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Malau-Aduli AEO, Otto JR, Suybeng B, Kashani A, Lane PA, Malau-Aduli BS and Nichols PD
The effect of oil-rich supplements on the expression of genes involved in lipogenesis and reproduction in pasturebased dairy cows is currently unknown, or at best, scanty and limited to impacts on cow liveweight, body condition score, milk composition, fatty acid and plasma metabolite profiles only. This research investigated the gene expression patterns of Aralkylamine N-acetyltransferase (AANAT), B-cell translocation gene-2 (BTG2) and Fatty Acid Synthase (FASN) genes in response to incremental levels of dietary crude degummed canola oil (CDCO). We tested the hypothesis that the relative mRNA abundance and gene expression profiles of AANAT, BTG2 and FASN in primiparous Holstein-Friesian cows will be up-regulated in response to post-partum dietary supplementation with CDCO in a typical pasture-based dairy production system. Thus, the primary objective of this study was to investigate the expression of AANAT, BTG2 and FASN genes in response to incremental levels of CDCO. A random allocation of primiparous Holstein-Friesian dairy cows into four treatment groups comprising wheat-based pelleted with no supplemental CDCO (control), or with CDCO added at 25 ml kg-1 DM (low), 35 ml kg-1 DM (medium) and 50 ml kg-1 DM (high) was utilized in a ten-week experimental feeding trial including two weeks of adjustment. Both level of supplementation and their interaction with duration were significant sources of variation (P<0.05) that influenced BTG2 expression, while the expressions of AANAT and FASN genes were unaffected (P>0.05). The high (0.67 fold), medium (0.87 fold) and low (0.56 fold) treatments had suppressed BTG2 expressions compared to the control (1.0 fold) group. The low expression of BTG2 might be important when the reproductive system of cows is recovering from the effect of gestation and new cell growth is required.