US EPA

5324090 

Journal Article 

In vitro rumen biohydrogenation kinetics of mixed linoleic and alfa-linolenic acids 

Vargas, JAC; Olivera-Angel, M; Ribeiro, CVDM; Daza, EE 

2018 

1 

Revista Colombiana de Ciencias Pecuarias
ISSN: 0120-0690 

31 

3 

213-222 

10.17533/udea.rccp.v31n3a06 

WOS:000442540700006 

Background: Dietary linoleic (LA) and alpha-linolenic (LN) acids are extensively isomerized and hydrogenated by rumen microbes, and this activity can further contribute to the fatty acid profile ofruminantderived food products. Objective: To evaluate the effects of LA:LN ratio in lipid supplements on the rumen biohydrogenation kinetics of LA and LN, as well as on the trans-vaccenic acid (VA) production, using an in vitro system. Methods: Rumen fluid was collected from a fistulated steer, diluted with incubation buffer, and then incubated with 500 mg of kikuyu grass (Cenchrus clandestinus) supplemented with 16.3 mg of different LA:LN mixtures (100:0, 75:25, 50:50, 25:75 or 0:100). Incubations were performed in triplicate for a period of 0, 2, 4, 6, 8 or 16 hours. Differences between treatments were evaluated in a completely randomized design. Alternatively, computational chemistry was used to determine the changes in the Gibbs free energy (Delta G(rxn)) at 39 degrees C for the principal steps of LA and LN ruminal biohydrogenation. Results: Partial replacement of LA by LN decreased the VA concentration and its accumulation rate; it also increased the stearic acid concentration and the rates of transfer from LA to conjugated linoleic acid (CLA), and from CLA to VA. The conversion from CLA to VA (Delta G(rxn)= -2.65 kJ/mol) was more spontaneous than that from trans-11, cis-15 octadecadienoic acid (TA) to VA (Delta G(rxn) = -0.29 kJ/mol). Conclusion: The LA:LN ratio in lipids can modulate LA and LN biohydrogenation (BH) kinetics, as well as the VA production in the rumen. 

Fatty acids; kinetics of biohydrogenation; lipid supplement; multi-compartmental model; thermodynamics of biohydrogenation