Beyond Fifty Shades: The Genetics of Horse Colors

Since the dawn of horse domestication, coat colors have always fascinated humankind. In the last century, knowledge of genetics and development of scientific tools have become powerful enough so that the effects of many DNA mutations could be critically studied. Coat color nomenclature varies according to countries and breed associations; in addition, many factors can modify the color of the coat, such as sun exposure, age, sex, and nutritional status of the animal. Nevertheless, horses are capable of producing only two pigments. Several genes have been indicated as putative to coat color modification, altering the basic color by dilution, redistribution, or lacking of pigments

Use of a colloid to optimize centrifugation in the selection of bovine sperm for IVF

This study aimed to evaluate the effect of the force and duration of centrifugation and the impact of cushioned centrifugation on sperm selection by Percoll gradient, on sperm quality and development kinetics of in vitro produced bovine embryos. Two experiments were performed. In Experiment I, a pool of semen was selected by Percoll gradients and the pellet was divided into four groups and distributed in a 2 × 2 factorial, with two forces (2200 × g or 9000 × g) and two durations (1 min or 3 min) of centrifugation. In Experiment II, semen was divided into two groups and selected by Percoll gradient with Cushion Fluid (CF) or without CF (Control) in the second centrifugation. The morphofunctionality, biochemical characteristics and fertilizing capacity of the selected sperms were evaluated. In addition, the development of the resulting bovine embryos was monitored for 48 h post-insemination. Duncan and Chi-square tests (P 0.05). In Experiment II, the recovery rate and reactive oxygen species (ROS) production in semen were similar among treatments (P > 0.05) although a higher ROS production was observed in the CF fertilization medium. Total fertilization rate was superior in the CF group (65.4 ± 5.3%) compared to that in Control (39.6 ± 4.9%). However, the normal fertilization and cleavage rate did not differ between the Control (94 ± 6.3% and 58.3 ± 8.3%) and CF (89 ± 7.1% and 75.0 ± 7.3%) groups. The reduction in the force and duration of centrifugation did not decrease the sperm recovery during selection by the Percoll gradient and the use of CF in the second centrifugation did not affect the normal fertilization and development of bovine IVF embryos up to 48 h

Produtividade acumulada como critério de seleção em fêmeas da raça nelore Accumulated productivity as selection criteria in nellore breed females

O presente trabalho teve por objetivo determinar os componentes de variância e estimar a herdabilidade da produtividade acumulada (PAC) de 15.070 fêmeas, criadas em diferentes rebanhos participantes do Programa de Melhoramento Genético da Raça Nelore. A PAC é um índice que considera a produção total de bezerros desmamados em kg, o tempo total de produção de bezerros e o início de parição. As análises estatísticas foram realizadas por meio do programa SAS (Statistical Analysis System) e os componentes de variância pelo método de máxima verossimilhança restrita utilizando o software MTDFREML. A média da PAC foi de 130kg de bezerros desmamados por vaca ao ano, e os efeitos do pai da vaca, rebanho e ano de nascimento da vaca foram significativos (P<0,0001) na variação dessa característica. O coeficiente de herdabilidade da PAC foi estimado em 0,15, indicando a existência de variabilidade genética suficiente para sua inclusão nos programas de melhoramento, o que resultaria na obtenção de fêmeas mais produtivas nos rebanhos.<br>This work had for objective to determine the variance components and to estimate the heritability of the accumulated productivity (ACP) of 15,070 females, reared in different participant herds of the Nellore Breeding Program. ACP is an index that considers the total production of calves weaned in kg, the total time of production of calves and the calving beginning. The statistical analyses were accomplished through the SAS program (Statistical Analysis System) and the variance components for the restricted maximum likelihood method using the software MTDFREML. The average of ACP was of 130kg of calves weaned by cow to the year, and the sire of cow effects, herd and year of the birth cow significatly (P<0.0001) affected in the variation of this characteristic. The coefficient of heritability of ACP was estimated in 0.15, indicating the existence of enough genetic variability for its inclusion in the improvement programs, what would result in the obtaining of more productive females in the herds