F1 boars and 54 F1 sows were typed for a total of five microsatellite markers. The data were analyzed by multiple regressions developed for the analysis of crosses between outbred lines, using the QTL Express software. Significant evidence for QTL was found for pig chromosome 4 regarding carcass and internal organ traits. All QTL were detected in the same region of the chromosome, designated FAT1.