Abstract
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). 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.
Highlights
Nutritional attempts to remedy infertility are of interest to the dairy industry [1] because the antagonistic relationship between high milk production and fertility in modern, high genetic-merit cows has concomitantly led to a gradual but progressive decline in reproductive performance in diverse dairy production systems around the world
We tested the hypothesis that the relative mRNA abundance and gene expression profiles of Aralkylamine N-acetyltransferase (AANAT), B-cell translocation gene-2 (BTG2) and Fatty Acid Synthase (FASN) in primiparous Holstein-Friesian cows will be up-regulated in response to post-partum dietary supplementation with crude degummed canola oil (CDCO) in a typical pasture-based dairy production system
The present study found that supplementation of lactating Holstein-Friesian cows with CDCO repressed the expression of BTG2 significantly
Summary
Nutritional attempts to remedy infertility are of interest to the dairy industry [1] because the antagonistic relationship between high milk production and fertility in modern, high genetic-merit cows has concomitantly led to a gradual but progressive decline in reproductive performance in diverse dairy production systems around the world. In a typical pasture-based dairy system, different sources of lipids fed to lactating cows have been trialled to primarily increase the energy density of the diet in order to enhance milk production when negative energy balance peaks [3]. A new, effective and long-term nutritional strategy that can assist in a better understanding of nutrition-fertility interactions in pasture-based systems is a potential solution to the subfertility problem in dairy cows.
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