Acid versus crude oils for broiler chicken diets: In vitro lipid digestion and bioaccessibility

Exploring the fates and molecular changes of different diacylglycerol-rich lipids during in vitro digestion

This study aimed to support the pursuit of healthy oils and investigate the relationships between lipid compositions and digestion fates of diacylglycerol (DAG)-rich lipids using an in vitro digestion model. Soybean-, olive-, rapeseed-, camellia-, and linseed-based DAG-rich lipids (termed SD, OD, RD, CD, and LD, respectively) were selected. These lipids exhibited identical lipolysis degrees (92.20-94.36 %) and digestion rates (0.0403-0.0466 s^-1). The lipid structure (DAG or triacylglycerol) was a more important factor affecting the lipolysis degree than other indices (glycerolipid composition and fatty acid composition). For RD, CD and LD with similar fatty acid compositions, the same fatty acid had different release levels, probably due to their different glycerolipid compositions (causing different distributions of the fatty acid in UU-DAG, USa-DAG and SaSa-DAG; U: unsaturated fatty acids, Sa: saturated fatty acids). This study provides insights into the digestion behaviors of different DAG-rich lipids and supports their food or pharmaceutical applications.

Influence of free fatty acid content and degree of fat saturation on production performance, nutrient digestibility, and intestinal morphology of laying hens

This study was conducted to evaluate the effects of dietary free fatty acid (FFA) content and degree of fat saturation on production performance, lipid and calcium digestibility, and intestinal function of laying hens. For a 15-week period, a total of 144 laying hens (19 weeks old) were randomly assigned to 8 dietary treatments, which were obtained by gradually replacing crude soybean oil with soybean acid oil (AO), or crude palm oil with palm fatty acid distillate (FAD). Thus, there were 4 soybean and 4 palm diets with 6% added fat varying in their FFA percentage (10%, 20%, 30%, and 45%), following a 2 × 4 factorial design. Each treatment included 6 replicates with 3 birds per replicate. Average daily feed intake and final body weight were significantly higher in palm diets (P < 0.001), while no differences were found in egg mass and feed conversion ratio. Higher levels of FFA in soybean diets resulted in lower egg production and higher egg weight (linear, P < 0.01). Regarding the degree of fat saturation, hens fed soybean diets presented higher digestibility of ether extract (EE), fatty acids, and calcium than palm diets (P < 0.001). The dietary FFA percentage negatively affected the digestibility of EE and calcium (P < 0.01), while having little effect on FA digestibility. There was a significant interaction in the AME; lower values were reported in soybean diets as the dietary FFA percentage increased (linear, P < 0.01), whereas palm diets remained unaffected. The experimental diets had little effect on gastrointestinal weight and length. However, the jejunum of soybean diets showed higher villus height and higher villus height-to-crypt depth ratio than palm diets (P < 0.05), and the dietary FFA percentage increased the crypt depth and decreased the villus height-to-crypt depth ratio (linear, P < 0.05). It was concluded that varying dietary FFA content did not affect fat utilization as much as the degree of saturation did, supporting the use of AO and FAD as alternative fat ingredients.

Importance of adapted digestion conditions to simulate in vitro lipid digestion of broilers in different life stages

In vitro digestion studies demonstrate large potential to gain more and quicker insights into the underlying mechanisms of feed additives, allowing the optimization of feed design. Unfortunately, current in vitro digestion models relevant for broiler chickens lack sufficient description in terms of protocols and standardisation used. Furthermore, no distinction is made between the different life phases of these animals (starter, grower, and finisher). Hence, our research aimed to establish adapted in vitro digestion conditions, corresponding to the 3 life phases in broilers, with specific focus on lipid digestion. The effect of 3 different bile salt concentrations of 2, 10, and 20 mM, and 3 different lipase activities of 5, 20, and 100 U/mL, on in vitro lipid digestion kinetics were evaluated using a full factorial design. These values were selected to represent starter, grower, and finisher birds, respectively. Our findings showed that the extent of lipid digestion was mainly influenced by lipase activity. The rate of lipid digestion was affected by an interplay between bile salt concentration and lipase activity, due to possible lipase inhibition at certain bile salt concentrations. Overall, this work resulted in 3 in vitro lipid digestion models representative for starter, grower, and finisher birds. In conclusion, this research showed the impact of adapted in vitro digestion conditions on lipid digestion kinetics and thus the need for these conditions relevant for each life phase of broilers.

Olive pomace oil and acid oil as alternative fat sources in growing-finishing broiler chicken diets

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.

Olive Pomace and Soybean-Sunflower Acid Oils as Alternative Fat Sources in European Seabass (Dicentrarchus labrax) Diets: Effects on Performance, Digestibility and Flesh Fatty Acid Composition and Quality Parameters

The effects of dietary inclusion of soybean-sunflower and olive pomace acid oils on growth, digestibility and flesh composition were studied in European seabass. Eight diets were fed for 100 days (101.37 ± 0.33 g initial weight, mean ± SD), differing in the added fat source (25% fish oil, 75% experimental oil): S (crude soybean oil), SA (soybean-sunflower acid oil), O (crude olive pomace oil) or OA (olive pomace acid oil); 3 blends: S-O, S-OA, SA-OA at a 1:1 ratio; and a diet containing only fish oil (F) as a control. Animals fed OA showed the worst performance among dietary treatments, with the lowest weight, specific growth ratio, average daily gain and the highest feed conversion ratio (p < 0.01). In contrast, other diets including acid oils did not impair performance. Acid oil diets did not affect the apparent digestibility of dry matter, crude protein or total fatty acids (p > 0.05), but a lower digestibility of lipids and saturated fatty acids was observed (p < 0.001). Flesh composition and fatty acid profile were not affected by the high dietary free FA content (p > 0.05). Hence the results suggest that the studied acid oils may potentially be used in fish diets although further studies are needed.

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

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.

Soybean Oil Replacement by Palm Fatty Acid Distillate in Broiler Chicken Diets: Fat Digestibility and Lipid-Class Content along the Intestinal Tract

Simple Summary

Palm fatty acid distillate is a by-product of palm oil refining. It is of both environmental and economic interest to include it in the diets of broiler chickens. However, its high saturation degree and acidity level limit its use. This study aimed to assess the effect of replacing soybean oil with increasing levels of palm fatty acid distillate on the utilization of fat by broilers. Dietary fat hydrolysis was mostly affected by the age of the bird and including palm fatty acid distillate mainly affected the absorption process. The replacement of soybean oil by palm fatty acid distillate reduced the total fat utilization, and in starter chicks delayed the site of fatty acid absorption. As the age increased, the digestibility of saturated fatty acids improved, and, above all, it improved the free fatty acid utilization. Therefore, the potential inclusion of palm fatty acid distillate for broiler feeds depends on the age of the bird. It would not be recommended to include this by-product in starter feeds. However, for the grower-finisher phase, blending palm fatty acid distillate with soybean oil (1:3, w/w) could be a suitable alternative, that does not have negative repercussions for either fatty acid absorption or growth performance.

Abstract

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.