Eicosapentaenoic acid (EPA) from freeze-dried biomass of Nannochloropsis oceanica microalgae resists ruminal biohydrogenation in vitro, but in vivo demonstration is needed. Therefore, the present study was designed to test the rumen protective effects of N. oceanica in lambs. Twenty-eight lambs were assigned to one of four diets: Control (C); and C diets supplemented with: 1.2% Nannochloropsis sp. oil (O); 12.3% spray-dried N. oceanica (SD); or 9.2% N. oceanica (FD), to achieve 3 g EPA /kg dry matter. Lambs were slaughtered after 3 weeks and digestive contents and ruminal wall samples were collected. EPA concentration in the rumen of lambs fed FD was about 50% higher than lambs fed SD or O diets. Nevertheless, the high levels of EPA in cecum and faeces of animals fed N. oceanica biomass, independently of the drying method, suggests that EPA was not completely released and absorbed in the small intestine. Furthermore, supplementation with EPA sources also affected the ruminal biohydrogenation of C18 fatty acids, mitigating the shift from the t10 biohydrogenation pathways to the t11 pathways compared to the Control diet. Overall, our results demonstrate that FD N. oceanica biomass is a natural rumen-protected source of EPA to ruminants.
Bibliographical noteFunding Information:
This research was funded by the Fundação para a Ciência e Tecnologia (FCT) through the PhD grant SFRH/ BD/136609/2018 awarded to ACM Vítor, the research contract to SPA (DL 57/2016/CP1438/CT0008), and the research projects PTDC/CAL-ZOO/29654/2017 and UIDB/00276/2020. The authors acknowledge the collaboration of Instituto Superior de Agronomia – University of Lisbon, namely Cátia Martins and David Santos for helping with the microalgae processing and Ana Mónica Godinho for helping with the animal’s management. The authors also acknowledge INIAV staff for the support in animal management, slaughter and chemical analysis.
© 2021, The Author(s).
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