Recent approaches of fish breedingAbordagens recentes do melhoramento genético de peixes

This review aims at addressing the main issues related to genetic improvement applied to fish species with zootechnical potential, such as selection, genetic parameters and use of biotechnology as well as address the importance of this area of study for the expansion of aquaculture and its development trend. Fish breeding is one of the most important areas of study for fish production development. Important techniques are applied in order to advance genetic progress in fish breeding (e.g., individual selection, genetic parameters estimation and the use of biotechnology). Traditional breeding in fish farming has been conducted mainly through biometric analysis, which helps in choosing selection criteria and in the assessment of genetic parameters such as heritability and correlations between interesting traits. The use of biotechnology in fish breeding has been successful; it is an important strategy that allows breeding results to be achieved faster, although at a greater cost than traditional breeding. Fish breeding in Brazil is currently in its initial stages; however, it is a field with great growth expectations, and there is still significant research to be conducted in this area. Abstract Esta revisão tem como objetivo a abordagem dos principais aspectos relacionados ao melhoramento genético aplicado em espécies de peixes com potencial zootécnico, tais como seleção, parâmetros genéticos e utilização da biotecnologia, bem como abordar a importância desta área de estudos para a ampliação da aquicultura e sua tendência de desenvolvimento. O melhoramento genético é uma das áreas prioritárias de estudo para o desenvolvimento da produção de peixes. Assim, importantes técnicas são aplicadas visando à obtenção de progresso genético no melhoramento de peixes, como por exemplo, a seleção individual, a estimativa de parâmetros genéticos e o uso da biotecnologia. O melhoramento genético tradicional na piscicultura tem sido realizado, principalmente, por intermédio de análises biométricas, que contribuem para a escolha dos critérios de seleção e para a estimativa de parâmetros genéticos, como a herdabilidade e as correlações. A utilização da biotecnologia no melhoramento de peixes tem sido notável para a piscicultura, a qual é caracterizada como uma importante estratégia que permite que sejam alcançados resultados mais rápidos no melhoramento, embora os seus custos sejam maiores quando comparados aos métodos tradicionais. O melhoramento genético de peixes no Brasil está em uma fase inicial e corresponde a um campo de grande aumento de expectativas, havendo ainda muitos estudos a serem realizados nesta área

Características de produção e de composição corporal de frangos em relação ao peso de peito avaliada por análise de trilha

O peso do peito possui grande importância econômica na indústria de frangos, podendo estar associado a outras variáveis passíveis de seleção. Estimaram-se correlações fenotípicas entre características de desempenho (peso vivo aos 7, 28 dias e ao abate e profundidade de músculo peitoral por ultra-sonografia), carcaça (peso eviscerado e de pernas) e composição corporal (peso do coração, do fígado e da gordura abdominal), em uma linhagem de frangos, e quantificou-se a influência direta e indireta destas variáveis sobre o peso do peito. Para tanto, utilizou-se a análise de trilha, desdobrando-se a matriz de correlações parciais em coeficientes que forneceram a influência direta de uma variável sobre a outra, independentemente das demais. A manutenção das variáveis peso vivo ao abate e peso eviscerado na matriz de correlações pode ser prejudicial à análise estatística que envolve os sistemas de equações normais, como a análise de trilha, devido à multicolinearidade observada. O peso vivo ao abate e a profundidade do músculo peitoral por ultra-sonografia apresentaram efeitos diretos importantes sobre o peso de peito e foram identificadas como as principais responsáveis pela magnitude dos coeficientes de correlação obtidos. Assim, uma pré-seleção individual para estas características pode favorecer um aumento no peso de peito nesta linhagem, se mantidas as condições ambientais de criação dos frangos, uma vez que o peso vivo ao abate e a profundidade de músculo peitoral por ultra-sonografia afetam fenotipicamente e diretamente o peso de peito.Breast weight has great economic importance in poultry industry, and may be associated with other variables. This work aimed to estimate phenotypic correlations between performance (live body weight at 7 and 28 days, and at slaughter, and depth of the breast muscle measured by ultrasonography), carcass (eviscerated body weight and leg weight) and body composition (heart, liver and abdominal fat weight) traits in a broiler line, and quantify the direct and indirect influence of these traits on breast weight. Path analysis was used by expanding the matrix of partial correlation in coefficients which give the direct influence of one trait on another, regardless the effect of the other traits. The simultaneous maintenance of live body weight at slaughter and eviscerated body weight in the matrix of correlations might be harmful for statistical analysis involving systems of normal equations, like path analysis, due to the observed multicollinearity. The live body weight at slaughter and the depth of the breast muscle as measured by ultrasonography directly affected breast weight and were identified as the most responsible factors for the magnitude of the correlation coefficients obtained between the studied traits and breast weight. Individual pre-selection for these traits could favor an increased breast weight in the future reproducer candidates of this line if the broilers' environmental conditions and housing are maintained, since the live body weight at slaughter and the depth of breast muscle measured by ultrasonography were directly related to breast weight

Heritability and genetics correlations for body weight in escargots

The objective of this study was to estimate genetic parameters for body weight at 60 (P60), 90 (P90), and 120 (P120) days of age in escargots of the subspecies Cornu aspersum maximum, evaluating the influence of fixed and covariable effects on these traits. The data used were collected from escargots kept in a total confinement system. The significant fixed effects and covariates for these traits were tested in a general linear model by the F-test, considering a level of significance of 5%. Both the fixed effects of box and birth year and the quadratic effect of age of weighing as a covariate were significant (p < 0.05) for P60, P90, and P120. The Restricted Maximum Likelihood (REML) methodology was used to estimate (co)variance components and genetic parameters. High heritability for P60, P90, and P120 (0.38, 0.55 and 0.78, respectively) and high genetic correlations (0.58 to 0.77) among the traits were observed. The genetic parameters can be used as a basis for studies and practical applications to increase zootechnical indexes in this population

Estimates of heritability and genetic correlations for meat quality traits in broilers

Broiler meat quality is one of the primary factors considered by the poultry industry. This study was conducted to estimate heritability and genetic correlation coefficients for meat quality traits in a single male broiler line. The meat ultimate pH (24 h after slaughter) and lightness presented the highest heritability estimates. Given the estimated genetic correlations, the pH measured at 15 min and 24 h after slaughtering, as well as lightness, were characterized by a close and negative genetic relationship with water holding capacity traits. In contrast, meat quality traits exhibited only non-significant genetic correlations with performance and carcass traits. Noticed exceptions were breast weight, which was genetically and favorably associated with the initial pH and thawing-cooking losses, and ultrasound record of pectoral muscle depth, which was genetically and unfavourably associated with the shear force of meat. Meat pH values at 24 h after slaughtering or lightness may be a favorable selection criterion for the poultry industry for improving meat quality, since these traits are associated with the water holding capacity of the meat. Out of the traits studied, lightness is most easily assessed on the industrial slaughtering line. The direct selection for breast weight could improve the initial pH and thawing-cooking losses of meat, even as selection for ultrasound records of Pectoralis major may affect the meat tenderness in this lin

Perfil genético das linhagens de touros leiteiros Holandês e Jersey disponíveis no Brasil

The Holstein and Jersey dairy cattle breeds are among the most prevalent in Brazil. To evaluate differences among the PTAs (predicted transmitting abilities) of these breeds and their lines, data were collected on 385 Holstein bulls and 82 Jersey sires with semen commercially available from nine Brazilian companies. Three different sire lines for each breed were found. The general linear models method was used for the comparison among lines and between breeds. The two most prevalent lines of Holstein breed presented higher average PTAs for milk yield (1,061.04 pounds and 975.32 pounds) and lower PTAs for percentage of milk solids (from -0.05% to -0.0003%) (P<0.05). These results indicate the supply of sires that mostly increase the milk yield in the Brazilian market. The Jersey breed presented a higher inbreeding coefficient (6.62%) than the Holstein breed (5.14%) (P<0.05). Although the Holstein breed presented higher PTAs for milk yield and lower PTAs for percentage of milk solids (P<0.05), the productive life of the Jersey breed (1.17 months) was longer than it was in the Holstein breed (0.40 months) (P<0.05). We identified the existence of an important variability of the available genetic profiles, what allows the Brazilian producers to choose the most adequate semen for their production system. It is necessary to consider the genetic profiles of sires' lines offered for artificial insemination in Brazil to understand and direct the genetic pattern of Brazilian dairy cattle

Heritability for milk production and composition traits in Holstein dairy cattle

Todos os textos, informa??es e resultados apresentados s?o de inteira responsabilidade dos autores.O Brasil se encontra entre os seis maiores produtores de leite do mundo. A produ??o deste alimento depende do potencial gen?tico do animal e do ambiente, tendo o melhoramento animal um papel fundamental nesta atividade. Com o objetivo de estimar a herdabilidade para as caracter?sticas produ??o de leite, teor de lactose, gordura e prote?na, um banco de dados composto de mais de 13 mil amostras de leite oriundas tr?s fazendas no Estado de S?o Paulo foi analisado. Os resultados obtidos para a estimativa de herdabilidade para caracter?stica de produ??o e composi??o do leite, teor de lactose, gordurae prote?na foram de0,51 ? 0,01, 0,48 ? 0,01, 0,22 ? 0,01 e 0,43 ? 0,01. A produ??o de leite, teor de lactose, gordura e prote?na, s?o caracter?sticas que podem ser utilizadas como crit?rio de sele??o dentro dos rebanhos estudados, quando o objetivo for aumentar a produ??o e a qualidade do leite.Brazil is one of the six largest producers of milk in the world. The milk production depends on the genetic potential of the animal and the environment, and animal breeding plays a key role in this activity. In order to estimate the heritability for the milk production and quality traits, lactose, fat, and protein, a database consisting of more than 13 thousand milk samples from three different farms in the state of S?o Paulo were analyzed. The heritability estimates milk production, lactose, fat, and protein were 0.51 ? 0,01, 0.48 ? 0,01, 0.22 ? 0,01, and 0.43 ? 0,01. Milk production, lactose, fat, and protein may be used as selection criteria in the population analyzed, when the objective is the increase of milk production and quality

Evaluation inbreeding coefficient effects in pH and meat tenderness of male broiler line

Todos os textos, informa??es e resultados apresentados s?o de inteira responsabilidade dos autores.Foi realizada avalia??o dos efeitos da magnitude do coeficiente de endogamia sobre os fen?tipos de caracter?sticas de pH e maciez da carne no peito de frangos, pertencentes a uma linhagem macho. Este efeito foi avaliado sobre as medidas de pH em 15 minutos (pH inicial) e 24 horas ap?s o abate (pH final) e for?a de cisalhamento e estimado atrav?s de modelos de regress?o quadr?tica (com identifica??o do ponto de m?xima e m?nima resposta) e linear, considerando o n?vel de signific?ncia estat?stica de 5%. O modelo de regress?o quadr?tica foi significativo para pH inicial e for?a de cisalhamento, enquanto para pH final n?o foi observado signific?ncia para os coeficientes linear e quadr?tico. Os pontos de m?xima resposta para pH inicial e for?a de cisalhamento, respectivamente, foram 4,09% e 3,47%, indicando que incrementos no coeficiente de endogamia podem resultar em redu??o dessas caracter?sticas. A utiliza??o destas informa??es deve ser ponderada pela industria, com vista aos limites m?ximos ideais e salientando que a intensifica??o endog?mica pode promover deprecia??o de aspectos qualitativos e desfavorecer a qualidade da carne de frango.The effects of inbreeding coefficient on the phenotype characteristics of pH and tenderness of poultry breast meat, belonging to a male broiler line were evaluated. These effects were evaluated under the measurements of initial and final pH (15 min and 24 h after animal?s death, respectively), and shear strength, estimated using the quadratic (with identification of maximum and minimum points of response) and the linear regression models, with statistical significance of p < 0.05%. The quadratic model of regression was significant for initial pH and shear strength, whereas for final pH both quadratic and linear models were not significant. The maximum response points for initial pH and shear strength were 4.09% and 3.47%, respectively, which indicates that a increasing in the inbreeding coefficient may result in a reduction of these characteristics. The use of information based on the present results should be considered by the industry, considering the optimum of maximum limits and highlighting that the inbreeding intensification may promote depreciation of qualitative aspects and disadvantaging the quality of poultry meat

Evaluation inbreeding coefficient effects in water holding of male broiler line

Todos os textos, informa??es e resultados apresentados s?o de inteira responsabilidade dos autores.O presente estudo avaliou o efeito da magnitude do coeficiente de endogamia sobre os fen?tipos de caracter?sticas relativas ? capacidade de reten??o de carne no peito de frangos de linhagem macho. Este efeito foi avaliado sobre os valores gen?ticos das vari?veis perdas por descongelamento, cozimento e exsuda??o e estimado por interm?dio de modelos de regress?o quadr?tica e linear, considerando-se o n?vel de signific?ncia estat?stica de 5%. O modelo de regress?o linear foi significativo (p=0,0418) para perdas por cozimento. Os modelos de regress?o quadr?tico e linear n?o foram significativos para perdas por descongelamento e exsuda??o. O coeficiente de regress?o linear para perdas por cozimento foi de 19,49% para cada 1% de aumento no coeficiente de endogamia. Este fato sugere que o aumento nas propor??es de acasalamentos endog?micos pode favorecer os fen?tipos da perdas por cozimento e assim reduzir a qualidade da carne e o peso do produto final. A ind?stria pode utilizar esses resultados em programas de melhoramento que visam a qualidade da carne, sempre se atentando aos limites extremos dessa vari?vel.ABSTRACT The effect of inbreeding coefficient on the phenotypic characteristics of water holding in broiler breast meat, belonging to a male broiler line, was evaluated. This effect were evaluated on the genetic measurements of the fallowing variables, drip, shrink and weep losses using the quadratic and linear regression models, with statistical significance of p < 0.05%. The linear regression model was significant (p=0.0418) for shrink losses. Both quadratic and linear models were not significant for drip and weep losses. The linear regression coefficient for shrink losses was 19.49% for each 1% of increasing in the inbreeding coefficient. These results suggest that and increasing in the inbreeding mating may favor the phenotypes of shrink losses, thus reducing the meat quality and the final product weight. The industry should use these results on programs of improvement aimed in the meat quality, always considering the external limits of this variable.