Identificação e caracterização fenotípica dos grupos genéticos da raça Girolando nos rebanhos leiteiros do estado de Roraima

Abstract

The dairy cattle in the State of Roraima is supported by crossbred Holstein x Gir cattle, more adapted to the tropical climate and traditional production systems. However, there is a need to adapt the genetic groups to the production systems and to raise awareness about the importance of the use of phenotypic visual evaluations as a tool to assist in the selection of animals. The objectives of the research were to identify the frequency and characterize the phenotype of the genetic groups ¼ Hol + ¾ Gir, ⅜ Hol + ⅝ Gir, ½ Hol + ½ Gir, ⅝ Hol + ⅜ Gir, ¾ Hol + ¼ Gir and ⅞ Hol + ⅛ Gir of the Girolando breed in the herds of the State of Roraima. The data were obtained from visual morphological evaluations to identify the genetic groups and to characterize the phenotype of the animals from August 2016 to February 2017. The following distribution of the frequency of genetic groups: 210 (21.26%) of the group ¼ Hol + ¾ Gir; 145 (14.68%) of the group ⅜ Hol + ⅝ Gir; 249 (25.20%) of the ½ Hol + ½ Gir; 166 (16.80%) of the group ⅝ Hol ⅜ + Gir; 126 (12.75%) of the ¾ Hol + ¼ Gir and 92 (9.3%) of the group ⅞ Hol + ⅛ Gir. In the phenotypic evaluations there were statistically significant differences (p <0.05) in the genetic group ¾ Hol + ¼ Gir for General Appearance (GA), in the genetic groups ⅝ Hol + ⅜ Gir and ⅞ Hol + ⅛ Gir for Body Capacity (CC), in the ½ Hol + ½ Gir group for Dairy Characteristics (CL) and in the groups ¾ Hol + ¼ Gir and ⅞ Hol + ⅛ Gir for Reproductive and Apparatus e aprumos (AR/A). The genetic group ½ Hol + ½ Gir presented superior characteristics in the Body Capacity (CC), the Milk Characteristics (CL) and the Reproductive and Apparatus e aprumos (AR/A), being better classified as to the type of Girolando breed demonstrating better characterization and uniformity by selective process.