Gene Expression Differences Associated with Fatty-Acid Deposition in Beef Cattle Fed Diets with Supplemental Flaxseed

Supplementation of beef cattle diets with flaxseed has been shown to increase the omega-3 fatty-acid (FA) content of muscle and fat tissues. Towards the goal of enhancing beef FA composition, 64 crossbred cull cows (~30 months of age) of  similar breed  were ranked by weight/body condition and randomly assigned to one of four 50:50 forage:concentrate (DM basis) diets. The diets contained either hay or barley silage, supplemented with 0 or 15% ground flaxseed. Forty genes related to FA metabolism were selected for high-throughput real-time PCR gene expression analysis in the Longissimus thoracis (LT) muscle and subcutaneous (SC) fat samples collected at slaughter to identify expression differences between flax-supplemented  versus non-supplemented cows. Correlation analysis of the 40 expressed genes and FA profiles of LT and SC resulted in the identification of 22 genes significantly associated with an increase in percentage of desirable FAs such as omega-3s, or in the amount of harmful saturated-FAs. For example, expression of sphingomyelin synthase 1 (SGMS1) was associated with higher amounts of omega-3 and omega-6 FAs, and lower amounts of C15:0.  The sterile alpha motif domain containing 8 (SAMD8) was associated with lower amounts of saturated-FAs such as C14:0 and C15:0. Gene expression that correlates to FAs may have the potential to screen cattle for healthier FAs in their tissues, and the sequence of these genes can be interrogated to discover new single nucleotide polymorphisms associated with FA profiles.