A study with 2 ruminant species (goats and coww with inherent difmetice n lipid miitabolikim war per- formed to the hypothesis that milk fat depression (MFD) due to marine lipid Rupplements or diets con- taining amounts of starch and plant oil is caused by different mechanisms and that each ruminuant spe responds differently. Cows and Roats wure allocated to 1 of 3 group cows and 6g ts per group and diets containing no additional oil (control) on Eupple- mented with fish oil or rumflowpr oil and wheat starch (SOS) according to a 3 x 3 Latin square de with 20-d experituaiental periods. in cows milk fat lowered by FO and SOS whereas only FO decreased milk fat content in goats compared with the control, Furthermore, FO and SOS decreased milk fat yield in cows, but not in goati. both species, FO and SOS decreased the seeretion of