Association between the social rank, body mass, testicular circumference and linear body measures of rams

Abstract

The social rank refers to the relative position of an individual animal within the dominant hierarchy developed in a group. In rams, social rank is mostly associated with body mass, body size and body condition. However, although the body mass is generally considered as one of the main determinants of social rank, only few studies have been carried out for the purpose of associating of the social behavior and body development of these animals. Objective of this research was to determine how the ram body development measures relate to establishment of social hierarchy. Social rank was established using food competition test at the age of animals between 4 and 17 months. Testing was done on total of 20 male animals of which number 12 animals were selected for further testing (6 dominant and 6 submissive animals). Body mass and testicular circumferences were measured at the age of 4, 7, 12 and 18 months, and linear body measures were taken at the age of 12 and 18 months. Dominant males had higher body mass and greater testicular circumference. The social rank had no significant effect on linear body measures of rams, except for chest girth (P<0.05) in both control periods. Body mass was moderately to highly positively associated with studied body parameters. Significant positive correlations were established between body mass and body length (r=0.58; P<0.01), chest width (r=0.44; P<0.05), chest girth (r=0.65; P<0.01) and testicular circumference (r=0.62; P<0.01). Results obtained in this study indicate that it is justified to observe the body mass as one of the main determinants of social rank, as well as the possibility of earlier maturation of dominant animals.