Ruminal Biohydrogenation Kinetics of Defatted Flaxseed and Sunflower Is Affected by Heat Treatment.

The effect of heat treatment on biohydrogenation of linoleic acid (LA) and linolenic acid (LNA) and formation of stearic acid (SA), cis-9, trans-11 conjugated LA (CLA), trans-10, cis-12 CLA and trans-vaccenic acid (VA) was studied in in vitro incubations with diluted rumen fluid as inoculum and partly defatted flaxseed (DF) and partly defatted sunflower (DS) as test feeds. Feeds were heated in a laboratory oven at 110 °C for 0 (unheated), 45, or 90 min. Michaelis-Menten kinetics was applied for quantifying biohydrogenation rate. The DF heated for 90 min showed the lowest biohydrogenation rate of LNA and LA, indicated by the lowest V _max value (P < 0.04 and P < 0.03, respectively). The DS heated for 45 min had the lowest biohydrogenation rate of LNA, indicated by the lowest V _max value (P < 0.04). In conclusion, heat treatment decreased biohydrogenation of LA and LNA in DF and LNA in DS.