RESUMEN
The objective of the present study was to evaluate the effects of an olive leaf extract obtained with an up-to-date laboratory method, when supplemented at different levels in laying hens' diets, on egg quality, egg yolk antioxidant parameters, fatty acid content, and liver pathology characteristics. Thus, 96 laying hens of the ISA-Brown breed were allocated to 48 experimental cages with two hens in each cage, resulting in 12 replicates per treatment. Treatments were: T1 (Control: basal diet); T2 (1% olive leaf extract); T3 (2.5% olive leaf extract); T4 (Positive control: 0.1% encapsulated oregano oil). Eggshell weight and thickness were improved in all treatments compared to the control, with T2 being significantly higher till the end of the experiment (p < 0.001). Egg yolk MDA content was lower for the T2 and T4 groups, while total phenol content and Haugh units were greater in the T2. The most improved fatty acid profile was the one of T3 yolks. The α-tocopherol yolk content was higher in all groups compared to T1. No effect was observed on cholesterol content at any treatment. Based on the findings, it can be inferred that the inclusion of olive leaf extract at a concentration of 1% in the diet leads to enhancements in specific egg quality attributes, accompanied by an augmentation of the antioxidant capacity.
RESUMEN
Olive leaves are byproducts οf the agro-industrial sector and are rich in bioactive compounds with antioxidant properties. They could be supplemented in poultry diets powdered or less frequently as extracts to improve performance, health and product quality. The objective of this study was to investigate the possible beneficial effects of an aqueous isopropanol olive leaf extract-purified through filtration (250-25 µm) and a resin (XAD-4)-when supplemented in broiler chickens' diets, on meat quality parameters, focusing mainly on antioxidant parameters as there is limited published information. For this purpose, four-hundred-and-eighty-day-old broilers were randomly assigned to four dietary treatments: T1 (control: basal diet); T2 (1% olive leaf extract); T3 (2.5% olive leaf extract); T4 (positive control: 0.1% encapsulated oregano oil commercially used as feed additive). At the end of the experimental period (day 42), the birds were slaughtered, and samples from breast, thigh meat and liver were collected for antioxidant parameters evaluation. On day 1, after slaughter, in thigh meat, Malondialdehyde (MDA) was lower in T2 compared to T3, and total phenolic content (TPC) was higher in T2 compared to T3 and T4. Total antioxidant capacity (TAC) was increased in T2 and T4 breast meat compared to the control. In liver, T4 treatment resulted in higher TPC. The lack of dose-dependent effect for olive leaf extract may be attributed to the pro-oxidant effects of some bioactive compounds found in olive leaves, such as oleuropein, when supplemented at higher levels. In summary, it can be inferred that the inclusion of 1% olive leaf extract in the feed of broilers has the potential to mitigate oxidation in broiler meat and maybe enhance its quality.
RESUMEN
Pomegranate contains bioactive compounds in all its parts. In this study, two levels of pomegranate peel byproduct (PPB) with or without the inclusion of xylanase enzyme were used to supplement laying hens' diet, in a 2 × 2 full factorial design. A total of 48 Isa brown laying hens were fed the following experimental diets for 8 weeks: T1 (2.5% PPB); T2 (2.5% PPB and xylanase); T3 (5% PPB); T4 (5% PPB and xylanase). Eggs collected were analyzed for egg quality parameters. Moreover, egg yolks were analyzed for Malondialdehyde content (MDA), fatty acid profile and total phenolic content. The T2 eggs showed enhanced yolk coloration and greater yolk total phenolic content. The T3 and T4 egg yolks showed lower MDA levels compared with T1, T2. Overall, results have shown that (a) xylanase inclusion affected egg yolk coloration and total phenolic content when combined with 2.5% PPB dietary supplementation; (b) dietary supplementation of 5% PPB resulted in eggs with reduced MDA levels.
RESUMEN
Wheat is rich in non-starch polysaccharides (NSP) and their degradation in poultry diets is promoted by exogenous carbohydrases. The objective here was to evaluate the effect of adding an intrinsically thermostable xylanase on wheat-based diets for laying hens in yolk color, carotenoid and fatty acid profiles of eggs. A total of 128 laying hens were used for 12 weeks. They were randomly allocated to four dietary treatments with different levels of xylanase: T1: control (no xylanase), T2: 30,000 U/g, T3: 45,000 U/g and T4: 90,000 U/g, with 32 birds, 16 replicates per treatment (2 birds/replicate). At the end of the experimental period, egg yolk color index, redness (a*) and yellowness (b*) of egg yolks were found significantly higher in all the enzyme supplemented diet groups (T2, T3, T4) compared with the control (T1). Canthaxanthin levels were significantly higher in T3 than T1 (p < 0.05). Total n-3, n-6 and total polyunsaturated fatty acids (FAs) were significantly higher in T4 compared with the control (p < 0.01), while the reverse trend was evidenced for monounsaturated FAs. Additionally, total n-3 FAs were higher in the T2 than T1 (p < 0.005). Overall, the results showed that exogenous xylanase enzyme supplementation in wheat-based diets for laying hens contribute to maintaining egg yolk color. Overall, exogenous xylanase enzyme supplemented at all levels in wheat-based laying hens' diets improved egg yolk color compared to the control diet. The enzyme supplemented at the higher level (90,000 U/g) improved polyunsaturated and reduced monounsaturated egg yolk fatty acid content.
