Effects of fish oil protection on ruminal metabolism of fatty acids, in vitro digestibility and ruminal parameters

A set of in vitro experiments conducted to determine ruminal metabolism of fish oil fatty acids (Complete randomized block design), effects of fish oil on protozoa population, rumen parameters and nutrient digestibility (Complete randomized design). Also the effects of oil protection methods on these parameters were addressed. Extent of apparent fatty acid biohydrogenation was too far from accumulation of corresponding saturated fatty acids, which indicated incomplete biohydrogenation of fish oil fatty acids. Different biohydrogenation intermediates of 18, 20 and 22 carbon length was detected in incubation vessels and their contribution on apparent biohydrogenation was calculated. Protection of fish oil affected extent of ruminal fatty acid biohydrogenation and also production and accumulation of biohydrogenation intermediates. Unprotected oil and fatty acids had major effects on protozoa counts, VFA and ammonia nitrogen concentrations. Protection methods were resulted in increased concentration of VFA and cell wall digestibility and molar proportions of acetate. However, different protection methods with different oil concentration had different effects. Further experiments to fully describe effects of oil microencapsulation on biohydrogenation and also in vivo experiments are warranted.