Abstract
Genetic evaluations are an efficient tool to select sires, and for them it is necessary to have identification of environmental effects, genetic parameters, and acceptable degree of connectedness between herds. Evaluation of Limousin breed genetics has been developing since 2012. The objectives were to determine the most relevant fixed environmental effects of the characteristics in the genetic evaluation and to estimate the degree of connectedness between herds. The productive and genealogical records were extracted from the Limousin genetic evaluation database of the National Institute of Agricultural Research. Objective measurements were available for the characteristics birth weight (916 records), weaning (818), 18 months (438), ribeye area (435), and 12th-13th rib fat thickness (435) for 2012, 2013, 2014, 2015 and 2016 corresponding to four herds. The results showed that the fixed environmental effects considered presented a significant value (p<0.05), and that herds were connected to each other with average values of prediction error variance (pevd), and connectedness rating (cr) of 113.9 and 7.9, respectively. Concluding that the most relevant fixed environmental effects were year, sex, herd, age at weaning and age at 18 months, and that herds were connected with a low connectedness degree.
Highlights
Genetic evaluations are tools for the objective selection of sires that allow achieving genetic progress in production animals
The objective is to achieve a population genetic evaluation, for which it is necessary to have the identification of the environmental factors that affect the evaluated characteristics, the genetic parameters estimated for the population, and the acceptable connectedness levels between the participating herds
The adequate definition of contemporary groups (CG) is key to correct by environmental effects in a genetic evaluation(3), and they were defined by Cundiff and others(1) as the groups of animals of the same breed, sex and who have similar ages and management
Summary
Genetic evaluations are tools for the objective selection of sires that allow achieving genetic progress in production animals. The objective is to achieve a population genetic evaluation, for which it is necessary to have the identification of the environmental factors that affect the evaluated characteristics, the genetic parameters estimated for the population, and the acceptable connectedness levels between the participating herds. Genetic evaluations predict the genetic merit of an animal, based on its phenotype and/or that of its relatives. It must be corrected by known factors that influence its expression, such as nongenetic or environmental effects(1). The adequate definition of contemporary groups (CG) is key to correct by environmental effects in a genetic evaluation(3), and they were defined by Cundiff and others(1) as the groups of animals of the same breed, sex and who have similar ages and management
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