EVOLUÇÃO GENÉTICA NAS CARACTERISTICAS DE FACILIDADE DE ORDENHA E TEMPERAMENTO DE VACAS DA RAÇA GIR ANTES E DEPOIS DO PNMGL

The Dairy Gir is the result of selective breeding since the 1930s of Gir cattle (Bos Taurus indicus) originally imported from India. The objective of this study was to analyze the genetic evolution of ease of milking and reactivity in Gir dairy cattle. Data were obtained on the standardized predicted breeding values for udder conformation and milking behavior of 7,635 cows born from 1987 to 2015. The influence of tested bulls on genetic trends was discussed, with special focus on the period after 1993, the year when the predicted breeding values of the first group of tested bulls were released. Behavioral traits were also altered by the use of proven bulls. Before the implementation of the breeding program in 1993, there was no effect on STA values for ease of milking or reactivity representing no genetic gains. Since 1993, there has been a change in linear trend for ease of milking and reactivity. Regarding behavioral traits, this population has evolved to less-reactive animals that are easier to milk.