NUTRITION ▶▶▶


Tomato peel and rosehip improve egg quality


Re-utilisation of agro-industrial waste and by-products that possess compounds with added value is important not only to decrease the volume of waste but also to develop re-utilisation strategies that add economic value, thus moving from a linear to a circular economy.


BY MATTHEW WEDZERAI A


study published in the journal Research on Animal Production showed that a dietary inclusion of 4% and 12% tomato powder in Japanese quail diet decreases the concentration of malondialdehyde,


a marker of oxidative stress, while increasing the activity of the antioxidant enzyme, glutathione peroxidase, suggesting that tomato powder improves antioxidant activity in quails. Another study in Poultry Science showed that the addition of rosehip to broiler diets decreases the by-product of lipid per- oxidation, TBARS (Thiobarbituric acid reactive substances). It was against this background that the researchers involved in the study described here sought to investigate the effects of dietary supplementation with tomato peel and rosehip meal on the transfer of phytochemicals to eggs, antioxidant profile and the markers of lipid peroxidation in stored eggs. In addi- tion, explaining the contribution of the two products to increased levels of vitamin A and vitamin E in eggs. Tomato residue is a good source of bioactive molecules, espe- cially carotenoids such as β-carotene and lycopene. The seeds of rosehip fruit represent approximately 29% of rosehip weight, however, they are usually discarded as waste after the processing of rosehip. The seeds contain up to 8% oil which is valuable due to its concentration of bioactive lipids, including tocols and sterols. These two phytochemical-rich products have beneficial bio- activities, specifically antioxidant activities.


The study A group of 42-week-old laying hens was used in this study to


gain insight into the effects of dietary supplementation with tomato peel and rosehip meal on the transfer of phytochemi- cals to eggs, antioxidant profile and the markers of lipid per- oxidation in stored eggs. The birds were assigned to three di- etary treatments with 30 birds in each trial, as follows: a control group (a corn-soybean diet with no by-product addi- tion); a tomato peel group (control + 2% tomato peel) and a rosehip meal group (control + 2% rosehip meal).


Antioxidant profile The researchers found that supplementation of both the to- mato peel and rosehip meal increased the lutein and zeaxan- thin (main carotenoids in egg yolk) carotenoid content and antioxidant capacity in eggs compared to the control group. Vitamin E content in eggs was increased by the tomato peel, while vitamin A was increased by rosehip, compared to the control. The polyphenols were higher overall in the eggs of birds fed the tomato peel diet, while the rosehip meal diet had lower total polyphenols. The higher vitamin E content of the eggs was attributed to the higher levels of vitamin E (149 mg/kg DM) found in the tomato peel compared to a lower vitamin E content (19 mg/kg DM) in the rosehip meal. What was of interest to the researchers is that in a previous


Table 1 – Effect of tomato peel and rosehip meal supplementation on productive parameters of laying hens and the antioxidant profile of eggs (fresh basis) at the end of the experiment.


Item


Production parameters Feed intake (g/hen) FCR


Laying % Egg weight (g)


Egg antioxidant profile Vitamin E (μg/g) Vitamin A (μg/g)


Lutein + zeaxanthin (μg/g) Total polyphenols (mg GAE/g)


Antioxidant capacity (mmol equiv. AA)


Experimental diets Control


108 1.88 95.7 61.0


125.4 8.55 5.92


0.296 4.89


Tomato peel


110 1.86 96.7 61.7


134.5 8.08 6.15


0.306 4.91


▶ ALL ABOUT FEED | Volume 29, No. 8, 2021 Rosehip meal


109 1.91 96.1 61.0


124.3 9.58 6.05


0.288 5.00


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