Abstract

MAGANA-VALENCIA, Fabián; NUNEZ-DOMINGUEZ, Rafael; RAMIREZ-VALVERDE, Rodolfo  and  RODRIGUEZ-ALMEIDA, Felipe A.. Connectedness in animal genetic evaluations: 1. Methodologies. Agrociencia [online]. 2012, vol.46, n.7, pp.677-692. ISSN 2521-9766.

Predicting genetic values with mixed model equations together with the animal model is the most reliable tool for selection of sires and dams, and the degree of data connectedness is one of the factors that influence selection quality. In populations where selection and genetic drift have an influence on the genetic means of contemporary groups (GC), predictions of genetic values may be biased and less reliable if the GCs are disconnected. The objective of this essay was to present a compilation and description of the main methods available in the literature for evaluating genetic connectedness among GC. Twelve methods that determine genetic connectedness among GC were described, two qualitative and 10 quantitative. A method for determining connectedness should ideally identify disconnected and directly and indirectly connected GC. It should also evaluate the degree of connectedness, and it should be practical and easy to apply and interpret. The qualitative methods for evaluating connectedness among GC only allow separating GC that are connected from those that are not, while quantitative methods additionally evaluate the degree of connectedness. The methods described are alternatives that need to be compared considering a single structure of data for common scenarios in genetic evaluations of animals.

Keywords : genetic connectedness; connectedness methods; genetic evaluation.