Awassi Ancestry-Associated Serum Metabolomic Signatures Reveal Immune–Metabolic Features Related to Health Robustness in Dairy Sheep

Genetic background can shape metabolic phenotypes and may contribute to differences in health robustness among livestock breeds. This study investigated Awassi-associated serum metabolic characteristics in dairy sheep by integrating untargeted metabolomic profiling with farm-level morbidity information. Serum samples were collected from 36 adult sheep representing six genetic groups raised under common feeding and management conditions, Awassi, East Friesian, Hu, and three Awassi–East Friesian–Hu crossbred groups, with six animals per group and an equal number of males and females. Following data preprocessing and normalization, 2284 metabolic features were retained for comparative analysis. Principal component analysis revealed marked differences in serum metabolic profiles among the genetic groups, with Awassi sheep displaying a distinct metabolic pattern relative to the purebred and crossbred populations. Across five comparisons between Awassi and the other genetic groups, 17 metabolic features were consistently more abundant in Awassi sheep. These features were mainly associated with lipid mediator metabolism, glycerophospholipid metabolism, aromatic and indole-related metabolism, and host–microbial co-metabolism. A metabolic signature derived from the Awassi–East Friesian comparison differed significantly among the six groups and was positively associated with Awassi ancestry at the individual level. However, the two crossbred groups with 50% Awassi ancestry did not show a simple intermediate metabolic pattern, suggesting that crossbred metabolic phenotypes may involve non-additive genetic effects. Farm records showed lower total morbidity in Awassi and the three crossbred populations than in the East Friesian and Hu populations. Because the morbidity data were summarized at the population level and were not individually matched to the metabolomic samples, they were interpreted as supporting production context rather than direct metabolite–disease associations. Collectively, these results reveal a distinctive Awassi-associated serum metabolic signature and provide new insights into breed- and ancestry-related metabolic variation in dairy sheep.