1. Investigación

The aim of the present study was to investigate the effect of dietary supplementation of olive pomace oil and olive pomace acid oil, which are rich in monounsaturated fatty acids (FA) but differ in free FA content, on growth performance, digestibility and FA profile of abdominal fat and breast meat. A total of 3,048 one-day-old mixed-sex broiler chickens (Ross 308) were randomly distributed into 24 pens and 3 dietary treatments (8 replicates per treatment). Experimental diets were administered for growing (from 22 to 29 d) and finishing (from 30 to 39 d) periods, consisting of a basal diet supplemented with 6% (as-fed basis) palm oil (PO), olive pomace oil (O), or olive pomace acid oil (OA). Animals fed O achieved the lowest feed conversion ratio (P < 0.01), together with the highest AME value (P = 0.003), but no differences were observed between OA and PO. Regarding FA digestibility, O and OA showed higher values than PO for all FA in both apparent ileal digestibility (AID) and apparent total tract digestibility. Comparing the AID between O and OA, no differences were observed for total FA, monounsaturated FA, or polyunsaturated FA, but animals fed OA showed lower AID values for saturated FA than those fed O (P < 0.001). The FA profile of abdominal fat and breast meat reflected that of the diet, with higher monounsaturated FA and lower saturated FA in animals fed O and OA compared to those fed PO. In sum, the inclusion of both olive pomace oil and acid oil in growing-finishing broiler chicken diets led to great performance parameters and high FA digestibility values, together with an enrichment with monounsaturated FA in abdominal fat and breast meat compared to the use of palm oil. However, a better AID of saturated FA and feed conversion ratio is achieved with O compared to OA.

The aim of the present study was to evaluate the effect of dietary free fatty acid (FFA) content and the degree of saturation on egg quality, yolk fatty acid (FA) profile, and yolk cholesterol content. For a 15-wk period, a total of 144 laying hens (19- wk-old) were randomly assigned to 8 treatments arranged in a 2 £ 4 factorial design, with 2 sources of crude oil (soybean oil and palm oil) and 4 levels of FFA (10, 20, 30, and 45%). The dietary treatments were achieved by progressively substituting the original oils with equivalent amounts of their corresponding acid oils (soybean acid oil and palm fatty acid distillate, respectively). No differences in ADFI or egg mass were found. However, dietary FFA reduced egg production (linear, P < 0.05) and increased the feed conversion ratio (linear, P < 0.05). Higher levels of FFA in soybean diets resulted in higher egg weight with higher albumen and yolk weights (linear, P < 0.01). Palm diets presented higher yolk:albumen ratio than soybean diets (P < 0.001), but the effect of FFA did not follow a linear trend. Hens fed soybean diets laid eggs with higher Haugh units (HU) than palm diets (P < 0.001), although increasing the dietary FFA% reduced the HU values in both (linear, P < 0.001). Palm diets enhanced shell quality with greater resistance to breakage, and higher dry matter and ash content than soybean diets (P < 0.05). No differences in egg chemical composition and yolk cholesterol content were found (P > 0.05). The saturation degree had a significant effect on all the analyzed yolk FA (P < 0.001) except for arachidonic acid (C20:4 n-6), whereas increasing the FFA content did not affect to a great extent. These results show that varying dietary FFA level did not affect egg quality and yolk composition as much as the dietary fat source did, supporting the use of acid oils and fatty acid distillates as fat ingredients for feed.

The aim of the present study is to assess the effect of the free-fatty-acid (FFA) content and saturation degree of dietary fat (added at 6%) on the fattyacid (FA) digestibility and lipid-class content along the gastrointestinal tract and excreta in broilers from 22 to 37 d of age. This is essential to determine the potential use of acid oils (refining by-products rich in FFA) in broiler diets as an alternative to crude oils. The study consisted of a 2 £ 4 factorial arrangement, which included 2 fat sources (soybean oils − unsaturated, or palm oils − saturated) and 4 levels of FFA (5, 15, 35, and 50%). Samples of digestive content of the gizzard, duodenum, jejunum, ileum and of the excreta were obtained at 37 d of age. Irrespective of the dietary fat source, more than 80% of total FA (TFA) was absorbed in the jejunum. Broilers fed with unsaturated diets had a higher absorption efficiency of FA than did those fed with saturated diets. This conclusion is supported by the lower FFA content and the higher TFA and polyunsaturated FA (PUFA) digestibility coefficients in the ileum (P < 0.001) observed in the former group. The dietary FFA level did not affect the FA absorption process as much as the dietary fat source did. This was supported by the lack of statistical differences among the diets with a similar saturation degree but rather different levels of FFA, for TFA, saturated FA, and PUFA digestibility coefficients both in the jejunum and ileum. However, the interactions reported in the ileum for triacylglycerol and diacylglycerol contents (P < 0.001), as well as for monounsaturated FA digestibility coefficients (P < 0.05) show that the dietary FFA content affects the FA absorption process. The present results show that the inclusion of acid oils in grower-finisher broiler diets with FFA levels up to 35% does not have a negative impact on the FA absorption process.

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.

Palm fatty acid distillate (PFAD) is a by-product of palm oil (P) refining. Its use in chicken diets is a way to reduce the cost of feed and the environmental impact. Its low unsaturated:saturated fatty acid ratio (UFA:SFA) and its high free fatty acid (FFA) level could be partially counteracted by its blending with soybean oil (S). The objective was to assess the effect of replacing S with different levels of PFAD on lipid-class content and fatty acid (FA) digestibility along the intestinal tract and in the excreta of 11 and 35-day-old broiler chickens. Five experimental diets were prepared by supplementing a basal diet with S (S6), PFAD (PA6), two blends of them (S4-PA2 and S2-PA4), or P (P6) at 6%. Replacing S with PFAD did not affect performance parameters (p > 0.05) but negatively affected feed AME, FA digestibility, and FFA intestinal content (p < 0.05), especially in starter chicks. Including PFAD delayed total FA (TFA) absorption (p < 0.05) at 11 days, but at 35 days it did not affect the TFA absorption rate. The use of PFAD blended with S, when FFA 30% and UFA:SFA 2.6, led to adequate energy utilization in broiler grower-finisher diets.