Replacement of Palm Oil with Soybean Acid Oil in Broiler Chicken Diet: Fat Digestibility and Lipid Class Content along the Intestinal Tract

SIMPLE SUMMARY: Soybean acid oil is a by-product rich in free fatty acids obtained from the soybean oil refining industry. Its inclusion in chicken diet is a way for it to be upcycled and to reduce the cost of feed. Its high degree of unsaturation could enhance the absorption of saturated fatty acids from palm oil. The objective of this study was to assess the effect of replacing palm oil with increasing amounts of soybean acid oil on fat digestion and absorption in starter and grower chickens. The replacement of palm oil with soybean acid oil improved fat utilization in both 11 and 35-day-old broiler chickens. With the age, the contribution of the upper ileum to a better fat absorption increases. In grower chickens, soybean acid oil at 6% of total inclusion or a blend of palm oil with soybean acid oil (2:4, w/w) led to adequate fat utilization, similar to soybean oil at 6%. The results suggest that the use of soybean acid oil blended with palm oil is a good solution for inclusion in broiler chicken diet. ABSTRACT: This study aimed to evaluate the replacement of palm oil (P) with increasing levels of soybean acid oil (SA), a by-product of soybean oil (S) refining, on lipid class content and fatty acid (FA) digestibility in the intestine and excreta of chickens at 11 and 35 days (d). Five experimental diets were obtained by supplementing a basal diet with 6% of P (P6), 6% of SA (SA6), 4% of P + 2% SA (P4-SA2), 2% of P + 4% of SA (P2-SA4) and 6% of S (S6). A total of 480 one-d-old female broiler chickens (Ross 308) were housed in metabolic cages (6 cages/treatment, with 16 birds/cage). Replacing P with SA improved fat absorption at 11 and 35 d (p < 0.05), but not feed AME values and saturated FA (SFA) digestibility at 11 d. As age increased, the absorption of SFA and free fatty acids (FFA) improved, and the contribution of the upper ileum to FA absorption increased (p < 0.05). At 35 d, SA6 (56% FFA) and P2-SA4 (40% FFA, 2.6 unsaturated-to-saturated FA ratio) could replace S6 without impairing fat utilization. The replacement of P with SA represents a suitable strategy to use this by-product.