ABSTRACT This study was conducted to evaluate the effects of long-chain fatty acid soaps (LCFAS) of soybean oil on the production and quality of aspirated cumulus-oocyte complexes (COC) of lactating Nellore (Bos taurus indicus) cows. The effects of LCFAS on the plasma concentration of lipoproteins, total cholesterol, triacylglycerol, urea N, and insulin were also addressed. Thirty lactating Nellore cows were randomly assigned to one of two dietary groups. Cows were grazed on a Tifton 85 pasture throughout the experiment (100 days). Treatments consisted of a supplement with no fat included (CONT); and a supplement containing 47.2 g/kg of LCFAS on a dry matter basis. After 14 days of treatment, animals were subjected to 4.93±1.55 rounds of consecutive ovum pickup (OPU) at intervals of 21.71±11.76 days. Blood samples were collected from all cows throughout the experiment at 25-day intervals (four samples per cow). Cows that were fed LCFAS supplements and cows that were fed CONT supplements had similar numbers of total aspirated oocytes (viable and not viable) by OPU and grades of viable oocytes. Plasma concentrations of high-density lipoprotein (HDL) were increased in cows supplemented with LCFAS. Plasma concentrations of LDL and total cholesterol were increased by LCFAS supplementation after 50 days on dietary treatment and insulin concentration was increased from 75 days on treatment. Long-chain fatty acid soaps from soybean oil added at 47.2 g/kg have no effect on the number of aspirated COC or their quality in Nellore lactating cows even with changes in plasma concentration of HDL, LDL, total cholesterol, and insulin. Thus, this supplementation has no benefits when the main objective is to improve oocyte production and quality.