Seleno-methionine decreases biohydrogenation of C18 unsaturated fatty acids in ovine ruminal fluid incubated in vitro with α-linolenic acid

The influence of seleno-methionine (Se-Met) added to an ovine ruminal fluid containing α-linolenic acid (α-LNA) on the profile of fatty acids (FA) was investigated. The fluid was incubated in vitro at 39°C under CO2 either alone (the control ruminal fluid; RF) or with α-LNA (1.67 mg/mL) or with a combination of α-LNA with either a low (1.25 µg/mL) or high (4.16 µg/mL) concentration of Se as Se-Met. Tubes with fluids were removed after 0, 6, 12, 18 or 24 h of incubation. α-LNA in the fluids with/without Se-Met stimulated the accumulation of C14:0 and C16:0 compared with the RF. The fluids containing Se-Met reduced the concentration of C18:0 compared with the RF. α-LNA in the fluids with/without Se-Met increased concentrations of cis9C14:1, cis9C18:1 and trans11C18:1 compared with the RF and the fluids with Se-Met. The fluids with α-LNA and Se-Met increased the accumulation of trans9trans11cis15C18:3 compared with the fluids with α-LNA. The fluids with α-LNA and Se-Met decreased the biohydrogenation to C18:0 compared with the RF. Se-Met in the fluids elevated the concentration of trans11C18:1 and lowered the capacity of the biohydrogenation to C18:0 in the fluids incubated for 24 h. Added Se-Met affected the FA profile in incubated fluids. 1 Practical applications Selenium and polyunsaturated fatty acids n-3 (PUFAn-3) are very important for human health and nutrition. Recent studies documented that a higher content of mono-conjugated isomers of α-linolenic acid (α-LNA) in diets reduced the abundance of PUFAn-3 in the brain, liver and heart of experimental animals. Due to the increasing world population, overfishing of the seas and usually low concentrations of PUFAn-3 and essential trace elements (like selenium) in animal products, there is a demand for better methods of feeding livestock. Considering the above, it was desirable to study the extent to which dietary seleno-compounds (like seleno-methionine) may contribute to concentrations of mono-conjugated α-LNA (C-α-LNA) isomers, as C-α-LNA isomers may perturb the PUFA balance (or imbalance) in tissues of animals and humans. Moreover, further studies are needed to determine if dietary seleno-compounds, α-LNA and C-α-LNA isomers also induce changes in concentrations of fatty acids, especially PUFAn-3, in tissues of lambs. Seleno-methionine has an influence on the concentrations of fatty acids, especially unsaturated fatty acids, in in vitro incubated ovine ruminal fluid, irrespective of the presence of α-linolenic acid. Seleno-methionine added to the incubated fluids affects the capacity of the bacterial isomerases and modified activities of ruminal bacteria. The simultaneous addition of α-linolenic acid and Se-Met to the ruminal fluids decreased the yield of final biohydrogenation to C18:0 in comparison with the in vitro incubated control fluids.