Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2025
Publication Date: 5/13/2025
Citation: Lindholm-Perry, A.K., Bradford, H.L., Foote, A.P., Freetly, H.C., Chitko-McKown, C.G., Kuehn, L.A., Keele, J.W., Neville, B.W., Oliver, W.T., Keel, B.N. 2025. The association between hematological profiles and whole-blood transcriptome genes identified using quantitative analysis with average daily gain and feed efficiency in forage-fed beef heifers. International Journal of Molecular Sciences. 26(10). Article 4633. https://doi.org/10.3390/ijms26104633.
DOI: https://doi.org/10.3390/ijms26104633

Interpretive Summary: Cattle that are more feed efficient can improve producer profits, as they are able to achieve higher body weights consuming fewer feed inputs. Much work has been done to determine differentially expressed genes (DEGs) in various tissues (muscle, liver, gut, etc.) that are at least partly responsible for the variation in feed efficiency. However, obtaining these types of samples are invasive and sometimes can only be taken from euthanized animals. Whole blood has increasingly been used for RNA sequencing to determine DEGs expressed in blood cells. Blood is easily accessible from live animals with minimal invasiveness and recently gene expression from whole blood has been associated with feed efficiency. ARS researchers have determined the association between hematology parameters (blood cell types) and DEGs for average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (Gain:Feed) in heifers consuming a forage diet. White cell types were associated with ADG and Gain:Feed, and red blood cell count was associated with ADFI in the current study. Hemoglobin concentration in red blood cells was associated with both ADG and G:F. Three of the differentially expressed genes for G:F and ADG (PLOD1, FAH and COL1A2) had been previously associated with feed efficiency in livestock and may be useful for further validation in other populations of cattle. These hematology data suggest that oxygen transport in the blood is associated with feed efficiency in heifers consuming a forage diet.

Technical Abstract: Feed is the single greatest cost for cattle producers. Improvements to feed efficiency, or how animals convert feed to body weight gain, will ultimately improve producer profits. The objective of this study was to determine whether the expression of genes in the transcriptome of whole blood from heifers (n = 61) on a forage ration was related to the quantitative phenotypes for average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed (G:F). Total RNA was isolated from whole blood collected mid-study on day 42 on feed and was used for hematologic analysis and RNA-sequencing. Lymphocyte (LYM) count was negatively associated with ADG, and mean corpuscular hemoglobin concentration (MCHC) was positively associated (p < 0.05). Red blood cell (RBC) count was negatively associated with ADFI. While MCHC was positively associated with G:F, white blood cell (WBC), LYM, and basophil (BAS) counts were negatively associated with G:F (p