The present experiment was conducted to evaluate the effect of the different levels of soybean oil on endogenous losses, apparent and true ileal digestibility of amino acids in growing pigs diets. Four isoprotein corn and soybean meal based diets meeting the nutritional requirements for this phase, supplemented with crescent levels of soybean oil, (0.0, 1.5, 3.0, and 4.5) were evaluated. Chromic oxide (0.25%) was added to serve as digestibility marker. Sixteen cannulated pigs (simple T-cannula), with weight of 48.0 ± 6.0 kg, were distributed to a complete randomized block design, based in the animal weight. There was no effect of the supplement of soybean oil levels on the apparent ileal digestibility coefficients of glutamate, glycine, arginine, alanine, proline, tyrosine, histidine and lysine. A linear effect was observed with the supplementation of soybean oil levels to the true and apparent ileal digestibility coefficient of threonine and serine and a quadratic effect on the true and apparent ileal digestibility coefficients of valine, phenylalanine, total of non-essential amino acids and total of essential amino acids. True ileal digestibility coefficients of arginine and tyrosine, also showed quadratic effect of soybean oil supplementation. Better values of true and apparent ileal digestibility of essential and non-essential amino acids are obtained with the addition of 2.8 to 3.0% of soybean oil to diets for growing pigs.
