Liver transcriptomic profiles of ruminants fed spent hemp biomass
The inclusion of spent hemp biomass (SHB), an extracted byproduct from industrial cannabidiol (CBD) production, in the diets of ruminants have provided evidence on possible long-term beneficial effects on production performance and health of lambs and dairy cows that could be partly associated with delta9-tetrahydrocannabinol and CBD contained in the SHB. However, it remains largely unknown how those major cannabinoids present in the SHB play a role in affecting production traits especially in the liver, a central hub of metabolic processes. Therefore, the goal of this study was to study transcriptional profile of the liver of lambs and dairy cows fed SHB. We collected the liver from finishing lambs (n = 7 lambs per group) fed control diet (CON), 10 (LH2) or 20 percent (HH2) SHB for 2 months or 1 month followed by 1-month SHB withdrawal (LH1 and HH1, respectively). For dairy cows, liver was obtained by using biopsies from lactating Jersey cows (245 DIM; n = 9 cows/group) fed 13 percent SHB for four weeks of intervention (IP) and four weeks of withdrawal periods (WP). RNA sequencing was performed to analyze the transcriptomic profile. The DESeq2 analysis revealed a significant TRT x Period interactions effect both in dairy cows and lambs whereas the larger DEGs of period effects were identified than the dietary SHB treatment effect. In dairy cows, 29 DEGs were identified in HEMP vs. CON during IP which consisted of 10 upregulated genes and 19 downregulated genes Following SHB withdrawal, HEMP vs. CON at WP only identified 4 DEGs. A larger number of DEGs was uncovered in both HEMP and CON groups after withdrawal periods. In lambs, few number of DEGs were identified, similar to what was found in dairy cows. As expected, the largest number of DEGs was identified in the HH2 vs. CON comparison which included 143 upregulated and 111 downregulated genes where 4 among them were also identified in the LH2 vs. CON (Figure 2). Less than 25 DEGs remained after a month of SHB withdrawal as indicated by the LH2 vs. LH1 and HH2 vs. HH1 or when LH1 and HH1 were compared to CON. The comparison based on SHB levels (HH2 vs LH2) identified 41 upregulated and 39 downregulated genes. Our results provide important insights on the roles of SHB-containing cannabinoids on liver transcriptomic profile of lambs and dairy cows.