Application of deep learning with bivariate models for genomic prediction of sow lifetime productivity-related traits.

OBJECTIVE: Pig breeders cannot obtain phenotypic information at the time of selection for sow lifetime productivity (SLP). They would benefit from obtaining genetic information of candidate sows. Genomic data interpreted using deep learning (DL) techniques could contribute to the genetic improvement of SLP to maximize farm profitability because DL models capture nonlinear genetic effects such as dominance and epistasis more efficiently than conventional genomic prediction methods based on linear models. This study aimed to investigate the usefulness of DL for the genomic prediction of two SLP-related traits; lifetime number of litters (LNL) and lifetime pig production (LPP). METHODS: Two bivariate DL models, convolutional neural network (CNN) and local convolutional neural network (LCNN), were compared with conventional bivariate linear models (i.e., genomic best linear unbiased prediction, Bayesian ridge regression, Bayes A, and Bayes B). Phenotype and pedigree data were collected from 40,011 sows that had husbandry records. Among these, 3,652 pigs were genotyped using the PorcineSNP60K BeadChip. RESULTS: The best predictive correlation for LNL was obtained with CNN (0.28), followed by LCNN (0.26) and conventional linear models (approximately 0.21). For LPP, the best predictive correlation was also obtained with CNN (0.29), followed by LCNN (0.27) and conventional linear models (approximately 0.25). A similar trend was observed with the mean squared error of prediction for the SLP traits. CONCLUSION: This study provides an example of a CNN that can outperform against the linear model-based genomic prediction approaches when the nonlinear interaction components are important because LNL and LPP exhibited strong epistatic interaction components. Additionally, our results suggest that applying bivariate DL models could also contribute to the prediction accuracy by utilizing the genetic correlation between LNL and LPP.

Development of a Pedicle Screw Fixation Simulation Model for Surgical Training Using a 3-Dimensional Printer.

OBJECTIVE: Training surgeons in pedicle screw fixation (PSF) techniques during actual surgery is limited because of patient safety, complications, and surgical efficiency issues. Recent technical developments are leading the world to an era of personalized three-dimensional (3D) printing. This study aimed to evaluate the educational effect of using a 3D-printed spine model to train beginners in PSF techniques to improve screw accuracy and procedure time. METHODS: Computed tomography (CT) scan data were used in a 3D printer to produce a life-size lumbar spine replica of L1-3 vertebrae. Four residents performed PSF thrice. Each resident performed 18 screw fixations on both sides (6 screws per trial). The time to complete the procedure and pedicle violation was recorded. RESULTS: The average time for the 3 procedures was 42.1±2.9 minutes, 38.8±3.3 minutes, and 32.1±2.5 minutes, respectively. Furthermore, the average pedicle screw score for the 3 procedures was 13.0±0.8, 14.5±0.6, and 16.0±0.8, respectively. As the trial was repeated, the procedure time decreased and the accuracy of screw fixation tended to be more accurate. CONCLUSIONS: It was possible to decrease the procedure time and increase accuracy through repeated training using the 3D-printed spine model. By implementing a 3Dprinted spine model based on the patient's actual CT data, surgeons can perform simulation surgery before the actual surgery. Therefore, this technology can be useful in educating residents to improve their surgical skills.

Genetic Parameter Estimation and Genome-Wide Association Analysis of Social Genetic Effects on Average Daily Gain in Purebreds and Crossbreds.

Average daily gain (ADG) is an important growth trait in the pig industry. The direct genetic effect (DGE) has been studied mainly to assess the association between genetic information and economic traits. The social genetic effect (SGE) has been shown to affect ADG simultaneously with the DGE because of group housing systems. We conducted this study to elucidate the genetic characteristics and relationships of the DGE and SGE of purebred Korean Duroc and crossbred pigs by single-step genomic best linear unbiased prediction and a genome-wide association study. We used the genotype, phenotype, and pedigree data of 1779, 6022, and 7904 animals, respectively. Total heritabilities on ADG were 0.19 ± 0.04 and 0.39 ± 0.08 for purebred and crossbred pigs, respectively. The genetic correlation was the greatest (0.77 ± 0.12) between the SGE of purebred and DGE of crossbred pigs. We found candidate genes located in the quantitative trait loci (QTLs) for the SGE that were associated with behavior and neurodegenerative diseases, and candidate genes in the QTLs for DGE that were related to body mass, size of muscle fiber, and muscle hypertrophy. These results suggest that the genomic selection of purebred animals could be applied for crossbred performance.

Genome-Wide Assessment of a Korean Composite Pig Breed, Woori-Heukdon.

A Korean synthetic pig breed, Woori-Heukdon (WRH; F3), was developed by crossing parental breeds (Korean native pig [KNP] and Korean Duroc [DUC]) with their crossbred populations (F1 and F2). This study in genome-wide assessed a total of 2,074 pigs which include the crossbred and the parental populations using the Illumina PorcineSNP60 BeadChip. After quality control of the initial datasets, we performed population structure, genetic diversity, and runs of homozygosity (ROH) analyses. Population structure analyses showed that crossbred populations were genetically influenced by the parental breeds according to their generation stage in the crossbreeding scheme. Moreover, principal component analysis showed the dispersed cluster of WRH, which might reflect introducing a new breeding group into the previous one. Expected heterozygosity values, which were used to assess genetic diversity, were .365, .349, .336, .330, and .211 for WRH, F2, F1, DUC, and KNP, respectively. The inbreeding coefficient based on ROH was the highest in KNP (.409), followed by WRH (.186), DUC (.178), F2 (.107), and F1 (.035). Moreover, the frequency of short ROH decreased according to the crossing stage (from F1 to WRH). Alternatively, the frequency of medium and long ROH increased, which indicated recent inbreeding in F2 and WRH. Furthermore, gene annotation of the ROH islands in WRH that might be inherited from their parental breeds revealed several interesting candidate genes that may be associated with adaptation, meat quality, production, and reproduction traits in pigs.

Association of the ubiquitin specific peptidase 9X -linked and Afadin expression patterns with sexual maturation in boar testis.

Closely correlated expression patterns between ubiquitin specific peptidase 9X-linked (USP9X) and adherens junction formation factor (Afadin) in mouse testis development suggests that Usp9x regulates the deubiquitination of Af-6 (also known as Afadin, AFDN), and subsequently, the cell adhesion dynamics during gametogenesis. However, this relationship has not yet been tested in other domestic animals. The study was examined the temporal and spatial expression patterns of porcine USP9X and AFDN from the pre-pubertal to adult stages using real time-PCR and immunohistochemistry. Furthermore, we detected the transcripts of USP9X and AFDN in the testis of 1-, 6- and 12-months old boar, respectively. USP9X and AFDN were found to have similar expressions patterns, with basal expression after 1 month followed by a significant up-regulation from 6 months (puberty) onwards. In addition, neither the AFDN or USP9X proteins were detected in spermatogenic cells but they were expressed in the leydig cells and sertoli cells. USP9X was detected around the basal lamina during pre-puberty, and predominantly expressed in the leydig cells at puberty. Finally, in adult testis, USP9X was increased at the sertoli cell-cell interface and the sertoli cell-spermatid interface. In summary, closely correlated expression patterns between USP9X and AFDN in boar testis supports the previous findings in mice. Furthermore, the junction connections between the sertoli cells may be regulated by the ubiquitination process mediated via USP9X.

Genetic relationship between purebred and synthetic pigs for growth performance using single step method.

OBJECTIVE: The objective of this study was to estimate the genetic correlation (rpc) of growth performance between purebred (Duroc and Korean native) and synthetic (WooriHeukDon) pigs using a single-step method. METHODS: Phenotypes of 15,902 pigs with genotyped data from 1,792 pigs from a nucleus farm were used for this study. We estimated the rpc of several performance traits between WooriHeukDon and purebred pigs: day of target weight (DAY), backfat thickness (BF), feed conversion rate (FCR), and residual feed intake (RFI). The variances and covariances of the studied traits were estimated by an animal multi-trait model that applied the Bayesian inference. RESULTS: rpc within traits was lower than 0.1 for DAY and BF, but high for FCR and RFI; in particular, rpc for RFI between Duroc and WooriHeukDon pigs was nearly 1. Comparison between different traits revealed that RFI in Duroc pigs was associated with different traits in WooriHeukDon pigs. However, the most of rpc between different traits were estimated with low or with high standard deviation. CONCLUSION: The results indicated that there were substantial differences in rpc of traits in the synthetic WooriHeukDon pigs, which could be caused by these pigs having a more complex origin than other crossbred pigs. RFI was strongly correlated between Duroc and WooriHeukDon pigs, and these breeds might have similar single nucleotide polymorphism effects that control RFI. RFI is more essential for metabolism than other growth traits and these metabolic characteristics in purebred pigs, such as nutrient utilization, could significantly affect those in synthetic pigs. The findings of this study can be used to elucidate the genetic architecture of crossbred pigs and help develop new breeds with target traits.

Mechanical Properties and Metal-Ceramic Bond Strength of Co-Cr Alloy Manufactured by Selective Laser Melting.

Cobalt-chromium (Co-Cr) metal is one of the widely used biomaterials in the fabrication of dental prosthesis. The purpose of this study was to investigate whether there are differences in the properties of metals and bond strength with ceramics depending on the manufacturing methods of Co-Cr alloy. Co-Cr alloy specimens were prepared in three different ways: casting, milling, and selective laser melting (SLM). The mechanical properties (elastic modulus, yield strength, and flexural strength) of the alloys were investigated by flexure method in three-point bending mode, and microstructures of the specimens were analyzed. After application of the veneering ceramic through the three-point bending test, bond strength of the Metal-Ceramic was investigated. The cracked surfaces were observed by means of energy dispersive X-ray (EDX) spectroscopy and scanning electron microscopy (SEM) with backscattered electron (BSE) images. In mechanical properties, the elastic modulus was highest for the casting group, and the yield strength and flexural strength were lowest for the milling group. The SLM group showed finer homogeneous crystalline-microstructure, and a layered structure was observed at the fractured surface. After the ceramic bond strength test, all groups showed a mixed failure pattern. The casting group showed the highest bond strengths, whereas there was no significant difference between the other two groups. However, all groups have met the standard of bond strength according to international standards organization (ISO) with the appropriate passing rate. The results of this study indicate that the SLM manufacturing method may have the potential to replace traditional techniques for fabricating dental prosthesis.

Genome-wide investigation of a Korean synthetic breed, Woori-Heukdon using the Illumina PorcineSNP60K BeadChip.

BACKGROUND: Woori-Heukdon (KWH) is a Korean synthetic pig breed generated using Chookjin-Duroc (KCD), Chookjin-Chamdon (KCC), and their crossbreds. Currently, there is a severe lack of studies investigating the Korean breed populations including wild boars (KWB) throughout the genome. OBJECTIVE: This study was performed to investigate the genetic characteristics of Korean pig populations at the genome-wide level. METHODS: Using the SNP dataset derived from genotyped and downloaded datasets using the Illumina PorcineSNP60K BeadChip, we compared the genomes of 532 individuals derived from 23 pig breeds to assess the genetic diversity, inbreeding coefficient, genetic differentiation, and population structure. RESULTS: KWB showed the lowest average expected heterozygosity (HE = 0.1904), while KWH showed the highest genetic diversity (HE = 0.02859) among Korean populations. We verified that the genetic composition of KWH, showing USD of 74.8% and KCC of 25.2% in ADMIXTURE analysis. In population structure analyses, KCC was consistently shown to be separated from other pig populations. In addition, we observed gene flow from Western pigs to a part of Chinese populations. CONCLUSION: This study showed that Korean native pigs, KCC have genetic differences in comparison with Chinese and Western pigs; despite some historical records and recent genetic studies, we could not find any clear evidence that KCC was significantly influenced by Chinese or Western breeds in this study. We also verified the theoretical genomic composition of KWH at the molecular level in structure analyses. To our knowledge, this is the first genomic study to investigate the genomic characteristics of KWH and KCC.

Single-step genome-wide association study for social genetic effects and direct genetic effects on growth in Landrace pigs.

In livestock social interactions, social genetic effects (SGE) represent associations between phenotype of one individual and genotype of another. Such associations occur when the trait of interest is affected by transmissible phenotypes of social partners. The aim of this study was to estimate SGE and direct genetic effects (DGE, genetic effects of an individual on its own phenotype) on average daily gain (ADG) in Landrace pigs, and to conduct single-step genome-wide association study using SGE and DGE as dependent variables to identify quantitative trait loci (QTLs) and their positional candidate genes. A total of 1,041 Landrace pigs were genotyped using the Porcine SNP 60K BeadChip. Estimates of the two effects were obtained using an extended animal model. The SGE contributed 16% of the total heritable variation of ADG. The total heritability estimated by the extended animal model including both SGE and DGE was 0.52. The single-step genome-wide association study identified a total of 23 QTL windows for the SGE on ADG distributed across three chromosomes (i.e., SSC1, SSC2, and SSC6). Positional candidate genes within these QTL regions included PRDM13, MAP3K7, CNR1, HTR1E, IL4, IL5, IL13, KIF3A, EFHD2, SLC38A7, mTOR, CNOT1, PLCB2, GABRR1, and GABRR2, which have biological roles in neuropsychiatric processes. The results of biological pathway and gene network analyses also support the association of the neuropsychiatric processes with SGE on ADG in pigs. Additionally, a total of 11 QTL windows for DGE on ADG in SSC2, 3, 6, 9, 10, 12, 14, 16, and 17 were detected with positional candidate genes such as ARL15. We found a putative pleotropic QTL for both SGE and DGE on ADG on SSC6. Our results in this study provide important insights that can help facilitate a better understanding of the molecular basis of SGE for socially affected traits.

The effects of breed and gender on meat quality of Duroc, Pietrain, and their crossbred.

This study evaluated the effects of breed and gender in Duroc (D), Pietrain (P), and crossbred (DP) pigs. Loin samples were collected from D (n = 79), P (n = 42), and DP (n = 45) pigs. Intramuscular fat content was significantly lower in P (p < 0.001), and pH was lowest in DP pigs (p < 0.001). Gilts had higher intramuscular fat (IMF) and pH values than did castrated males (p < 0.05). Water-holding capacity was lower in DP pigs than that in D and P pigs (p < 0.001). Shear force in DP pigs was higher than that in D and P pigs (p < 0.001). Lightness and yellowness of meat in DP pigs was increased compared with coloring of P pig meat (p < 0.01). Meat from DP pigs was redder compared with meat from in D and P pigs, and it was higher in gilts than in castrates (p < 0.001). The C16:0 content was lower in P and DP pigs than in D pigs (p < 0.01). C18:2 content was higher in P and DP pigs than in D pigs (p < 0.001). Unsaturated and saturated fatty acids increased in P pigs compared with levels in D pigs (p < 0.05). Our results suggest that meat quality can be controlled by crossbreeding to increase or reduce selected properties. This study provides the basic data on the meat characteristics of F1 DP pigs. Thus, further study should be conducted to estimate the meat quality of various crossbreeds.

Genetic Diversity and Ancestral Study for Korean Native Pigs Using 60K SNP Chip.

The Korean native pig (KNP; Sus scrofa coreanus) is an indigenous porcine breed in South Korea considered as a valuable but dwindling genetic resource. Studies using diverse methodologies and genetic markers suggest that this population originated from the Manchu province of Northeastern China and migrated approximately 3000 years ago into the Korean peninsula. This study aimed to verify those findings by performing diversity and ancestral analyses using the 60K single-nucleotide polymorphism (SNP) BeadChip on 891 pigs of 47 breeds worldwide. We also performed principal component analysis (PCA), ancestry analyses, phylogenetic tree analysis using SNPhylo, and linkage disequilibrium analysis. Furthermore, we generated heatmap, obtained Nei's genetic distance and FST values, and explored the heterozygosity of commercial and native Korean pigs. The results demonstrated that KNP pigs are more closely related to European breeds than to Chinese breeds. In addition, as previous studies have suggested, our admixture analyses indicated that KNP pigs showed distinguishable genetic structure.

Clinico-radiologic features of molar-incisor malformation in a case series of 38 patients: A retrospective observational study.

Molar-incisor malformation (MIM) is a recently defined dental abnormality of molar root and incisors, and introduced as one of the causes of periapical and periodontal abscess. The purpose of this study was to investigate the clinical and radiological features of MIM, with special emphasis on various medical history. A total of 38 patients with MIM were included in this study. Radiographic features and clinical data, including medical history, chief complaint, associated complications, treatment, and prognosis, were retrospectively investigated. On radiographs, the affected molars showed short, slender, underdeveloped roots and constricted pulp chambers. All affected incisors and canines exhibited dilacerated short roots, wedge-shaped defect on the cervical part of the crown. Complications included periodontal bone loss (52.6%), endodontic lesion (50.0%), and endodontic-periodontal lesion (28.9%). The medical histories of the patients with MIM indicate that almost all (94.7%) were hospitalized due to problems during the neonatal period. MIM may cause various dental problems, such as periapical and periodontal abscess and early loss of the affected teeth. The early diagnosis of MIM on radiographs and appropriate treatment will contribute to a favorable prognosis, especially for young and adolescent patients.

Application of single-step genomic evaluation using social genetic effect model for growth in pig.

OBJECTIVE: Social genetic effects (SGE) are an important genetic component for growth, group productivity, and welfare in pigs. The present study was conducted to evaluate i) the feasibility of the single-step genomic best linear unbiased prediction (ssGBLUP) approach with the inclusion of SGE in the model in pigs, and ii) the changes in the contribution of heritable SGE to the phenotypic variance with different scaling ω constants for genomic relationships. METHODS: The dataset included performance tested growth rate records (average daily gain) from 13,166 and 21,762 pigs Landrace (LR) and Yorkshire (YS), respectively. A total of 1,041 (LR) and 964 (YS) pigs were genotyped using the Illumina PorcineSNP60 v2 BeadChip panel. With the BLUPF90 software package, genetic parameters were estimated using a modified animal model for competitive traits. Giving a fixed weight to pedigree relationships (τ: 1), several weights (ωxx, 0.1 to 1.0; with a 0.1 interval) were scaled with the genomic relationship for best model fit with Akaike information criterion (AIC). RESULTS: The genetic variances and total heritability estimates (T2) were mostly higher with ssGBLUP than in the pedigree-based analysis. The model AIC value increased with any level of ω other than 0.6 and 0.5 in LR and YS, respectively, indicating the worse fit of those models. The theoretical accuracies of direct and social breeding value were increased by decreasing ω in both breeds, indicating the better accuracy of ω0.1 models. Therefore, the optimal values of ω to minimize AIC and to increase theoretical accuracy were 0.6 in LR and 0.5 in YS. CONCLUSION: In conclusion, single-step ssGBLUP model fitting SGE showed significant improvement in accuracy compared with the pedigree-based analysis method; therefore, it could be implemented in a pig population for genomic selection based on SGE, especially in South Korean populations, with appropriate further adjustment of tuning parameters for relationship matrices.

Genome-wide analysis of spatiotemporal gene expression patterns during floral organ development in Brassica rapa.

Flowering is a key agronomic trait that directly influences crop yield and quality and serves as a model system for elucidating the molecular basis that controls successful reproduction, adaptation, and diversification of flowering plants. Adequate knowledge of continuous series of expression data from the floral transition to maturation is lacking in Brassica rapa. To unravel the genome expression associated with the development of early small floral buds (< 2 mm; FB2), early large floral buds (2-4 mm; FB4), stamens (STs) and carpels (CPs), transcriptome profiling was carried out with a Br300K oligo microarray. The results showed that at least 6848 known nonredundant genes (30% of the genes of the Br300K) were differentially expressed during the floral transition from vegetative tissues to maturation. Functional annotation of the differentially expressed genes (DEGs) (fold change ≥ 5) by comparison with a close relative, Arabidopsis thaliana, revealed 6552 unigenes (4579 upregulated; 1973 downregulated), including 131 Brassica-specific and 116 functionally known floral Arabidopsis homologs. Additionally, 1723, 236 and 232 DEGs were preferentially expressed in the tissues of STs, FB2, and CPs. These DEGs also included 43 transcription factors, mainly AP2/ERF-ERF, NAC, MADS-MIKC, C2H2, bHLH, and WRKY members. The differential gene expression during flower development induced dramatic changes in activities related to metabolic processes (23.7%), cellular (22.7%) processes, responses to the stimuli (7.5%) and reproduction (1%). A relatively large number of DEGs were observed in STs and were overrepresented by photosynthesis-related activities. Subsequent analysis via semiquantitative RT-PCR, histological analysis performed with in situ hybridization of BrLTP1 and transgenic reporter lines (BrLTP promoter::GUS) of B. rapa ssp. pekinensis supported the spatiotemporal expression patterns. Together, these results suggest that a temporally and spatially regulated process of the selective expression of distinct fractions of the same genome leads to the development of floral organs. Interestingly, most of the differentially expressed floral transcripts were located on chromosomes 3 and 9. This study generated a genome expression atlas of the early floral transition to maturation that represented the flowering regulatory elements of Brassica rapa.

Genetic association between sow longevity and social genetic effects on growth in pigs.

OBJECTIVE: Sow longevity is important for efficient and profitable pig farming. Recently, there has been an increasing interest in social genetic effect (SGE) of pigs on stress-tolerance and behavior. The present study aimed to estimate genetic correlations among average daily gain (ADG), stayability (STAY), and number of piglets born alive at the first parity (NBA1) in Korean Yorkshire pigs, using a model including SGE. METHODS: The phenotypic records of ADG and reproductive traits of 33,120 and 11,654 pigs, respectively, were evaluated. The variances and (co) variances of the studied traits were estimated by a multi-trait animal model applying the Bayesian with linear-threshold models using Gibbs sampling. RESULTS: The direct and SGEs on ADG had a significantly negative (-0.30) and neutral (0.04) genetic relationship with STAY, respectively. In addition, the genetic correlation between the social effects on ADG and NBA1 tended to be positive (0.27), unlike the direct effects (-0.04). The genetic correlation of the total effect on ADG with that of STAY was negative (-0.23) but non-significant, owing to the social effect. CONCLUSION: These results suggested that total genetic effect on growth in the SGE model might reduce the negative effect on sow longevity because of the growth potential of pigs. We recommend including social effects as selection criteria in breeding programs to obtain satisfactory genetic changes in both growth and longevity.

Social behavior and group growth of finishing pigs with divergent social breeding values / Comportamiento social y crecimiento grupal de cerdos en etapa de finalización con valores divergentes de crianza sociales / Comportamento social e crescimento grupal de porcos de engorda com valores divergentes de criação social

Abstract Background: Behavioral traits of pigs have been shown to be partly under genetic control, which raises the possibility that behavior might be altered by genetic selection, resulting in pigs with better growth performance. Objective: To evaluate the behavior and growth of finishing pigs and investigate pigs selected for high or low social breeding value (SBV) in relation to social behavior and group growth. Methods: Thirty-five females and 35 boars from five positive and five negative SBV groups of finishing pigs were grown from 30 to 90 kg and housed in 10 test pens (3.0 × 3.3 m, 7 pigs/pen). Pigs were recorded with video technology for nine consecutive hours on days 1, 15, and 30 after mixing. Pigs were weighed at approximately 90 kg body weight and the number of days to reach 90 kg was then calculated. Results: The frequency and duration of behaviors were present in the positive and negative SBV groups after mixing. On day 1 after mixing, agonistic behavior was significantly higher (p=0.027) for the -SBV group compared with the +SBV group. Feeding and feeding-together behaviors were significantly higher (p<0.003) in the +SBV group on days 1 and 30 after mixing. Moreover, growth performance to reach 90 kg body weight was significantly faster (p<0.002) in the +SBV group than in the -SBV group. Conclusion: Social interactions, such as feeding-together behavior, among pen mates might affect their growth rate and feed intake. Selection for SBV could be used as an indirect technique for improving growth performance of pigs.

Resumen Antecedentes: Se ha demostrado que los rasgos conductuales de los cerdos están parcialmente bajo control genético, lo que plantea la posibilidad de que el comportamiento pueda ser alterado vía selección genética y resulte en cerdos con mejores rendimientos de crecimiento. Objetivo: Evaluar el comportamiento y crecimiento de los cerdos en etapa de finalización e investigar cerdos seleccionados por un valor alto o bajo de crianza social (SBV) en relación al comportamiento social y al crecimiento grupal. Métodos: Treinta y cinco hembras y 35 verracos, pertenecientes a cinco grupos positivos y cinco grupos negativos de SBV de cerdos en etapa de finalización, llevados hasta los 90, desde 30 kg de peso, alojados en 10 corrales de prueba (3,0 x 3,3 m, 7 cerdos/corral). Los cerdos fueron observados con la ayuda de tecnología de vídeo por nueve horas consecutivas en los días 1, 15 y 30 luego de ser mezclados. Además, los cerdos se pesaron a los 90 kg de peso aproximadamente y se calculó el número de días para alcanzar dicho peso. Resultados: La frecuencia y duración de los comportamientos de los cerdos en la etapa de finalización se presentaron en los grupos de SBV negativos y positivos luego de ser mezclados. El día 1 luego de la mezcla, el comportamiento agonístico fue significativamente mayor (p=0,027) en el grupo -SBV que en el grupo +SBV. Los comportamientos de consumo de alimento y de consumo en compañía fueron significativamente mayores (p<0,003) en el grupo +SBV en los días 1 y 30 luego de la mezcla. Además, el crecimiento para alcanzar 90 kg de peso corporal fue significativamente más rápido (p=0,002) en el grupo +SBV que el grupo -SBV. Conclusiones: Las interacciones sociales, tales como el comportamiento de consumo de alimento en compañía, entre los compañeros de corral, pueden afectar la tasa de crecimiento y consumo de alimento. La selección por SBV podría usarse como técnica indirecta para mejorar el rendimiento de crecimiento en cerdos.

Resumo Antecedentes: Os traços comportamentais dos porcos demonstraram estar parcialmente sob controle genético, o que aumenta a possibilidade de que o comportamento possa ser alterado pela seleção genética e resulte em porcos com melhor comportamento de crescimento. Objetivo: Avaliar o comportamento e o crescimento dos porcos de engorda e investigar os porcos selecionados para alto ou baixo valor de reprodução social (SBV) em relação ao comportamento social e crescimento do grupo. Métodos: Trinta e cinco fêmeas e 35 machos, pertencentes a cinco grupos de SBV positivos e cinco negativos de porcos de engorda, foram engordados até 90 de 30 kg e alojados em 10 currais de teste (3,0 × 3,3 m, 7 porcos/curral). Os porcos foram observados com o auxílio de tecnologia de vídeo durante nove horas consecutivas nos dias 1, 15 e 30 após a mistura. Além disso, os porcos foram sopesados em aproximadamente 90 kg de peso corporal e o número de dias para atingir 90 kg foi então calculado. Resultados: A frequência e a duração dos comportamentos dos porcos de engorda foram apresentadas com grupos de SBV positivo e negativo após a mistura. No dia 1 após a mistura, o comportamento agonístico foi significativamente maior (p=0,027) no grupo -SBV do que no grupo +SBV. Os comportamentos de alimentação e alimentação conjunta foram significativamente maiores (p<0,003) no grupo +SBV nos dias 1 e 30 após a mistura. Além disso, o comportamento de crescimento do grupo para atingir 90 kg de peso corporal foi significativamente mais rápido (p<0,002) no grupo +SBV do que no grupo -SBV. Conclusão: As interações sociais, como o comportamento de alimentação conjunta, entre companheiros de curral podem afetar a taxa de crescimento e a ingestão alimentar. A seleção para SBV pode ser uma técnica indireta para melhorar o comportamento de crescimento dos porcos.

A genome-wide association study of social genetic effects in Landrace pigs.

OBJECTIVE: The genetic effects of an individual on the phenotypes of its social partners, such as its pen mates, are known as social genetic effects. This study aims to identify the candidate genes for social (pen-mates') average daily gain (ADG) in pigs by using the genome-wide association approach. METHODS: Social ADG (sADG) was the average ADG of unrelated pen-mates (strangers). We used the phenotype data (16,802 records) after correcting for batch (week), sex, pen, number of strangers (1 to 7 pigs) in the pen, full-sib rate (0% to 80%) within pen, and age at the end of the test. A total of 1,041 pigs from Landrace breeds were genotyped using the Illumina PorcineSNP60 v2 BeadChip panel, which comprised 61,565 single nucleotide polymorphism (SNP) markers. After quality control, 909 individuals and 39,837 markers remained for sADG in genome-wide association study. RESULTS: We detected five new SNPs, all on chromosome 6, which have not been associated with social ADG or other growth traits to date. One SNP was inside the prostaglandin F2α receptor (PTGFR) gene, another SNP was located 22 kb upstream of gene interferon-induced protein 44 (IFI44), and the last three SNPs were between 161 kb and 191 kb upstream of the EGF latrophilin and seven transmembrane domain-containing protein 1 (ELTD1) gene. PTGFR, IFI44, and ELTD1 were never associated with social interaction and social genetic effects in any of the previous studies. CONCLUSION: The identification of several genomic regions, and candidate genes associated with social genetic effects reported here, could contribute to a better understanding of the genetic basis of interaction traits for ADG. In conclusion, we suggest that the PTGFR, IFI44, and ELTD1 may be used as a molecular marker for sADG, although their functional effect was not defined yet. Thus, it will be of interest to execute association studies in those genes.

Behaviors and body weight of suckling piglets in different social environments.

OBJECTIVE: This study was conducted to characterize the behaviors and the body weight of suckling piglets in different social environments. METHODS: Two groups of sows and suckling piglets housed either in individual farrowing crates in separate pens (1.8×2.4 m, the control group) or in groups of three sows with their piglets in farrowing crates in a large common enclosure (5.4×2.2 m, the treatment group) were observed with the aid of video technology for 9 consecutive hours on days 1, 2, and 3, after mixing. RESULTS: Suckling, agonistic, and elimination behaviors of suckling piglets were significantly higher in the control group than in the treatment group. Inactive behavior was higher in the treatment group than in the control group. Most of the effects of the social environment on the suckling piglets seem to be the result of large reductions in behaviors and body weight for piglets switching from high activity to low activity. Moreover, suckling behavior and birth body weight were highly correlated with body weight at the end of the test. CONCLUSION: The social environment that resulted from mixing, thus, had significant effects on the behavior and body weight of suckling piglets, and behavioral characteristics, therefore, should be considered when making improvements to the husbandry and care methods used in swine production.

Reduction of GIGANTEA expression in transgenic Brassica rapa enhances salt tolerance.

KEY MESSAGE: Here we report the enhancement of tolerance to salt stress in Brassica rapa (Chinese cabbage) through the RNAi-mediated reduction of GIGANTEA ( GI ) expression. Circadian clocks integrate environmental signals with internal cues to coordinate diverse physiological outputs. The GIGANTEA (GI) gene was first discovered due to its important contribution to photoperiodic flowering and has since been shown to be a critical component of the plant circadian clock and to contribute to multiple environmental stress responses. We show that the GI gene in Brassica rapa (BrGI) is similar to Arabidopsis GI in terms of both expression pattern and function. BrGI functionally rescued the late-flowering phenotype of the Arabidopsis gi-201 loss-of-function mutant. RNAi-mediated suppression of GI expression in Arabidopsis Col-0 and in the Chinese cabbage, B. rapa DH03, increased tolerance to salt stress. Our results demonstrate that the molecular functions of GI described in Arabidopsis are conserved in B. rapa and suggest that manipulation of gene expression through RNAi and transgenic overexpression could enhance tolerance to abiotic stresses and thus improve agricultural crop production.

Behavioral Characteristics of Weaned Piglets Mixed in Different Groups.

With regard to animal welfare concerns, behavioral information of weaned and mixed piglets is great interest in swine production. The aim of this study was to demonstrate the change in behavior of weaned piglets over time in two different groups (littermates and piglets from different litters) after mixing. Two weaned groups of piglets (72 individuals in all) housed either with littermates or with foreign piglets (6 individuals in 1.8 m×1.4 m pens, 28°C±1°C temperature) were observed with the aid of video technology for 9 consecutive hours on days 1, 2, and 3 after mixing. The behaviors of the weaned piglets in the control and treatment groups were significantly different among the days after mixing. Piglets were, however, more active and aggressive in the groups with foreign piglets. This study reveals a lower level of agonistic behavior in groups of piglets that came from the same litter.