Evaluation of the Physiological and Behavioural Relationships of Yearling Bucks by Generalized Procrustes Analysis

Abstract

The aim of this study is to evaluate the relationships between some sexual behaviours and physiological traits such as serum testosterone concentration, body weight loss and presence of horns of yearling bucks using Generalized Procrustes Analysis (GPA). In the study, 11 yearling bucks being sexually in- experienced were used. The sexual behaviours were determined with a total of four tests, which consisted of exposing the yearling bucks individually to three unrestrained estrous ewes for 15 min. In these tests, some behavioural characteristics such as number of ejaculations, flehmen response, number of mounts and serum testosterone concentration were determined. In the GPA analysis, the first two factors explained approximately 98% of the total variation between animals (Dimension 1 = 95.57%, Dimension 2 = 2.68%). It was determined that there was a positive and high correlation between tests and the number of mounts, which had a high correlation with the first dimension. Ejaculation frequency, flehmen response and testosterone levels decreased in line with in- creases in the number of mounts. As a result, it can be suggested that GPA can be effectively evaluated quantitative and qualitative behavioural characteristics without requiring any prior assumptions and reducing variability among animals.