403 Supplementing omega-6 fatty acids to enhance reproductive performance of beef cows

Abstract

Abstract Our research group has focused on how Ca salts of soybean oil (CSSO) supplementation, a source of omega-6 fatty acids (FA), impacts reproductive performance of beef cows. In Nelore (Bos indicus) grazing cows assigned to fixed-time artificial insemination (AI), supplementing 100 g/d (as-fed basis) of CSSO for 21 d after AI increased (P < 0.01) pregnancy rates from 38.1% (623/1635 as pregnant/total non-supplemented cows) to 49.0% (843/1720 as pregnant/total CSSO-supplemented cows). These outcomes were later associated with enhanced early embryonic development and pregnancy establishment from supplemental omega-6 FA. More specifically, supplementing 100 g/d of CSSO to Nelore cows increased (P ≤ 0.05) incorporation of omega-6 FA in circulation and in the conceptus, increased (P ≤ 0.04) conceptus length (2.2-fold increase), and upregulated mRNA expression of interferon-tau (4.1-fold increase) on d 15 of gestation. Similar outcomes were noted in B. taurus beef cows receiving 100 g/d of CSSO for 21 d after AI. Supplementing CSSO to Angus-influenced cows increased (P = 0.01) pregnancy rates from 51.7% (193/388 as pregnant/total non-supplemented cows) to 60.2% (226/383 as pregnant/total CSSO-supplemented cows), increased (P < 0.01) plasma concentrations of omega-6 FA, and upregulated (P = 0.05) mRNA expression of interferon-tau in d 15 conceptuses (1.8-fold increase). Across these research efforts, CSSO was mixed with granular feed ingredients and hand-fed to cows, which demands labor and may discourage the use of CSSO supplementation by commercial cow-calf producers. Accordingly, our research group also demonstrated that CSSO inclusion into a self-fed low-moisture block resulted in similar incorporation (P ≥ 0.35) of omega-6 FA in the circulation of Angus-influenced cows compared with CSSO inclusion into a hand-fed granular concentrate. Collectively, CSSO improves reproductive performance of B. indicus and B. taurus beef cows, and may be supplemented via self-fed low-moisture blocks to minimize labor needs.