Influence of social rank on certain stress response variables and behavioral characteristics of adult rams

Abstract

Dominance rank within a group can affect the stress level of an animal. However, there is no consensus on whether the dominant or subordinate animals are physiologically more stressed. It was aimed herein to determine the effect of social rank on the stress level and expression of some behaviors of adult Hemsin, Chios, and Karakul rams. According to their dominance index (DI) values, the rams were classified as low-ranked (DI < 0.33; n = 13), medium-ranked (DI: 0.33-0.66; n = 13), and high-ranked (DI > 0.66; n = 13) individuals. The low-ranked rams had lower body weight, body length, chest depth, chest circumference, cannon bone circumference, and tail width than the medium- and high-ranked rams. The high-ranked rams tended to exhibit more rumination than the low- and medium-ranked rams (P = 0.066). The rank group had no influence on the frequency of vocalization, butting other animals, and itching behaviors. The low-ranked rams had lower hematocrit, hemoglobin, and red blood cell counts than the medium- and high-ranked rams. The rank group had no influence on the white blood cell count, neutrophil:lymphocyte ratio, and cortisol level. In conclusion, under the conditions of the current study, the welfare of the low-ranked rams was not adversely affected.