Udder morphology and linear udder scoring as indicators for functionality and selection in Yemeni indigenous sheep breeds

Abstract

Yemeni indigenous sheep are well adapted to diverse agro-ecological environments, however, limited information is available regarding their udder morphology and linear udder characteristics. The present study evaluated the measurements of udder and teats, linear udder scores, and their relationships in Yemeni indigenous sheep breeds. A total of 150 lactating ewes representing six indigenous breeds were assessed in semi-extensive management conditions. Eight udders and teat measurements and four linear udder traits (scored on a 1- 9 scale) were recorded. The mean udder length, depth, and circumference were 13.49, 12.70, and 24.61 cm, respectively, indicating considerable phenotypic variation among animals. Most of udder measurements (P < 0.01) and linear udder scores were significantly affected by breed, whereas dam age significantly influenced only udder circumference and udder width. Udder circumference and udder width had a high positive correlation (r = 0.82, P < 0.01), while distance between teats had negative correlation with distance to the ground (r = -0.49, P < 0.01). Significant correlations were also observed between objective udder measurements and linear udder scores, indicating consistency between the two evaluation approaches. The results demonstrated substantial variation in udder morphology among Yemeni indigenous sheep breeds and suggested that both udder measurements and linear scoring traits may serve as a useful criteria for phenotypic characterization and within-breed selection programs.