Carcass fat composition of cattle fed a forage-based diet might be inferior with maize silage compared to
grass-silage based systems. This was quantified using complete diets with concentrate. To test whether
supplements may influence carcass fat properties as well, the maize-silage diet was additionally
supplemented either with Acacia mearnsii tannins, garlic, maca or lupines, feeds rich in secondary
metabolites. The perirenal fat of 6×6 bulls fed these six diets was analysed for fatty acid profile and shelf
life. The n−6/n−3 ratio was always higher than 11 with the maize silage treatments and 2 with grass silage.
The supplements did not affect the occurrence of biohydrogenation intermediates, including rumenic acid.
Shelf life, being twice as long with maize compared to grass silage, was either unaffected or tended to be
impaired, especially with supplementary garlic. Overall, supplementation was not efficient in improving
carcass fat properties of maize-silage fed bulls.