Características morfológicas e desempenho de crescimento de monossexo macho de tilápia da variedade GIFT e Saint Peter®

<p class="Default"><span>Este estudo teve como objetivo comparar as características morfológicas e o desempenho de populações monossexo macho de tilápia da variedade <em>Genetic Improved Farmed Tilapia </em>(GIFT) e Saint Peter® cultivadas em um sistema misto. O experimento foi conduzido durante o período de junho a novembro de 2012, na Estação da Piscicultura Sgarbi, no Município de Palotina. Os juvenis da GIFT foram obtidos de reprodutores da Estação de Piscicultura da Universidade Estadual de Maringá (UEM/Codapar) e os híbridos vermelhos foram oriundos de reprodutores da Estação da Piscicultura Sgarbi. Os valores genéticos médios da variedade GIFT para três grupos genéticos (I, II e III) foram obtidos por meio de uma avaliação genética pelo <em>Best Linear Unbiased Prediction </em>(BLUP), utilizando o controle de parentesco das tilápias. Informação de pedigree completo da GIFT desde a sua introdução no Brasil foi utilizado e os grupos genéticos foram classificados como I (grupo superior), II (grupo intermediário) e III (grupo inferior). Utilizou-se o sistema semi-intensivo, sendo adotada a densidade de 4,7 peixes m-2 de lâmina de água. Foram alojados 480 peixes da variedade GIFT e 1400 peixes do híbrido vermelho, totalizando 1880 animais, com peso médio inicial de 15 g. Os peixes foram identificados individualmente através de <em>Passive Integrated Transponder (PIT) tags</em>. A despesca foi realizada ao final do período de 160 dias. Os dados de peso final e ganho em peso diário, e das características morfológicas incluindo comprimento total, comprimento padrão, comprimento da cabeça, altura da cauda, altura do corpo, largura da cauda, largura do corpo, comprimento da cabeça/comprimento padrão, área e volume corporal foram avaliados. Aplicou-se a análise de variância (ANOVA) e o teste de Tukey a 5% de probabilidade. Os valores médios de peso final e ganho em peso diário entre os três grupos genéticos da GIFT não apresentaram diferenças significativas. Porém, todos os grupos genéticos da GIFT apresentaram valores médios do desempenho e das características morfológicas superiores ao híbrido Saint Peter®. Entre os grupos genéticos da variedade GIFT houve diferença significativa (p&lt;0,001) apenas para a altura do corpo entre os grupos I e III. As características morfológicas e de desempenho foram superiores para a variedade GIFT, independente do grupo genético, quando comparada à Saint Peter®, com exceção da relação comprimento da cabeça/comprimento padrão. </span></p

Association between performance traits of Nile tilapia during the culture period

O objetivo deste trabalho foi estimar as herdabilidades e a estrutura de correlações genéticas entre as características de desempenho de tilápia-do-nilo (Oreochromis niloticus) da linhagem GIFT, em diferentes estágios do ciclo de produção. As tilápias foram cultivadas em tanques‑rede. Mediu-se ganho em peso diário total, peso vivo e ganho em peso diário, em quatro períodos, com intervalos de aproximadamente 30 dias. Foram realizadas análises unicaracter para as medidas, em todas as biometrias e, nas análises bicaracter, as medidas de mesma característica foram combinadas duas a duas e com o ganho em peso diário total. As estimações de herdabilidade variaram de 0,15 a 0,11 para peso vivo, 0,16 a 0,09 para ganho em peso diário e 0,17 a 0,12 para ganho em peso diário total, nas análises unicaracter. Os valores estimados de correlação genética para peso vivo e ganho em peso diário, associados ao ganho em peso diário total, variaram entre 0,37 a 0,98 e 0,74 a 0,88, respectivamente. A forte associação genética estimada entre peso vivo em biometrias intermediárias e ganho em peso diário total sugere que a seleção para velocidade de crescimento pode ser realizada de forma precoce.The objective of this work was to estimate the structure and heritability of genetic correlations between the performance traits of Nile tilapia (Oreochromis niloticus) of the GIFT lineage during different stages of the production cycle. The Nile tilapias were grown in net cages. Daily total weight gain, live weight, and daily weight gain were measured in four periods, in approximately 30-day intervals. One‑trait analyses were performed for all biometric measurements, and, in the two‑trait analyses, measurements of the same traits were combined in pairs and to daily total weight gain. Estimated heritabilities ranged from 0.15 to 0.11 for live weight, from 0.16 to 0.09 for daily weight gain, and from 0.17 to 0.12 for daily total weight gain in the one‑trait analyses. Estimated values of genetic correlation for live weight and daily weight gain, associated with daily total weight gain, ranged from 0.37 to 0.98 and from 0.74 to 0.88, respectively. The high genetic correlation estimated between live weight in intermediate biometric measurements and daily total weight gain suggests that selection for growth rate may be performed earlier

Genetic evaluation of Nile tilapia in a five‑year selection

O objetivo deste trabalho foi estimar parâmetros genéticos e valores genéticos das características peso à despesca e ganho de peso diário de tilápias‑do‑nilo (Oreochromis niloticus), avaliadas durante cinco anos de cultivo em tanques‑rede. O conjunto de dados continha registros de 6.650 animais, com valores genéticos preditos de 8.590 animais na matriz de parentesco. O número de animais avaliados foi de 2.196 (33 famílias), em 2008; 1.721 (58 famílias), em 2009; e 2.733 (78 famílias), em 2010. Análises uni‑ e bicaracter do conjunto de dados foram realizadas com uso do método de inferência bayesiana, por meio do programa computacional MTGSAM. As estimativas de herdabilidade obtidas foram de média magnitude: 0,273, para ganho de peso diário; e 0,282, para peso à despesca. A participação dos efeitos de ambiente comum na variação total foi de 15% para larvicultura e de 5% para alevinagem. As correlações genéticas e fenotípicas foram de 95%, o que indica forte associação entre as características. O ganho genético foi de 3,8% por geração, com acumulado de 15% em quatro gerações. Houve progresso genético e mudanças, causadas pela seleção de tilápias‑do‑nilo, nas condições de cultivo avaliadas. A seleção quanto ao ganho de peso permite ganhos indiretos relacionados ao peso.The objective of this work was to estimate genetic parameters and breeding values for body weight at harvest and daily weight gain of Nile tilapia (Oreochromis niloticus), evaluated in cages for five years. The data set contained records of 6,650 animals, with predicted breeding values of 8,590 animals in the relationship matrix. The number of animals evaluated was 2,196 (33 families) in 2008; 1,721 (58 families) in 2009; and 2,733 (78 families) in 2010. Single and two‑trait analyses from the data set were performed using Bayesian inference methodology by the computer program MTGSAM. The obtained heritability estimates were of medium magnitude, as follows: 0.273, for daily weight gain; and 0.282, for body weight at harvest. The participation of common environmental effects in the total variation was of 15% for larvae and 5% for nurseries. The genetic and phenotypic correlations were of 95%, indicating a strong association between the traits. Genetic gain was 3.8% per generation, with accumulated 15% over four generations. There were genetic progress and changes caused by the selection of Nile tilapia in the evaluated growing conditions. The selection for weight gain allows of indirect gains associated to weight

Genomics to accelerate genetic improvement in tilapia

Selective breeding of tilapia populations started in the early 1990s and over the past three decades tilapia has become one of the most important farmed freshwater species, being produced in more than 125 countries around the globe. Although genome assemblies have been available since 2011, most of the tilapia industry still depends on classical selection techniques using mass spawning or pedigree information to select for growth traits with reported genetic gains of up to 20% per generation. The involvement of international breeding companies and research institutions has resulted in the rapid development and application of genomic resources in the last few years. GWAS and genomic selection are expected to contribute to uncovering the genetic variants involved in economically relevant traits and increasing the genetic gain in selective breeding programs, respectively. Developments over the next few years will probably focus on achieving a deep understanding of genetic architecture of complex traits, as well as accelerating genetic progress in the selection for growth-, quality- and robustness-related traits. Novel phenotyping technologies (i.e. phenomics), lower-cost whole-genome sequencing approaches, functional genomics and gene editing tools will be crucial in future developments for the improvement of tilapia aquaculture.Nucleo Milenio INVASAL - Chile's government program, Iniciativa Cientifica Milenio from Ministerio de Economia, Fomento y Turismo Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) CONICYT FONDECYT 319055

Bayesian genome wide association analysis for body weight in farmed Atlantic salmon (Salmo salar L.)

We performed a genome-wide association study to detect markers associated with growth traits in Atlantic salmon. The analyzed traits included body weight at tagging (BWT) and body weight at 25 months (BW25M). Genotypes of 4662 animals were imputed from the 50K SNP chip to the 200K SNP chip using FIMPUTE software. The markers were simultaneously modeled using Bayes C to identify genomic regions associated with the traits. We identified windows explaining a maximum of 3.71% and 3.61% of the genetic variance for BWT and BW25M respectively. We found potential candidate genes located within the top ten 1-Mb windows for BWT and BW25M. For instance, the vitronectin (VTN) gene, which has been previously reported to be associated with cell growth, was found within one of the top ten 1-Mb windows for BWT. In addition, the WNT1-inducible-signaling pathway protein 3, melanocortin 2 receptor accessory protein 2, myosin light chain kinase, transforming growth factor beta receptor type 3 and myosin light chain 1 genes, which have been reported to be associated with skeletal growth in humans, growth stimulation during the larval stage in zebrafish, body weight in pigs, feed conversion in chickens and growth rate of sheep skeletal muscle respectively, were found within some of the top ten 1-Mb windows for BW25M. These results indicate that growth traits are most likely controlled by many variants with relatively small effects in Atlantic salmon. The genomic regions associated with the traits studied here may provide further insight into the functional regions underlying growth traits in this species.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) 2014/20626-4 2015/25232-7 CNPq 308636/2014-

Genome-wide association analysis for body weight identifies candidate genes related to development and metabolism in rainbow trout (Oncorhynchus mykiss)

Growth is one of the most important traits from both a physiological and economic perspective in aquaculture species. Thus, identifying the genomic regions and genes underpinning genetic variation for this trait is of particular interest in several fish species, including rainbow trout. In this work, we perform a genome-wide association study (GWAS) to identify the genomic regions associated with body weight at tagging (BWT) and at 18 months (BW18M) using a dense SNP panel (57 k) and 4596 genotyped rainbow trout from 105 full-sib families belonging to a Chilean breeding population. Analysis was performed by means of single-step GBLUP approach. Genetic variance explained by 20 adjacent SNP windows across the whole genome is reported. To further explore candidate genes, we focused on windows that explained the highest proportion of genetic variance in the top 10 chromosomes for each trait. The main window from the top 10 chromosomes was explored by BLAST using the first and last SNP position of each window to determine the target nucleotide sequence. As expected, the percentage of genetic variance explained by windows was relatively low, due to the polygenic nature of body weight. The most important genomic region for BWT and BW18M were located on chromosomes 15 and 24 and they explained 2.14% and 3.02% of the genetic variance for each trait, respectively. Candidate genes including several growth factors, genes involved in development of skeletal muscle and bone tissue and nutrient metabolism were identified within the associated regions for both traits BWT and BW18M. These results indicate that body weight is polygenic in nature in rainbow trout, with the most important loci explaining as much as 3% of the genetic variance for the trait. The genes identified here represent good candidates for further functional validation to uncover biological mechanisms underlying variation for growth in rainbow trout

Genomic prediction accuracy for resistance against piscirickettsia salmonis in farmed rainbow trout

Salmonid rickettsial syndrome (SRS), caused by the intracellular bacterium Piscirickettsia salmonis, is one of the main diseases affecting rainbow trout (Oncorhynchus mykiss) farming. To accelerate genetic progress, genomic selection methods can be used as an effective approach to control the disease. The aims of this study were: (i) to compare the accuracy of estimated breeding values using pedigree-based best linear unbiased prediction (PBLUP) with genomic BLUP (GBLUP), single-step GBLUP (ssGBLUP), Bayes C, and Bayesian Lasso (LASSO); and (ii) to test the accuracy of genomic prediction and PBLUP using different marker densities (0.5, 3, 10, 20, and 27 K) for resistance against P. salmonis in rainbow trout. Phenotypes were recorded as number of days to death (DD) and binary survival (BS) from 2416 fish challenged with P. salmonis. A total of 1934 fish were genotyped using a 57 K single-nucleotide polymorphism (SNP) array. All genomic prediction methods achieved higher accuracies than PBLUP. The relative increase in accuracy for different genomic models ranged from 28 to 41% for both DD and BS at 27 K SNP. Between different genomic models, the highest relative increase in accuracy was obtained with Bayes C (approximate to 40%), where 3 K SNP was enough to achieve a similar accuracy to that of the 27 K SNP for both traits. For resistance against P. salmonis in rainbow trout, we showed that genomic predictions using GBLUP, ssGBLUP, Bayes C, and LASSO can increase accuracy compared with PBLUP. Moreover, it is possible to use relatively low-density SNP panels for genomic prediction without compromising accuracy predictions for resistance against P. salmonis in rainbow trout.Aguas Claras S.A. Corporacion de Fomento de la Produccion 11IEI-12843 Fondo Nacional de Desarrollo Cientifico y Tecnologico Regular 1171720 Nucleo Milenio de Salmonidos Invasores Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) 2014/20626-4 2015/25232-7 National Council for Scientific and Technological Development fellowship 308636/2014-