66 Blood MicroRNAomes Revealed Signatures of Lameness Phenotypes in Feedlot Cattle

Abstract

Abstract Lameness is a significant health issue in Canadian feedlots resulting in substantial economic losses. However, the high frequency of misdiagnosis of lameness using traditional methods leads to ineffective treatment, suggesting a new diagnostic method is needed. Growing evidence indicates that microRNAs (miRNAs) can be used as biomarkers for identifying the animals’ physiological status and the diagnosis of certain diseases, but this approach has not been utilized in beef cattle. The objective of this study was to compare blood miRNA profiles between lame and healthy cattle to investigate the relationship between miRNA expression patterns and specific lameness phenotypes. Blood samples were collected from 156 feedlot cattle at 0, 1, 2 and 3 weeks after being diagnosed with either digital dermatitis (DD; n=62), toe tip necrosis syndrome (TTNS; n = 40), or footrot (FR; n = 40) and healthy controls (HC; n = 12) for miRNA libraries construction and sequencing. A total of 314 expressed miRNAs were identified in 89 blood samples collected at week 0 across all groups, with TTN having the largest number of expressed miRNAs (291, P < 0.01) compared to all other groups (HC=276, DD=281, FR=278). Although miRNA profiles did not differ among the lameness types, type-specific miRNAs were identified; 6 in DD, 10 in TTN, 5 in FR and 7 in HC cattle. In addition, 3, 6 and 7 DE miRNAs were detected in DD, TTNS and FR when compared with HC cattle. Most of the DE and group-specific miRNAs are related to inflammation and skin diseases. The DE miRNAs were different between week 0 and all other weeks, indicating miRNA profiles may differ over time and with disease progression and recovery. These findings provide an initial understanding of the relationship between the cattle blood miRNAome and lameness and suggest that miRNA expression holds promise in the discovery of novel biomarkers for identifying lameness.